In reply We thank Sharek et al for their comments. We disagree with the conclusion that their study design was sufficient to show efficacy of pediatric medical emergency team (PMET) implementation. First, the statistical technique of ARIMA time-series analysis is superior to simple before-and-after comparisons, as it can model the effects of random error over time. We do not believe that ARIMA can “eliminate the biases of a simple before-and-after design,” completely account for unmeasured confounding factors that are temporally coincident (or even temporally related by delayed effects) to the intervention, nor solve the problem of systematic bias noted in studies involving historical controls.1-3 With only 19 postimplementation event rates in their ARIMA model,4 there is risk of type I error.1 A recent publication graphs 8 additional postimplementation event rates: hospital mortality increased again, and the ARIMA model parameter estimate for PMET intervention was no longer visually or statistically significant (Figure 1 and Table 3).5 Moreover, the hospital had several quality interventions (infection and adverse drug event reduction strategies and creation of a hospitalist program) implemented over the period of the PMET study that may be confounders.5 Of note, ARIMA was not used for analysis of ward code rates.4 More than 40% of deaths were in “newborns and other neonates with conditions originating in the perinatal period”; improvements may have been driven by perinatal care and less by care in the general pediatric population.4 Second, Sharek et al used case-mix index adjustment, as documented in our eTable 1.6 However, this may not adequately adjust for complex and continuous case-mix changes over time and therefore ensure no confounding. For example, there was significant difference in patient sex, race/ethnicity, and length of hospital stay before and after PMET, possibly indicating a change in case mix.4 In our study, we did not adjust for case mix, similar to most published PMET studies; this is one factor that may account for confounding in before-and-after studies. Third, Sharek et al, as documented in our eTable 1,6 found reduced ward code rates. A code was defined as “tracheal intubation, chest compressions, or both.”4 In our article,6 we only claim that the Sharek et al study did not report a separate cardiopulmonary arrest rate outcome. We believe that the limitations of using historical controls in observational studies, and the possibility of systematic bias not accounted for by ARIMA models, do not allow definitive conclusions regarding the efficacy of PMET implementation. Back to top Article Information Correspondence: Dr Joffe, 3A3.07 Stollery Children's Hospital, 8440 112 St, Edmonton, AB T6G 2B7, Canada (email@example.com). Author Contributions:Study concept and design: Joffe, Anton, and Burkholder. Drafting of the manuscript: Joffe. Critical revision of the manuscript for important intellectual content: Joffe, Anton, and Burkholder. Administrative, technical, and material support: Joffe, Anton, and Burkholder. Financial Disclosure: None reported. References 1. Nelson BK. Statistical methodology, V: time series analysis using autoregressive integrated moving average (ARIMA) models. Acad Emerg Med. 1998;5(7):739-7449678399PubMedGoogle ScholarCrossref 2. Sacks H, Chalmers TC, Smith H Jr. Randomized versus historical controls for clinical trials. Am J Med. 1982;72(2):233-2407058834PubMedGoogle ScholarCrossref 3. Ioannidis JPA, Haidich AB, Pappa M, et al. Comparison of evidence of treatment effects in randomized and nonrandomized studies. JAMA. 2001;286(7):821-83011497536PubMedGoogle ScholarCrossref 4. Sharek PJ, Parast LM, Leong K, et al. Effect of a rapid response team on hospital-wide mortality and code rates outside the ICU in a children's hospital. JAMA. 2007;298(19):2267-227418029830PubMedGoogle ScholarCrossref 5. Longhurst CA, Parast L, Sandborg CI, et al. Decrease in hospital-wide mortality rate after implementation of a commercially sold computerized physician order entry system. Pediatrics. 2010;126(1):14-2120439590PubMedGoogle ScholarCrossref 6. Joffe AR, Anton NR, Burkholder SC. Reduction in hospital mortality over time in a hospital without a pediatric medical emergency team: limitations of before-and-after study designs. Arch Pediatr Adolesc Med. 2011;165(5):419-42321536956PubMedGoogle ScholarCrossref
Archives of Pediatrics & Adolescent Medicine – American Medical Association
Published: Dec 5, 2011
Keywords: hospitals, pediatric,medical emergency team
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