Changes in Antipsychotic Pharmacotherapy and Healthcare Costs Following a New Diagnosis of Diabetes among Patients with Schizophrenia Douglas L. Leslie, PhD Robert Rosenheck, MD New England Mental Illness Research, Education and Clinical Center (MIRECC); VA Northeast Program Evaluation Center (NEPEC); Yale Medical School

Background First-generation antipsychotics were introduced in the 1950’s Second-generation antipsychotics –clozapine, olanzapine, risperidone, quetiapine –At least as effective as first-generation drugs –Have fewer side effects –Associated with weight gain and diabetes FDA warning

Objectives To determine risk of new-onset diabetes associated with antipsychotic medications. To identify the costs associated with treatment of new-onset diabetes. To determine whether patients switch antipsychotic medications after diagnosis of diabetes.

Sample Patients with schizophrenia treated in the VA Healthcare System. No pre-existing diabetes. “Stable” on an antipsychotic medication. Followed for up to 2 years between June 1999 and September ,849 patients included in the study.

Methods Patients with a new diagnosis of diabetes were identified. Cox proportional hazards model. A matched control group of patients who did not develop diabetes was identified. Medication changes and costs were compared.

Stable period (3 months) Diabetes onset date Diabetes patient Study timeline D Stable period (3 months) Pseudo diabetes onset date Matched non- diabetes patient D June 1999September 2001

Results Patients were followed for an average of 15.7 months 4,132 patients had a new diagnosis of diabetes – annual incidence rate of 4.36% Unadjusted diabetes risk was highest for clozapine and olanzapine Total healthcare costs were $3,104 higher for patients with diabetes

Month

Percentage of patients who switch/discontinue antipsychotic medication after diabetes onset Last medication before “diabetes date” NodiabetesWithdiabetes p clozapine9.8%4.6%0.092 olanzapine25.2%23.1%0.179 quetiapine40.1%31.9%0.053 risperidone28.2%24.2%0.023 conventional24.3%22.0%0.097

Diabetes risk and costs attributable to second-generation drugs MedicationAttributablerisk Attributable cost per day* clozapine2.03%$0.134 olanzapine0.63%$0.042 quetiapine0.80%$0.053 risperidone0.05%$0.003 * Based on average cost of $198/month per case of diabetes Average cost per day of therapy $8.34 $6.86 $3.72 $3.65

Conclusions Very high rate of diabetes onset in this population (4-5% per year) Results do not support a “class effect” Onset of diabetes does not affect antipsychotic pharmacotherapy Diabetes risk and treatment costs attributable to second-generation drugs are small