Using pharmacy data on partial adherence to inform clinical care of patients with serious mental illness

Objective: Low adherence to antipsychotic medications is a risk factor for poor outcomes for people with serious mental illness. Pharmacy data might be used by health systems to identify partially adherent patients for interventions. This study assessed whether using pharmacy data is an accurate screening method for identifying at-risk patients. Methods: Administrative data were used to identify 1,712 veterans as having schizophrenia or a schizoaffective or bipolar disorder and who had 12-month antipsychotic medication possession ratios (MPRs) of less than .80. Patients' charts were reviewed for alternative explanations for low rates of filling prescriptions for antipsychotic medication. Results: Of 1,712 patients whose pharmacy data indicated partial adherence (MPRs less than .80), 17% (N= 297) may have been adherent. Patients with bipolar disorder had higher odds of receiving a false-positive designation (adjusted odds ratio of 1.8, 95% confidence interval of 1.31-2.39). Conclusions: MPRs constructed from pharmacy data can be a useful first screen for identifying patients who need assistance with medication adherence.