Generalizability of clinical trial results for bipolar disorder to community samples: findings from the National Epidemiologic Survey on Alcohol and Related Conditions

Abstract

Background: Research on the generalizability of clinical trial results for bipolar disorder is limited. The present post hoc study sought to quantify the generalizability of clinical trial results in individuals with DSM-IV bipolar disorder to a large representative community sample.

Method: Data were derived from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a large, nationally representative sample of 43,093 adults from the United States population. We applied a standard set of eligibility criteria representative of clinical trials to all adults with DSM-IV bipolar depression (n = 785) or mania (n = 724) in the past 12 months and then to a subsample of participants seeking treatment for bipolar depression (n = 276). Our aim was to determine the proportion of participants with bipolar depression or acute mania who would have been excluded from a clinical trial by typical eligibility criteria.

Results: We found that more than 5 of 10 participants with bipolar depression (58.17%) or mania (55.75%) would have been excluded by at least 1 eligibility criterion. In the subgroup of participants with bipolar depression who sought treatment, the exclusion rate by at least 1 criterion was higher (63.87%). Having a significant risk of suicide was the criterion excluding the highest percentage of participants in the bipolar depression samples, while having a current DSM-IV diagnosis of alcohol abuse or dependence was the one leading to the greatest exclusion rate in clinical trials for participants with acute mania. Exclusion rates were higher for participants with bipolar I depression compared with those with bipolar II depression.

Conclusions: Traditional clinical trials tend to exclude a majority of individuals with bipolar disorder. Clinical trials should carefully consider the impact of eligibility criteria on the generalizability of their results and explain the rationale for their use. Future trials should weigh the trade-offs between internal validity and the representativeness of the study.