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.