Outcomes associated with initiation of tiotropium or fluticasone/salmeterol in patients with chronic obstructive pulmonary disease

Introduction: Adherence to long-acting bronchodilator therapy for management of chronic obstructive pulmonary disease (COPD) is a critical clinical and cost issue. Low adherence is associated with relatively higher exacerbation rates and illness burden.

Purpose: To compare adherence between patients with COPD initiating therapy on tiotropium or fluticasone/salmeterol and examine the association between adherence and respiratory-related costs.

Patients and methods: This retrospective claims data analysis evaluated patients initiating tiotropium or combination fluticasone/salmeterol from December 1, 2004 to December 31, 2005. Patients had ≥1 COPD diagnosis (International Classification of Diseases, 9th Revision, Clinical Modification [ICD-9-CM] 491.xx, 492.x, 496) and were observed during 6-month pre-index and variable (12-18-month) post-index periods. Outcomes were adherence to and discontinuation of therapy, and respiratory-related inpatient, medical, and total health care costs. Adherence was medication possession ratio ≥0.80. Discontinuation, adherence, and costs were analyzed with Cox proportional hazards regression, logistic regression, and generalized linear model regressions, respectively. Regressions controlled for demographic, sociodemographic, and health status factors.

Results: The study population comprised 1561 tiotropium and 2976 fluticasone/salmeterol patients. In unadjusted comparisons: 19.5% and 8.5% of tiotropium and fluticasone/salmeterol patients, respectively, were adherent (P < 0.001); tiotropium patients versus fluticasone/salmeterol patients had higher mean respiratory-related pharmacy costs (US$1080 versus US$974, P = 0.002) and health care costs (US$3751 versus US$2932, P = 0.031). Regression analysis showed tiotropium patients were 31.6% less likely to discontinue therapy (95% confidence interval [CI]: 0.64-0.73) and had 2.25 times higher odds of adherence (CI: 1.85-2.73) versus fluticasone/salmeterol patients. The associations between index therapy and costs were not significant. Adherence versus nonadherence was associated with: 46.9% higher health care costs (CI: 1.13-1.91); 37.1% lower medical costs (CI: 0.43-0.91); and 53.4% lower inpatient costs (CI: 0.30-0.72).

Conclusion: Patients with COPD initiating long-acting bronchodilator therapy were more likely to be adherent to tiotropium than to fluticasone/salmeterol. Adherence to either tiotropium or to fluticasone/salmeterol was associated with lower respiratory-related medical and inpatient costs, and with higher respiratory-related total health care costs.