Purpose: To determine whether published cost-effectiveness studies on inhaled corticosteroids (ICS) in asthma adhered to basic analytical standards as defined in health economic textbooks and in guidelines assessing and comparing efficacy and safety.
Methods: Original cost-effectiveness studies published between 1990 and 2000 in general medical or economic journals were reviewed to assess the adherence to five fundamental methodological principles: (1) design of the study, (2) choice of perspective and corresponding costs, (3) choice of outcome measure, (4) marginal cost analysis, and (5) sensitivity analysis and discussion about external validity. For each principle, the studies were ranked as high, medium or low quality.
Results: Most of the 18 studies included were ranked medium on the first two principles. The studies adhered to a higher degree to the remaining three principles. Only three studies were high ranked in all five principles. The number of principles fulfilled increased over time. Studies comparing pharmaceutical products from competing companies were typically short-term studies, designed for other purposes than health economic analyses, and, in general, did not use therapeutically equivalent dosing.
Conclusions: Attention should be drawn to the study design, the weak correspondence between perspective and costs, and especially to the impact of bias in health economic results when comparing different doses of ICSs.