Comparative effectiveness of tiotropium and ipratropium in prevention of hospital readmission for COPD: a population-based cohort study.

In the treatment of chronic obstructive pulmonary disease (COPD), tiotropium bromide has a longer duration of action than ipratropium bromide; however, tiotropium bromide is a more expensive alternative treatment. At issue is whether tiotropium reduces the risk for hospital readmissions for COPD compared with ipratropium. A population-based cohort study was conducted to assess whether tiotropium reduces the risk for hospital readmissions for COPD compared with ipratropium. British Columbia (BC) linked provincial administrative health databases were used to identify new patients with COPD (aged ≥45 years) with a first hospital admission for COPD from 2003 to 2011. The study period was defined as the 30-day tiotropium or ipratropium treatment-initiation period after hospital discharge. Patients were followed up for ≤6 months from drug initiation to hospital readmission for COPD. In a subanalysis, the 2 treatment groups were matched on age, sex, and high-dimensional propensity scores derived from 200 empirically identified and predefined covariates. The risk for hospital readmission was estimated using multivariate Cox proportional hazards and logistic regression analyses. In total, 3723 patients with COPD were dispensed tiotropium (n = 992) or ipratropium (n = 2731) within 30 days from the index hospital admission for COPD. The mean age of these patients was 72.8 years, and 50.8% were women. Tiotropium-treated patients were more likely to be in a higher income category and were more likely to use a greater number of medications compared with ipratropium-treated patients. Among the subset of 1500 matched patients, 215 (14.3%) were readmitted to hospital within 6 months. There was no statistically significant group difference in hospital readmissions using either analytical approach (hazard ratio = 0.98 [95% CI, 0.72-1.34]; odds ratio = 0.97 [95% CI, 0.70-1.36]). In this select group of patients, neither tiotropium nor ipratropium was effective in significantly decreasing the risk for rehospitalization for COPD within 6 months.