Methodological characteristics of academic clinical drug trials - a retrospective cohort study of applications to the Danish Medicines Agency 1993-2005

Abstract

The aim of this study was to investigate the temporal trends in characteristics of academic clinical drug trials. We here report characteristics on trial methodology. A review of 386 approved applications of academic clinical drug trials submitted to the Danish Medicines Agency 1993-2005 was carried out. Data on 11 methodological characteristics were collected, e.g. statement of primary endpoint, use of control group, blinding, randomization, method for generation of allocation sequence, monitoring according to the principles of Good Clinical Practice (GCP monitoring) and publication. Statement of primary endpoint increased from 60 to 90% of trials (P < 0.0001). Comparing the period before and after implementation of the Clinical Trials Directive in 2004, intention of GCP monitoring increased from 13% to 94%. Control of medicine compliance increased from 42% to 76% (P < 0.0001) among trials with self-administration of the investigational medicinal product. Among controlled trials use of randomization increased from 78% to 94% (P= 0.0063) of trials. Remaining characteristics did not change significantly. In total 68% (264/386) were randomized controlled trials. Our study shows that randomization, definition of primary endpoint, GCP monitoring, and control of medicine compliance form part of a significantly increasing percentage of academic clinical drug trials. This indicates an increase in the quality of academic clinical drug research in Denmark 1993-2005. However, high numbers of unblinded randomized controlled trials and randomized controlled trials utilizing unacceptable methods for generation of allocation sequence emphasize the potential for further improvement of trial methodology.