Objective: To compare asthma-related resource utilization, adherence and costs among adults prescribed asthma controller regimens.
Research design and methods: Medical and pharmacy claims from a US managed-care claims database were used to identify adults (18-56 years) initiating asthma controller therapy. Patients had 2 years continuous enrollment and ≥ 1 medical claims for asthma (ICD9: 493.xx) (January 2004 - March 2009). Asthma exacerbations, short-acting β-agonist (SABA) fills, adherence (MPR ≥ 0.80) and asthma-related costs were assessed for 1 year after the initial asthma controller medication claim. Separate logistic and negative binomial regression models for monotherapy and combination therapy were developed to examine the impact of controller therapy on outcomes.
Results: A total of 28 074 patients [inhaled corticosteroids (ICS) (26.3%), leukotriene modifiers (LM) (23.2%), ICS + long acting β-agonist (LABA) (48.5%), ICS + LM (2%)] were included. LM patients had lower odds of ≥ 6 SABA fills (OR(adj) = 0.83, 95% CI: 0.73-0.96) and lower rates of asthma exacerbations (RR(adj) = 0.82, 0.75-0.89) vs. ICS patients. Odds of ≥ 6 SABA fills were similar for ICS + LM vs. ICS + LABA (OR(adj) = 1.3, 0.96-1.76); the rate of asthma exacerbations was greater for ICS + LM compared with ICS + LABA (OR(adj) = 1.4, 1.2-1.6). The proportion adherent was greatest for LM (14.9%) and ICS + LABA (4.1%). LM patients had higher unadjusted pharmacy costs, but lower medical costs compared to ICS patients. For combination therapy, ICS + LM had higher unadjusted mean medical and pharmacy costs vs. ICS + LABA. Higher adjusted mean total costs in the post-index period were observed for LM vs. ICS patients ($837 vs. 684) and for ICS + LM vs. ICS + LABA patients ($1223 vs. 873).
Conclusions: LM monotherapy was associated with lower medical costs but higher total costs resulting from greater treatment adherence. Conversely, higher costs for ICS + LM resulted from greater exacerbations compared to ICS + LABA despite similar adherence. Higher total costs with LM were due to drug costs. Precise utilization of the medications filled by patients could not be determined.