Cardiovascular-Related Healthcare Resource Utilization and Costs
Community Survey) in terms of age and sex, although the population in the database is slightly younger, because all members are commercially insured. All personally identifiable data used in this study were deidentified and were accessed with protocols that are compliant with the Health Insurance Portability and Accountability Act of 1996. Patient confidentiality was preserved, and the anonymity of all patient data w as safeguarded throughout the study. No waiver of informed consent was required from an Institutional R eview Board.
Study Design Claims were obtained from the HealthCore Integrated Research Database during the study period (July 1, 2007-June 30, 2013). Patients included in the analysis were aged ≥18 years with a diagnosis of hypertension (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] 401.xx-404.xx) in an inpatient or outpatient setting during the patient identification period (January 1, 2008-December 31, 2012). To be included in the analysis, patients had to receive metoprolol for at least 6 months before switching to nebivolol, and then receive nebivolol for at least 6 months after switching from metoprolol. A treatment gap of less than 30 days of prescription supply was considered a continuous or stable drug regimen. The index date was defined as the date the patient switched from metoprolol to nebivolol; the preperiod (baseline) was defined as the 6 months of treatment with metoprolol before the index date, and the postperiod was the 6 months of continuous treatment with nebivolol after the index date. All patients were continuously enrolled in a health plan during the preperiod and postperiod (Figure 1). Patients were excluded from the analysis if they had any compelling indications identified by ICD-9-CM diagnosis codes, for which metoprolol but not nebivolol is an approved treatment (eg, angina [ICD-9-CM codes 411.1x and 413.xx], myocardial infarction [410.xx and 412.xx], or congestive heart failure [428.xx, 402.01, 402.11, 402.91, 404.x1, and 404.x3]). Patients were also excluded if they did not maintain a stable background treatment of other classes of antihypertensive medications (eg, angiotensin-II receptor blockers) during the preperiod and postperiod (Figure 2). Outcome Measures The primary outcome measures were healthcare resource utilization and costs associated with specific CV events, including cerebrovascular disease (including stroke), chronic ischemic heart disease, acute coronary syndrome, peripheral vascular disease, valvular disease, arrhythmia, and aortic aneurysm. CV-related resource utilization was calculated as the
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number of times a healthcare resource was utilized divided by the number of months of follow-up during the preperiod or postperiod, multiplied by 100 patients, to reach the healthcare resource utilization per 100 patients per month. Figure 1 Study Design Study period July 1, 2007-June 30, 2013 Patient identification period January 1, 2008-December 31, 2012 Index date (initial fill date for nebivolol)
X
Preindex period (6 months)
Postindex period (6 months)
Metoprolol users who switched to nebivolol
Outcomes of interest: 1. P reindex to postindex change in CV-related PPPM healthcare costs 2. P reindex to postindex change in CV-related healthcare utilization
CV indicates cardiovascular; PPPM, per-patient per-month.
Figure 2 Study Cohort Selection
4,326,022
Included patients aged ≥18 years at the first observed diagnosis of hypertension in the inpatient or outpatient setting during the patient identification period
1751
Included patients who started using metoprolol and continued for at least 6 months, then switched to nebivolol and continued for at least 6 months during the continuous health plan enrollment
1547
Excluded patients with any compelling indications for metoprolol (eg, angina, myocardial infarction, congestive heart failure) during the preperiod and postperiod
765
Excluded patients who did not maintain a stable background treatment of other classes of antihypertensive medication, for example, angiotensin-II receptor blockers (defined as prescription supply gap of <30 days), during the preperiod and postperiod
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