title: A framework for describing the impact of antidepressant medications on population health status.
abstract: BACKGROUND
  In the absence of strategies for primary prevention, public health initiatives for major depression have generally focused on secondary and tertiary strategies such as case-finding, public and professional education and disease management. Much emphasis has been placed on low reported rates of antidepressant utilization. In principle, increased rates of treatment utilization should lead to improved mental health status at the population level. However, methods for relating antidepressant utilization to population health status have not been described.
  
  
  METHODS
  An incidence-prevalence model was developed using data from a Canadian national survey, supplemented by parameter estimates from literature reviews. The lifetime sick-day proportion (LSP) was used to approximate point prevalence.
  
  
  RESULTS
  Mathematical simulations using this model produced reasonable approximations of point prevalence for major depression. The model suggests that an improved rate of treatment utilization may not, in itself, lead to substantially reduced prevalence. Reducing the rate of relapse in those with highly recurrent disorders, which can be accomplished by long-term antidepressant treatment, is predicted to have a more substantial impact on population health status.
  
  
  CONCLUSIONS
  The model presented here offers a framework for describing the impact of antidepressant treatment on population health status. Mathematical models may assist with decision-making and priority setting in the public health sphere, as illustrated by the model presented here, which challenges some commonly held assumptions.
authors.affiliation: Department of Community Health Sciences, Department of Psychiatry, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada. patten@ucalgary.ca
authors.forename: Scott B
authors.initials: SB
authors.lastname: Patten
mesh_terms: D000928:Antidepressive Agents / Q000627:therapeutic use*; D002170:Canada / Q000453:epidemiology; D003866:Depressive Disorder / Q000188:drug therapy* / Q000453:epidemiology; D004363:Drug Utilization / Q000639:trends; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D011634:Public Health
chemical_list: D000928:Antidepressive Agents