Background. Chronic fatigue is a common condition, frequently presenting in primary care. The aim of this study was to compare the cost-effectiveness of cognitive behavioural therapy (CBT) and graded exercise therapy (GET), and to compare therapy with usual care plus a self-help booklet (BUC).

Method. Patients drawn from general practices in South East England were randomized to CBT or GET. The therapy groups were then compared to a group receiving BUC recruited after the randomized phase. The main outcome measure was clinically significant improvements in fatigue. Cost-effectiveness was assessed using the net-benefit approach and cost-effectiveness acceptability curves.

Results. Costs were available for 132 patients, and cost-effectiveness results for 130. Costs were dominated by informal care. There were no significant outcome or cost differences between the therapy groups. The combined therapy group had significantly better outcomes than the standard care group, and costs that were on average £149 higher (a non-significant difference). Therapy would have an 81·9% chance of being cost-effective if society were willing to attach a value of around £500 to each four-point improvement in fatigue.

Conclusion. The cost-effectiveness of cognitive behavioural therapy and graded exercise were similar unless higher values were placed on outcomes, in which case CBT showed improved cost-effectiveness. The cost of providing therapy is higher than usual GP care plus a self-help booklet, but the outcome is better. The strength of this evidence is limited by the use of a non-randomized comparison. The cost-effectiveness of therapy depends on how much society values reductions in fatigue.