Methodological steps used by authors of systematic reviews and meta-analyses of clinical trials: a cross-sectional...

The quality of systematic reviews and meta-analyses (SR/MAs) depends on the extent of the methods used. We investigated the methodological steps used by authors of SR/MAs of clinical trials via an author survey.

We conducted an email-based cross-sectional study by contacting corresponding authors of SR/MAs that were published in 2015 and 2016 and retrieved through the PubMed database. The 27-item questionnaire was developed to study the methodological steps used by authors when conducting a SR/MA and the demographic characteristics of the respondent. Besides the demographic characteristics, methodological questions regarding the source, extraction and synthesis of data were included.

From 10,292 emails sent, 384 authors responded and were included in the final analysis. Manual searches were carried out by 69.2% of authors, while 87.3% do updated searches, 49.2% search grey literature, 74.9% use the Cochrane tool for risk of bias assessment, 69.8% assign more than two reviewers for data extraction, 20.5% use digital software to extract data from graphs, 57.9% use raw data in the meta-analysis, and 43.8% meta-analyze both adjusted and non-adjusted data. There was a positive correlation of years of experience in conducting of SR/MAs with both searching grey literature (P = 0.0003) and use of adjusted and non-adjusted data (P = 0.006).

Many authors still do not carry out many of the vital methodological steps to be taken when performing any SR/MA. The experience of the authors in SR/MAs is highly correlated with use of the recommended tips for SR/MA conduct. The optimal methodological approach for researchers conducting a SR/MA should be standardized.