How do clinical trial participants compare to other patients with schizophrenia?

Patients with schizophrenia enrolled in a trial of long-acting injectable risperidone at multiple sites of the Veterans Health Administration (VHA). We considered if the trial participants were representative of the targeted group of high-utilization patients with poor adherence to anti-psychotics.

Participants' characteristics, health services utilization, and cost in the year prior to randomization were compared to a randomly selected time-matched cohort of 10,000 other patients with schizophrenia who were not in the trial.

There were few differences in the characteristics, utilization, or cost between trial participants and non-participants who met the key trial inclusion criterion of a history of psychiatric hospitalization in the prior 24 months. Trial participants were more likely to be African-American (45.5% vs. 35.1%, p<.001) and were less likely to have had a medical-surgical hospitalization in the study year (8.2% vs. 19.2% p<.001). Compared to non-participants who did not meet the inclusion criterion, trial participants were more likely to have a psychiatric condition in addition to schizophrenia (81.0% vs. 51.3%, p<.001), more likely to have a substance abuse disorder (46.3% vs. 13.9% p<.001), and less likely to be adherent with their anti-psychotic medication (21.3% vs. 37.9%, p<.001). They also incurred more than three times the annual cost ($42,563 vs. $12,270, p<.001).

Trial participants appeared to be representative of the 23.3% of VHA patients with schizophrenia who met the key trial inclusion criterion, suggesting that trial findings will be relevant to the broader group of high risk patients.