BACKGROUND: Unacknowledged inconsistencies in the reporting of clinical trials undermine the validity of the results of the trials. Little is known about inconsistency in the reporting of academic clinical drug trials. Therefore, we investigated the prevalence of consistency between protocols and published reports of academic clinical drug trials.

METHODS: A comparison was made between study protocols and their corresponding published reports. We assessed the overall consistency, which was defined as the absence of discrepancy regarding study type (categorized as either exploratory or confirmatory), primary objective, primary endpoint, and--for confirmatory trials only--hypothesis and sample size calculation. We used logistic regression, χ(2), and Fisher's exact test.

RESULTS: A total of 282 applications of academic clinical drug trials were submitted to the Danish Health and Medicines Authority in 1999, 2001, and 2003, 95 of which fulfilled the eligibility criteria and had at least one corresponding published report reporting data on trial subjects. Overall consistency was observed in 39% of the trials (95% CI: 29 to 49%). Randomized controlled trials (RCTs) constituted 72% (95% CI: 63 to 81%) of the sample, and 87% (95% CI: 80 to 94%) of the trials were hospital based.

CONCLUSIONS: Overall consistency between protocols and their corresponding published reports was low. Motivators for the inconsistencies are unknown but do not seem restricted to economic incentives.