Long Ge1, Jin-Hui Tian2, Ya-Nan Li3, Jia-Xue Pan4, Ge Li5, Dang Wei2, Xin Xing3, Bei Pan4, Yao-Long Chen2, Fu-Jian Song6, Ke-Hu Yang7. 1. The First Clinical Medical College of Lanzhou University, Lanzhou 730000, China; Evidence-Based Medicine Center, School of Basic Medical Sciences of Lanzhou University, Lanzhou 730000, China; Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou 730000, China. 2. Evidence-Based Medicine Center, School of Basic Medical Sciences of Lanzhou University, Lanzhou 730000, China; Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou 730000, China. 3. Evidence-Based Medicine Center, School of Basic Medical Sciences of Lanzhou University, Lanzhou 730000, China; Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou 730000, China; School of Public Health, Lanzhou University, Lanzhou 730000, China. 4. School of Public Health, Lanzhou University, Lanzhou 730000, China. 5. School of Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China. 6. Norwich Medical School, Faculty of Medicine and Health Science, University of East Anglia, Norwich, Norfolk, UK. Electronic address: Fujian.Song@uea.ac.uk. 7. Evidence-Based Medicine Center, School of Basic Medical Sciences of Lanzhou University, Lanzhou 730000, China; Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou 730000, China. Electronic address: kehuyangebm2006@126.com.
Abstract
OBJECTIVES: The aim of this study was to investigate the differences in main characteristics, reporting and methodological quality between prospectively registered and nonregistered systematic reviews. STUDY DESIGN AND SETTING: PubMed was searched to identify systematic reviews of randomized controlled trials published in 2015 in English. After title and abstract screening, potentially relevant reviews were divided into three groups: registered non-Cochrane reviews, Cochrane reviews, and nonregistered reviews. For each group, random number tables were generated in Microsoft Excel, and the first 50 eligible studies from each group were randomly selected. Data of interest from systematic reviews were extracted. Regression analyses were conducted to explore the association between total Revised Assessment of Multiple Systematic Review (R-AMSTAR) or Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) scores and the selected characteristics of systematic reviews. RESULTS: The conducting and reporting of literature search in registered reviews were superior to nonregistered reviews. Differences in 9 of the 11 R-AMSTAR items were statistically significant between registered and nonregistered reviews. The total R-AMSTAR score of registered reviews was higher than nonregistered reviews [mean difference (MD) = 4.82, 95% confidence interval (CI): 3.70, 5.94]. Sensitivity analysis by excluding the registration-related item presented similar result (MD = 4.34, 95% CI: 3.28, 5.40). Total PRISMA scores of registered reviews were significantly higher than nonregistered reviews (all reviews: MD = 1.47, 95% CI: 0.64-2.30; non-Cochrane reviews: MD = 1.49, 95% CI: 0.56-2.42). However, the difference in the total PRISMA score was no longer statistically significant after excluding the item related to registration (item 5). Regression analyses showed similar results. CONCLUSION: Prospective registration may at least indirectly improve the overall methodological quality of systematic reviews, although its impact on the overall reporting quality was not significant.
OBJECTIVES: The aim of this study was to investigate the differences in main characteristics, reporting and methodological quality between prospectively registered and nonregistered systematic reviews. STUDY DESIGN AND SETTING: PubMed was searched to identify systematic reviews of randomized controlled trials published in 2015 in English. After title and abstract screening, potentially relevant reviews were divided into three groups: registered non-Cochrane reviews, Cochrane reviews, and nonregistered reviews. For each group, random number tables were generated in Microsoft Excel, and the first 50 eligible studies from each group were randomly selected. Data of interest from systematic reviews were extracted. Regression analyses were conducted to explore the association between total Revised Assessment of Multiple Systematic Review (R-AMSTAR) or Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) scores and the selected characteristics of systematic reviews. RESULTS: The conducting and reporting of literature search in registered reviews were superior to nonregistered reviews. Differences in 9 of the 11 R-AMSTAR items were statistically significant between registered and nonregistered reviews. The total R-AMSTAR score of registered reviews was higher than nonregistered reviews [mean difference (MD) = 4.82, 95% confidence interval (CI): 3.70, 5.94]. Sensitivity analysis by excluding the registration-related item presented similar result (MD = 4.34, 95% CI: 3.28, 5.40). Total PRISMA scores of registered reviews were significantly higher than nonregistered reviews (all reviews: MD = 1.47, 95% CI: 0.64-2.30; non-Cochrane reviews: MD = 1.49, 95% CI: 0.56-2.42). However, the difference in the total PRISMA score was no longer statistically significant after excluding the item related to registration (item 5). Regression analyses showed similar results. CONCLUSION: Prospective registration may at least indirectly improve the overall methodological quality of systematic reviews, although its impact on the overall reporting quality was not significant.