Characteristics of participants and nonparticipants in medication trials for treatment of schizophrenia

Objective: The study compared the characteristics of patients who participa ted in efficacy trials of medications for treatment of schizophrenia with t hose of the other patients in the clinical population from which the trial participants had been selected. Methods: Study participants from ten trials of treatment efficacy conducted at a community mental health center in the early and mid-1990s were compared with nonparticipants using data on demog raphic and diagnostic characteristics and service-utilization from the cent er's administrative database. Six of the trials selected patients with schi zophrenia and no concurrent substance use disorder, and four selected patie nts with dual diagnoses of schizophrenia and a substance use disorder. Resu lts: Compared with nonparticipants, participants in both types of trial wer e about six to eight years younger, were two to four times less likely to h ave ever married, and used more services. Participants in trials that selec ted patients with no substance use disorder were more likely to be high sch ool graduates and were four times more likely to work full time, compared w ith nonparticipants. Participants in trials that selected patients with dua l diagnoses were likely to be minorities and less likely to have medical co morbidities, compared with nonparticipants. Conclusions: Participants in tr eatment efficacy trials differed substantially from nonparticipants, Some c haracteristics of the trial participants, including reduced likelihood of e ver having been married and male gender, have been associated with poorer t reatment outcomes in earlier studies. Other characteristics, such as younge r age and greater likelihood of having graduated from high school and of wo rking full time, have been associated with better outcomes.