Impact of document type on reporting quality of clinical drug trials: a comparison of registry reports, clinical study reports, and journal publications.

Objective: To investigate to what extent three types of documents for reporting clinical trials provide sufficient information for trial evaluation.

Design: Retrospective analysis

Data Sources: Primary studies and corresponding documents (registry reports, clinical study reports, journal publications) from 16 health technology assessments of drugs conducted by the German Institute for Quality and Efficiency in Health Care between 2006 and February 2011. Data analysis We assessed reporting quality for each study and each available document for six items on methods and six on outcomes, and dichotomised them as "completely reported" or "incompletely reported.