Pulmonary Medication Adherence and Health-care Use in Cystic Fibrosis

BACKGROUND: Poor treatment adherence is common in cystic fibrosis (CF) and may lead to worse health outcomes and greater health-care use. This study evaluated associations of adherence to pulmonary medications, age, health-care use, and cost among patients with CF. METHODS: Patients with CF aged >= 6 years were identified in a national commercial claims database. A 12-month medication possession ratio (MPR) was computed for each pulmonary medication and then averaged for a composite MPR (CMPR) for each patient. The CMPR was categorized as low (< 0.50), moderate (0.50-0.80), or high (>= 0.80). Annual health-care use and costs were measured during the first and second year and compared across adherence categories by multivariable modeling. RESULTS: Mean CMPR for the sample (N = 3,287) was 48% +/- 31%. Age was inversely related to CMPR. In the concurrent year, more CF-related hospitalizations were observed among patients with low (event rate ratio [ERR], 1.35; 95% CI, 1.15-1.57) and moderate (ERR, 1.25; 95% CI, 1.05-1.48) vs high adherence; similar associations were observed for all-cause hospitalizations and CF-related and all-cause acute care use (hospitalizations + ED) in the concurrent and subsequent year. Rates of CF-related and all-cause outpatient visits did not differ by adherence. Low and moderate adherence predicted higher concurrent health-care costs by $14,211 ($5,557-$24,371) and $8,493 (-$1,691 to $19,709), respectively, compared with high adherence. CONCLUSIONS: Worse adherence to pulmonary medications was associated with higher acute health-care use in a national, privately insured cohort of patients with CF. Addressing adherence may reduce avoidable health-care use.