Research on factors that influence prescribing patterns and the extent
of change produced by clinical trial findings is limited.
To examine the changes in prescribing of α-blockers for hypertension
treatment before and after the April 2000 publication of the unfavorable Antihypertensive
and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) early
termination involving the study's doxazosin mesylate arm. Changes in prescribing
were considered in the context of other potential concurrent influences on
medication use between 1996 and 2002, including changes in α-blocker
drug prices, generic conversion, drug promotion, and competition.
Design, Setting, and Patients
Using 2 national pharmaceutical market research reports published by
IMS HEALTH, α-blocker prescription orders reported in the National Prescription Audit—a random computerized sample of about 20 000
of 29 000 retail, independent, and mail order pharmacies and mass merchandise
and discount houses—and office-based physician α-blocker prescribing
patterns reported in the National Disease and Therapeutic Index—a random
stratified sample of about 3500 physician offices—were tracked.
Trends in physician-reported use of α-blockers and α-blocker
prescribing and dispensing by US pharmacies.
There were steady increases in α-blocker new prescriptions, dispensed
prescriptions, and physician drug use from 1996 through 1999. There was a
moderate reversal in these trends following ALLHAT early termination and subsequent
publications in early 2000. Between 1999 and 2002, new annual α-blocker
prescription orders declined by 26% (from 5.15 million to 3.79 million), dispensed
prescriptions by 22% (from 17.2 million to 13.4 million), and physician-reported
drug use by 54% (from 2.26 million to 1.03 million). Other potential influences
did not appear to have contributed significantly to this decline although
cessation of α-blocker marketing may have hastened the decline.
Modest yet statistically significant declines in the use of doxazosin
and other α-blockers coincided with the early termination of the ALLHAT
doxazosin arm. Although physicians responded to this new evidence, strategies
to augment the impact of clinical trials on clinical practice are warranted.