Cochran's Q test was useful to assess heterogeneity in likelihood ratios in studies of diagnostic accuracy

Objectives: Empirical evaluations have demonstrated that diagnostic accuracy frequently shows significant heterogeneity between sub-groups of patients within a study. We propose to use Cochran's Q test to assess heterogeneity in diagnostic likelihood ratios (LRs). Study Design and Setting: We reanalyzed published data of six articles that showed within-study heterogeneity in diagnostic accuracy. We used the Q test to assess heterogeneity in LRs and compared the results of the Q test with those obtained using another method for stratified analysis of LRs, based on subgroup confidence intervals. We also studied the behavior of the Q test using hypothetical data. Results: The Q test detected significant heterogeneity in LRs in all six example data sets. The Q test detected significant heterogeneity. in LRs more frequently than the confidence interval approach (38% vs. 20%). When applied to hypothetical data, the Q test would be able: to detect relatively small variations in LRs, of about a twofold increase, in a study including 300 participants. Conclusion: Reanalysis of published data using the Q test can be easily performed to assess heterogeneity in diagnostic LRs between subgroups of patients, potentially providing important information to clinicians who base their decisions on published LRs. (C) 2015 Elsevierc Inc. All rights reserved.