Objective: Pharmacy refill records were used to compare medication adherence in outpatient veterans receiving typical versus atypical antipsychotic medications.
Method: Consecutive patients meeting selection criteria and receiving prescriptions for haloperidol (N=57), perphenazine (N=60), risperidone (N=80), olanzapine (N=63), and quetiapine (N=28) over a 3-month period were identified from a computerized database. The hospital policy at the time of this study required failure in trials of at least two typical antipsychotics before initiation of an atypical agent. Patients' adherence with the antipsychotic regimen was calculated by analyzing refill records for up to 12 months. The cumulative mean gap ratio (the number of days when medication was unavailable in relation to the total number of days) and the compliant fill rate (the number of prescription fills indicating adherence in relation to the total number of prescription fills) at 6 and 12 months were calculated.
Results: Adherence rates at 6 and 12 months were moderately higher in patients who received atypical antipsychotics than in those who received typical agents. Cumulative mean gap ratios were 23.2% for typical and 14.1% for atypical antipsychotics at 12 months; thus, patients who received typical agents were without medication for an average of 7 days per month, compared with 4 days per month for those who received atypical agents. At 12 months, compliant fill rates were 50.1% for typical and 54.9% for atypical antipsychotics.
Conclusions: Interventions to improve adherence are warranted even for patients who receive atypical antipsychotic medications.