This research explores the association between the interruption or ter
mination of antihypertensive drug therapy and total health care costs
among non-institutionalized Medicaid patients older than age 40 who su
rvive the first year after treatment. Multivariate regression analysis
was used to estimate the statistical relationship between post-treatm
ent costs and patient demographic characteristics, prior use of servic
es, the type of medication used as initial therapy and whether the pat
ient maintained continuous therapy. Paid claims data from the Californ
ia Medicaid (Medi-Cal) program were used in the analysis. Total cost o
f health care in the first year after the initiation of drug therapy w
as the primary outcome variable. Components of total costs (e.g., hosp
ital, outpatient and physician services, prescription drugs) were also
investigated. Nearly 86% of new antihypertensive drug therapy patient
s interrupted or discontinued purchasing any form of antihypertensive
medication during the first year. Patients with interrupted antihypert
ensive drug therapy consumed an additional $873 per patient (P < .0001
) in health care during the first year, not counting a reduction in pr
escription drug cost of $281 (P < .0001). Increased costs were primari
ly due to increased hospital expenditures of $637 (P < .0002).