Economics of medically unexplained symptoms: a systematic review of the literature

Objective: To review cost-of-illness studies (COI) and economic evaluations (EE) conducted for medically unexplained symptoms and to analyze their methods and results. Methods: We searched the databases PubMed, PsycINFO and National Health Service Economic Evaluations Database of the University of York. Cost data were inflated to 2006 using country-specific gross domestic product inflators and converted to 2006 USD purchasing power parities. Results: We identified 5 COI and 8 EE, of which 6 were cost-minimization analyses and 2 were cost-effectiveness analyses. All studies used patient level data collected between 1980 and 2004 and were predominantly conducted in the USA (n = 10). COI found annual excess health care costs of somatizing patients between 432 and 5,353 USD in 2006 values. Indirect costs were estimated by only one EE and added up to about 18,000 USD per year. In EE, educational interventions for physicians as well as cognitive-behavioral therapy approaches for patients were evaluated. For both types of interventions, effectiveness was either shown within EE or by previous studies. Most EE found (often insignificant) cost reductions resulting from the interventions, but only two studies explicitly combined changes in costs with data on effectiveness to cost-effectiveness ratios (ratio of additional costs to additional effects). Conclusions: Medically unexplained symptoms cause relevant annual excess costs in health care that are comparable to mental health problems like depression or anxiety disorders and which may be reduced by interventions targeting physicians as well as patients. More extensive research on indirect costs and cost-effectiveness is needed.