Maslej MM, et al. - A meta-analysis of placebo-controlled randomized clinical trials was designed to evaluate the assumption of systematic variability in symptomatic response to antidepressants and to assess whether this variability is associated with the severity of the major depressive disorder, antidepressant class, or year of study publication. Researchers searched the following databases from inception to January 8, 2016: the Cochrane Central Register of Controlled Trials, CINAHL, Embase, LILACS database, MEDLINE, MEDLINE In-Process, and PsycINFO. Between August 14 and November 18, 2019, these data were examined. Researchers included a total of 87 eligible randomized placebo-controlled trials involving a total of 17,540 unique individuals. The results of this study displayed that individual differences may be systematically correlated with responses to antidepressants in major depressive disorder beyond placebo effects or statistical factors. This research gives empirical support for distinguishing moderators and personalizing antidepressant treatment.