[Skip to Content]
[Skip to Content Landing]
Views 549
Citations 0
Original Investigation
September 2017

Comparison of Clinical Trial and Systematic Review Outcomes for the 4 Most Prevalent Eye Diseases

Author Affiliations
  • 1Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
  • 2Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California
  • 3Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York
  • 4Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
  • 5Department of Ophthalmology, Howard University Hospital, Washington, DC
  • 6Frank and Ray Stark Foundation, David Geffen School of Medicine at UCLA, Los Angeles, California
  • 7Eye Clinic, Department of Translational Surgery and Medicine, University of Florence, Careggi Hospital, Florence, Italy
JAMA Ophthalmol. 2017;135(9):933-940. doi:10.1001/jamaophthalmol.2017.2583
Key Points

Question  For the 4 most prevalent eye diseases (age-related macular degeneration, cataract, diabetic retinopathy, and glaucoma), what is the overlap between outcomes named in Cochrane reviews and outcomes reported in the trials included in the reviews?

Findings  In this cross-sectional study, for each disease the trials included a considerably greater number of outcomes than did the reviews, ranging from 2.9 times greater (glaucoma) to 4.9 times greater (cataract). Although most review outcomes were reported in the trials, most trial outcomes were not reported in the reviews.

Meaning  Inconsistency in trial outcomes impedes research synthesis efforts and indicates the need for disease-specific core outcome sets in ophthalmology.

Abstract

Importance  Suboptimal overlap in outcomes reported in clinical trials and systematic reviews compromises efforts to compare and summarize results across these studies.

Objectives  To examine the most frequent outcomes used in trials and reviews of the 4 most prevalent eye diseases (age-related macular degeneration [AMD], cataract, diabetic retinopathy [DR], and glaucoma) and the overlap between outcomes in the reviews and the trials included in the reviews.

Design, Setting, and Participants  This cross-sectional study examined all Cochrane reviews that addressed AMD, cataract, DR, and glaucoma; were published as of July 20, 2016; and included at least 1 trial and the trials included in the reviews. For each disease, a pair of clinical experts independently classified all outcomes and resolved discrepancies. Outcomes (outcome domains) were then compared separately for each disease.

Main Outcomes and Measures  Proportion of review outcomes also reported in trials and vice versa.

Results  This study included 56 reviews that comprised 414 trials. Although the median number of outcomes per trial and per review was the same (n = 5) for each disease, the trials included a greater number of outcomes overall than did the reviews, ranging from 2.9 times greater (89 vs 30 outcomes for glaucoma) to 4.9 times greater (107 vs 22 outcomes for AMD). Most review outcomes, ranging from 14 of 19 outcomes (73.7%) (for DR) to 27 of 29 outcomes (93.1%) (for cataract), were also reported in the trials. For trial outcomes, however, the proportion also named in reviews was low, ranging from 19 of 107 outcomes (17.8%) (for AMD) to 24 of 89 outcomes (27.0%) (for glaucoma). Only 1 outcome (visual acuity) was consistently reported in greater than half the trials and greater than half the reviews.

Conclusions and Relevance  Although most review outcomes were reported in the trials, most trial outcomes were not reported in the reviews. The current analysis focused on outcome domains, which might underestimate the problem of inconsistent outcomes. Other important elements of an outcome (ie, specific measurement, specific metric, method of aggregation, and time points) might have differed even though the domains overlapped. Inconsistency in trial outcomes may impede research synthesis and indicates the need for disease-specific core outcome sets in ophthalmology.

×