Socio-demographic and clinical predictors of non-response/non-remission in treatment resistant depressed patients: A systematic review

Up to one third of patients adequately treated for Major Depressive Disorder (MDD) do not respond to multiple interventions. Many studies investigated predictors in MDD outcome, but no study focused on predictors of non-response or non-remission to antidepressants in subjects with treatment resistant depression (TRD). The present study aimed to evaluate possible socio-demographic and clinical predictors of non-response and non-remission in MDD patients who failed to benefit from at least one antidepressant trial. A total of 51 papers were included. A number of severity indicators, such as longer duration of depressive episode, moderate-high suicidal risk, anxious comorbidity, higher number of hospitalizations and higher dosage of antidepressants, were associated with non-response as well as age. Interestingly, severity of illness, as well as comorbid personality disorders and anxiety symptoms, had also a predictive value in non-remission with the addition of marital status. Considering limitations, selected studies were observational or randomized non controlled/controlled trials and different TRD definitions and outcome measures were used. Overall, predictors of outcome were similar to MDD, but specific socio-demographic and clinical factors should be considered in clinical practice to formulate a more focused treatment in TRD patients.