Context: Research on factors that influence prescribing patterns and the extent of change produced by clinical trial findings is limited.
Objective: To examine the changes in prescribing of alpha-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 alpha-blocker drug prices, generic conversion, drug promotion, and competition.
Design, setting, and patients: Using 2 national pharmaceutical market research reports published by IMS HEALTH, alpha-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 alpha-blocker prescribing patterns reported in the National Disease and Therapeutic Index--a random stratified sample of about 3500 physician offices--were tracked.
Outcome measures: Trends in physician-reported use of alpha-blockers and alpha-blocker prescribing and dispensing by US pharmacies.
Results: There were steady increases in alpha-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 alpha-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 alpha-blocker marketing may have hastened the decline.
Conclusions: Modest yet statistically significant declines in the use of doxazosin and other alpha-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.