Clinical trial registry use in anaesthesiology systematic reviews: A cross-sectional study of systematic reviews published in anaesthesiology journals and the Cochrane Library.

BACKGROUND: Publication bias within systematic reviews may result in incorrect conclusions leading to inappropriate clinical decisions and a decreased quality of patient care. Searching clinical trial registries for unpublished studies is one possible solution to minimise publication bias. OBJECTIVES: To examine rates of clinical trial registry searches in systematic reviews published in respected anaesthesiology journals and whether these searches found trials (or data) eligible for inclusion; to compare rates of registry searches between published reviews and similar reviews within the Cochrane Anaesthesia, Critical and Emergency Care Group; to conduct trial registry searches for a subset of reviews, determining whether eligible studies were overlooked; to investigate whether reporting of results in completed anaesthesia trials on ClinicalTrials.gov followed guidelines. DESIGN: A cross-sectional study of systematic reviews published in 10 anaesthesiology journals and the Cochrane Library. SETTING AND PARTICIPANTS: PubMed and the Cochrane Library were searched for systematic reviews or meta-analyses. MAIN OUTCOME MEASURES: The primary outcome was the number of systematic reviews that searched clinical trial registries for unpublished trials. Secondary outcomes included the number of registered trials in the ClinicalTrial.gov registry and the number of trials reporting trial results which were available on the ClinicalTrials.gov database and which should have been considered in a systematic review. RESULTS: The PubMed search yielded 507 records, and 415 remained after exclusions. Of these, 49 (11.8%) included a search of clinical trial registries. In total, 12 systematic reviews reported finding unpublished data but only five incorporated the data into their analyses. Of the Cochrane reviews, 58.9% (43/73) reported registry searches. Among a sample of 30 systematic reviews that omitted registry searches, we found many studies within the registries that were probably eligible to be included in the systematic reviews. For completed trials within the ClinicalTrials.gov database, only 15.4% reported results. CONCLUSION: The majority of systematic reviews in anaesthesiology did not include data from clinical trial registries. Exclusion of statistically nonsignificant data may lead to a biased interpretation of the data and hence inappropriate clinical interventions. TRIAL REGISTRATION: Registered in University hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN000021932).

Publication Bias and Nonreporting Found in Majority of Systematic Reviews and Meta-analyses in Anesthesiology Journals.

BACKGROUND: Systematic reviews and meta-analyses are used by clinicians to derive treatment guidelines and make resource allocation decisions in anesthesiology. One cause for concern with such reviews is the possibility that results from unpublished trials are not represented in the review findings or data synthesis. This problem, known as publication bias, results when studies reporting statistically nonsignificant findings are left unpublished and, therefore, not included in meta-analyses when estimating a pooled treatment effect. In turn, publication bias may lead to skewed results with overestimated effect sizes. The primary objective of this study is to determine the extent to which evaluations for publication bias are conducted by systematic reviewers in highly ranked anesthesiology journals and which practices reviewers use to mitigate publication bias. The secondary objective of this study is to conduct publication bias analyses on the meta-analyses that did not perform these assessments and examine the adjusted pooled effect estimates after accounting for publication bias. METHODS: This study considered meta-analyses and systematic reviews from 5 peer-reviewed anesthesia journals from 2007 through 2015. A PubMed search was conducted, and full-text systematic reviews that fit inclusion criteria were downloaded and coded independently by 2 authors. Coding was then validated, and disagreements were settled by consensus. In total, 207 systematic reviews were included for analysis. In addition, publication bias evaluation was performed for 25 systematic reviews that did not do so originally. We used Egger regression, Duval and Tweedie trim and fill, and funnel plots for these analyses. RESULTS: Fifty-five percent (n = 114) of the reviews discussed publication bias, and 43% (n = 89) of the reviews evaluated publication bias. Funnel plots and Egger regression were the most common methods for evaluating publication bias. Publication bias was reported in 34 reviews (16%). Thirty-six of the 45 (80.0%) publication bias analyses indicated the presence of publication bias by trim and fill analysis, whereas Egger regression indicated publication bias in 23 of 45 (51.1%) analyses. The mean absolute percent difference between adjusted and observed point estimates was 15.5%, the median was 6.2%, and the range was 0% to 85.5%. CONCLUSIONS: Many of these reviews reported following published guidelines such as PRISMA or MOOSE, yet only half appropriately addressed publication bias in their reviews. Compared with previous research, our study found fewer reviews assessing publication bias and greater likelihood of publication bias among reviews not performing these evaluations.