PURPOSE: Treatment adherence for chronic obstructive pulmonary disease (COPD) reduces costly outcomes including emergency department visits and hospitalizations. It is unclear whether adherence rates of initial maintenance therapy differ by various controllers.
METHODS: We used a large health plan database to identify individuals aged 40 and older with evidence of COPD through medical claims with International Classification of Disease, Ninth Revision (ICD-9) diagnosis codes between 1/1/2001 and 8/30/2003. All patients were required to have 18 months of continuous enrollment (12 months pre-index and 6 months post-index). Index date were set as the patient's first pharmacy claim for ipratropium (IPR), salmeterol (SAL), inhaled corticosteroids (ICS), fluticasone and salmeterol combination (FSC), or IPR and albuterol (IPA). Patients were not permitted to receive any COPD treatment other than oral corticosteroids, short-acting β2 agonists (SABA), or theophylline in the 12 months prior to the index date. Adherence rates were measured in both refill counts as well as annual medication possession ratios (MPR). Ordinary least squares (OLS) regression was used to compare the MPR by treatment groups while controlling for key variables.
RESULTS: In all, 9,743 patients were identified, 1,486 IPR, 842 SAL, 2,903 ICS, 2,254 FSC and 2,258 IPA. 65% of the FSC group had refills compared to 40% of SAL, 37% of ICS, 43% of IPA, and 42% of IPR. The mean refill counts (standard deviation) were 3.13 (2.90) for FSC, 2.31 (2.32) for SAL, 1.94 (1.88) for ICS, 2.56 (2.96) for IPA, and 2.57 (2.96) for IPR. MPRs were 0.26 (0.24) for FSC, 0.19 (0.19) for SAL, 0.16 (0.15) for ICS, 0.21 (0.24) for IPA, and 0.21 (0.24) for IPR. Compared to FSC, the MPR for IPR was 5% lower (p<0.001), ICS was 9% lower (p<0.0001), IPA was 5% lower (p<0.0001), and SAL was 7% lower (p<0.0001).
CONCLUSION: Patients initiating FSC had a significantly higher MPR and refill count indicating better adherence to their initial maintenance therapy than patients initiating IPR.
CLINICAL IMPLICATIONS: Adherence is an important factor in determining patient treatment options.
DISCLOSURE: Christopher Blanchette, No Product/Research Disclosure Information; University grant monies NA; Grant monies (from sources other than industry) NA; Grant monies (from industry related sources) NA; Shareholder GlaxoSmithKline; Employee Employee of GlaxoSmithKline; Fiduciary position (of any organization, association, society, etc, other than ACCP NA; Consultant fee, speaker bureau, advisory committee, etc. NA; Other NA