Acceptance and rejection: cost-effectiveness and the working nephrologist

While many nephrologists have developed a sophisticated approach to appraising clinical trials, an equal comfort in critiquing cost-effectiveness literature is often lagging. Readers can wonder how new results compare to those from other cost-effectiveness trials, and whether they should accept a new intervention as cost-effective or reject it as too costly for the benefit it produces. Critical readers should first judge whether the authors have made the correct trade-off between complexity and generalizability when selecting a study perspective, and should examine the method of linkage between costs and effectiveness. The most popular method is the incremental cost-effectiveness ratio (ICER), which has limitations that have led some authors to prefer the net monetary benefit (NMB), where confidence intervals are more easily determined and which can more readily be used in regression analyses. Interpretation of the ICER and NMB require the choice of a cost-effectiveness ceiling, representing the maximum that society would be willing to pay for an incremental health benefit, and the development of a decision rule based on this maximum. Comparing cost-effectiveness studies from different disciplines requires the use of "universal" effectiveness measures, such as the quality-adjusted life-year (QALY). An understanding of study perspective, the relative strengths of different cost-effectiveness measures, the methods for measuring uncertainty in these estimates, and how to select and use cost-effectiveness ceiling ratios will help the critical reader to determine if a new intervention should be accepted or rejected.