Impact of formulary-related pharmacy claim rejections of cariprazine on health care utilization and treatment patterns among patients with bipolar I disorder.

BACKGROUND: Formulary restrictions, intended to limit inappropriate medication use and decrease pharmacy costs, may prevent or delay patients with bipolar I disorder from initiating cariprazine, a dopamine D3 -preferring D3 /D2 and serotonin 5HT1A receptor partial agonist that is approved to treat manic/mixed or depressive episodes associated with bipolar I disorder. Little is known about the downstream consequences of formulary-related cariprazine prescription rejections.

OBJECTIVE: To evaluate the impact of formulary-related cariprazine claim rejections on health care resource utilization (HCRU) and treatment patterns among patients newly prescribed cariprazine for bipolar I disorder.

METHODS: Symphony Health Integrated Dataverse was used to identify commercially insured adults (aged ≥18 years) with bipolar I disorder and at least 1 pharmacy claim for cariprazine (rejected because of formulary restrictions or approved; date of the first claim is the index date) from March 2015 through October 2020. Formulary-related rejection reasons included noncoverage, prior authorization requirement, and step therapy requirement. Baseline characteristics were evaluated during the 12 months pre-index and balanced between rejected and approved cohorts using 1:2 propensity score matching. HCRU outcomes included all-cause and mental health (MH)-related hospitalizations, emergency department (ED) visits, and outpatient visits. Treatment patterns were analyzed descriptively and included treatment delay and atypical antipsychotic use. HCRU was reported per patient-year and compared between cohorts using rate ratios; 95% CIs and P values were calculated using nonparametric bootstrap procedures.

RESULTS: The matched rejected and approved cohorts comprised 1,554 and 3,108 patients, respectively. The rejected cohort had 22% more all-cause and 24% more MH-related hospitalizations per patient-year vs the approved cohort (rate ratio [95% CI], all-cause: 1.22 [1.01-1.48], P = 0.024; MH-related: 1.24 [1.01-1.55], P = 0.044). ED and outpatient visits were numerically, but not significantly, greater in the rejected cohort. Of patients in the rejected cohort, 34.7% never received an atypical antipsychotic and 76.8% never received cariprazine. For those who later received cariprazine or another atypical antipsychotic, the average treatment delay was approximately 6 months (188 days) and approximately 4 months (123 days) after the initial rejection, respectively.

CONCLUSIONS: Patients with bipolar I disorder and formulary-related cariprazine claim rejections experienced significantly more hospitalizations than patients whose initial claim was approved; ED and outpatient visits were similar between cohorts. Less than a quarter of patients whose initial claim was rejected later received cariprazine, and more than one-third never received any atypical antipsychotic. To our knowledge, this is the first study to evaluate the impact of formulary-related rejections of cariprazine on HCRU and treatment patterns in patients with bipolar I disorder.