TY - JOUR
AU - Johnson, Lisa M
AB - Abstract Background Fecal calprotectin (FC) is a screening test for intestinal inflammation, and often used by clinicians to help identify and monitor patients with inflammatory bowel disease (IBD). Improvements in FC assays include moving to more automated immunoassays compared to ELISAs and simple-to-use extraction devices compared to manual weighing for the extraction process. Methods A method comparison was performed between the PhiCal ELISA and LIAISON immunoassay for 53 stool samples, and the screening results were compared to the gold standard endoscopy with biopsy results. Clinical accuracy was assessed by comparing the FC results from each assay to the presence or absence of inflammation determined from the biopsy report. The performance of the extraction device was compared to manually weighing. Additional studies were completed to verify the manufacturer’s claims. Results The FC results were compared to the biopsy results for detecting inflammation. PhiCal ELISA had a sensitivity of 86% and specificity of 100%, while the LIAISON immunoassay had a sensitivity of 97% with specificity of 94%. Therefore, the LIAISON immunoassay performed better than the PhiCal ELISA. The extraction device performed well compared to manual weighing if stool samples were <800 μg/g, within Bristol stool types 2-6, and did not contain a significant amount of undigested material, fibrous material, or mucus. Conclusion The LIAISON immunoassay with extraction device has acceptable performance for clinical use in measuring fecal calprotectin. calprotectin, inflammatory bowel disease, stool, validation, extraction Impact Statement Fecal calprotectin assays have become more automated with easy-to-use stool extractions devices, while maintaining high clinical performance in screening for intestinal inflammation. Introduction Calprotectin is a calcium and zinc binding protein which is abundant in the cytoplasm of neutrophils. It is a highly sensitive and specific marker of intestinal inflammation when measured in stool (1). Fecal calprotectin (FC) is a screening test for patients with chronic gastrointestinal (GI) issues (e.g., diarrhea, abdominal pain, weight loss) (2). If FC is elevated or the patient is at high risk for inflammatory bowel disease (IBD), then the patient should proceed to the gold standard procedure of endoscopy with biopsies to diagnose an inflammatory condition such as IBD (3). Meta-analyses have reported pooled clinical sensitivity of 93% and pooled clinical specificity of 92% for FC testing in detecting intestinal inflammation in adult patients (1). FC testing is also used for disease monitoring in patients with IBD in order to qualitatively assess treatment response and to detect relapse of disease (4, 5). General trends in FC assay design have moved toward increased automation to speed up testing in order to meet the growing demand. One of the first FDA-approved assays was the PhiCal ELISA (6, 7). This assay consists of manually weighing stool using an analytical balance prior to extraction, extracting calprotectin into buffer through a series of steps, and performing an approximately 3 h ELISA assay to obtain results. Patient samples must be run in duplicate in the PhiCal ELISA plate, which is required by the manufacturer in the package insert (8). From beginning to end, this process takes a laboratory approximately 6 h to release 40 results for 1 batch. Two of the major bottlenecks in the process are the manually weighing extraction protocol and the ELISA assay. In order to speed up the extraction process, manufacturers offer fecal extraction devices which are pre-packaged tubes that have a wand with precisely-shaped grooves that the manufacturer claims accurately and precisely collects a certain amount of stool. These extraction devices are currently gaining FDA approval for use in specific stool tests such as calprotectin and pancreatic elastase (9–11). Also, ELISA assays have been converted into automated immunoassays that can be run on random access immunoassay analyzers with much higher throughput (9, 12, 13). Given all the advancements in the newer FC assays, our laboratory made the decision to switch from the PhiCal ELISA, a manual assay that we have used for over 12 years, to the more automated DiaSorin LIAISON calprotectin immunoassay. Our objective was to thoroughly evaluate the clinical and analytical performance of the newly FDA-approved DiaSorin