Commentary

This “real life” study by Simon et al gives us insight into how antidepressants are used in practice and the associated costs. Randomised controlled trials with economic modelling tell us a limited amount about the real world. We know that newer drugs cost more but we don't know how their putative benefits translate into outcome or cost effectiveness.

In this study, the lower rate of switching because of adverse effects suggests that fluoxetine was better tolerated than tricyclics; outcome and willingness to continue taking antidepressants, however, was not affected. The human cost of this difference is difficult to know. Starting treatment with fluoxetine led to greater drug costs than with tricyclics but switching between antidepressants reduced this difference. The increase in the acquisition costs of fluoxetine may have been balanced by lower medical costs, although the study had limited power to estimate these costs precisely. This means that the study could not detect a difference in medical costs of about the same amount as the difference in drug costs. Therefore, although we can be fairly confident that first line fluoxetine led to a larger drug bill we are less certain about how overall costs compared between groups. Even if the costs balance, interpretation will depend on which budget you control and on your healthcare system.

The situation is complicated further because we cannot assume that results with fluoxetine will be the same with other SSRIs and new antidepressants.

Were many of these patients with mainly mild depression appropriately given an antidepressant at all? The mean HDRS was at about the threshold below which antidepressants have not been shown to be beneficial¹; half of these patients therefore could have had up to 2 years of unnecessary drug treatment. Targeting more severely ill patients is at least as important as choosing which antidepressant to use.