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- Copyright
- © Society of Behavioral Medicine 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
- ISSN
- 0883-6612
- eISSN
- 1532-4796
- DOI
- 10.1093/abm/kax062
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- See Article on Publisher Site
Abstract
Abstract Background Greater marital quality is associated with better psychological and physical health. The quality of daily marital interactions is likely to be especially important for individuals with chronic illness, but this question has received little attention. Purpose Using data from two diary studies, the current study examined whether individuals with chronic illness would experience more severe symptoms on days with more marital tension due in part to greater negative affect on those days. Methods The samples included individuals with knee osteoarthritis (OA, N = 145) or type 2 diabetes mellitus (T2DM, N = 129) and their spouses. Participants reported on daily marital interaction quality, affect, and symptom severity (patients only) for 22 days (knee OA) or 24 days (T2DM). Separate multilevel models were run for patients and spouses, controlling for the partner’s marital tension and negative affect as well as both partners’ daily marital enjoyment and positive affect. We examined same-day and across-day associations. Results For individuals with T2DM or knee OA, more severe symptoms on days with more marital tension were due in part to their greater negative affect on those days. Individuals with knee OA who experienced more pain had more negative affect and marital tension the next day. Conclusions Negative marital interactions may exacerbate physical symptoms. Effects of daily marital tension likely accumulate over time and have long-term implications for health. chronic illness, couples, daily interactions, symptom severity Introduction There is compelling evidence that individuals who report a higher level of marital quality also experience better psychological and physical health [1, 2]. The quality of daily marital interactions is likely to be especially important for individuals living with chronic illness, but this question has received much less research attention. The present study focused on two illness contexts—knee osteoarthritis (OA) and type 2 diabetes mellitus (T2DM). Using data from daily diary studies, we first examined day-to-day variability in daily marital tension, enjoyment, and affect as reported by each partner as well as in patient symptom severity. Second, we tested the hypothesis that patients would experience more severe illness symptoms on days with higher levels of daily marital tension due in part to greater negative affect on those days. The perception of high marital quality—often defined as a subjective, global evaluation of the relationship [3]—is predictive of future physical health. In several conceptual frameworks, researchers propose that marital quality affects a range of health outcomes including subjective clinical endpoints (e.g., self-rated health and symptoms) and objective clinical endpoints (e.g., functional status and mortality) [2, 4, 5]. A recent meta-analysis examined the evidence for these links between marital quality and health, based on data from 126 studies of couples who were healthy or living with chronic illness [2]. This review showed small but consistent associations of greater marital quality with lower risk of mortality and less cardiovascular reactivity during marital conflict. Individuals who experienced greater marital quality also reported better self-rated health and fewer physical symptoms with the exception of pain severity. An important and growing area of research that was not examined in the review of Robles and colleagues focuses on daily marital interactions and health. In this type of study, data from the repeated assessment of daily experiences over multiple days or weeks are used to examine associations within persons (WP) or within couples. Most previous research on marriage and health has focused on the differences between individuals or couples, which can mask variation that occurs within an individual’s or a couple’s day-to-day experience. The focus on couples’ experiences as they go about their daily lives also yields data with high ecological validity, and assessment of events close in time to their occurrence reduces bias due to errors in memory. A small body of work on healthy couples has examined links between daily marital interactions and health. Findings from these two studies show that health is better on days when marital interactions are of better quality. In one study, higher quality marital interactions (more positive, less negative) as reported by wives were associated with husbands’ better sleep efficiency that night, and husbands who had better sleep efficiency reported less negative marital interactions the next day [6]. In a second study, married individuals had lower cortisol levels, an indicator of less stress, on days when they experienced greater physical intimacy [7]. Day-to-day fluctuations in the quality of marital interactions may have implications for other daily indicators of health, such as the severity of physical symptoms, and therefore be especially important for those living with a chronic illness [8]. This association may reflect that patients’ symptoms are exacerbated on days with more negative marital interactions. Alternatively, the quality of marital interactions may be reduced on days when patients experience more severe symptoms. Both of these possibilities suggest that it is important to examine bidirectional associations and to assess marital interaction quality from the perspective of the spouse as well as the patient. The potential connection between daily illness symptoms and marital interactions has received little attention. A study of married individuals with diabetes and arthritis did not find that patients’ daily symptom severity was related to marital quality on the same day [9]. However, this study focused only on spouse reports of marital quality and was limited by a small sample size (N = 27). Research focused on couples’ daily lives can also lead to a better understanding of mechanisms underlying connections between marital interactions and health. In the conceptual frameworks of marriage and health described above, affective processes are specified as one pathway linking marital quality with subjective clinical endpoints such as symptoms [2, 7]. This is supported by research showing that daily mood fluctuates with perceived changes in relationship quality [10]. Given the known links between negative affect and poorer health [11, 12], including heightened pain perceptions [13], daily negative affect is a strong candidate as a mechanism in the association between daily marital interaction quality and symptom severity. In the current study, we conducted secondary analyses of data from two daily diary studies to examine indirect effects of daily marital interactions on patients’ health through patients’ and spouses’ daily negative affect. The two chronic illnesses that were the focus of this study—knee OA and T2DM—are among the five most common and costly adult illnesses in the USA [14]. The cardinal symptom of knee OA is pain, whereas common