Fixed-dose combination and single active ingredient drugs: a comparative cost analysis.
OBJECTIVE This study evaluated the use and drug costs of inhaled corticosteroids (ICSs), long-acting beta2-agonists (LABAs), and fluticasone propionate and salmeterol in a fixed-dose combination (FSC) and their relationship to asthma exacerbations before and after the market introduction of FSC in April 2001. METHODS This is a retrospective analysis of employer-sponsored health insurance claims filed between January 1, 1998, and December 31, 2003 to detect impact of introduction of FSC (approved by the US Food and Drug Administration in August 2000) on utilization and cost of FSC, any ICS (excluding FSC), and any LABA (excluding FSC) along with utilization of medical services related to asthma exacerbations. Asthma medications were identified using National Drug Codes and Redbook, whereas asthma exacerbations were identified using ICD-9-CM primary diagnosis code 493.x. These medical and pharmacy claims were converted to rates per 100 asthma office visits. RESULTS For all ICSs, the average pharmacy claims per 100 office visits increased from 383 in the year before FSC was introduced to 407 (120 [29.5%] were for FSC and 287 [70.5%] were for single-entity ICSs) in 2003. LABA prescribing increased from 72 in the year before FSC to 147 (120 from FSC, 27 single-entity LABA) in 2003 (p < 0.001). An additional $13,511 per 100 asthma office visits was spent on the FSC product (p < 0.001). After the introduction of FSC, there was no significant difference in asthma admissions (p = 0.17), whereas emergency department (ED) visits increased by 0.92 visits per 100 office visits (p = 0.03). The diagnosis and severity of asthma was inferred from the pharmacy claims and patients with chronic obstructive pulmonary disease could not be excluded. In addition, the study was not designed to assess the impact of other asthma medications on the disease and/or associated costs, and patient adherence to claimed medication could not be monitored. CONCLUSIONS The introduction of FSC was associated with increased LABAs/FSC patient exposure and expenditure with no change in asthma hospitalizations and an increase in ED visits.