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Abstract
Objectives
To evaluate the comparative effectiveness of treatment regimens with theophylline compared to the regimen without theophylline.
Design
Retrospective cohort study
Setting
United States Veterans Affairs healthcare system from October 2001 through September 2005.
Participants
Patients with a diagnosis of chronic obstructive pulmonary disease that were 45 years or older
Measurements adn Main Results
Primary outcome measures were all-cause mortality, chronic obstructive pulmonary disease exacerbations and chronic obstructive pulmonary disease-related hospitalizations. Two approaches were used, the first where treatment assignment was based on medication use at baseline, and the second where exposure was measured as a time-varying covariate. Treatment groups were stratified based on propensity to receive theophylline. Mortality was compared using Cox proportional hazards models and other outcomes were compared using negative binomial models. Comparisons were conducted within individual treatment regimens that were the same with the exception of theophylline. A total of 183,573 patients were included. In the largest group, patients treated with ipratropium plus theophylline, compared to ipratropium alone, had a 1.11-fold increase in the risk of death (95% CI, 1.04-1.18). In comparisons of other regimens the risk of mortality associated with theophylline in the regimen was greater than regimens without theophylline (HRs from 1.17 to 1.31). In the time- varying exposure analysis, theophylline (HR=1.23 [95% CI 1.09 to 1.39]) was associated with an increased mortality risk.
Conclusion
Compared to similar regimens, patients in regimens that included theophylline had slightly increased risks of mortality, chronic obstructive pulmonary disease exacerbations and chronic obstructive pulmonary disease hospitalizations; however we are unable to measure the impact on other factors including symptoms and quality of life.