LIAISON calprotectin immunoassay, which will be referred to as the LIAISON immunoassay in this article, and its associated Quantitative Stool Extraction and Test (Q.S.E.T) device. Material and Methods Validation of FC on the DiaSorin LIAISON® XL automated platform required verification of the manufacturer's specifications. Studies included method comparisons, extraction performance (manual weighing versus Q.S.E.T. device), assay precision, linearity, and reference interval verification. Testing was performed on the LIAISON XL according to manufacturers’ instructions. This study was exempt by the Institutional Review Board of the University of Utah. Samples Analyses were conducted on 53 residual stool samples (22 male/31 female; median age 36 years) who had endoscopy with biopsy results within 2 months of stool sample collection for calprotectin testing. Twenty-two of the patients had active IBD, 4 had IBD in remission, 8 had a diagnosis of other inflammatory disorder (e.g., microscopic colitis, ischemic colitis, diverticulosis), and 19 did not have a diagnosis related to an inflammatory disorder, but were being seen by gastroenterologists for chronic abdominal issues (i.e., irritable bowel syndrome or no diagnosis). To limit variability of freeze/thaw cycles on samples, stool was homogenized, split into 1 g aliquots, and frozen prior to use. Samples were assessed by Bristol stool type 1-7 for use of the extraction device (14). Bristol stool type 1 has a hard/dry consistency, and 7 has liquid consistency; both 1 and 7 should not be extracted by the Q.S.E.T. device, per the package insert (15). Extraction quality control (QC) samples were prepared by pooling stool samples in 3 different FC measurement ranges (low: <50 μg/g; medium: 50–120 μg/g; high: >120 μg/g). The 3 extraction QC pools (low, medium, and high) were thoroughly homogenized with an immersion blender and series of strainers. Water was added to the pools to assist with mixing. The pools were aliquoted into microcentrifuge tubes and frozen prior to use. Individual aliquots were thawed, used once, and then discarded. The 3 extraction QC samples, termed low, medium, and high, had a Bristol stool type 6. Samples were thawed at room temperature, thoroughly mixed, and extracted per the manufacturer’s instructions, using both extraction methods. The extraction method of manual weighing is considered to be superior to the Q.S.E.T. device. Guidance for the method evaluation was taken from the package insert (15), 510(k) evaluation (16), CLSI guidelines (17–19), performance metrics from our current PhiCal ELISA assay, and analyses of previous INSTAND proficiency testing reports (20). Additionally, certain studies were performed prior to the validation to help determine the acceptability criteria. Method Comparisons Calprotectin testing was conducted on both the PhiCal ELISA (Eurospital S.p.A., Trieste, Italy) and LIAISON immunoassay (DiaSorin Inc., Stillwater, MN, USA). The reference intervals for both assays are <50 μg/g = normal, 50–120 μg/g = borderline, and >120 μg/g = elevated. For method comparison, all samples were extracted using the manually weighing method. Both qualitative and quantitative evaluations were performed between the FC assays (21). Three different comparisons were performed. First, the acceptance criteria for qualitative agreement between the 2 assays was ≥80% agreement of result categorization. Second, the acceptance criteria for the quantitative comparison between the LIAISON immunoassay versus the PhiCal ELISA were that the Deming regression analysis demonstrated a slope between 0.85–1.15 with an overall bias within ±15% for undiluted FC results; these criteria were set by performing a study prior to the validation. Third, both assays were compared to the gold standard procedure of endoscopy with biopsy results. Qualitative agreement between the FC screening tests and the gold standard results was assessed by comparing the calprotectin result of <50 μg/g of normal or ≥50 μg/g as abnormal to the absence or presence of inflammation detected in the biopsy results. Also, the biopsy results contained a description of mild, moderate, or severe which was used to grade the degree of intestinal inflammation present (22). The highest level of inflammation seen (severe > moderate > mild) was semi-quantitatively compared to the FC results from the LIAISON immunoassay. Performance of the Extraction Method The accuracy of the Q.S.E.T. device