Objective: To measure and compare persistency stratified by age groups for initially prescribed antipsychotics and whether improved persistency lowers total mental healthcare cost; specifically, we compared quetiapine to other antipsychotics.
Design: Using longitudinal claims data from approximately 180 managed care organizations (MCOs), we identified 220 newly diagnosed psychotic patients who were initiated on quetiapine monotherapy during an 18-month period.
Materials and Methods: Patients were randomly selected to match the study start dates for the quetiapine group to populate the haloperidol, olanzapine, and risperidone groups and a composite cohort consisting of olanzapine, risperidone, and clozapine (all other atypicals besides quetiapine). Patients were then divided into 2 groups; patients 45 to 64 years and ³65 years. Patients were monitored for over 1 year to determine how many remained on initially prescribed monotherapy, added to their existing therapy, switched to another antipsychotic, or discontinued medication. Overall cost analysis included multivariate regression analyses for costs of total annual healthcare, outpatient services and inpatient services.
Results: Persistence with initially prescribed medication was found to reduce average annual healthcare costs to MCOs from $1218.76 to $900.10 for the 45- to 64-year-old age group and from $896.95 to $421.81 for the 65-year-old group. For those aged 45 to 64 years, quetiapine-treated patients remained on treatment for 284 versus 144 monodays for haloperidol (P<0.01), 284 versus 147 for olanzapine (P<0.01), 281 versus 261 for risperidone (P=0.71), and 293 versus 164 for the composite cohort (P=0.02). Corresponding cost analyses indicated savings for this age group of $665.34/year per patient versus haloperidol, $95.05 versus risperidone, $651.08 versus olanzapine, and $422.96 versus the composite cohort. In the 65 group, patients persisted with quetiapine for 260 versus 68 monodays for haloperidol (P<0.01), 258 versus 192 monodays for olanzapine (P=0.16), 278 monodays versus 201 for risperidone (P=0.05), and 258 versus 199 monodays for the composite cohort (P=0.31). Cost savings for the 65 group were $912.46/year per patient for quetiapine versus haloperidol, $365.93 versus risperidone, $313.66 versus olanzapine, and $280.39 versus the composite cohort.
Conclusion: In this study, older patients persisted with initially prescribed monotherapy longer when they were treated with quetiapine. Persistence reduced overall healthcare costs, especially inpatient costs. The cost differential in our study was in favor of quetiapine in both age groups, even in the ³65-year-old patients (elderly population), where the average cost to MCOs is lower because of Medicare assistance.
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