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Bipolar Disorder Healthcare Costs for Quetiapine Extended-Release Versus Aripiprazole
Elise Pelletier, MS; Mariam Hassan, PhD; Berhanu Alemayehu, DrPh; Daniel Smith, MA; and Jennifer Kim, PharmD

Bipolar Disorder Healthcare Costs for Quetiapine Extended-Release Versus Aripiprazole

Elise Pelletier, MS; Mariam Hassan, PhD; Berhanu Alemayehu, DrPh; Daniel Smith, MA; and Jennifer Kim, PharmD
In patients with bipolar disorder, greater reductions in all-cause and mental health“related costs were seen after treatment initiation with quetiapine XR than with aripiprazole.
Objectives: To compare changes in all-cause and mental health–related costs after initiation of extended-release quetiapine (quetiapine XR) or aripiprazole among patients with bipolar disorder enrolled in managed care plans.

Study Design: Retrospective cohort study.

Methods: The cohort consisted of adults with at least 2 prescriptions for quetiapine XR or aripiprazole from June 1, 2007, to June 30, 2008, and at least 2 diagnoses of bipolar disorder within 6 months before the first prescription (index date). The difference in all-cause and mental health–related costs (6 months after index date minus 6 months before index date) and their components (ie, inpatient, outpatient, pharmacy) were compared between treatments using Wilcoxon rank-sum tests.

Results: A total of 287 bipolar disorder patients initiated therapy with quetiapine XR and 4554 initiated therapy with aripiprazole. There were signifi cantly greater reductions in mean costs per patient with quetiapine XR compared with aripiprazole for total all-cause healthcare costs (P = .029), all-cause hospitalizations (P = .006), total mental health–related costs (P <.001), and mental health–related hospitalizations (P = .003).

Conclusions: In patients with bipolar disorder, greater reductions in all-cause and mental health–related costs were seen after treatment initiation with quetiapine XR than with aripiprazole.

Am J Pharm Benefits. 2013;5(3):e73-e79
Extended-release quetiapine (quetiapine XR) and aripiprazole are 2 atypical antipsychotics approved for the treatment of bipolar disorder.
  • Quetiapine XR provided greater reductions in all-cause and mental health–related costs from 6 months before to 6 months after treatment initiation compared with aripiprazole.

  • Patients with bipolar disorder also had greater reductions in inpatient healthcare costs (after adjustment for inflation) with quetiapine XR than with aripiprazole.
Bipolar disorder affects approximately 2.6% (5.7 million) of adult Americans annually and is the most costly mental health disorder.1-3 Patients with bipolar disorder suffer from recurrent episodes of mania and depression, and the chronic relapsing course of the disease results in substantial use of direct medical resources.4,5

The total costs associated with bipolar disorder were estimated to be around $45.2 billion based on 2001 values.6 Hospitalizations in patients with bipolar disorder are common and represent the major cost driver.7-9 Among the different phases of bipolar disorder, bipolar depression has the highest rate of hospitalizations and overall medical costs within 12 months after diagnosis.10

There is limited research on the healthcare utilization and costs of patients treated with atypical antipsychotics for bipolar disorder.11-17 Extended-release quetiapine (quetiapine XR) and aripiprazole are 2 atypical antipsychotics approved for the treatment of bipolar disorder. The bipolar indication profiles for quetiapine XR and aripiprazole differ. Quetiapine XR is indicated for the acute treatment of bipolar I manic and mixed episodes, both as monotherapy and as an adjunct to lithium or divalproex; for the acute treatment of bipolar depressive episodes; and for maintenance treatment of bipolar I disorder as an adjunct to lithium or divalproex.18 Aripiprazole is indicated for acute and maintenance treatment of bipolar I manic and mixed episodes, both as monotherapy and as an adjunct to lithium or divalproex; however, it is not indicated for the treatment of acute bipolar depressive episodes.19 Because economic data are scant in the published literature on the use of quetiapine XR or aripiprazole for the management of bipolar disorder in real-world settings, the objective of this retrospective study was to assess any differences in all-cause and mental health–related costs after initiation of treatment with quetiapine XR or aripiprazole among patients with bipolar disorder in a managed care population.

METHODS

This retrospective cohort study extracted medical and pharmacy claims data from the IMS PharMetrics Database (IMS Lifelink Health Plan Claims Database) for the period from January 2007 through December 2008. This retrospective database includes fully adjudicated claims from more than 100 health plans across the United States. Patients in the database are representative of the national commercially insured population on a variety of demographic measures including age and sex. The data also are longitudinal, with an average member enrollment time of 2 years. Inpatient and outpatient diagnoses (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] format), procedures (Current Procedural Terminology, 4th Edition, Healthcare Common Procedure Coding System), and standard and mail order prescription records are included in the data set. Reimbursed payments and charged amounts are available for all services rendered, as well as dates of service for all claims. Additional data elements include demographic variables (age, sex, geographic region),plan type  (eg, health maintenance organization [HMO], preferred provider organization [PPO]), payer type (eg, commercial, self-pay), provider specialty, and start and stop dates for plan enrollment.

Inclusion and Exclusion Criteria

Patients were included in the study if they had at least 2 prescriptions for quetiapine XR or aripiprazole from June 1, 2007, to June 30, 2008, were at least 18 years of age on the date of the first quetiapine XR or aripiprazole prescription (index date), were continuously enrolled in the same health plan for at least 6 months prior to and 6 months after the index date, and had at least 2 diagnoses of bipolar disorder based on ICD-9-CM codes (296.0x-296.8x) on 2 separate days within the 6 months prior to or on the index date. Patients were excluded if they were members of a health plan that carved out mental health services (completeutilization and cost data were unavailable for these members), had invalid data on days of supply, or if they were 65 years or older with incomplete claims records.

