The impact of cost sharing on antidepressant use among older adults in British Columbia.
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.
Wang
Philip S
PS
National Institute of Mental Health, Bethesda, MD 20892-9629, USA. wangphi@mail.nih.gov
Patrick
Amanda R
AR
Dormuth
Colin R
CR
Avorn
Jerry
J
Maclure
Malcolm
M
Canning
Claire F
CF
Schneeweiss
Sebastian
S
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
D018759:Adrenergic Uptake Inhibitors; D000928:Antidepressive Agents; D007099:Imipramine