Mass media release of medical research results: an analysis of antihypertensive drug prescribing in the aftermath of the calcium channel blocker scare of March 1995

Abstract

Background: Disclosure of medical research results to the public creates tension between lay medical reporters and the medical profession.

Objective: To explore the early effect of media attention on the risks associated with short-acting calcium channel blockers (CCBs) for treating hypertension after publication at a national meeting and following publication.

Design: Time-series analysis of prescription claims data. SETTING AND DATA SOURCE: National third-party pharmaceutical benefits manager.

Patients: Employed or retired persons and their families, 18 years of age or older, receiving prescription benefits from 1 of 4 national companies that contracted with the pharmaceutical benefits manager exclusively for prescription drug coverage.

Measurements: Prescription claims for antihypertensive drugs by fill date converted to a percentage of all cardiovascular drug claims. Data were grouped into weekly intervals before and immediately after the national release of negative information about CCBs on March 10, 1995 and following publication of the results on August 23, 1995.

Results: The most prevalent antihypertensive drugs were diuretics (21% of cardiovascular prescription claims) and calcium channel blockers (19%). A 10% decline in prescriptions filled for CCBs occurred 4 weeks following the intense media attention. Only prescriptions for long-acting calcium channel blockers declined. Alpha-1-blocker prescriptions increased by approximately the same amount that prescriptions for CCBs declined, suggesting substitution of one drug for the other. Changes in diuretic or beta-blocker prescriptions filled were not statistically significant. No immediate change in other cardiovascular drug classes occurred following journal publication.

Conclusions: Intense media publicity regarding a controversial study measurably and unpredictably changed prescription claims.

FIGURE 1

Numbers of media citations with coverage of a study concerning risk of myocardial infarction with the use of calcium channel blockers (CCBs) for hypertension. Time zero is the date of the announcement of the study results to the medical and popular media at the annual meeting of the American Heart Association (AHA) meeting (black bars), the date of the release of the peer-reviewed publication of the study results in JAMA (open bars), or the date of the publication of the Circulation meta-analysis/National Heart, Lung, and Blood Institute (NHLBI) warning (hatched bars).

FIGURE 2

Trends in the prescribing of cardiovascular drugs by type. The weekly percent of prescription claims by drug type was computed as the number of prescriptions for a specific drug class divided by the sum of all cardiovascular drugs times 100. Detailed data for periods of media coverage appear in Table 2 and Figures 4 and 5.

FIGURE 3

Trends in the prescribing of calcium channel blocker subgroups. The weekly percent of prescription claims was computed as the number of prescriptions for a specific subgroup divided by the sum of all cardiovascular drugs times 100. Short-acting calcium channel blockers are short-acting nifedipine, diltiazem, and verapamil combined.

FIGURE 4

Plot of the observed and predicted percent of prescription claims for calcium channel blockers, as calculated in Figure 2, before and immediately after the AHA presentation on calcium channel blockers. Each point represents 1 week of claims. Actual prescribing of calcium channel blockers was below the predicted lower limit of the 95% confidence interval in the second week after the AHA presentation.

FIGURE 5

Plot of the observed and predicted percent of prescription claims for α-1 blockers, as calculated in Figure 2, before and immediately after the AHA presentation on calcium channel blockers. Each point represents 1 week of claims. Actual prescribing of α-1 blockers was above the predicted upper limit of the 95% confidence interval for 2 of the weekly periods following the AHA presentation.