title: What is the threshold for a clinically relevant effect? The case of major depressive disorders.
abstract: BACKGROUND
  Randomized trials can show whether a treatment effect is statistically significant and can describe the size of the effect. There are, however, no validated methods available for establishing the clinical relevance of these outcomes. Recently, it was proposed that a standardized mean difference (SMD) of 0.50 be used as cutoff for clinical relevance in the treatment of depression.
  
  
  METHODS
  We explore what the effect size means and why the size of an effect has little bearing on its clinical relevance. We will also examine how the "minimally important difference," as seen from the patient perspective, may be helpful in deciding where the cutoff for clinical relevance should be placed for a given condition.
  
  
  RESULTS
  Effect sizes in itself cannot give an indication of the clinical relevance of an intervention because the outcome itself determines the clinical relevance and not only the size of the effects. The "minimal important difference" (MID) could be used as a starting point for pinpointing the cutoff for clinical relevance. A first, rough attempt to implement this approach for depression resulted in a tentative clinical relevance cutoff of SMD = 0.24. Using this cutoff, psychotherapy, pharmacotherapy, and combined treatment have effect sizes above this cutoff.
  
  
  CONCLUSIONS
  Statistical outcomes cannot be equated with clinical relevance. The "MID" may be used for pinpointing the cutoff for clinical relevance, but more work in this area is needed.
authors.affiliation: Department of Clinical Psychology, VU University Amsterdam, The Netherlands; EMGO Institute for Health and Care Research, VU University Medical Center Amsterdam, VU University Amsterdam, The Netherlands; Leuphana University, Lünebrug, Germany.
authors.forename: Pim
authors.initials: P
authors.lastname: Cuijpers
authors.forename: Erick H
authors.initials: EH
authors.lastname: Turner
authors.forename: Sander L
authors.initials: SL
authors.lastname: Koole
authors.forename: Annemiek
authors.initials: A
authors.lastname: van Dijke
authors.forename: Filip
authors.initials: F
authors.lastname: Smit
mesh_terms: D000928:Antidepressive Agents / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000523:psychology / Q000628:therapy*; D006801:Humans; D010043:Outcome and Process Assessment, Health Care / Q000706:statistics & numerical data*; D011594:Psychometrics; D011613:Psychotherapy
chemical_list: D000928:Antidepressive Agents
keywords: clinical relevance; depression; effect size; minimal important difference