Clinical Decisionmaking

National guidelines and clinical evidence only modestly influence prescribing of antihypertensive agents

According to a new study, physician prescribing of antihypertensive medications in the past 15 years has been only modestly influenced by clinical guidelines. Doctors tend to prescribe the newer, more expensive antihypertensive medications rather than older antihypertensive agents for patients with high blood pressure (hypertension). Yet the older agents, such as diuretics and beta blockers, are still recommended as first-line medications. The newer agents include angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers (CCBs), and angiotensin II receptor blockers (ARBs).

A range of clinical and market factors, such as drug promotion, market competition, medical coverage, and purchasing contracts may balance or even offset the effects of guidelines and clinical evidence on physician prescribing, explains Randall S. Stafford, M.D., Ph.D., of Stanford University. He and colleagues call for strategies to align practice with the recommendations to use thiazide diuretics alone or in combination with other antihypertensive medications for treating most patients with elevated blood pressure. They analyzed data on antihypertensive prescribing from 1990 through 2004 from a survey of a national sample of U.S. office-based physicians.

Researchers found that diuretics ranked among the top three antihypertensive drug classes from 1990 through 2004. However, they were superseded by both ACE inhibitors and CCBs between 1993 and 1999, and subsequently by ACE inhibitors through 2004. Publication of study results in December 2002 which showed the clinical equivalence of thiazide diuretics to CCBs and ACE inhibitors prompted an immediate increase in prescription of thiazide diuretics in the first half of 2003. Prescription of all diuretics significantly surpassed that of CCBs in 2003 as the second most prescribed antihypertensive drug class. Despite being another recommended class of first-line antihypertensive agents, beta-blockers were consistently the fourth most commonly prescribed antihypertensive until 2003, when they were exceeded by ARBs. The study was supported in part by the Agency for Healthcare Research and Quality (HS13405).

See "Long-term and short-term changes in antihypertensive prescribing by office-based physicians in the United States," by Dr. Stafford, Veronica Monti, M.S., R.D., Curt D. Furberg, M.D., and Jun Ma, M.D., R.D., Ph.D., in the August 2006 Hypertension 48, pp. 213-218.

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