Cost effectiveness of amoxicillin for lower respiratory tract infections in primary care: an economic evaluation accounting for the cost of resistance

Background: Lower respiratory tract infections are a major disease burden and are often treated with antibiotics. Typically, studies evaluating use of antibiotics focus upon immediate costs of care, and do not account for the wider implications of antimicrobial resistance.

Aim: This study sought to establish whether antibiotics (principally, amoxicillin) are cost effective in patients with lower respiratory tract infections, and to explore the implications of taking into account costs associated with resistance.

Design and Setting: Multinational randomised double-blinded trial in 2060 patients with acute cough/lower respiratory tract infections recruited in 12 European countries.

Methods: A cost-utility analysis (CUA) from a health system perspective with a time horizon of 28 days was conducted. The primary outcome measure was the Quality-Adjusted Life-Year (QALY). Hierarchical modelling was used to estimate incremental cost-effectiveness ratios (ICER).

Results: Amoxicillin was associated with an ICER of €8,216 (£6,540) per QALY gained when the cost of resistance was excluded. If the cost of resistance is greater than €11(£9) per patient, then amoxicillin treatment is no longer cost-effective. Including possible estimates of the cost of resistance resulted in ICERs ranging from €14,730(£11,949) per QALY gained if only multi-drug resistance bacterial and health care costs are included to €727,135(£589,856) per QALY gained if broader societal costs are included.

Conclusion: Economic evaluation of antibiotic prescribing strategies that do not include the cost of resistance may provide misleading results that could be of questionable use to policy makers. However, further work is required to estimate robust costs of resistance.