was assessed by extracting 38 of the 53 samples within Bristol stool types 2-6 by Q.S.E.T. device versus manual weighing, and then comparing the FC results quantitatively. Three patient samples with elevated calprotectin results (>1000 μg/g) were also compared by device versus manual weighing to assess the accuracy of the device for very elevated FC concentrations. Additionally, samples that contained undigested material, fibrous material, and mucus were compared. With-in run and total imprecision for each extraction procedure were determined using the low, medium, and high extraction QC samples. Extraction QC samples were tested in 10 replicates in a single day using manual weighing and the Q.S.E.T. device. For inter-assay precision, the extraction QC samples were tested in quadruplicate over 5 days for a total of 20 replicates. The acceptance criterion for the pooled stool QC samples was <30%CV, which was set by analyzing the imprecision of the extraction QC samples in the current PhiCal ELISA. Analytical Imprecision Within-run and total imprecision of the assay were determined using DiaSorin commercial QC material (19). Intra-assay precision was performed by testing 10 replicates of each DiaSorin QC in a single day. For inter-assay precision, DiaSorin QC samples were tested in quadruplicate over five days for a total of 20 replicates. The acceptance criteria was <20%CV, which was set by analyzing the imprecision of the vendor-supplied QC samples for the current PhiCal ELISA and the DiaSorin studies (15, 16). Additional Studies In the Supplementary Information (sections #1 and 2), we have included a description of linearity and reference interval verification. In brief, calibrator verifiers and extracted stool samples were used to assess linearity (17), and 30 stool samples from healthy volunteers were measured to verify the reference interval (18). Data Analysis Data analysis was performed in EP Evaluator (Data Innovations LLC, South Burlington, VT, USA), GraphPad Prism (GraphPad Software, La Jolla, CA, USA), and Microsoft Excel (Microsoft Corporation, Redmond, WA, USA). Analyses included Deming regressions, bias calculations from EP Evaluator, qualitative agreement of FC result classification (normal, borderline, elevated), clinical sensitivity and specificity, %CV for imprecision, and % difference. The Supplemental Information contains the FC results for individual patients from various studies. Results Method Comparisons The PhiCal ELISA and LIAISON immunoassay were compared by analyzing the 53 stool samples. Figure 1 below shows the concordance between the result categories of normal, borderline, and elevated calprotectin. The LIAISON immunoassay gave higher results compared to the PhiCal ELISA, despite having the same reference intervals. Six patients had borderline results by the LIAISON immunoassay versus normal by PhiCal ELISA, and 5 patients had elevated results by the LIAISON immunoassay versus borderline by the PhiCal ELISA. Overall, the percent agreement was 80% between the 2 assays when excluding the borderline results. The quantitative comparison between the 2 methods showed that the LIAISON immunoassay had a positive bias of 38% compared to the PhiCal ELISA (supplemental information #3). Fig. 1 Open in new tabDownload slide Comparison of result categorization between the PhiCal ELISA and LIAISON immunoassay for fecal calprotectin. Fifty-three samples were measured on both assays. Reference intervals were specified by the manufacturer (<50 μg/g = normal, 50–120 μg/g = borderline, and >120 μg/g = elevated). Fig. 1 Open in new tabDownload slide Comparison of result categorization between the PhiCal ELISA and LIAISON immunoassay for fecal calprotectin. Fifty-three samples were measured on both assays. Reference intervals were specified by the manufacturer (<50 μg/g = normal, 50–120 μg/g = borderline, and >120 μg/g = elevated). The FC results were also compared to the gold standard endoscopy with biopsy results. A list of the fecal calprotectin results from each assay, clinical history, and results from the endoscopy with biopsy are listed in the Supplemental Information #4. One patient (#34) was excluded from the analysis because of a recent gastrointestinal operation (Roux-en-Y gastric bypass surgery), as postsurgical inflammation would confound the measurement of intestinal inflammation. Based on the results in the biopsy reports, the PhiCal ELISA had a clinical sensitivity of 