symptoms of T2DM are fatigue, excessive thirst, and excessive urination. More severe symptoms from these conditions add to patients’ emotional distress and functional impairment, as well as health care costs [15]. Thus, it is critical to identify interpersonal factors associated with greater severity of symptoms. In terms of marital interactions, our focus was daily marital tension. Negative interactions with close family members are often more powerful predictors of health than are positive interactions, but it is important to account for the effects of both factors [16, 17]. Therefore, we controlled for marital enjoyment in our analyses. Our first aim was to compare, within each sample, average levels and day-to-day (i.e., WP) variability in marital tension, enjoyment, and affect reported by patients and spouses. We also examined day-to-day variability in patients’ reports of daily symptom severity. Previous research on healthy couples did not find differences in partners’ levels of daily positive and negative marital functioning [6], but it is not known whether this is true for chronic illness populations, or the extent to which symptom severity and perceptions of daily marital interactions vary from day to day. These analyses were exploratory and conducted for the purpose of interpreting findings within each sample. The second aim of this study was to test the hypothesis that daily marital tension would be indirectly associated with greater symptom severity through negative affect, within each sample. Specifically, we expected that on days when marital tension was higher than usual, negative affect would also be greater and that negative affect would in turn be related to more severe illness symptoms for patients (i.e., greater arthritis pain or more severe diabetes symptoms). This hypothesis was tested separately for patients and spouses, controlling for the partner’s marital tension and negative affect as well as both partners’ daily marital enjoyment and positive affect. We examined same-day associations as well as bidirectional associations across days (i.e., effects of daily marital interactions on next-day symptom severity, and vice versa). This study is an extension of work published by Iida and colleagues [18] that focused solely on the T2DM sample and did not examine indirect effects of daily marital tension on patient symptom severity or bidirectional, across-day associations. Methods Sample 1: Individuals With Knee OA and Their Spouses Participants included 145 adults and their spouses. To be eligible for the study, patients had to be diagnosed with knee OA by a physician, experience usual knee pain of moderate or greater intensity, be at least 50 years of age, and be married or in a long-term relationship (self-defined) in which they shared a residence with their partner. Exclusion criteria were also applied [19]. Patients were excluded if they had a comorbid diagnosis of fibromyalgia or rheumatoid arthritis because these conditions differ from OA in their causes, symptoms, and treatments. Patients and spouses were excluded if they used a wheelchair because the larger study included an assessment of daily physical activity using accelerometry. In addition, patients were excluded if they planned to have hip or knee surgery within the following 6 months because the larger study examined long-term change in patient functioning and surgical intervention would have been a confounding factor. Spouses were excluded from the study if they had arthritis pain of moderate or greater intensity or required assistance with personal care activities. These criteria helped us to ensure that even if both partners experienced OA, one of them had more severe symptoms and required more assistance with daily activities (i.e., the “patient”) than the other (i.e., the spouse). Primary sources of recruitment were research registries for rheumatology clinic patients and older adults interested in research, flyers distributed to the University of Pittsburgh staff and faculty, and word of mouth. A total of 606 couples were screened for eligibility. Of these, 221 couples declined to participate, and the most frequent reasons were lack of interest (n = 87) or illness in the family (n = 55). A total of 233 couples were not eligible, and the most frequent reasons were lack of OA in the knee (n = 55) or knee OA pain that was mild (n = 47). The total enrolled sample comprised 152 couples (i.e., 304 individuals) which included three same-sex couples. A total of 145 couples completed the diary assessment component of the study. Procedure The larger study combined three in-person interviews conducted over an 18-month period with a 22-day assessment of daily experiences immediately after the T1 interview, and included measurement of daily physical activity using accelerometry. The 22-day assessment period was chosen in order to provide adequate statistical power to capture variability at WP and between-person (BP) levels of analysis. During the daily assessment protocol, patients and spouses used a handheld computer to answer questions three times per day [i.e., beginning of day, afternoon, and end of day (EOD)]. The current report utilizes data from the T1 interviews and EOD assessments of marital quality and pain severity, as well as three daily assessments of affect. Of a potential 6,380 daily observations (290 individuals × 22 days), a total of 5,855 beginning of day (92 per cent), 5,803 afternoon (91 per cent), and 5,875 EOD (92 per cent) assessments were completed. Timing of the EOD assessment was evaluated by comparing the time of the handheld computer entries with participants’ written log of daily bedtimes. EOD assessments that were completed >120 min before bedtime were excluded from analysis in order to ensure that participants were reporting on marital interactions and symptom severity from the entire day. Using these criteria, 5,317 of the 5,875 completed observations were included in analysis (i.e., 91 per cent of the completed observations or 83 per cent of the total possible observations). Measures During the T1 interview, data were collected on patient age, gender, race, education, employment status, body mass index, years married, marital satisfaction, years since knee OA diagnosis, and OA severity. Patients’ knee OA severity was measured by the Western Ontario McMaster Universities Index (WOMAC), and items were summed to create a total score with a possible range of 0 to 96 (M = 34.77; SD = 14.64; α = 0.94) [20]. Overall marital satisfaction was assessed using the 10-item satisfaction subscale of the Dyadic Adjustment Scale, with a possible range of 0 to 50 (α = 0.89) [21]. Average marital satisfaction was 39.69 (SD = 6.28) and 39.09 (SD = 6.51) for patients and spouses, respectively. Daily marital tension and enjoyment At the end of the day, both patients and spouses reported how tense and how enjoyable their interactions were with their spouse throughout the day on a scale from 1 to 3 (not at all, to very much). These items were taken from previous research [22]. Average tension was 1.21 (SD = 0.27) and 1.24 (SD = 0.28), and average enjoyment was 2.43 (SD = 0.45) and 2.42 (SD = 0.41) for patients and spouses, respectively. Daily negative and positive affect Both patients and spouses reported their