Cost-effectiveness of CAC scan depends on statin factors

In an era of generic statins, the cost-effectiveness of coronary artery calcium (CAC) scans in patients at risk of coronary heart disease may come down to preference. An analysis published online March 11 in Circulation: Cardiovascular Quality and Outcomes found no advantage in scenarios where statins were inexpensive and considered easy to use.

Mark J. Pletcher, MD, MPH, of the University of California, San Francisco, and colleagues used a cardiovascular disease transition-state simulation model to study the cost-effectiveness of CAC testing to guide statin therapy. CAC scans provide information about a patient’s risk of future coronary heart disease that could be used to determine primary prevention strategies but they also carry costs and expose patients to radiation.

The base case in the model was a 55-year-old woman with total cholesterol of 221 mg/dL, high-density lipoprotein of 40 mg/dL and no other coronary heart disease risk factors. The model applied five possible interventions: three that required a single CT scan and statins prescribed for CAC scores of either zero or more, 100 or more or 300 or more; and two strategies that didn’t use a CAC score and took either treat-all or treat-none approaches.

They assumed a radiation dose per scan of 2.3 mSv and set the daily cost of statins at either 13 cents a pill or $1 a pill. Statins were either easy to use (favorable statin assumptions) or had a quality of life penalty (less favorable statin assumptions).   

Ten years of statin treatment in 10,000 women fitting the base case profile led to the prevention of 32 lifetime MIs, caused 70 cases of statin-induced myopathy and added 1,108 years of total life expectancy. Prescribing statins in 2,500 women with CAC scores of zero or more added 501 life years but required all 10,000 women to be screened at a cost of $2.25 million and nine radiation-induced cancers.

The treat-all approach tended to be favorable with low-cost statins and favorable assumptions. When statins cost $1 a pill under less favorable assumptions, CAC screening and statin treatment for patients with CAC scores of zero or more was considered reasonable. It produced a cost of $18,000 per quality-adjusted life year (QALY) compared with treat none and $78,000 per QALY compared with treat all.

A parallel analysis based on men produced similar results. The model also showed CAC scans to be cost effective when pills cost $1 a day under less favorable assumptions in intermediate-risk scenarios.

“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,” Pletcher and colleagues wrote.

CAC screening may be beneficial in scenarios where patients or physicians struggle with making a decision about statin therapy, though.