86% and specificity of 100%, whereas the LIAISON immunoassay had a clinical sensitivity of 97% and specificity of 94% (Supplemental Information #4). Additionally, since the pathologists estimated the degree of inflammation present in the biopsies (22), the highest level noted in the report was semiquantitatively correlated to the LIAISON FC result (Fig. 2). Eighteen patients had no inflammation per the biopsy reports, 16 patients had mild, 10 had moderate, and 8 had severe inflammation. Supplemental Information #4 lists the individual results. The trend suggests that FC results can help estimate the degree of inflammation present in the biopsy, but there is a wide degree of overlap. Fig. 2 Open in new tabDownload slide Box plots of LIAISON fecal calprotectin results (μg/g) and degree of intestinal inflammation seen by biopsy results for 53 patients. Individual patient results are shown. Fig. 2 Open in new tabDownload slide Box plots of LIAISON fecal calprotectin results (μg/g) and degree of intestinal inflammation seen by biopsy results for 53 patients. Individual patient results are shown. Performance of Extraction Method The LIAISON FC results extracted by the Q.S.E.T. device versus manual weighing were compared for 38 of 53 stools samples by Deming regression analyses; 14 of the 53 samples were excluded from the analysis due to Bristol stool type 7 (liquid) classification. Figure 3A shows the FC results of 38 stool samples that were within Bristol stool type 2–6 and <8000 μg/g. One sample was >8000 μg/g by the LIAISON immunoassay, and also excluded from the quantitative analysis because the LIAISON immunoassay package insert lists an FC measurement range of 5–8000 μg/g with dilution (15). The Deming regression was y = 1.3x-57, with an average positive bias of 16% for the Q.S.E.T. device compared to manual weighing. However, when samples which required a dilution were excluded, the bias was negligible (Fig. 3B). Fig. 3 Open in new tabDownload slide Deming Regression comparison of LIAISON FC results extracted by manual weighing versus Q.S.E.T. device. Panel (A) shows 38 samples of Bristol stool type 2–6 in the range of 5–8000 μg/g FC (y = 1.3 × -57, positive bias of 16% for Q.S.E.T. device versus manual weighing). Panel (B) shows 32 samples in the undiluted range of 5–800 μg/g FC (y = 1.06 × -11, negative bias of 0.03% for Q.S.E.T. device versus manual weighing). Dashed horizontal lines show the cut-offs set by the manufacturer. Fig. 3 Open in new tabDownload slide Deming Regression comparison of LIAISON FC results extracted by manual weighing versus Q.S.E.T. device. Panel (A) shows 38 samples of Bristol stool type 2–6 in the range of 5–8000 μg/g FC (y = 1.3 × -57, positive bias of 16% for Q.S.E.T. device versus manual weighing). Panel (B) shows 32 samples in the undiluted range of 5–800 μg/g FC (y = 1.06 × -11, negative bias of 0.03% for Q.S.E.T. device versus manual weighing). Dashed horizontal lines show the cut-offs set by the manufacturer. We noted that certain stool samples above 1000 μg/g calprotectin had drastically different FC results if they were extracted by Q.S.E.T. device versus manual weighing (Fig. 3A). A small precision study was performed on 3 of these samples to determine if the imprecision could be attributed to the sample matrix or the extraction process (Supplemental Information #5). The imprecision of both extraction methods when testing in triplicate was <6% CV; however, the percent difference between device versus manual weighing ranged from -14% to 67%. Therefore, the imprecision of the extremely elevated FC samples is likely due to the difference between the extraction processes and the heterogeneity of stool samples. Stool samples that contained undigested material, fibrous material, and mucus were extracted by Q.S.E.T device versus manual weighing (Supplemental Information #6). The Q.S.E.T. device under-recovered calprotectin for samples with these characteristics (percent difference >30%). The manufacturer claims that the Q.S.E.T. device collects 10.5 ± 0.1 mg of stool (16). Stool samples with these characteristics do not properly coat the grooves of the wand for the extraction device, and therefore they should be extracted by manually weighing. Additionally, the 14 stool samples that were excluded from the performance comparison because they were liquid (Bristol Stool 7) were extracted by the Q.S.E.T. device to verify the manufacturer’s claim that FC results obtained by