Personalized Psychotherapy for Adult Depression: A Meta-Analytic Review.

Personalized medicine is aimed at identifying which characteristics of an individual predict the outcome of a specific treatment, in order to get a better match between the individual and the treatment received. We conducted a systematic review and meta-analysis of randomized trials comparing two psychotherapies directly in a group of depressed patients with a specific characteristic. We focused on the six most examined types of psychotherapy for adult depression. Our searches resulted in 41 studies with 2,741 patients who met inclusion criteria. These 41 studies examined 27 specific characteristics of patients. Power calculations indicated that we would need 4 studies for each characteristic to find a clinically relevant effect size set at g = 0.50 and 16 studies for an effect size of 0.24. Only 3 patient characteristics were found to have sufficient power and to significantly moderate treatment outcomes. Cognitive-behavioral therapy was found to be more effective than other therapies in older adults (g = 0.29), in patients with comorbid addictive disorders (g = 0.31), and in university students (g = 0.46). Risk of bias was considerable in most of the included studies. It was estimated that it will take another 326 years to have sufficient statistical power for showing an effect size of g = 0.50 of the 27 characteristics, and 1,372 years to show an effect size of 0.24. Although several dozens of studies have compared the effects of psychotherapies in specific target groups, we will need to develop more powerful alternatives to comparative outcome studies in order to identify personalized treatments for depression.