Changing patterns in reporting and sharing of review data in systematic reviews with meta-analysis of the effects of interventions: a meta-research study

Objectives: To examine changes in completeness of reporting and frequency of sharing data, analytic code and other review materials in systematic reviews (SRs) over time; and factors associated with these changes. Design: Cross-sectional meta-research study. Sample: A random sample of 300 SRs with meta-analysis of aggregate data on the effects of a health, social, behavioural or educational intervention, which were indexed in PubMed, Science Citation Index, Social Sciences Citation Index, Scopus and Education Collection in November 2020. Analysis/Outcomes: The extent of complete reporting and frequency of sharing review materials in these reviews were compared with 110 SRs indexed in February 2014. Associations between completeness of reporting and various factors (e.g. self-reported use of reporting guidelines, journal's data sharing policies) were examined by calculating risk ratios (RR) and 95% confidence intervals (CI). Results: Several items were reported sub-optimally among 300 SRs from 2020, such as a registration record for the review (38%), a full search strategy for at least one database (71%), methods used to assess risk of bias (62%), methods used to prepare data for meta-analysis (34%), and funding source for the review (72%). Only a few items not already reported at a high frequency in 2014 were reported more frequently in 2020. There was no evidence that reviews using a reporting guideline were more completely reported than reviews not using a guideline. Reviews published in 2020 in journals that mandated either data sharing or inclusion of Data Availability Statements were more likely to share their review materials (e.g. data, code files) (18% vs 2%). Conclusion: Incomplete reporting of several recommended items for systematic reviews persists, even in reviews that claim to have followed a reporting guideline. Data sharing policies of journals potentially encourage sharing of review materials.