Is therapy adherence with inhaled tiotropium in COPD related to hospitalization, pneumonia or mortality?

Objective: To study the relationship between therapy adherence to tiotropium and morbidity and mortality in COPD. Methods: Therapy adherence of tiotropium Handihaler of 438 patients was recorded from pharmacy records over 3 years. It was expressed as percentage and deemed good at 75–125%, suboptimal 50-75%, and poor 125%. The relationship between adherence and morbidity and mortality was analyzed by Cox Regression. We corrected for lung function at baseline. Results: Overuse of tiotropium is related to increased risk of hospital admission and mortality compared to optimal use, with respectively hazard ratio9s of 2.2 and 2.9. Patients with underuse have a 2.4-fold higher risk of dying compared to optimal use. Adherence was not related to time to first pneumonia. Conclusion: Patients with overuse and underuse of tiotropium Handihaler have a higher risk of dying. Furthermore, overuse is related to increased risk of hospital admission.The question remains whether improving adherence reduces mortality and morbidity.