Abstract
BACKGROUND: Rapid growth in prescription drug costs has compelled insurers to require increased patient cost-sharing. OBJECTIVE: The aim of this study was to compare the effects of 2 recent cost-sharing policies on emergency hospitalizations due to chronic obstructive pulmonary disease, asthma, or emphysema (CAE), and on physician visits. METHODS: We analyzed data from a large-scale natural experiment in British Columbia (BC), Canada. The cost-sharing policies were a fixed copayment policy (fixed copay policy) and an income-based deductible (IBD) policy with 25% coinsurance (IBD policy). Prescription, physician billing, and hospitalization records were obtained from the BC Ministry of Health. From the total population of BC residents > or = 65 years of age, we extracted data from all patients dispensed an inhaled corticosteroid, beta(2)-agonist, or anticholinergic from June 30, 1997, to April 30, 2004. Poisson regression was used to evaluate the impact of the policies in a cohort of patients receiving long-term inhaler treatment. An identically defined historical control group unaffected by the policy changes was used for comparison. RESULTS: The study population included 37,320 users of long-term inhaled medications from the BC population of 576,000 persons > or = 65 years of age. During the IBD period but not the fixed copay period, emergency hospitalizations for CAE increased 41% (95% CI for adjusted rate ratio [RR], 1.24-1.60) in patients > or = 65 years of age. There was also a significant increase in physician visits of 3% (95% CI for adjusted RR, 1.01-1.05). No significant increases were observed during the fixed copay period. In a secondary analysis using a concurrent control group, we estimated a smaller but significant increase in emergency CAE hospitalizations of 29% (95% CI for adjusted RR, 1.09-1.52). This analysis also showed increases in physician visits (fixed copay period RR, 1.03 [95% CI for adjusted RR, 1.01-1.05]; IBD period RR, 1.07 [95% CI for adjusted RR, 1.05-1.08]). CONCLUSION: The results suggest that the IBD policy was likely associated with an increased risk for emergency hospitalization and physician visits in these users of inhaled medications who were aged > or = 65 years.