title: Predicting treatment response in major depressive disorder: the impact of early symptomatic improvement.
abstract: OBJECTIVE
  Antidepressants (ADs) are the mainstay of treatment for major depressive disorder (MDD). Despite their widespread usage, a consensus does not exist as to the timing of clinically significant symptomatic improvement during an AD trial. The objective of this review is to provide practitioners with empirically based recommendations pertaining to the optimal duration of index (initial) AD therapy before a clinical intervention is warranted.
  
  
  METHODS
  We conducted a nonsystematic review, using a combination of a MeSH key word search, Google Scholar, and the Scopus database. Our search strategy focused on research papers reporting on the early symptomatic response to AD therapy.
  
  
  RESULTS
  Available evidence suggests that there are several subpopulations that exist within whole-group data assigned to an AD treatment. Among the responder subgroups, an early responder group (that is, less than 3 weeks) and later responder group (that is, 3 weeks or more) are identified. People who exhibit early partial symptomatic improvement are more likely to respond to therapy thereafter. However, the interpretability of extant evidence is complicated by the use of disparate statistical approaches with differing computational complexity and sample heterogeneity.
  
  
  CONCLUSIONS
  Response outcomes in MDD are heterogeneous. Available data suggest that people may respond early, late, and (or) continuously over time, and may represent distinct subpopulations that provide a proximate indication for treatment response outcomes. Notwithstanding, a pragmatic recommendation would be to consider a treatment intervention (for example, dosage optimization and [or] augmentation) if, after 3 to 4 weeks, symptomatic improvement is insufficient.
authors.affiliation: University Health Network, Toronto, Ontario, Canada.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kudlow
authors.forename: Danielle S
authors.initials: DS
authors.lastname: Cha
authors.forename: Roger S
authors.initials: RS
authors.lastname: McIntyre
mesh_terms: D000928:Antidepressive Agents / Q000627:therapeutic use*; D003865:Major Depressive Disorder / Q000188:drug therapy*; D005544:Forecasting; D006801:Humans; D011379:Prognosis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000928:Antidepressive Agents