Impact of splitting risperidone tablets on medication adherence and on clinical outcomes for patients with schizophrenia.

Tablet splitting is a strategy aimed at reducing the cost of prescriptions. Some clinicians question whether patients with psychosis can understand and follow tablet-splitting instructions. The clinical impact of tablet splitting for individuals with severe mental illness is unknown. The research objectives were to determine whether risperidone tablet splitting is associated with changes in medication adherence, service utilization, or clinical outcomes. The study was a retrospective analysis of administrative data from the New York-New Jersey region of the Veterans Health Administration for 2,436 individuals with schizophrenia or schizoaffective disorder who were prescribed risperidone from January 2001 through March 2003. Antipsychotic medication adherence was measured by medication possession ratio (MPR). Clinical outcomes included attendance at scheduled and unscheduled outpatient appointments and psychiatric and medical admission rates. The MPR increased from .83 to .90 (p<.001) after initiating tablet splitting. The rate of unscheduled mental health appointments increased significantly, particularly in the first 60 days after initiating splitting; attendance at scheduled outpatient mental health appointments was unchanged. Psychiatric admission and general medical admission rates were unchanged. The results provide some assurance that prescribing tablet splitting for patients with schizophrenia does not result in poor outcomes as measured by psychiatric and medical inpatient admissions. Increased MPRs and unscheduled appointments suggest that some patients may have experienced minor difficulty, especially early on (crumbled tablets or misunderstood splitting instructions). Patients should be instructed carefully when tablet splitting is prescribed. Future studies should address longer-term clinical outcomes and systemwide costs.