title: Comprehensive review of factors implicated in the heterogeneity of response in depression.
abstract: BACKGROUND
  Heterogeneity in overall response and outcomes to pharmacological treatment has been reported in several depression studies but with few sources that integrate these results. The goal of this study was to review the literature and attempt to identify nongenetic factors potentially predictive of overall response to depression treatments.
  
  
  METHODS
  A comprehensive review of the literature from the last 10 years was performed using three key databases (PubMed, EMBASE, and Cochrane). All relevant studies that met the inclusion criteria were selected and scored for their levels of evidence using the NICE scoring method. A subjective assessment of the strength of evidence for each factor was performed using predefined criteria.
  
  
  RESULTS
  Our broad search yielded 76 articles relevant to treatment heterogeneity. Sociodemographic factors, disease characteristics, and comorbidities were the most heavily researched areas. Some of the factors associated with more favorable overall response include being married, other social support, and low levels of baseline depressive symptoms. Evidence relating to baseline disease severity as a factor predictive of antidepressant response was particularly convincing among the factors reviewed. The presence of comorbid anxiety and pain contributed to worse antidepressant treatment outcomes.
  
  
  CONCLUSIONS
  Several factors either predictive of or associated with overall response to antidepressant treatment have been identified. Inclusion of factors predictive of response in the design of future trials may help tailor treatments to depression patients presenting to the average clinical practice, resulting in improved outcomes.
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA.
authors.forename: Gebra Cuyún
authors.initials: GC
authors.lastname: Carter
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Cantrell
authors.lastname: Victoria Zarotsky
authors.forename: Virginia S
authors.initials: VS
authors.lastname: Haynes
authors.forename: Glenn
authors.initials: G
authors.lastname: Phillips
authors.forename: Carlos I
authors.initials: CI
authors.lastname: Alatorre
authors.forename: Iris
authors.initials: I
authors.lastname: Goetz
authors.forename: Rosirene
authors.initials: R
authors.lastname: Paczkowski
authors.forename: Lauren B
authors.initials: LB
authors.lastname: Marangell
mesh_terms: D003866:Depressive Disorder / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D016896:Treatment Outcome