Evaluating the cost-effectiveness of tiotropium versus salmeterol in the treatment of chronic obstructive pulmonary disease

Abstract

Objective: To assess the cost-effectiveness of 3 treatments (tiotropium, salmeterol, and no treatment) in patients with moderate chronic obstructive pulmonary disease (COPD).

Methods: A Markov model with a time horizon of 1 year was developed. A hypothetical cohort of 100,000 subjects with moderate COPD with mean age of 65 years, smoking history of 50 pack-years, and disease duration of 9.5 years were included in the model. The efficacy and withdrawal data were taken from published randomized clinical trials. The effectiveness measure was exacerbations avoided per patient per year. Incremental cost-effectiveness ratio (ICER) was calculated as additional cost per patient to prevent 1 exacerbation, compared with the next most expensive option. A payer's perspective was used and only direct costs were included in the study. Sensitivity analyses were conducted to test the robustness of the baseline estimates and study assumptions.

Results: The mean annual costs for the no treatment, salmeterol, and tiotropium groups were $392.1, $1268.7, and $1408.6, respectively. The ICER of tiotropium compared with no treatment was $1817.36 per exacerbation avoided, while the ICER of salmeterol compared with no treatment was $2454.48 per exacerbation avoided. Thus, in patients with moderate COPD, tiotropium is more cost-effective than salmeterol and no treatment.

Keywords: chronic obstructive pulmonary disease; cost-effectiveness; markov model; salmeterol; tiotropium.

Figure 1

Markov model demonstrating the various Markov states. Notes: (+) indicates that the same tree is repeated for each of the arms.

Figure 2

Costs and effectiveness of different treatments for patients with moderate COPD (cost-effectiveness analysis from Monte Carlo simulation). Notes: The x-axis represents effectiveness (exacerbations avoided per patient per year) and the y-axis gives the direct cost in US$.

Figure 3

Effect of different drug compliance rates on effectiveness (exacerbations avoided per patient per year). Notes: 1 = Tiotropium 100%, salmeterol 100%, no treatment 100% compliance; 2 = Tiotropium 75%, salmeterol 75%, no treatment 50% compliance; 3 = Tiotropium 100%, salmeterol 75%, no treatment 50% compliance; 4 = Tiotropium 90%, salmeterol 50%, no treatment 50% compliance; 5 = Tiotropium 90%, salmeterol 100%, no treatment 50% compliance; 6 = Tiotropium 90%,salmeterol 75%, no treatment 25% compliance; 7 = Tiotropium 90%, salmeterol 75%, no treatment 75% compliance.