Lisa M Wilson1, Ritu Sharma2, Sydney M Dy2, Julie M Waldfogel3, Karen A Robinson4. 1. Department of Health Policy and Management, Johns Hopkins University Bloomberg School of Public Health, 624 N. Broadway, 6th Floor, Baltimore, MD 21205, USA. Electronic address: lisawilson@jhmi.edu. 2. Department of Health Policy and Management, Johns Hopkins University Bloomberg School of Public Health, 624 N. Broadway, 6th Floor, Baltimore, MD 21205, USA. 3. Department of Pharmacy, Johns Hopkins Hospital, 1800 Orleans Street, Carnegie 180, Baltimore, MD 21287, USA. 4. Department of Medicine, Johns Hopkins University School of Medicine, 1830 E. Monument Street, 8th Floor, Baltimore, MD 21205, USA.
Abstract
OBJECTIVES: We assessed the effect of searching ClinicalTrials.gov on the conclusions of a systematic review. STUDY DESIGN AND SETTING: We conducted this case study concurrently with a systematic review. We searched ClinicalTrials.gov on March 9, 2016, to identify trial records eligible for inclusion in the review. Two independent reviewers screened ClinicalTrials.gov records. We compared conclusions and strength of evidence grade with and without ClinicalTrials.gov records for 31 comparisons and 2 outcomes. RESULTS: We identified 106 trials (53 in the peer-reviewed literature only, 23 in ClinicalTrials.gov only, and 30 in both sources). For one comparison, the addition of results identified through ClinicalTrials.gov reduced the pooled effect size. We found evidence of selective outcome reporting for two comparisons and suspected publication bias for another two comparisons. For all other comparisons, searching ClinicalTrials.gov did not change conclusions or the strength of evidence grading for the two outcomes. CONCLUSION: Our search of ClinicalTrials.gov bolstered suspicions of reporting biases but did not change either the conclusions or the strength of evidence grading. Further research is needed to determine the effect of searching ClinicalTrials.gov on the conclusions of systematic reviews in different topic areas and as the new rules for registration of trial results take effect.
OBJECTIVES: We assessed the effect of searching ClinicalTrials.gov on the conclusions of a systematic review. STUDY DESIGN AND SETTING: We conducted this case study concurrently with a systematic review. We searched ClinicalTrials.gov on March 9, 2016, to identify trial records eligible for inclusion in the review. Two independent reviewers screened ClinicalTrials.gov records. We compared conclusions and strength of evidence grade with and without ClinicalTrials.gov records for 31 comparisons and 2 outcomes. RESULTS: We identified 106 trials (53 in the peer-reviewed literature only, 23 in ClinicalTrials.gov only, and 30 in both sources). For one comparison, the addition of results identified through ClinicalTrials.gov reduced the pooled effect size. We found evidence of selective outcome reporting for two comparisons and suspected publication bias for another two comparisons. For all other comparisons, searching ClinicalTrials.gov did not change conclusions or the strength of evidence grading for the two outcomes. CONCLUSION: Our search of ClinicalTrials.gov bolstered suspicions of reporting biases but did not change either the conclusions or the strength of evidence grading. Further research is needed to determine the effect of searching ClinicalTrials.gov on the conclusions of systematic reviews in different topic areas and as the new rules for registration of trial results take effect.
Authors: Gaelen P Adam; Stacey Springs; Thomas Trikalinos; John W Williams; Jennifer L Eaton; Megan Von Isenburg; Jennifer M Gierisch; Lisa M Wilson; Karen A Robinson; Meera Viswanathan; Jennifer Cook Middleton; Valerie L Forman-Hoffman; Elise Berliner; Robert M Kaplan Journal: Syst Rev Date: 2018-04-16