Therapy persistence and adherence in patients with chronic obstructive pulmonary disease: multiple versus single long-acting maintenance inhalers.

OBJECTIVE: To compare persistence and adherence among patients with chronic obstructive pulmonary disease (COPD) treated with either multiple- or single- long-acting maintenance inhalers.
METHODS: Patients with ≥2 COPD medical claims and ≥2 prescriptions for a long-acting inhaler within 1 year were classified as single- or multiple-inhaler users based on their treatment regimen (MarketScan database; 2004-2008) and matched on demographics and statistically significant baseline characteristics. Persistence, analyzed via time to treatment discontinuation, and treatment adherence, measured by proportion of days covered (PDC), were compared between the two groups over a 12-month period. Sensitivity analyses were conducted in patients with poorly and well-controlled disease.
RESULTS: A total of 23,494 patients were grouped into 11,747 matched pairs. After adjusting for confounding factors, multiple-inhaler users had a significantly higher discontinuation rate [Hazard ratio = 1.40, p < 0.0001] compared with single-inhaler users. Multiple-inhaler users were less likely to be adherent than single-inhaler users with an average PDC of 0.51 (SD = 0.272) vs. 0.55 (SD = 0.279), respectively (p < 0.0001). These results were consistent for the poorly- and well-controlled disease groups.
CONCLUSIONS: Multiple long-acting inhaler users demonstrated lower treatment persistence and adherence rates than single long-acting inhaler users. Limitations of the study are related to the retrospective, observational design and use of claims data.