title: The impact of cost sharing on antidepressant use among older adults in British Columbia.
abstract: OBJECTIVE
  Antidepressant therapies are underused among older adults and could be further curtailed by patient cost-sharing requirements. The authors studied the effects of two sequential cost-sharing policies in a large, stable population of all British Columbia seniors: change from full prescription coverage to 10-25 dollars copayments (copay) in January 2002 and replacement with income-based deductibles and 25% coinsurance in May 2003.
  
  
  METHODS
  PharmaNet data were used to calculate monthly dispensing of antidepressants (in imipramine-equivalent milligrams) among all British Columbia residents age 65 and older beginning January 1997 through December 2005. Monthly rates of starting and stopping antidepressants were calculated. Population-level patterns over time were plotted, and the effects of implementing cost-sharing policies on antidepressant use, initiation, and stopping were examined in segmented linear regression models.
  
  
  RESULTS
  Implementation of the copay policy was not associated with significant changes in level of antidepressant dispensing or the rate of dispensing growth. Subsequent implementation of the income-based deductible policy also did not lead to a significant change in dispensing level but led to a significant (p=.02) decrease in the rate of growth of antidepressant dispensing. The copay policy was associated with a significant (p=.01) drop in the frequency of antidepressant initiation among persons with depression. Income-based deductibles reduced the rate of increase in antidepressant initiation over time. Implementation of the copay and income-based deductible policies did not have significant effects on stopping rates.
  
  
  CONCLUSIONS
  Introducing new forms of medication cost sharing appears to have the potential to reduce some use and initiation of antidepressant therapy by seniors. The clinical consequences of such reduced use need to be clarified.
authors: National Institute of Mental Health, Bethesda, MD 20892-9629, USA. wangphi@mail.nih.gov
authors: Philip S
authors: PS
authors: Wang
authors: Amanda R
authors: AR
authors: Patrick
authors: Colin R
authors: CR
authors: Dormuth
authors: Jerry
authors: J
authors: Avorn
authors: Malcolm
authors: M
authors: Maclure
authors: Claire F
authors: CF
authors: Canning
authors: Sebastian
authors: S
authors: Schneeweiss
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000627:therapeutic use; D000368:Aged; D000928:Antidepressive Agents / Q000627:therapeutic use*; D001955:British Columbia / Q000453:epidemiology; D017047:Cost Sharing / Q000706:statistics & numerical data*; D003866:Depressive Disorder / Q000188:drug therapy* / Q000453:epidemiology*; D004358:Drug Therapy / Q000706:statistics & numerical data / Q000639:trends; D005260:Female; D006291:Health Policy; D006801:Humans; D007099:Imipramine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015995:Prevalence
chemical_list: D018759:Adrenergic Uptake Inhibitors; D000928:Antidepressive Agents; D007099:Imipramine