NCDEU Poster Session 2012

Impact of Antipsychotic Drug Adherence on the Management of Schizophrenia Among US Medicare Patients

Dario Mirski, MD; Steve Offord, PhD; Bruce Wong, MD; Jay Lin, PhD; and Ross Baker, PhD
From Otsuka America Pharmaceutical, Inc, Princeton, New Jersey (Drs Mirski and Offord); the University of Pennsylvania, Philadelphia, Pennsylvania (Dr Wong); Novosys Health, Flemington, New Jersey (Dr Lin); and Otsuka Pharmaceutical Development and Commercialization, Inc, Princeton, New Jersey (Dr Baker).

This poster presentation was supported by Otsuka America Pharmaceutical, Inc.

Background: Treatment of schizophrenia patients is complicated by drug non-adherence. This study examined the impact of antipsychotic drug adherence on the healthcare usage among Medicare patients with schizophrenia.

Methods: Schizophrenic patients, identified by ICD-9 codes from the MarketScan Medicare claims database from 1/1/2005 to 9/30/2010, were required to have ≥12 months of continuous coverage before and after (follow-up) earliest antipsychotic use. Drug adherence was estimated by medication possession ratio (MPR). High adherence (HA) was defined as a follow-up period MPR ≥0.7; a MPR <0.7 indicated low adherence (LA). Follow-up period healthcare usage was assessed.

Results: 354 patients were identified, 228 (64%) had LA and 126 (36%) had HA with mean ± standard deviation MPRs of 0.24±0.19 and 0.94±0.09, respectively. LA patients had a greater number of hospitalizations (0.68 vs. 0.44; p=0.02) with a longer length of stay (LOS) (7.0 vs. 2.6 days; p=0.005), more schizophrenia-related inpatient services (18.9% vs. 10.3%; p=0.04) and a greater number of schizophrenia relapse hospitalizations (0.22 vs. 0.11; p=0.03) with significantly longer LOS (3.2 vs. 0.7 days; p=0.03). HA patients had a greater number of pharmacy claims (72.97 vs. 49.54; p<0.001) and use of schizophrenia-related medications (11.13 vs. 4.57; p<0.001). After adjusting for major patient characteristics with Generalized Linear Model, high adherence was associated with fewer any-cause hospitalizations (p<0.001) and shorter LOS (p<0.001).

Conclusions: Schizophrenia patients in Medicare have poor adherence to antipsychotics. Patients with low medication adherence vs. high adherence are associated with lower use of schizophrenia-related medication, but more inpatient care and longer LOS.

Learning Objectives:
Poor antipsychotic medication adherence is common among Medicare schizophrenia patients

Poor antipsychotic medication adherence is associated with increased healthcare resource usage

References
Ascher-Svanum H, Zhu B, Faries DE, et al. Medication adherence levels and differential use of mental-health services in the treatment of schizophrenia. BMC Res Notes. 2009;2:6. PubMed

Khaykin E, Eaton WW, Ford DE, et al. Health insurance coverage among persons with schizophrenia in the United States. Psychiatr Serv. 2010;61(8):830–834. PubMed

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