The potential economic impact of restricted access to angiotensin-receptor blockers

Background

The use of angiotensin-receptor blockers increased by more than 4000% in Canada from 1996 to 2006. The benefit of these medications over angiotensin-converting-enzyme (ACE) inhibitors has not been proven aside from a reduction in dry cough. We estimated the potential cost savings that might have been achieved had access to angiotensin-receptor blockers been restricted.

Methods

We performed a cost-minimization analysis with a decision-tree model using a societal perspective over a one-year period. Sources of data for model parameters included IMS Health Canada data collected from one-third of all retail pharmacies for the cost and use of angiotensin-receptor blockers and ACE inhibitors in each province, as well as published studies for administrative costs and incidence of dry cough. We used Monte Carlo simulations with 10 000 iterations to test the impact of several model parameters (e.g., drug prices, administrative costs and the incidence of dry cough). All data are in 2006 Canadian dollars.

Results

A policy that would have restricted access to angiotensin-receptor blockers might have saved more than $77 million in Canada in 2006. The simulations yielded similar savings for the year (mean $58.3 million, 95% confidence interval $29.3 million to $90.8 million). Every simulation showed a cost savings.

Interpretation

Had access to angiotensin-receptor blockers been restricted, the potential cost savings to the Canadian health care system might have been more than $77 million in 2006, likely without any adverse effect on cardiovascular health.Costs of cardiovascular drugs in Canada increased by more than 200% from 1996 to 2006. The use of angiotensin-receptor blockers grew at an especially high rate, rising by more than 4000% during that period.¹ Such an increase in the use of these agents is not strongly supported by evidence.¹ Although angiotensin-receptor blockers were effective in reducing mortality and morbidity associated with hypertension in one large trial, patients in the control group were not given an angiotensin-converting-enzyme (ACE) inhibitor.² Instead, they received atenolol, a β-blocker, a drug class whose use is increasingly being questioned in the management of high blood pressure uncomplicated by prior myocardial infarction, heart failure or tachyarrhythmia.^3,4 Although angiotensin-receptor blockers are not associated with dry cough, a side effect reported by 5%–35% of patients taking ACE inhibitors,⁵ this side effect is benign and fully reversible once the drug is stopped. Meta-analyses that included several randomized trials failed to show superiority of angiotensin-receptor blockers over ACE inhibitors for the treatment of hypertension,⁶ heart failure⁷ or the secondary prevention of coronary artery disease.⁸Innovative policies are needed to offset the ever-increasing costs of cardiovascular drugs in Canada. Currently, British Columbia is the only province that restricts access to angiotensin-receptor blockers. Given that these agents can safely be substituted by ACE inhibitors and still yield similar clinical outcomes,^6–8 restricting their access is expected to lead to cost savings without adversely affecting patient heath. We estimated the potential cost savings that might have been achieved had access to angiotensin-receptor blockers been restricted in Canada in 2006.