Demographic information along with claim information for hospitalizations, outpatient services, and prescription medications were extracted for patients in the cohort. All data conformed to Health Insurance Portability and Accountability Act patient privacy standards.

Measurement of Cost

The “allowed amount,” a predetermined amount of the billed charge that the insurance company has agreed to pay to the provider, was used as a proxy for medical (inpatient, outpatient, and pharmacy) costs. The allowed amount was chosen in this study, as it reflects the real-world cost of services to the insurer. All costs were expressed in 2008 US dollars and were adjusted, as necessary, using the medical care component of the US Consumer Price Index. All-cause healthcare costs included all inpatient and outpatient services and prescriptions. Mental health–related healthcare costs included inpatient and outpatient services with an ICD-9-CM code for a mental health disorder (290.xx-316.xx) and pharmacy costs for psychiatric medications.

All-cause and mental health–related costs per patient were calculated for each treatment group during the 6 months prior to the index date and the 6 months following the index date. These 2 time periods were compared to determine the change in cost per patient after initiating therapy with quetiapine XR or aripiprazole.

Statistical Analyses

Unadjusted changes in all-cause and mental health–related total costs as well as component costs (inpatient services, outpatient services, and pharmacy services) per patient during the 6 months before and 6 months after the index date were compared between treatments using Wilcoxon rank-sum tests. All analyses were conducted using SAS versions 8.2 and 9.1 (SAS Institute Inc, Cary, North Carolina), and findings with a P value of <.05 were considered statistically significant.

RESULTS

During the index period, 287 patients with bipolar disorder were treated with quetiapine XR and 4554 patients were treated with aripiprazole (Table 1). Most patients were between 18 and 64 years of age, enrolled in a commercial plan, and had a Charlson Comorbidity Index20 score of 0 or 1. Of the baseline characteristics, only sex and geographic region were significantly different between the 2 treatment groups. The quetiapine XR group included a greater proportion of males compared with aripiprazole-treated patients (41.1% vs 31.0%, respectively; P <.001). Although there was a statistically significant difference between the 2 treatment groups in geographic region (P <.001), with the largest difference being for patients from the West, the overall distributions were similar (ie, greater proportions of patients from the Northeast and Midwest).

All-Cause Healthcare Costs

During the 6-month preindex period, the mean (standard deviation, median) total all-cause healthcare costs per patient were $11,213 ($12,942, $6967) for the quetiapine XR group and $10,395 ($14,491, $6331) for the aripiprazole group. For both treatments, all-cause total costs and inpatient costs were reduced in the 6 months after treatment initiation compared with the 6 months before treatment initiation, but to a significantly greater extent in quetiapine XR patients versus aripiprazole patients (Figure 1; Table 2). The mean per patient reductionin costs for all-cause total health services was $1368 for quetiapine XR and $8 for aripiprazole (P = .029), while the reduction for all-cause hospitalizations was $2577 for quetiapine XR and $1395 for aripiprazole (P = .006) (Table 2). The proportion of patients with at least 1 admission decreased by 16.4% in the quetiapine XR group and 11.3% in the aripiprazole group, while the mean length of stay decreased by 1.4 days in quetiapine XR patients and 0.2 days in aripiprazole patients. The time to first hospitalizationpostindex was longer with quetiapine XR than with aripiprazole (93.4 vs 77.3 days, respectively). Pharmacy costs increased in the 6-month postindex period for both cohorts, but aripiprazole patients had a significantly greater mean per patient cost increase compared with quetiapine XR patients (P = .022) (Table 2). In the 6-month postindex period, the mean number of quetiapine XR prescriptions in the quetiapine XR cohort was 4.7 and the mean number of aripiprazole prescriptions in the aripiprazole cohort was 4.6.

Mental Health–Related Healthcare Costs

The mean per patient reduction in costs for all mental health–related services was $1303 for quetiapine XR compared with an increase of $302 per patient with aripiprazole (P <.001) (Table 3). Mean per patient inpatient costs for mental health–related services were lowered with both treatments, while mean per patient outpatient mental health–related costs were not significantly different. The reduction in inpatient costs was significantly greater in the quetiapine XR patients than in the aripiprazole patients (Figure 2; Table 3). The mean per patient reduction in costs for mental health–related hospitalizations was $2195 for quetiapine XR and $1038 for aripiprazole (P = .003). The proportion of patients with at least 1 admission decreased by 16% in the quetiapine XR group and 10.8% in the aripiprazole group. The mean length of stay decreased by 1.3 days in quetiapine XR patients and increased by 0.5 days in aripiprazole patients. The time to first hospitalization in the postindex period was longer with quetiapine XR than with aripiprazole (83.8 vs 74.7 days, respectively). The mean increase in mental health–related pharmacy costs was higher in the aripiprazole group ($1451) compared with the quetiapine XR group ($1163) (P = .004) (Table 3).

DISCUSSION

This study compared the healthcare costs of quetiapine XR and aripiprazole, 2 atypical antipsychotics used in the treatment of patients with bipolar disorder. Although quetiapine XR and aripiprazole are approved for the treatment of bipolar disorder, they have different US Food and Drug Administration–approved bipolar indications.18,19 Although previous studies have compared other second-generation antipsychotics,11-17 there are no data on the comparative healthcare costs of quetiapine XR and aripiprazole in bipolar disorder.

 
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