extraction with the Q.S.E.T. device were inaccurate compared to manual weighing. The average percent difference between Q.S.E.T. device versus manual weighing was -37% with median percent difference of -33% for Bristol Stool type 7. The Q.S.E.T. device under-recovered FC compared to manual weighing for liquid samples. Three extraction QC samples were used to further assess the imprecision of Q.S.E.T. device versus manual weighing. Table 1 shows the imprecision of the Q.S.E.T. device and manual weighing extraction methods. The Q.S.E.T. device often had a slightly lower FC concentration, but the percent difference between the means was <20%. Also, the Q.S.E.T. device had greater imprecision than manual weighing, but %CVs were <20%. The difference in the means and imprecision could be attributed to the addition of water to the pools; Bristol stool type 6 is one of the more liquid stool types in which the device can still be used for extraction. Table 1 Imprecision by extraction procedure. . Manual weighing . Q.S.E.T. Device . Manual weighing . Q.S.E.T. Device . Extraction QC . Within-Day (n = 10) . Within-Day (n = 10) . Total (n = 20) . Total (n = 20) . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . Low 44 6.1% 35 9.5% 43 4.8% 38 17.7% Medium 77 2.6% 63 3.6% 77 13.2% 62 12.2% High 476 2.4% 435 3.2% 467 3.0% 406 9.3% . Manual weighing . Q.S.E.T. Device . Manual weighing . Q.S.E.T. Device . Extraction QC . Within-Day (n = 10) . Within-Day (n = 10) . Total (n = 20) . Total (n = 20) . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . Low 44 6.1% 35 9.5% 43 4.8% 38 17.7% Medium 77 2.6% 63 3.6% 77 13.2% 62 12.2% High 476 2.4% 435 3.2% 467 3.0% 406 9.3% Open in new tab Table 1 Imprecision by extraction procedure. . Manual weighing . Q.S.E.T. Device . Manual weighing . Q.S.E.T. Device . Extraction QC . Within-Day (n = 10) . Within-Day (n = 10) . Total (n = 20) . Total (n = 20) . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . Low 44 6.1% 35 9.5% 43 4.8% 38 17.7% Medium 77 2.6% 63 3.6% 77 13.2% 62 12.2% High 476 2.4% 435 3.2% 467 3.0% 406 9.3% . Manual weighing . Q.S.E.T. Device . Manual weighing . Q.S.E.T. Device . Extraction QC . Within-Day (n = 10) . Within-Day (n = 10) . Total (n = 20) . Total (n = 20) . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . mean (μg/g) . %CV . Low 44 6.1% 35 9.5% 43 4.8% 38 17.7% Medium 77 2.6% 63 3.6% 77 13.2% 62 12.2% High 476 2.4% 435 3.2% 467 3.0% 406 9.3% Open in new tab Assay Imprecision The LIAISON FC immunoassay had acceptable imprecision with the DiaSorin QC samples (Table 2). Table 2 Imprecision of QC samples for LIAISON immunoassay. . Within-Day (n = 10) . Total (n = 20) . . mean (μg/g) . %CV . mean (μg/g) . %CV . QC1 46 1.7% 45 3.8% QC2 270 4.2% 271 6.0% . Within-Day (n = 10) . Total (n = 20) . . mean (μg/g) . %CV . mean (μg/g) . %CV . QC1 46 1.7% 45 3.8% QC2 270 4.2% 271 6.0% Open in new tab Table 2 Imprecision of QC samples for LIAISON immunoassay. . Within-Day (n = 10) . Total (n = 20) . . mean (μg/g) . %CV . mean (μg/g) . %CV . QC1 46 1.7% 45 3.8% QC2 270 4.2% 271 6.0% . Within-Day (n = 10) . Total (n = 20) . . mean (μg/g) . %CV . mean (μg/g) . %CV . QC1 46 1.7% 45 3.8% QC2 270 4.2% 271 6.0% Open in new tab Additional Studies Results for linearity and reference interval verification are shown in the Supplementary Information #1 and #2. In brief, linearity for extracted stool samples had percent recoveries between 92.7%–109.3%. The reference interval was verified utilizing 28 of 30 (93%) stool samples from healthy, adult volunteers with FC results <50 μg/g. Discussion The accuracy of the LIAISON FC immunoassay was assessed in several ways. First, FC assays are not standardized, and do not compare well quantitatively (9, 12, 13). However, we expected that the qualitative comparisons would be acceptable for the categories of normal and elevated (12, 13, 23, 24). One caveat is that the borderline region of FC assays is a gray area, often not included in concordance analyses because clinicians should make decisions based on other factors (clinical symptoms, other laboratory results, NSAID use). In the 510(k) pre-market submission, DiaSorin compared their assay to the PhiCal ELISA and found agreement of 100% between both FC assays if excluding borderline results (16). During our studies, we found that the agreement was 80% between the 2 assays, and the LIAISON immunoassay had a positive bias of 38% compared to PhiCal ELISA. The PhiCal ELISA FC