negative and positive affect over the past 30 min at the beginning of day, afternoon, and EOD. These three assessments were averaged to create a daily affect score for each participant. A total of nine items were rated on a 7-point scale (0 = not at all; 6 = extremely) [23]. Five items (i.e., depressed or blue, frustrated, angry or hostile, unhappy, and worried or anxious) were averaged to create a mean score of negative affect that day (α = 0.89 and α = 0.90 for patients and spouses, respectively), and four items (i.e., happy, joyful, pleased, and enjoyment) were averaged to create a mean score of positive affect that day (α = 0.94 and α = 0.94 for patients and spouses, respectively). These items were adapted from previous daily diary research [23]. Average daily negative affect was 0.53 (SD = 0.62) and 0.47 (SD = 0.61), and average daily positive affect was 2.74 (SD = 1.26) and 2.55 (SD = 1.21) for patients and spouses, respectively. Daily symptom severity At the end of the day, patients reported their overall arthritis pain throughout the day on a scale from 0 to 3 (not at all to severe). The average level of pain was 1.51 (SD = 0.51) for the sample. This question was taken from the Arthritis Impact Measurement Scales (AIMS2) [24]. Sample 2: Individuals with T2DM and Their Spouses Participants included 129 adults with T2DM and their spouses. Brochures describing the study were placed in medical offices, diabetes education clinics, and senior citizen centers, and advertisements were published or broadcasted in commercial media. To be eligible, patients had to have a primary medical diagnosis of T2DM, be at least 55 years of age and in a marriage or marriage-like relationship (self-defined), reside in the community, and have received in the previous 3 months a recommendation from a health care provider to make dietary improvements. Eligibility criteria for spouses included living in the same household as the patient, being the primary person to assist the patient with diabetes care, and not being diagnosed with diabetes. A total of 235 couples was screened for eligibility. Fifty-eight couples were not eligible because the spouse had diabetes (n = 17), the patient was younger than 55 years of age (n = 12), the patient was not currently married or in a marriage-like relationship (n = 11), or the patient was not diagnosed with T2DM (n = 9). After initial contact, some eligible couples could not be reached (n = 17) or subsequently declined to participate (n = 31), primarily due to lack of time or interest. The sample was comprised of 129 couples. Procedure Participants completed diaries every evening between 08:00 pm and 11:59 pm for 24 consecutive days on a laptop computer. Each daily record was time and date specific and could only be accessed during this 4-hr window. Of the potential 6,192 (258 individuals × 24 days) diary records, 97.3 per cent (6,025) were completed. The current report utilizes data from the T1 interviews and evening assessments of marital quality, affect, and diabetes symptom severity. Measures During the T1 interview, data were collected on patient age, gender, race, education, employment status, body mass index, years married, marital satisfaction, years since T2DM diagnosis, and diabetes severity. Patients’ diabetes severity was measured with the Diabetes Impact Measurement Scale [25]. Patients indicated the frequency or intensity of five symptoms (e.g., excessive urination, numbness, or tingling in feet or hands) on a 6-point scale ranging from 1 (never/no discomfort) to 6 (always/unbearable), and items were averaged to create a mean score for symptom severity (α = 0.64). Average diabetes severity was 2.17 (SD = 0.75). Overall marital satisfaction was assessed using the 5-item Quality Marriage Index [26], with a possible range of 5 to 35 (α = 0.88). Average marital satisfaction was 32.53 (SD = 2.98) and 31.57 (SD = 4.51) for patients and spouses, respectively. Daily marital tension and enjoyment. At the end of the day, both patients and spouses reported how tense and how enjoyable their interactions were with their spouse throughout the day on a scale from 0 to 10 (not at all, to as tense/enjoyable as they could possibly be). These items were taken from previous research [22]. Average tension was 2.04 (SD = 1.70) and 2.21 (SD = 1.57), and average enjoyment was 8.20 (SD = 1.44) and 8.10 (SD = 1.63) for patients and spouses, respectively. Daily negative and positive affect. At the end of the day, both patients and spouses reported their current negative and positive affect [27]. Eleven items were rated on a 5-point scale (1 = not at all; 5 = extremely). Six items (i.e., distressed, upset, scared, nervous, afraid, and guilty) were averaged to create a mean score of negative affect (α = 0.94 and α = 0.93 for patients and spouses, respectively), and five items (i.e., excited, enthusiastic, alert, inspired, and active) were averaged to create a mean score of positive affect (α = 0.96 and α = 0.95 for patients and spouses, respectively). These items were taken from the Positive and Negative Affect Schedule [27]. Average negative affect was 1.24 (SD = 0.32) and 1.14 (SD = 0.27) and average positive affect was 2.38 (SD = 0.83) and 2.57 (SD = 0.81) for patients and spouses, respectively. Daily symptom severity. Each evening, patients reported the severity of their diabetes symptoms that day on a scale from 0 = not severe at all to 10 = as severe as they could possibly be. This item was created to capture patients’ global assessment of symptom severity in a format that could be administered daily. Average daily symptom severity was 1.51 (SD = 1.57). Data Analysis Across the two studies, identical questions were used to assess daily marital interaction quality, and similar questions were used to assess affect and patient symptom severity. However, the T2DM study used a wider range of response options than the knee OA study for marital interaction quality and symptom severity (e.g., 1 to 10 vs. 0 to 3) and thus was better able to capture day-to-day (i.e., WP) variability. Therefore, we tested our hypothesis regarding indirect effects in each sample separately and noted similar or dissimilar patterns of findings, rather than aggregating data or comparing the strength of effects across samples. Data were analyzed with multilevel modeling using SAS PROC MIXED [28, 29]. The data were structured hierarchically with daily assessments (Level 1) nested WP (Level 2). Full maximum likelihood was used for model estimation and robust standard errors were used for fixed effects hypothesis testing. In addition, the interdependence of the outcome assessments WP was accounted for by using an autoregressive (AR) covariance structure for residual errors in all models [1]. All Level 1 predictors and covariates were centered relative to each person’s mean score in order to remove BP variance in these scores, and Level 2 covariates were grand-mean centered. In order to examine day-to-day (i.e., WP) variability in marital interaction quality and patient symptom severity, null models were first tested to examine WP and BP variance in these variables. Second, heterogeneous variance multilevel models [30, 31] were used to assess whether the magnitude of WP variability in marital tension, enjoyment, and affect