Generalizability of clinical trial results for generalized anxiety disorder to community samples

Abstract

Background: There has been little research on the generalizability of clinical trials for generalized anxiety disorder (GAD). The present study examines the generalizability of pharmacological and psychotherapy clinical trials' results of individuals with DSM-IV GAD to a large community sample.

Methods: Data were drawn from the National Epidemiological Survey on Alcohol and Related Conditions (NESARC), a large national representative face-to-face sample of 43,093 adults of the United States population. We applied a standard set of eligibility criteria representative of GAD pharmacological and psychotherapy clinical trials to all adults with past 12 months GAD (n = 894), and to a subgroup of participants seeking treatment (n = 329). Our aim was to assess how many participants with GAD would fulfil typical eligibility criteria.

Results: We found that more than seven out of 10 participants with GAD were excluded by at least one criterion. In the subgroup of GAD participants who sought treatment, the exclusion rate by at least one criterion raised to more than eight out of 10 participants with GAD. For the overall sample and the treatment-seeking subsample, having a current depression was the criterion excluding the highest percentage of individuals. Having a lifetime history of bipolar disorder, a current significant medical condition, a current diagnosis of alcohol abuse or dependence, and a social or specific phobia also excluded a substantial proportion of individuals in both samples.

Conclusions: Clinical trials exclude a majority of adults with GAD. Clinical trials should carefully consider the impact of eligibility criteria on the generalizability of their results.