Objective: Based on The Clinical Antipsychotic Trial of Interventional Effectiveness (CATIE), discontinuation of antipsychotic medications is common (74%) among schizophrenia patients. This study investigated whether discontinuation of antipsychotics within the first 3 months of initiation predicts a patient's adherence to antipsychotic therapy over the following 9 months. Methods: Patients with schizophrenia were identified using the MarketScanTM Commercial and Medicare claims databases between 1/1/2005 and 9/30/2010 and categorized into early nonadherent (NAD) and adherent (AD) groups by evaluating whether they had a medication gap of ≥30 days within the first 90 days after drug initiation. For 12 months, medication possession ratios (MPR: time patients possessed antipsychotic medication compared to total expected duration of therapy) were determined in quarterly increments. Results: Sixty percent of commercially insured (873/1,462) and 54% (192/354) of Medicare insured schizophrena patients were nonadherent to antipsychotic therapy early. For the commercially insured NAD vs. AD groups, quarterly mean MPRs were Q1: 0.57 vs. 0.99, p<0.0001; Q2: 0.27 vs. 0.75, p<0.0001; Q3: 0.28 vs. 0.64, p<0.0001; Q4: 0.25 vs. 0.60, p<0.0001. For the Medicare insured NAD vs. AD groups, quarterly mean MPRs were Q1: 0.58 vs. 0.98, p<0.0001; Q2: 0.28 vs. 0.75, p<0.0001; Q3: 0.26 vs. 0.68, p<0.0001; Q4: 0.24 vs. 0.59, p<0.0001. Conclusion: A majority of patients with schizophrenia are nonadherent to antipsychotics within the first 3 months of treatment initiation and these patients are less likely to adhere to later antipsychotic therapy. Preventing early discontinuation of antipsychotics may improve medication adherence in the longer term of schizophrenia management.
Bruce Wong, MD; Steve Offord, PhD; Jay Lin, PhD, MBA; Dario Mirski, MD
Otsuka America Pharmaceutical, Inc.