statistically differed for patients and spouses in each chronic illness sample. Specifically, the chi-square difference test was used to compare the deviance of the heterogeneous WP variance model with the deviance of the homogeneous WP variance model. We controlled for patient gender in these models. We used mediation-multilevel models (M-MLMs) to examine the indirect effects of daily marital tension on symptom severity through negative affect on the same day in each chronic illness sample. Specifically, two M-MLMs were estimated for each sample to assess the following: (a) the indirect effect of patients’ daily marital tension on symptom severity through their negative affect controlling for patients’ daily marital enjoyment and positive affect and (b) the indirect effect of spouses’ daily marital tension on patients’ symptom severity through spouses’ negative affect controlling for spouses’ daily marital enjoyment and positive affect. Other covariates in each M-MLM included partners’ daily marital enjoyment and tension and day of study (Level 1); patients’ age, race, gender, years married, illness duration, and illness severity; and overall marital satisfaction of both partners (Level 2). We evaluated the M-MLMs using multivariate analysis in SAS [32, 33]. This approach combines the outcome variable and the mediator into a single stacked response variable and runs one mixed model to simultaneously obtain all of the values needed for assessing the indirect effect in mediation models: the effect of predictor on mediator (path a; i.e., marital tension on negative affect); the effect of mediator on outcome (path b; i.e., negative affect on symptom severity); the direct effect of predictor on outcome (path c; i.e., marital tension on symptom severity); and the asymptotic variances and covariance of these effects. To test the significance of each separate indirect pathway in the multilevel mediation model, we applied the Monte Carlo bootstrapping method for estimating the confidence intervals (CIs) for each indirect pathway [34]. This procedure was repeated a large number of times (i.e., 20,000), and the resulting distribution of the indirect effect (i.e., a × b) was used to estimate a 95 per cent confidence interval around the observed value of a × b. An indirect effect was interpreted as statistically significant if the CI did not include 0. In addition to the same-day analyses, we examined bidirectional, across-day effects in order to test whether marital tension (or symptom severity) had direct and indirect effects on symptom severity (or marital tension) the following day. Using two sets of M-MLMs, we tested the effects of lagged marital tension (day t-1) on symptom severity (day t) through negative affect (day t), and the reversed indirect effect of lagged symptom severity (day t-1) on marital tension (day t) through negative affect (day t). Each M-MLM also controlled for the concurrent effects of the predictor (e.g., marital tension on day t) and other covariates from the same-day models. Results Table 1 displays demographic characteristics of participants in each sample. Individuals with knee OA were 65.70 years of age on average (SD = 9.86), primarily Caucasian (87 per cent), and the majority was women (57 per cent). On average, these patients had been married for 34 years (SD = 16.69). The average knee OA severity score was 34.77 (SD = 14.64), indicating mild-to-moderate severity for the sample. Table 1 Background Information for Patients and Spouses Variables Knee OA sample T2DM sample Patient Spouse Patient Spouse M or % SD M or % SD M or % SD M or % SD Gender: male 42.76% 57.93% 49.61% 50.39% Age (years) 65.70 9.86 65.43 11.51 66.05 7.71 66.07 8.76 Race: White 86.90% 85.52% 74.42% 76.56% Education (years) 16.06 2.01 15.84 2.06 13.78 2.42 13.81 2.38 Employed 42.07% 45.52% 24.81% 37.21% Marital duration (years) 34.42 16.69 37.90 13.81 Marital satisfaction 39.69 6.28 39.09 6.51 32.53 2.98 31.57 4.51 Body mass index 31.34 5.94 31.16 7.49 Illness duration (years) 16.42 12.70 11.73 9.41 Illness severity 34.77 14.64 2.17 0.75 Variables Knee OA sample T2DM sample Patient Spouse Patient Spouse M or % SD M or % SD M or % SD M or % SD Gender: male 42.76% 57.93% 49.61% 50.39% Age (years) 65.70 9.86 65.43 11.51 66.05 7.71 66.07 8.76 Race: White 86.90% 85.52% 74.42% 76.56% Education (years) 16.06 2.01 15.84 2.06 13.78 2.42 13.81 2.38 Employed 42.07% 45.52% 24.81% 37.21% Marital duration (years) 34.42 16.69 37.90 13.81 Marital satisfaction 39.69 6.28 39.09 6.51 32.53 2.98 31.57 4.51 Body mass index 31.34 5.94 31.16 7.49 Illness duration (years) 16.42 12.70 11.73 9.41 Illness severity 34.77 14.64 2.17 0.75 OA Osteoarthritis; T2DM type 2 diabetes mellitus. N = 145 couples for knee OA sample, N = 129 couples for T2DM sample. View Large Table 1 Background Information for Patients and Spouses Variables Knee OA sample T2DM sample Patient Spouse Patient Spouse M or % SD M or % SD M or % SD M or % SD Gender: male 42.76% 57.93% 49.61% 50.39% Age (years) 65.70 9.86 65.43 11.51 66.05 7.71 66.07 8.76 Race: White 86.90% 85.52% 74.42% 76.56% Education (years) 16.06 2.01 15.84 2.06 13.78 2.42 13.81 2.38 Employed 42.07% 45.52% 24.81% 37.21% Marital duration (years) 34.42 16.69 37.90 13.81 Marital satisfaction 39.69 6.28 39.09 6.51 32.53 2.98 31.57 4.51 Body mass index 31.34 5.94 31.16 7.49 Illness duration (years) 16.42 12.70 11.73 9.41 Illness severity 34.77 14.64 2.17 0.75 Variables Knee OA sample T2DM sample Patient Spouse Patient Spouse M or % SD M or % SD M or % SD M or % SD Gender: male 42.76% 57.93% 49.61% 50.39% Age (years) 65.70 9.86 65.43 11.51 66.05 7.71 66.07 8.76 Race: White 86.90% 85.52% 74.42% 76.56% Education (years) 16.06 2.01 15.84 2.06 13.78 2.42 13.81 2.38 Employed 42.07% 45.52% 24.81% 37.21% Marital duration (years) 34.42 16.69 37.90 13.81 Marital satisfaction 39.69 6.28 39.09 6.51 32.53 2.98 31.57 4.51 Body mass index 31.34 5.94 31.16 7.49 Illness duration (years) 16.42 12.70 11.73 9.41 Illness severity 34.77 14.64 2.17 0.75 OA Osteoarthritis; T2DM type 2 diabetes mellitus. N = 145 couples for knee OA sample, N = 129 couples for T2DM sample. View Large Individuals with T2DM were 66.05 years of age on average (SD = 7.71), primarily Caucasian (74 per cent), and 50 per cent were women. On average, these patients had been married for 38 years (SD = 13.81). The average diabetes severity score was 2.17 (SD = 0.75), indicating a mild degree of severity for the sample. Approximately 19 per cent of individuals from the knee OA sample reported also having either type 1 or type 2 diabetes. A total of 14 per cent of individuals from the T2DM sample reported also having rheumatoid arthritis, lupus, or polymyalgia rheumatica. Individuals in the T2DM sample were not asked whether or not they have OA. Day-to-Day Variability in Marital Interaction Quality, Affect, and Patient Symptom Severity Table 2 provides information for key study variables in the two samples. On average, patients and spouses in both samples reported low levels of marital tension and negative affect and high levels of marital enjoyment and positive affect. Consistent with previous research (e.g., 6), patients and spouses in both samples did not differ in average levels of daily marital tension and enjoyment. Spouses of individuals with T2DM had