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Methodological Heterogeneity Seen in Clinical Trials

Trials registered with from 2007 to 2010 mainly small, single-center

TUESDAY, May 1 (HealthDay News) -- Clinical studies registered with from 2007 and 2010 are predominately small, single-center trials and contain significant heterogeneity in methodology, according to a study published in the May 2 issue of the Journal of the American Medical Association.

Robert M. Califf, M.D., from the Duke Translational Medicine Institute in Durham, N.C., and colleagues investigated the characteristics of 96,346 clinical studies from Interventional trials focusing on three clinical specialties -- cardiovascular, mental health, and oncology -- were identified and analyzed.

The researchers found that the number of registered interventional clinical trials increased from 28,881 from 2004 to 2007 to 40,970 in the period from 2007 to 2010, with a concurrent decrease in the number of missing data elements. The interventional trials registered from 2007 and 2010 were mainly small (62 percent enrolled 100 or fewer participants), single-center (66 percent), and funded by organizations other than the National Institutes of Health (NIH) or industry (47 percent). Methods varied by clinical specialty, sponsor type, and the reported use of data monitoring committees (DMCs), randomization, and blinding. Use of DMCs was less common in industry-sponsored studies compared to NIH-sponsored trials (adjusted odds ratio [OR], 0.11), earlier-phase trials compared to phase 3 trials (adjusted OR, 0.83), and in mental health trials compared to trials in the other two specialties. Randomization and blinding in trials were less frequently reported in earlier-phase trials, oncology trials, and device trials.

"Clinical trials registered in are dominated by small trials and contain significant heterogeneity in methodological approaches, including reported use of randomization, blinding, and DMCs," the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

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