The study took place in Group Health Cooperative
(GHC), a mixed-model HMO providing health
1994 but seniors newly insured through a group
plan may still have a prescription drug benefit as
part of their group coverage. Individuals enrolled
before 1994 were allowed to retain their drug benefit
while still enrolled in GHC. GHC currently
charges $115 per month for the individual pharmacy
benefit. GHC’s prescription benefits had no
annual or lifetime caps on expenditures and differed
only in copay amounts, which ranged from $0 to
$15 for a 1-month supply of medication. Persons
with Medicaid comprised 15% of those with prescription
coverage and had no copayments or caps