results were lower than expected, and we attribute this issue to the lot of reagent. However, the issue of low bias with this specific reagent lot of PhiCal ELISA was only based on our experience with the assay, and we did not confirm this finding with another laboratory using the same kit and lot. Unfortunately, the vendor could not provide us with a different lot, since the validation studies occurred in March and April of 2020. Instead of relying on the comparison between 2 FC assays, we verified the accuracy of the LIAISON FC results using clinical data. Calprotectin results from the PhiCal ELISA and LIAISON immunoassay were compared to the gold standard result of endoscopy with biopsy to assess accuracy. We found that the LIAISON immunoassay was better than the PhiCal ELISA in prediction if inflammation was seen on the biopsy results. Other studies have found that the LIAISON FC results have good clinical performance in differentiating patients with irritable bowel syndrome, a condition that does not have pathological findings of inflammation during the endoscopy procedure and therefore should have low FC, versus those with IBD (9, 25). Additionally, the LIAISON FC results were semi-quantitatively compared to the highest degree of inflammation reported in the biopsies. Overall, the trend showed that higher degrees of inflammation in the biopsies had higher FC results. There was a large degree of overlap, likely because both the degree of intestinal inflammation and the amount/regions of intestine affected contributes to the overall FC result; this would potentially explain why some patients with mild inflammation have very elevated FC results (>1000 mg/g), if large regions of the GI tract are affected. Given these additional comparisons, we found the clinical utility of the LIAISON immunoassay for FC to be acceptable. One of the main focuses during our verification was to determine the benefits and limitations of the extraction device. The obvious benefits are that the extraction devices save time and labor when compared to extraction by manually weighing stool samples. However, not all extraction devices work equally well. Other researchers have found that certain extraction devices have high or low biases if compared to weighing methods (10, 11, 26–28). One study even suggested a different reference interval for samples extracted by device (29). Buhlmann has sent out a field safety notice in the past because of a high bias due to their extraction device (30), but at least 1 recent study in the literature suggested that a high bias still existed with the new device (10). Therefore, we performed extensive studies to verify that the DiaSorin Q.S.E.T. device is comparable to manual weighing for an extraction process. Additionally, we investigated stool specimen consistencies and characteristics (undigested food, fibrous, mucous) to understand which specimen should be processed by manual weighing versus device. Overall, we found that the Q.S.E.T. device performed well compared to manual weighing for stool samples within Bristol stool types 2–6 and FC results <800 μg/g. Some stool samples seemed to give drastically different FC results if >800 μg/g, but we do not believe that these differences between extremely elevated FC concentrations would have much clinical significance, as any values >800 μg/g suggest FC is elevated and inflammation is present. We speculate that the extraction processes give different elevated FC results because the manually weighing of 50–100 mg of stool provides a more uniform average of a heterogeneous sample versus the 10.5 mg collected by the Q.S.E.T. device. In addition to stool samples of Bristol stool type 1 and 7, we found during our validation that stool samples with a significant amount of undigested material, fibrous material, and mucus should not be extracted by the Q.S.E.T. device. We currently sort samples into batches to be extracted by the Q.S.E.T. device or manual weighing based on the liquid consistency of stool. During the homogenization, if samples fail to meet the Q.S.E.T. acceptability criteria (undigested material, fibrous, mucous) they will be extracted by manual weighing. We estimate that approximate 70% of stool samples will be extracted by device and 30% will be extracted by manual weighing for our clinical samples. DiaSorin has recently revised the package insert with a new protocol to pipette 12 µL of liquid stool samples into a Q.S.E.T. device; we