Background: An important proportion of asthma patients remain uncontrolled despite the use of inhaled corticosteroids and long-acting beta-agonists. Some add-on therapies, like azithromycin, have been recommended for this subgroup of patients. The purpose of this study was to assess the cost-effectiveness of azithromycin as an add-on therapy to ICS + LABA for patients with severe asthma.

Methods: A probabilistic Markov model was created to estimate the cost and quality-adjusted life-years (QALYs) of patients with severe asthma in Colombia. The total costs and QALYS of two interventions, including standard therapy (ICS + LABA), and add-on therapy with azithromycin, were calculated over a lifetime horizon. Multiple sensitivity analyses were conducted. Cost-effectiveness was evaluated at a willingness-to-pay value of $19,000.

Results: The model suggests a potential gain of 0.037 QALYs per patient per year on azithromycin, with a difference of US $718 in favor of azithromycin, showing dominance with respect to SOC. A position of dominance negates the need to calculate an incremental cost-effectiveness ratio. In the deterministic sensitivity analyses, our base-case results were robust to variations in all assumptions and parameters.

Conclusion: Add-on therapy with azithromycin was found to be cost-effective when added to usual care in patients who remain uncontrolled despite treatment with medium or high-dose ICS/LABA.

Keywords: Azithromycin; Cost-effectiveness analysis; Decision analysis; Markov model; Uncontrolled asthma.