higher positive affect (t = −2.11, p < .05) and lower negative affect (t = 3.10, p < .01) than did patients, and there were no differences in average affect between patients and spouses in the knee OA sample. Average daily symptom severity was mild in the T2DM sample and mild to moderate in the knee OA sample. Table 2 Descriptive Information for Study Variables Knee OA patients Knee OA spouses M SD Range WP variance% M SD Range WP variance% Paired- t Tension 1.21 0.27 1–3 69% 1.24 0.28 1–3 67% −0.85 Enjoy 2.43 0.45 1–3 47% 2.42 0.41 1–3 52% 0.23 PA 2.74 1.26 0–6 23% 2.55 1.21 0–6 21% 1.43 NA 0.53 0.62 0–6 32% 0.47 0.61 0–6 34% 0.81 Symptom severity 1.51 0.51 0–3 45% T2DM patients T2DM spouses Tension 2.04 1.70 0–10 68%a 2.21 1.57 0–10 74%a −0.97 Enjoy 8.20 1.44 0–10 59%a 8.10 1.63 0–10 46%a 0.68 PA 2.38 0.83 1–5 30%a 2.57 0.81 1–5 33%a −2.11* NA 1.24 0.32 1–5 59%a 1.14 0.27 1–5 47%a 3.10** Symptom severity 1.51 1.57 0–10 58% Knee OA patients Knee OA spouses M SD Range WP variance% M SD Range WP variance% Paired- t Tension 1.21 0.27 1–3 69% 1.24 0.28 1–3 67% −0.85 Enjoy 2.43 0.45 1–3 47% 2.42 0.41 1–3 52% 0.23 PA 2.74 1.26 0–6 23% 2.55 1.21 0–6 21% 1.43 NA 0.53 0.62 0–6 32% 0.47 0.61 0–6 34% 0.81 Symptom severity 1.51 0.51 0–3 45% T2DM patients T2DM spouses Tension 2.04 1.70 0–10 68%a 2.21 1.57 0–10 74%a −0.97 Enjoy 8.20 1.44 0–10 59%a 8.10 1.63 0–10 46%a 0.68 PA 2.38 0.83 1–5 30%a 2.57 0.81 1–5 33%a −2.11* NA 1.24 0.32 1–5 59%a 1.14 0.27 1–5 47%a 3.10** Symptom severity 1.51 1.57 0–10 58% N = 145 for knee OA patient and spouse sample, N = 129 couples for T2DM patient and spouse sample. OA osteoarthritis; T2DM type 2 diabetes mellitus; PA positive affect; NA negative affect; WP within-person. aWP variance from patients and spouses was significantly different (p < .05) as determined by heterogeneous variance multilevel modeling controlling for gender. *p ≤ .05; **p≤ .01. View Large Table 2 Descriptive Information for Study Variables Knee OA patients Knee OA spouses M SD Range WP variance% M SD Range WP variance% Paired- t Tension 1.21 0.27 1–3 69% 1.24 0.28 1–3 67% −0.85 Enjoy 2.43 0.45 1–3 47% 2.42 0.41 1–3 52% 0.23 PA 2.74 1.26 0–6 23% 2.55 1.21 0–6 21% 1.43 NA 0.53 0.62 0–6 32% 0.47 0.61 0–6 34% 0.81 Symptom severity 1.51 0.51 0–3 45% T2DM patients T2DM spouses Tension 2.04 1.70 0–10 68%a 2.21 1.57 0–10 74%a −0.97 Enjoy 8.20 1.44 0–10 59%a 8.10 1.63 0–10 46%a 0.68 PA 2.38 0.83 1–5 30%a 2.57 0.81 1–5 33%a −2.11* NA 1.24 0.32 1–5 59%a 1.14 0.27 1–5 47%a 3.10** Symptom severity 1.51 1.57 0–10 58% Knee OA patients Knee OA spouses M SD Range WP variance% M SD Range WP variance% Paired- t Tension 1.21 0.27 1–3 69% 1.24 0.28 1–3 67% −0.85 Enjoy 2.43 0.45 1–3 47% 2.42 0.41 1–3 52% 0.23 PA 2.74 1.26 0–6 23% 2.55 1.21 0–6 21% 1.43 NA 0.53 0.62 0–6 32% 0.47 0.61 0–6 34% 0.81 Symptom severity 1.51 0.51 0–3 45% T2DM patients T2DM spouses Tension 2.04 1.70 0–10 68%a 2.21 1.57 0–10 74%a −0.97 Enjoy 8.20 1.44 0–10 59%a 8.10 1.63 0–10 46%a 0.68 PA 2.38 0.83 1–5 30%a 2.57 0.81 1–5 33%a −2.11* NA 1.24 0.32 1–5 59%a 1.14 0.27 1–5 47%a 3.10** Symptom severity 1.51 1.57 0–10 58% N = 145 for knee OA patient and spouse sample, N = 129 couples for T2DM patient and spouse sample. OA osteoarthritis; T2DM type 2 diabetes mellitus; PA positive affect; NA negative affect; WP within-person. aWP variance from patients and spouses was significantly different (p < .05) as determined by heterogeneous variance multilevel modeling controlling for gender. *p ≤ .05; **p≤ .01. View Large The amount of WP variability in study variables ranged from 21 to 74 per cent. In both samples, approximately half of the variability in patient symptom severity was within persons (i.e., 58 per cent in T2DM and 45 per cent in knee OA), indicating sufficient day-to-day variability for testing study hypotheses. Consistent with previous daily diary research, there was less WP variability in positive affect than in negative affect, in both samples [35]. Results from the heterogeneous variance multilevel models controlling for gender indicated that in the knee OA sample, patients and spouses did not differ in their day-to-day variability in marital enjoyment, tension, or affect. In the T2DM sample, spouses showed more variability in marital tension (χ2 (1) = 6.60, p ≤ .05) and less variability in marital enjoyment (χ2 (1) = 45.20, p ≤ .001) than did patients. Spouses in the T2DM sample also showed more variability in positive affect (χ2 (1) = 4.00, p ≤ .05) and less variability in negative affect (χ2 (1) = 397.60, p ≤ .001) than did patients. Table 3 displays WP, zero-order correlations between key study variables, with correlations above the diagonal for the T2DM sample and correlations below the diagonal for the knee OA sample. In T2DM, daily marital tension and enjoyment were correlated with patient symptom severity in the expected direction, for patients (r = .11 and −.09, p ≤ .001, respectively) and spouses (r = .08, p ≤ .001 and r = −.06, p ≤ .01, respectively). In knee OA, only patients’ reports of daily marital tension were associated with symptom severity (r = .04, p ≤ .05). Table 3 Within-Person Correlations for Study Variables in Two Samples Tensionpt Enjoypt PApt NApt Symptom severitypt Tensionsp Enjoysp PAsp NAsp Tensionpt – −0.23*** −0.12*** 0.15*** 0.11*** 0.15*** −0.17*** −0.05** 0.11*** Enjoypt −0.33*** – 0.11*** −0.19*** −0.09*** −0.13*** 0.21*** 0.07*** −0.08*** PApt −0.13*** −.23*** – −0.18*** −0.09*** −0.07*** 0.08*** 0.12*** 0.00 NApt 0.20*** −0.20*** −0.44*** – 0.16*** 0.06*** −0.10*** −0.06*** 0.16*** Symptom severitypt 0.04* −0.00 −0.03 0.08*** – 0.08*** −0.06** −0.03 0.03**** Tensionsp 0.29** −0.15* −0.08*** 0.12*** 0.02 – −0.23*** −0.12*** 0.17*** Enjoysp −0.15* 0.13* 0.09*** −0.08*** −0.02 −0.18** – 0.13*** −0.24*** PAsp −0.09*** 0.09*** 0.18*** −0.07*** 0.03 −0.11*** 0.19*** – −0.16*** Nasp 0.12*** −0.08*** −0.07*** 0.11*** 0.01 0.24*** −0.17*** −0.37*** – Tensionpt Enjoypt PApt NApt Symptom severitypt Tensionsp Enjoysp PAsp NAsp Tensionpt – −0.23*** −0.12*** 0.15*** 0.11*** 0.15*** −0.17*** −0.05** 0.11*** Enjoypt −0.33*** – 0.11*** −0.19*** −0.09*** −0.13*** 0.21*** 0.07*** −0.08*** PApt −0.13*** −.23*** – −0.18*** −0.09*** −0.07*** 0.08*** 0.12*** 0.00 NApt 0.20*** −0.20*** −0.44*** – 0.16*** 0.06*** −0.10*** −0.06*** 0.16*** Symptom severitypt 0.04* −0.00 −0.03 0.08*** – 0.08*** −0.06** −0.03 0.03**** Tensionsp 0.29** −0.15* −0.08*** 0.12*** 0.02 – −0.23*** −0.12*** 0.17*** Enjoysp −0.15* 0.13* 0.09*** −0.08*** −0.02 −0.18** – 0.13*** −0.24*** PAsp −0.09*** 0.09*** 0.18*** −0.07*** 0.03 −0.11*** 0.19*** – −0.16*** Nasp 0.12*** −0.08*** −0.07*** 0.11*** 0.01 0.24*** −0.17*** −0.37*** – Within-person correlations for type 2 diabetes mellitus sample are above the diagonal, and within-person correlations for knee osteoarthritis sample are below the diagonal. pt patient; sp spouse; PA positive affect; NA negative affect. *p ≤ .05; **p ≤ .01; ***p ≤ .001; ****p ≤ .10. View Large Table 3 Within-Person Correlations for Study Variables in Two Samples Tensionpt Enjoypt PApt NApt Symptom severitypt Tensionsp Enjoysp PAsp NAsp Tensionpt – −0.23*** −0.12*** 0.15*** 0.11*** 0.15*** −0.17*** −0.05** 0.11*** Enjoypt −0.33*** – 0.11*** −0.19*** −0.09*** −0.13*** 0.21*** 0.07*** −0.08*** PApt −0.13*** −.23*** – −0.18*** −0.09*** −0.07*** 0.08*** 