Abstract | May 2019
Objective: To simulate possible changes in systematic review results if rapid review methods were used.
Study design and setting: We recalculated meta-analyses for binary primary outcomes in Cochrane systematic reviews, simulating rapid review methods. We simulated searching only PubMed, excluding older articles (5, 7, 10, 15, and 20 years before the search date), excluding smaller trials (<50, <100, and <200 participants), and using the largest trial only. We examined percentage changes in pooled odds ratios (ORs) (classed as no important change [<5%], small [<20%], moderate [<30%], or large [≥30%]), statistical significance, and biases observed using rapid methods.
Results: Two thousand five hundred and twelve systematic reviews (16,088 studies) were included. Rapid methods resulted in the loss of all data in 3.7-44.7% of meta-analyses. Searching only PubMed had the smallest risk of changed ORs (19% [477/2,512] were small changes or greater; 10% [260/2,512] were moderate or greater). Changes in ORs varied substantially with each rapid review method; 8.4-21.3% were small, 1.9-8.8% were moderate, and 4.7-34.1% were large. Changes in statistical significance occurred in 6.5-38.6% of meta-analyses. Changes from significant to nonsignificant were most common (2.1-13.7% meta-analyses). We found no evidence of bias with any rapid review method.
Conclusion: Searching PubMed only might be considered where a ∼10% risk of the primary outcome OR changing by >20% could be tolerated. This could be the case in scoping reviews, resource limitation, or where syntheses are needed urgently. Other situations, such as clinical guidelines and regulatory decisions, favor more comprehensive systematic review methods.
Funding I.J.M. is supported by the UK Medical Research Council (MRC), through its Skills Development Fellowship program, MR/N015185/1. B.C.W. is supported by the Agency for Healthcare Research Quality (AHRQ), grant R03-HS025024. This study is the work of the authors alone; the funders had no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.
Citation Marshall IJ, Marshall R, Wallace BC, Brassey J, Thomas J. Rapid reviews may produce different results to systematic reviews: a meta-epidemiological study. J Clin Epidemiol. 2019 May;109:30-41. doi: 10.1016/j.jclinepi.2018.12.015. Epub 2018 Dec 25. PMID: 30590190; PMCID: PMC6524137.
