Impact of contacting study authors to obtain additional data for systematic reviews: diagnostic accuracy studies for hepatic fibrosis

Abstract

BackgroundSeventeen of 172 included studies in a recent systematic review of blood tests for hepatic fibrosis or cirrhosis reported diagnostic accuracy results discordant from 2 × 2 tables, and 60 studies reported inadequate data to construct 2 × 2 tables. This study explores the yield of contacting authors of diagnostic accuracy studies and impact on the systematic review findings.MethodsSixty-six corresponding authors were sent letters requesting additional information or clarification of data from 77 studies. Data received from the authors were synthesized with data included in the previous review, and diagnostic accuracy sensitivities, specificities, and positive and likelihood ratios were recalculated.ResultsOf the 66 authors, 68% were successfully contacted and 42% provided additional data for 29 out of 77 studies (38%). All authors who provided data at all did so by the third emailed request (ten authors provided data after one request). Authors of more recent studies were more likely to be located and provide data compared to authors of older studies. The effects of requests for additional data on the conclusions regarding the utility of blood tests to identify patients with clinically significant fibrosis or cirrhosis were generally small for ten out of 12 tests. Additional data resulted in reclassification (using median likelihood ratio estimates) from less useful to moderately useful or vice versa for the remaining two blood tests and enabled the calculation of an estimate for a third blood test for which previously the data had been insufficient to do so. We did not identify a clear pattern for the directional impact of additional data on estimates of diagnostic accuracy.ConclusionsWe successfully contacted and received results from 42% of authors who provided data for 38% of included studies. Contacting authors of studies evaluating the diagnostic accuracy of serum biomarkers for hepatic fibrosis and cirrhosis in hepatitis C patients impacted conclusions regarding diagnostic utility for two blood tests and enabled the calculation of an estimate for a third blood test. Despite relatively extensive efforts, we were unable to obtain data to resolve discrepancies or complete 2 × 2 tables for 62% of studies.

Becoming a parent: A systematic review and meta‐analysis of changes in BMI, diet, and physical activity

“…Further, although data extraction was 100% checked, it was not extracted in duplicate. We did not approach authors for additional information as we did not want to bias this review in the event of differential author response . Despite a large number of papers identified in our original search, relatively few studies were included in the synthesis, which suggests a paucity of data including measures of anthropometry, physical activity, or diet before and after parenthood.…”

How do authors of systematic reviews deal with research malpractice and misconduct in original studies? A cross-sectional analysis of systematic reviews and survey of their authors

“…This may have led to an underestimation of its real prevalence. duplicate publications, 9 selectively reporting on outcomes or adverse effects, 10 and presenting biased results that are in favour of the sponsors' 11 or the authors' 12 interests. The impact of other malpractices, such as gift or ghost authorship, is less clear.…”

Survey of Cochrane protocols found methods for data extraction from figures not mentioned or unclear

“…Thus, data extraction from figures should be considered in systematic reviews. Although review authors have an option to request data from study authors, it is well documented that such request seldom yields requested data, even if study was published in a journal with a strict data-sharing policy [13] and even if the authors make multiple requests for data [14].…”