have not yet evaluated if this process change for liquid stool samples gives acceptable accuracy and can be included in our work flow. Our laboratory routinely makes large batches of extraction QC samples from pooled, discarded stool samples to monitor the extraction process for the calprotectin assay. The extraction QC sample monitors the entire testing process (pre-analytical extraction + analytical measurement), and therefore gives us the best information in terms of quality control. Our extraction QC samples gave us acceptable results when comparing the Q.S.E.T. device and manual weighing for extraction process. Although FC results using the device were slightly lower and had higher imprecision compared to manual weighing, the overall result categories (normal, borderline, and elevated) remained the same and the variability is tolerated given the nature of stool samples (10, 31, 32). Even though our studies showed that the device compared well to manual weighing for the extraction steps, we noticed several design flaws in using the device in our clinical laboratory. One issue was that DiaSorin chose not pre-fill the Q.S.E.T. device with buffer, which adds more repetitive strain on the technologists’ wrists due to more twisting on/off the cap. Additionally, having a device that is capped at both ends was problematic because buffer would occasionally leak out the other end when trying to re-cap the tube. Also, the lip of the cap often caught the wire rack when removing the tube, potentially spilling all of the samples. Finally, our technologists did not like that the wand of the Q.S.E.T. device was short, and they often contaminated their gloves when trying to ensure that the grooves were properly filled with stool. All of these issues were reported to the vendor, and DiaSorin is planning on releasing a revised version of the device. In conclusion, we found the performance of the DiaSorin LIAISON calprotectin immunoassay to be acceptable for clinical use. Since stool is a challenging matrix for the clinical laboratory, we hope this thorough validation serves as a reference for other laboratories interested in performing fecal calprotectin testing. Especially since the newly FDA-approved assays will improve the work flow within the laboratory and streamline the testing process. Supplemental Material Supplemental material is available at The Journal of Applied Laboratory Medicine online. Nonstandard Abbreviations: FC, fecal calprotectin; IBD, inflammatory bowel disease; GI, gastrointestinal; Q.S.E.T, Quantitative Stool Extraction and Test; QC, quality control. Author Contributions: All authors confirmed they have contributed to the intellectual content of this paper and have met the following 4 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; (c) final approval of the published article; and (d) agreement to be accountable for all aspects of the article thus ensuring that questions related to the accuracy or integrity of any part of the article are appropriately investigated and resolved. S.P. Wyness, statistical analysis; L.M. Johnson, statistical analysis. Authors’ Disclosures or Potential Conflicts of Interest: Upon manuscript submission, all authors completed the author disclosure form. Disclosures and/or potential conflicts of interest. Employment or Leadership: None declared. Consultant or Advisory Role: None declared. Stock Ownership: None declared. Honoraria: None declared. Research Funding: None, but kits were provided by the manufacturer Expert Testimony: None declared. Patents: None declared. Role of Sponsor: The funding organizations played no role in the design of study, choice of enrolled patients, review and interpretation of data, preparation of manuscript, or final approval of manuscript. Acknowledgments The authors thank DiaSorin for providing all of the kits for the validation. REFERENCES 1 van Rheenen PF , Van de Vijver E , Fidler V. Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: diagnostic meta-analysis . Br Med J 2010 ; 341 : c3369 . 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TI - Clinical and Analytical Verification of an Automated Fecal Calprotectin Immunoassay with Extraction Device
JF - The Journal of Applied Laboratory Medicine
DO - 10.1093/jalm/jfaa236
DA - 2021-02-13
UR - https://www.deepdyve.com/lp/oxford-university-press/clinical-and-analytical-verification-of-an-automated-fecal-Djf9UHb730
SP - 1
EP - 1
VL - Advance Article
IS - 
DP - DeepDyve
ER -