Background: This prospective study measured adherence to conventional and atypical antipsychotics after hospital discharge in patients with a diagnosis of schizophrenia and schizoaffective disorder. We examined the interaction of several predictors such as gender, severity of illness, attitudes toward medications, side effects, and dose frequency.
Method: The sample consisted of consecutive randomized and nonrandomized patients who were discharged from an inpatient unit with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder between December 1995 and July 1999. All patients were taking oral antipsychotics and consented to the use of an electronic adherence monitor at discharge. Medications were prescribed by usual care providers, and medication adherence was followed weekly for 3 months. The outcome measure was the medication adherence rate registered in the electronic monitors.
Results: We found no significant difference in adherence between the combined groups of atypical and conventional antipsychotics. Individual medication analysis found better medication adherence with olanzapine in comparison with risperidone and conventional antipsychotics, but the difference disappeared in the final model controlling for dose frequency. Dose frequency, gender, and akathisia predicted adherence.
Conclusions: Olanzapine initially appeared to be associated with an adherence advantage over risperidone and conventional antipsychotics, but the apparent advantage may have been due to a usual care dose frequency practice that associated olanzapine more often with once-daily dosing. This study suggests that dose frequency is an important predictor of medication adherence. An important caveat is that these results apply only to short-term adherence.