What price depression? The cost of depression and the cost-effectiveness of pharmacological treatment.

The purpose of this study was twofold: to measure the overall direct costs of depression for 1990 in the UK, and to develop a model to illustrate issues in the evaluation of the relative cost-effectiveness of the pharmacological treatment of depression. We compared a tricyclic antidepressant, imipramine, with paroxetine, a newer antidepressant. For assessing the cost of illness, we used a top-down approach. We calculated direct but not indirect costs. Cost-effectiveness was evaluated by developing a simulation model based on the theory of clinical decision analysis to compare the costs and outcome of each treatment. From this we estimated the expected cost per patient and the cost per successfully treated patient. The total cost to the nation of depressive illness was estimated to be 222 pounds million. The expected costs per patient were found to be similar for paroxetine and imipramine (430 pounds v. 424 pounds). The costs per successfully treated patient were found to be lower for paroxetine (824 pounds) than for imipramine (1024 pounds). The results were stable when a sensitivity analysis was applied to the variables employed in the model. The most sensitive variable was the cost of treatment failure. Our model thus reveals that medication that appears expensive in terms of cost per day may not be so when patient compliance and the total costs of treatment are taken into account.