MODELING COST-EFFECTIVENESS ISSUES IN THE TREATMENT OF CLINICAL DEPRESSION

The cost to the National Health Service of treatment for clinical depr ession for England and Wales has been estimated as being in the area o f pound 416 million (1990 price level), and the social burden in terms of increased morbidity and mortality due to depression is known to be considerable. Prescription of antidepressants is the most common trea tment for people with clinical depression. The majority are diagnosed by general practitioners who issue 95% of all prescriptions for antide pressants. ge In 1992 the English National Health Service spent pound 81.1 million on antidepressant drugs. However, the understanding of th e disease process, the health, and economic impact of various treatmen t options are surrounded by much uncertainty. Few cost-effectiveness s tudies of antidepressive treatments can be found in the literature. Th ey are often based on small sample sizes, a short time horizon, and a narrow focus on subjective measures of process or intermediate outcome and are therefore less than robust when generalized to a wider popula tion of patients with clinical depression. We have developed a stochas tic simulation model aimed at analysing cost-effectiveness aspects of treatment for depression and have used it to test the consequences of a range of treatment policies. Features of the model are discussed in this paper. The model is described with a flow chart that shows patien ts' pathways through the health-care system. Based on the incidence ap proach, the model simulates a cohort of patients, using decision and c hance nodes which occur during treatment. A range of critical decision variables can be changed to assess the consequences for cost-effectiv eness.