Browsing by Author "Murray, Joseph A."

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    Estimating the Impact of Verification Bias on Celiac Disease Testing
    (Wolters Kluwer, 2021) Hujoel, Isabel A.; Jansson-Knodell, Claire L.; Hujoel, Philippe P.; Hujoel, Margaux L.A.; Choung, Rok Seon; Murray, Joseph A.; Rubio-Tapia, Alberto; Medicine, School of Medicine
    Goal: The goal of this study was to estimate the impact of verification bias on the diagnostic accuracy of immunoglobulin A tissue transglutaminase (IgA tTG) in detecting celiac disease as reported by an authoritative meta-analysis, the 2016 Comparative Effectiveness Review (CER). Background: Verification bias is introduced to diagnostic accuracy studies when screening test results impact the decision to verify disease status. Materials and methods: We adjusted the sensitivity and specificity of IgA tTG reported by the 2016 CER with the proportion of IgA tTG positive and negative individuals who are referred for confirmatory small bowel biopsy. We performed a systematic review from January 1, 2007, to July 19, 2017, to determine these referral rates. Results: The systematic review identified 793 articles of which 9 met inclusion criteria (n=36,477). Overall, 3.6% [95% confidence interval (CI): 1.1%-10.9%] of IgA tTG negative and 79.2.2% (95% CI: 65.0%-88.7%) of IgA tTG positive individuals were referred for biopsy. Adjusting for these referral rates the 2016 CER reported sensitivity of IgA tTG dropped from 92.6% (95% CI: 90.2%-94.5%) to 57.1% (95% CI: 35.4%-76.4%) and the specificity increased from 97.6% (95% CI: 96.3%-98.5%) to 99.6% (95% CI: 98.4%-99.9%). Conclusions: The CER may have largely overestimated the sensitivity of IgA tTG due to a failure to account for verification bias. These findings suggest caution in the interpretation of a negative IgA tTG to rule out celiac disease in clinical practice. More broadly, they highlight the impact of verification bias on diagnostic accuracy estimates and suggest that studies at risk for this bias be excluded from systematic reviews.
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    Latitude and Celiac Disease Prevalence: A Meta-Analysis and Meta-Regression
    (Elsevier, 2020) Celdir, Melis G.; Jansson-Knodell, Claire L.; Hujoel, Isabel A.; Prokop, Larry J.; Wang, Zhen; Murad, M. Hassan; Murray, Joseph A.; Medicine, School of Medicine
    Background & Aims The latitudinal gradient effect is described for several autoimmune diseases including celiac disease in the United States. However, the association between latitude and global celiac disease prevalence is unknown. We aimed to explore the association between latitude and serology-based celiac disease prevalence through meta-analysis. Methods We searched MEDLINE, Embase, Cochrane, and Scopus databases from their beginning through June 29, 2018, to identify screening studies that targeted a general population sample, used serology-based screening tests, and provided a clear location from which we could assign a latitude. Studies were excluded if sampling was based on symptoms, risk factors, or referral. Study selection and data extraction were performed by independent reviewers. The association measures between latitude and prevalence of serology-based celiac disease were evaluated with random-effects meta-analyses and meta-regression. Results Of the identified 4667 unique citations, 128 studies were included, with 155 prevalence estimates representing 40 countries. Celiac disease was more prevalent at the higher latitudes of 51° to 60° (relative risk [RR], 1.62; 95% CI, 1.09–2.38) and 61° to 70° (RR, 2.30; 95% CI, 1.36–3.89) compared with the 41° to 50° reference level. No statistically significant difference was observed at lower latitudes. When latitude was treated as continuous, we found a statistically significant association between CD prevalence and latitude overall in the world (RR, 1.03, 95% CI, 1.01–1.05) and a subregional analysis of Europe (RR, 1.05; 95% CI, 1.02–1.07) and North America (RR, 1.1; 95% CI, 1.0–1.2). Conclusions In this comprehensive review of screening studies, we found that a higher latitude was associated with greater serology-based celiac disease prevalence.