Clinical trials and systematic reviews addressing similar interventions for the same condition do not consider similar outcomes to be important: a case study in HIV/AIDS

Background The usefulness of clinical trials and systematic reviews is compromised when they report different outcomes. We compared outcomes in reviews of HIV/AIDS and the trials included in the reviews. Study Design and Setting We examined all Cochrane reviews of HIV/AIDS (as of June 2013) that included ≥1 trial and the trials that the reviews included. We compared outcomes within subgroups defined by type of intervention: clinical management, biomedical prevention, behavioral prevention, and health services. Results We included 84 reviews that encompassed 524 trials. Although the median number of outcomes per trial (8) and per review (7.5) was similar, the trials reported a considerably greater number of unique outcomes than the reviews (779 vs. 218), ranging from 2.3 times greater (clinical management) to 5.4 times greater (behavioral prevention). High proportions of trial outcomes were not in any review: 68% (clinical management) to 83% (behavioral prevention). Lower proportions of review outcomes were not in any trial: 11% (clinical management) to 39% (health services). Conclusion Outcomes in trials and reviews are not well aligned for appropriate inclusion of trial results in reviews and meta-analyses. Differences in perspectives, goals, and constraints between trialists and reviewers may explain differences in outcomes they consider important.