A comparison of demographic variables, symptom profiles, and measurements of functioning in symptomatic volunteers and an outpatient clinical population.

There is consistent concern about the generalizability of research findings generated by clinical trials. There are several reasons for concern about these findings: (1) most clinical trials involve symptomatic volunteers who are recruited by means of advertisements rather than patients recruited from general clinical populations; (2) most clinical trials have restrictive criteria for admission into the study; and (3) the design of most trials is not representative of prescribing practices in the community. These methodological issues require investigators to question whether results from trials adequately model what will be seen in a general clinical situation. This report begins to evaluate the representativeness of initial samples by studying the demographic characteristics, symptom profiles, and measurements of functional disability for clinical outpatients and symptomatic volunteers recruited for clinical trials. We found that symptomatic volunteers were statistically more likely to be older than outpatients, were less likely to be single, and reported using more alcohol and cigarettes than outpatients. The two groups had similar levels of functional impairment and similar ages at onset of symptoms, but symptomatic volunteers reported more symptoms of depression and anxiety than outpatients. However, we believe the differences identified in this study did not seem to be clinically significant.