0.12*** 0.00 NApt 0.20*** −0.20*** −0.44*** – 0.16*** 0.06*** −0.10*** −0.06*** 0.16*** Symptom severitypt 0.04* −0.00 −0.03 0.08*** – 0.08*** −0.06** −0.03 0.03**** Tensionsp 0.29** −0.15* −0.08*** 0.12*** 0.02 – −0.23*** −0.12*** 0.17*** Enjoysp −0.15* 0.13* 0.09*** −0.08*** −0.02 −0.18** – 0.13*** −0.24*** PAsp −0.09*** 0.09*** 0.18*** −0.07*** 0.03 −0.11*** 0.19*** – −0.16*** Nasp 0.12*** −0.08*** −0.07*** 0.11*** 0.01 0.24*** −0.17*** −0.37*** – Tensionpt Enjoypt PApt NApt Symptom severitypt Tensionsp Enjoysp PAsp NAsp Tensionpt – −0.23*** −0.12*** 0.15*** 0.11*** 0.15*** −0.17*** −0.05** 0.11*** Enjoypt −0.33*** – 0.11*** −0.19*** −0.09*** −0.13*** 0.21*** 0.07*** −0.08*** PApt −0.13*** −.23*** – −0.18*** −0.09*** −0.07*** 0.08*** 0.12*** 0.00 NApt 0.20*** −0.20*** −0.44*** – 0.16*** 0.06*** −0.10*** −0.06*** 0.16*** Symptom severitypt 0.04* −0.00 −0.03 0.08*** – 0.08*** −0.06** −0.03 0.03**** Tensionsp 0.29** −0.15* −0.08*** 0.12*** 0.02 – −0.23*** −0.12*** 0.17*** Enjoysp −0.15* 0.13* 0.09*** −0.08*** −0.02 −0.18** – 0.13*** −0.24*** PAsp −0.09*** 0.09*** 0.18*** −0.07*** 0.03 −0.11*** 0.19*** – −0.16*** Nasp 0.12*** −0.08*** −0.07*** 0.11*** 0.01 0.24*** −0.17*** −0.37*** – Within-person correlations for type 2 diabetes mellitus sample are above the diagonal, and within-person correlations for knee osteoarthritis sample are below the diagonal. pt patient; sp spouse; PA positive affect; NA negative affect. *p ≤ .05; **p ≤ .01; ***p ≤ .001; ****p ≤ .10. View Large Indirect Effects of Daily Marital Tension on Symptom Severity Through Negative Affect The second aim of our study was to test the hypothesis that experiencing more tension during marital interactions would be associated with patients’ greater symptom severity, and that these effects would occur indirectly through higher negative affect. This hypothesis was tested with patient and spouse reports. Analyses controlled for marital enjoyment and positive affect, partners’ tension and enjoyment, patient demographics, illness duration and severity, overall marital satisfaction of both partners, and day of study. Table 4 displays the effect of the predictor on mediator (path a), the effect of the mediator on outcome (path b), the direct effect of the predictor on the outcome (path c), and any statistically significant indirect effect (a × b) with 95 per cent confidence interval (p ≤ .05). Findings are organized by same-day analyses and cross-day analyses. Table 4 Mediation Findings for Knee OA Sample and T2DM Sample Mediation effect IV→M→DV a (IV→M) b (M→DV) Direct effect (cʹ) Indirect effect (a*b) Est. SE Est. SE Est. SE Est. 95% CI Same-day analyses OA sample Patient tension → patient NA → patient symptom severity 0.13 0.04*** 0.07 0.03* 0.03 0.03 0.01 [0.001,0.021] Spouse tension → spouse NA → patient symptom severity 0.15 0.03*** 0.03 0.03 −0.02 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.01 0.004*** 0.64 0.13*** 0.05 0.02* 0.01 [0.003,0.014] Spouse tension → spouse NA → patient symptom severity 0.01 0.003*** 0.05 0.20 0.03 0.02* – – Cross-day analyses: previous day’s tension → NA → symptom severity OA sample Patient tension → patient NA → patient symptom severity 0.002 0.03 0.08 0.03* 0.05 0.03 – – Spouse tension → spouse NA → patient symptom severity 0.02 0.03 0.03 0.03 −0.004 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.003 0.003 0.69 0.15*** 0.01 0.02 – – Spouse tension → spouse NA → patient symptom severity −0.002 0.001 0.78 0.15*** 0.02 0.01 – – Cross-day analyses: previous day’s symptom severity → NA → tension OA sample Patient symptom severity → patient NA → patient tension 0.06 0.01** 0.10 0.002** −0.03 0.02 0.01 [0.001,0.012] Patient symptom severity → spouse NA → spouse tension 0.00 0.01 0.15 0.03*** −0.01 0.02 – – T2DM sample Patient symptom severity → patient NA → patient tension −0.003 0.01 0.51 0.18** −0.04 0.03 – – Patient symptom severity → spouse NA → spouse tension −0.003 0.004 1.31 0.27*** −0.003 0.02 – – Mediation effect IV→M→DV a (IV→M) b (M→DV) Direct effect (cʹ) Indirect effect (a*b) Est. SE Est. SE Est. SE Est. 95% CI Same-day analyses OA sample Patient tension → patient NA → patient symptom severity 0.13 0.04*** 0.07 0.03* 0.03 0.03 0.01 [0.001,0.021] Spouse tension → spouse NA → patient symptom severity 0.15 0.03*** 0.03 0.03 −0.02 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.01 0.004*** 0.64 0.13*** 0.05 0.02* 0.01 [0.003,0.014] Spouse tension → spouse NA → patient symptom severity 0.01 0.003*** 0.05 0.20 0.03 0.02* – – Cross-day analyses: previous day’s tension → NA → symptom severity OA sample Patient tension → patient NA → patient symptom severity 0.002 0.03 0.08 0.03* 0.05 0.03 – – Spouse tension → spouse NA → patient symptom severity 0.02 0.03 0.03 0.03 −0.004 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.003 0.003 0.69 0.15*** 0.01 0.02 – – Spouse tension → spouse NA → patient symptom severity −0.002 0.001 0.78 0.15*** 0.02 0.01 – – Cross-day analyses: previous day’s symptom severity → NA → tension OA sample Patient symptom severity → patient NA → patient tension 0.06 0.01** 0.10 0.002** −0.03 0.02 0.01 [0.001,0.012] Patient symptom severity → spouse NA → spouse tension 0.00 0.01 0.15 0.03*** −0.01 0.02 – – T2DM sample Patient symptom severity → patient NA → patient tension −0.003 0.01 0.51 0.18** −0.04 0.03 – – Patient symptom severity → spouse NA → spouse tension −0.003 0.004 1.31 0.27*** −0.003 0.02 – – OA osteoarthritis; T2DM type 2 diabetes mellitus. Only significant indirect effects are shown (p ≤ .05). Covariates included patient age, gender, race, years married, illness duration, illness severity; patients’ and spouses’ overall marital satisfaction, interaction enjoyment, and positive affect; and study day. *p ≤ .05; **p ≤ .01; ***p ≤ .001. View Large Table 4 Mediation Findings for Knee OA Sample and T2DM Sample Mediation effect IV→M→DV a (IV→M) b (M→DV) Direct effect (cʹ) Indirect effect (a*b) Est. SE Est. SE Est. SE Est. 95% CI Same-day analyses OA sample Patient tension → patient NA → patient symptom severity 0.13 0.04*** 0.07 0.03* 0.03 0.03 0.01 [0.001,0.021] Spouse tension → spouse NA → patient symptom severity 0.15 0.03*** 0.03 0.03 −0.02 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.01 0.004*** 0.64 0.13*** 0.05 0.02* 0.01 [0.003,0.014] Spouse tension → spouse NA → patient symptom severity 0.01 0.003*** 0.05 0.20 0.03 0.02* – – Cross-day analyses: previous day’s tension → NA → symptom severity OA sample Patient tension → patient NA → patient symptom severity 0.002 0.03 0.08 0.03* 0.05 0.03 – – Spouse tension → spouse NA → patient symptom severity 0.02 0.03 0.03 0.03 −0.004 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.003 0.003 0.69 0.15*** 0.01 0.02 – – Spouse tension → spouse NA → patient symptom severity −0.002 0.001 0.78 0.15*** 0.02 0.01 – – Cross-day analyses: previous day’s symptom severity → NA → tension OA sample Patient symptom severity → patient NA → patient tension 0.06 0.01** 0.10 0.002** −0.03 0.02 0.01 [0.001,0.012] Patient symptom severity → spouse NA → spouse tension 0.00 0.01 0.15 0.03*** −0.01 0.02 – – T2DM sample Patient symptom severity → patient NA → patient tension −0.003 0.01 0.51 0.18** −0.04 0.03 – – Patient symptom severity → spouse NA → spouse tension −0.003 0.004 1.31 0.27*** −0.003 0.02 – – Mediation