Antidepressant effectiveness and clinical importance

Most antidepressant trials were done decades ago by pharmaceutical companies and were of people with severe depression recruited from specialist services. Antidepressants are now given to a much broader range of people including those with less severe depression. The PANDA trial studied the effectiveness of the SSRI antidepressant sertraline in a population more like those currently receiving antidepressants in UK primary care. We found evidence that it reduced anxiety symptoms but the effect on depressive symptoms was modest and appeared some weeks later.

We have also investigated how we can decide if treatment differences are clinically important by using an “anchor” method to establish the minimal clinically important difference for depressive symptom and anxiety scales. This is best estimated using a percentage rather than an absolute difference. I will discuss how these results can be applied to PANDA and in future to provide better guidance on prescribing antidepressants.