Cost-effectiveness studies: can benefit be shown only in high-risk populations?

In this summary of some of the fundamental aspects of costeffectiveness analysis, situations are discussed in which treating high-risk patients is more cost-effective than offering the same intervention (eg coronary artery bypass graft surgery) to a broader group of patients. In other cases a strategy of treating all patients may be superior to confining treatment to high-risk patients (eg in short-term therapy with inexpensive drugs, periodic nutritional supplements in children). The cost-effectiveness of an intervention should be carefully analysed in each case to assess whether a 'universal' approach or a 'targeted' one would be better.