effect IV→M→DV a (IV→M) b (M→DV) Direct effect (cʹ) Indirect effect (a*b) Est. SE Est. SE Est. SE Est. 95% CI Same-day analyses OA sample Patient tension → patient NA → patient symptom severity 0.13 0.04*** 0.07 0.03* 0.03 0.03 0.01 [0.001,0.021] Spouse tension → spouse NA → patient symptom severity 0.15 0.03*** 0.03 0.03 −0.02 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.01 0.004*** 0.64 0.13*** 0.05 0.02* 0.01 [0.003,0.014] Spouse tension → spouse NA → patient symptom severity 0.01 0.003*** 0.05 0.20 0.03 0.02* – – Cross-day analyses: previous day’s tension → NA → symptom severity OA sample Patient tension → patient NA → patient symptom severity 0.002 0.03 0.08 0.03* 0.05 0.03 – – Spouse tension → spouse NA → patient symptom severity 0.02 0.03 0.03 0.03 −0.004 0.03 – – T2DM sample Patient tension → patient NA → patient symptom severity 0.003 0.003 0.69 0.15*** 0.01 0.02 – – Spouse tension → spouse NA → patient symptom severity −0.002 0.001 0.78 0.15*** 0.02 0.01 – – Cross-day analyses: previous day’s symptom severity → NA → tension OA sample Patient symptom severity → patient NA → patient tension 0.06 0.01** 0.10 0.002** −0.03 0.02 0.01 [0.001,0.012] Patient symptom severity → spouse NA → spouse tension 0.00 0.01 0.15 0.03*** −0.01 0.02 – – T2DM sample Patient symptom severity → patient NA → patient tension −0.003 0.01 0.51 0.18** −0.04 0.03 – – Patient symptom severity → spouse NA → spouse tension −0.003 0.004 1.31 0.27*** −0.003 0.02 – – OA osteoarthritis; T2DM type 2 diabetes mellitus. Only significant indirect effects are shown (p ≤ .05). Covariates included patient age, gender, race, years married, illness duration, illness severity; patients’ and spouses’ overall marital satisfaction, interaction enjoyment, and positive affect; and study day. *p ≤ .05; **p ≤ .01; ***p ≤ .001. View Large Knee OA sample The top panel of Table 4 displays findings for individuals with knee OA and their spouses in the same-day analyses. The only significant covariate of daily pain severity in these models was baseline knee OA severity (b = 0.02, p ≤ .001, in both models). Results from the M-MLMs indicated that on days when patients reported more marital tension than usual, they also reported more negative affect (path a). Path b was also significant, indicating that patients’ pain was worse on days when patients reported more negative affect than usual. There was no direct effect of marital tension on symptom severity. Consistent with our hypothesis, the indirect effect was significant (estimate = 0.01, 95 per cent CI= 0.001–0.021), indicating that patients’ greater marital tension was associated with more negative affect that day which was in turn associated with more severe pain. Results from the M-MLMs for spouses of individuals with knee OA showed that on days when spouses reported more marital tension than usual, they also reported more negative affect. Path b and the direct effect were not significant, and there was no indirect effect of spouse tension on patients’ pain severity through spouses’ negative affect. The cross-day analyses of bidirectional lagged effects (bottom panel of Table 4) indicated that patients’ pain severity had a significant indirect effect on their marital tension the next day through their greater negative affect (estimate = 0.005, 95 per cent CI= 0.001–0.012). There were no other significant direct or indirect lagged effects. T2DM sample We also found support in the same-day analyses for our indirect effects hypothesis in the T2DM sample, for patients only (top panel of Table 4). Findings from the M-MLMs indicated that on days when patients reported more marital tension than usual, they also reported more negative affect (path a). In addition, patients’ negative affect was associated with greater symptom severity (path b) and the direct effect was significant. The significant indirect effect indicated that patients who reported greater marital tension also experienced more negative affect that day, which was in turn associated with more severe diabetes symptoms (estimate = 0.01, 95 per cent CI= 0.003–0.014). Significant covariates of diabetes symptom severity in this model were patients’ daily positive affect (b = −0.18, p ≤ .05), spouses’ daily tension (b = 0.03, p ≤ .05), patient race (i.e., White; b = 0.60, p ≤ .05), and overall diabetes severity (b = 0.79, p ≤ .001). Findings from the M-MLMs for spouses of individuals with T2DM showed that on days when spouses reported more marital tension than usual, they also reported more negative affect. In addition, the direct effect of marital tension on patients’ diabetes symptom severity was significant. However, there was no association between spouses’ daily negative affect and patient symptom severity, and therefore, the indirect effect was also not significant. Covariates of diabetes symptom severity were patients’ daily tension (b = 0.06, p ≤ .01), patient race (White; b = 0.61, p ≤ .05), and overall diabetes severity (b = 0.79, p ≤ .001). The cross-day analyses of bidirectional lagged effects indicated no significant direct or indirect effects across days. To summarize, there were both similarities and differences in the findings for T2DM and knee OA. In both illness samples, indirect effects of marital tension on patients’ same-day symptom severity through greater negative affect were found for patients but not spouses. In contrast, direct effects of marital tension on patients’ symptom severity were observed in T2DM but not in knee OA, for both patients and spouses. These direct effects are consistent with the correlational analyses and may reflect the greater day-to-day variability in symptom severity captured in the T2DM study (58 per cent) than in the knee OA study (45 per cent). There was a lagged effect across days in knee OA but not in T2DM, showing that patients who experienced more pain had more negative affect the next day and subsequently greater marital tension. Daily marital enjoyment from patients’ or spouses’ perspective was not a significant covariate of symptom severity in any of the same-day and cross-day analyses. Because a small number of patients reported both knee OA and T2DM, we re-ran our analyses within each sample controlling for this comorbidity. There was no change in our findings. Discussion Little is known about day-to-day changes in the quality of marital interactions and their implications for physical health in everyday life. These connections may be particularly strong for individuals living with chronic illness. Using daily diary data from two illness populations, we found that type 2 diabetes symptoms were worse on days when patients and their spouses experienced more marital tension. In addition, for individuals with type 2 diabetes or knee OA, more severe symptoms on days of greater marital tension were due in part to their greater negative affect on those days. The connections between marital interactions and symptomatology extended to the next day in only the knee OA sample, indicating weak support for our hypothesis when tested prospectively. These findings suggest that negative marital interactions may play a role in symptom exacerbation. Indeed, it has been suggested that the health impact of marital functioning may be strongest in those with biological systems that are dysregulated