Adherence to treatment with antipsychotic medication and health care costs among Medicaid beneficiaries with schizophrenia.
OBJECTIVE
The authors' goal was to evaluate the relationship between adherence to treatment with antipsychotic medication and health expenditures. A secondary objective was to identify risk factors predictive of nonadherence.


METHODS
Data included Medicaid eligibility and claims data from 1998 to 2000 for San Diego County, Calif. Pharmacy records were used to assess adherence to treatment with antipsychotic medication according to the cumulative possession ratio (the number of days medications were available for consumption divided by the number of days subjects were eligible for Medi-Cal). Regression models were used to examine risk factors, hospitalizations, and costs associated with nonadherence, partial adherence, adherence, and excess fills of antipsychotic medication.


RESULTS
Forty-one percent of Medicaid beneficiaries with schizophrenia were found to be adherent to treatment with their antipsychotic medications: 24% were nonadherent, 16% were partially adherent, and 19% were excess fillers. Rates of psychiatric hospitalization were lower for those who were adherent (14%) than for those who were nonadherent (35%), partially adherent (24%), or had excess fills (25%). Rates of medical hospitalization were lower for those who were adherent (7%) than for those who were nonadherent (13%) or had excess fills (12%). Those who were adherent had significantly lower hospital costs than the other groups; pharmacy costs were higher among those who were adherent than among those who were nonadherent or partially adherent and were highest for excess fillers. Total costs for excess fillers (14,044 US dollars) were substantially higher than total costs for any other group.


CONCLUSIONS
Despite the widespread use of atypical antipsychotic medications, alarmingly high rates of both underuse and excessive filling of antipsychotic prescriptions were found in Medicaid beneficiaries with schizophrenia. The high rates of antipsychotic nonadherence and associated negative consequences suggest interventions on multiple levels.
Gilmer
Todd P
TP
Department of Family and Preventive Medicine, University of California, San Diego, La Jolla 92093-0622, USA. tgilmer@ucsd.edu
Dolder
Christian R
CR
Lacro
Jonathan P
JP
Folsom
David P
DP
Lindamer
Laurie
L
Garcia
Piedad
P
Jeste
Dilip V
DV
D000328:Adult; D014150:Antipsychotic Agents / Q000191:economics* / Q000627:therapeutic use*; D002140:California; D002391:Catchment Area, Health; D005260:Female; D017048:Health Care Costs; D006302:Health Services Research; D006801:Humans; D008297:Male; D008484:Medicaid / Q000191:economics*; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D012559:Schizophrenia / Q000188:drug therapy* / Q000191:economics*; D012646:Self Administration / Q000191:economics* / Q000706:statistics & numerical data
D014150:Antipsychotic Agents