Although [email protected] may be useful for validating trial primary outcomes found on, it was far less useful for validating secondary outcomes and information about adverse events, including deaths. This finding is based on an analysis of data from 100 trials available on both websites.1

The comparison was funded by the National Library of Medicine and led by Lisa Schwartz, PhD, and Steven Woloshin, PhD, from The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire.

Primary outcomes are the answer to the most important question asked by a trial, and may report whether a new treatment is more effective than existing therapies. Secondary outcomes address other relevant questions related to the study, such as the effect on the overall cost of treatment or the impact on quality of life.

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All primary outcome measures posted on were matched with publically available data from [email protected] in the study sample and were found to be largely consistent. In contrast, only approximately half (51%) of the secondary outcomes listed on were identified at [email protected] Serious adverse events and deaths also could not be validated for most trials because [email protected] typically only reports such data aggregated across trials.

The researchers concluded that better integration between the 2 sites is needed. Even if all the numbers reported in were completely accurate, information on the trial design, conduct, or analysis would be incomplete and could affect conclusions about the trial results assessed in [email protected]


1. Schwartz LM, Woloshin S, Zheng E, et al. and [email protected]: A comparison of results reporting for new drug approval trials. Ann Intern Med. 2016 Jun 14. doi:10.7326/M15-2658. [Epub ahead of print]