Modelling the 5-year cost effectiveness of tiotropium, salmeterol and ipratropium for the treatment of chronic obstructive pulmonary disease in Spain

Our objective was to assess the 5-year cost effectiveness of bronchodilator therapy with tiotropium, salmeterol or ipratropium for chronic obstructive pulmonary disease (COPD) from the perspective of the Spanish National Health System (NHS). A probabilistic Markov model was designed wherein patients moved between moderate, severe or very severe COPD and had the risk of exacerbation and death. Probabilities were derived from clinical trials. Spanish healthcare utilisation, costs and utilities were estimated for each COPD and exacerbation state. Outcomes were exacerbations, exacerbation-free months, quality-adjusted life years (QALYs), and cost(-effectiveness). The mean (SE) 5-year number of exacerbations was 3.50 (0.14) for tiotropium, 4.16 (0.40) for salmeterol and 4.71 (0.54) for ipratropium. The mean (SE) number of QALYs was 3.15 (0.08), 3.02 (0.15) and 3.00 (0.20), respectively. Mean (SE) 5-year costs were €6,424 (€305) for tiotropium, €5,869 (€505) for salmeterol, and €5,181 (€682) for ipratropium (2005 values). Ipratropium and tiotropium formed the cost-effectiveness frontier, with tiotropium being preferred when willingness to pay (WTP) exceeded €639 per exacerbation-free month and €8,157 per QALY. In Spain, tiotropium demonstrated the highest expected net benefit for ratios of the willingness to pay per QALY, well within accepted limits.