This article is more than 5 years old. Information may no longer be current.
CAC testing useful for guiding statin therapy under certain conditions
Coronary artery calcium testing before prescribing a statin may be cost-effective for patients at intermediate risk for CHD, but only under certain circumstances related to treatment costs and effect on quality of life, according to recent findings.
Researchers used the University of North Carolina-Research Triangle Institute CVD prevention model to project and compare the prevalence of CVD, mortality, QOL and associated costs of five intervention strategies in a simulated cohort of women aged 55 years with total cholesterol of 221 mg/dL, HDL of 40 mg/dL and no other risk factors for CHD, with an estimated risk for CHD of 7.5% over 10 years.
Evaluated strategies included two interventions in which statin prescription was not guided by the results of a coronary artery calcium (CAC) scan: “treat none,” in which no patients received statins, and “treat all,” in which all patients received statins. The remaining three interventions involved the use of a single CAC test, with a statin prescribed according to CAC score (>300, >100 or >0).
Incremental cost-effectiveness ratio, measured in dollars/quality-adjusted life-years, was the study’s primary outcome measure. Two scenarios were evaluated: one in which the cost of a statin was assumed to be 13 cents per pill, and that taking statins had no negative effect on QOL; and one assuming a cost of $1 per pill, with a QOL penalty of 0.00384 per year of use.
In a simulation of 10,000 women aged 55 years comparing a treat all with treat none approach, 10 years of statin therapy was estimated to prevent 32 MIs and add 1,108 years to total life expectancy, but result in 70 cases of statin-induced myopathy. Limiting therapy to women with CAC >0 (n=2,500) yielded 501 additional life years, but the need to scan all 10,000 patients yielded an additional $2.25 million in costs and led to nine cases of radiation-induced cancer.
Assuming favorable costs and QOL for statin use, the treat all approach was more beneficial than CAC screening, the researchers wrote. Altering the estimated CHD risk for the population yielded similar results between 2.5% and 15% risk.
Under conditions less favorable for statins (assuming a $1/pill cost and QOL impairment), the treat all approach yielded more quality-adjusted life-years than approaches involving CAC scanning, but at a cost of $78,000 per year. Treatment according to a CAC score >100 or >300 was not cost-effective, but treatment at a score >0 yielded more quality-adjusted life-years than a treat none approach at a cost of $18,000 per year.
The cost-effectiveness of treatment at CAC score >0 persisted after alteration of the estimated CHD risk between 5% and 10%. Parallel analysis of a simulated cohort of males aged 55 years also yielded similar results.
“Our cost-effectiveness analysis supports a limited role for CAC testing in asymptomatic persons,” the researchers wrote. “When statins are expected to be effective, safe, and inexpensive, and the patient does not have a strong preference against taking the medication, our analyses suggest that the decision to prescribe a statin is relatively straightforward and that CAC testing is neither necessary nor cost-effective.”
Disclosure: The researchers report no relevant financial disclosures.