by a chronic condition [8]. Our findings are important because self-reported physical symptoms are a key indicator of health and a common daily experience for individuals living with chronic illness [36]. Moreover, greater symptomatology is associated with a more negative illness trajectory and long-term outcomes such as disability and cardiovascular disease. The lagged effect across days found for individuals with knee OA suggests a cyclical process whereby days of greater marital tension exacerbate pain, which in turn contributes to greater marital tension. In contrast, effects found in the T2DM sample did not extend across days. It is possible that processes unfold over different time scales (i.e., within minutes or hours) for different chronic conditions and that the impact of social interactions on individuals with diabetes may be constrained to the same day due to features of this illness [37]. We conducted a strong test of our indirect effects hypothesis by controlling for both partners’ perceptions of daily tension and enjoyment, and overall marital satisfaction. Marital satisfaction was not a significant covariate in our models, illustrating the greater influence of daily marital interactions on daily health. Daily marital enjoyment was also not associated with patients’ daily symptom severity. This finding is consistent with a body of research showing that negative social exchanges are more consequential than positive social exchanges for older adults’ health and well-being and suggests that this pattern extends to daily social exchanges [16]. We did not find support for our indirect effects hypothesis when examining spouses’ perceptions of daily marital tension, due in part to the lack of association between spouses’ negative affect and patients’ symptom severity. There were also few direct associations between spouses’ marital tension and patients’ symptom severity. Overall, our findings suggest that it is patients’ perception how well things are going in the relationship, and not spouses’ perceptions, that matter for patients’ health that day. In this study, we found that daily marital tension exerts its effect through negative affect. Other possible mechanisms in the link between daily interactions and physical symptoms include short-term changes in cardiovascular, endocrine, and immune function (e.g., 7). Greater tension may also lead spouses to pressure patients to better manage their illness. Such attempts at social control by close family members often backfire, which may ultimately exacerbate symptoms [38]. Using these same datasets, we have shown that spouses’ daily pressure on patients to be more physically active (knee OA sample) or adhere to the diabetic diet (T2DM sample) is associated with less daily activity and adherence [19, 39]. We compared patients and spouses within each sample in terms of day-to-day variability in marital interaction quality and affect. The purpose of these analyses was to help interpret different findings for patients and spouses in the multilevel models, but no clear pattern of variability emerged. In the T2DM sample, spouses showed more variability than patients in daily marital tension and positive affect, but less variability in marital enjoyment and negative affect. Consistent with a previous study of healthy couples, patients and spouses in both samples did not differ from each other in terms of average levels of daily marital tension and enjoyment [6]. There are several limitations of this study. First, we were not able to directly compare findings across samples due to differences in measurement, and negative affect was measured only at the end of the day in the diabetes sample. Second, individuals with diabetes were asked about the severity of diabetes symptoms in general rather than specific symptoms (e.g., fatigue) and therefore may have reported on different symptoms across the days. A clearer picture of the degree of change in specific illness symptoms over different time scales, as well as interpersonal predictors of that variability, would be useful information on the development of couple-oriented interventions for chronic illness. Third, although the focus of this study was a daily indicator of patient health that was similar across the two samples, future research may yield stronger conclusions by including objective measures of patients’ daily health such as blood glucose readings and gait speed [40]. To conclude, the current study extends the literature on marital quality and health by showing that the quality of daily marital interactions has implications for individuals living with chronic conditions. The illness populations that were the focus of this paper are among the most common and costly adult illnesses in the USA. We utilized two datasets that are well-suited for examining processes by which marriage affects health, and our focus on couples’ experiences as they go about their daily lives yields data with high ecological validity. Evidence for indirect effects of marital tension on symptom severity was found mainly in cross-sectional analyses and only according to patients’ reports. Our findings extend those from a study conducted by Yorgason and colleagues that focused only on spouse perceptions and did not find a daily association between marital quality and patients’ arthritis or diabetes severity [9]. Findings from this study may also have long-term implications for health. Individuals who experience more severe knee OA pain become disabled at a faster rate, and individuals with uncontrolled diabetes are at risk for multiple health complications including neuropathy, blindness, and kidney disease. More negative marital interactions may also accumulate over time and lead to subclinical disease, as suggested by a recent study of healthy adults in which higher quality marital interactions over 4 days were associated with less carotid artery intima-medial thickness, a risk factor for cardiovascular disease [41]. Finally, our findings provide useful information for researchers and clinicians. Clinicians working with older patients who are married or partnered should be aware that the severity of patients’ symptoms may be affected by the quality of interactions with close family members such as the spouse. Whether it is the case that tense interactions exacerbate symptoms, or symptoms lead to greater tension between partners, greater recognition of this link by clinicians and patients is important. Moreover, this knowledge can be incorporated in couple-oriented interventions that target effective ways to communicate symptoms and emotions, and lead to far-reaching benefits for older couples living with chronic conditions [42]. Acknowledgments Preparation of this manuscript was supported by National Institute on Aging Grants R01 AG024833 (M.A.P.S.), R01 AG026010 (L.M.M.), and K02 AG039412 (L.M.M.). Compliance with Ethical Standards Authors’ Statement of Conflict of Interest and Adherence to Ethical Standard Authors Lynn M. Martire, Rachel C. Hemphill, Ruixue Zhaoyang, Mary Ann Parris Stephens, Melissa M. Franks, and Ashley M. Stanford declare that they have no conflict of interest. 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Journal
Annals of Behavioral Medicine – Oxford University Press
Published: Sep 13, 2018