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Clinical Trials Exclude Patients for Questionable Reasons

Patients commonly excluded for medical conditions, age, medications, gender

TUESDAY, March 20 (HealthDay News) -- Clinical trials frequently exclude patients because they have common co-morbid conditions or are taking popular prescription medications, or due to gender or age, according to a report in the March 21 issue of the Journal of the American Medical Association. In particular, drug intervention and multicenter trials tend to have poorly justified exclusions that may limit their applicability of the results to the general population.

Robert A. Fowler, M.D., from Sunnybrook Hospital in Toronto, Ontario, Canada, and colleagues analyzed the nature and extent of exclusion criteria in 283 randomized controlled clinical trials that had been published. They judged the criteria as strongly, potentially, or poorly justified.

The researchers found that exclusion criteria often included common medical conditions (81.3 percent of trials), age (72.1 percent), commonly prescribed medications (54.1 percent), and female sex (39.2 percent). Twelve percent of studies did not report exclusion criteria. Only 47.2 percent of all exclusion criteria were graded as strongly justified for a specific trial.

Drug intervention trials and multicenter trials had a higher number of exclusion criteria (risk ratio 1.35 and 1.26, respectively), according to the study. Industry-sponsored trials and drug intervention trials were more likely to exclude individuals for reasons including concomitant medication use and medical co-morbidities, which were graded as poorly justified.

Such exclusions "may impair the generalizability of randomized controlled trial results," Fowler and colleagues conclude. "These findings highlight a need for careful consideration and transparent reporting and justification of exclusion criteria in clinical trials."

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