Coronary calcium scoring for guiding lipid‐lowering therapy is cost‐effective: time to remove barriers to its use

Widespread, inexpensive CAC scanning could economically expand access to statin therapy to those at highest risk

Coronary artery calcium (CAC) scores, in combination with traditional cardiovascular disease (CVD) risk factors, can help identify who would obtain the most and who the least benefit from statin treatment.1 However, there are drawbacks to routinely incorporating CAC scores into CVD risk assessment, including the direct medical cost ($US50–250 per scan in the United States) and indirect costs (time required for CAC scanning, incidentaloma detection, subsequent rescanning) for patients and the health care system.

In the study reported in this issue of the MJA, Venkataraman and colleagues2 compared the cost‐effectiveness of the current Australian guideline criterion for statin eligibility — absolute 5‐year cardiovascular disease risk (ACVDR) of at least 10% — with the lower treatment threshold strategy of the American College of Cardiology/American Heart Association (ACC/AHA) — 10‐year predicted risk (using the pooled cohort equation, PCE) of at least 7.5% — and with CAC‐guided strategies — ACVDR 5‐year risk of at least 2% and CAC>0 or CAC ≥100). The study population comprised participants in the Coronary Artery calcium score: Use to Guide Management of Hereditary Coronary Artery Disease (CAUGHT‐CAD) study, a randomised controlled trial examining CAC scoring for asymptomatic people at intermediate risk of CVD and a family history of premature coronary artery disease.2

Venkataraman and colleagues used Markov microsimulation to estimate the incremental cost‐effectiveness ratio (ICER) for each expanded strategy from the Australian health care system perspective over 15 years, compared with the current Australian guideline strategy. Total CAC cost included the direct cost of the computed tomography (CT) scan ($AU198) and additional costs related to adverse CAC‐related outcomes, incidental findings and their investigation, and later stress testing. The willingness‐to‐pay threshold set at $AU50000 per quality‐adjusted life year (QALY) gained. Sensitivity analyses tested the impact of varying certain parameter values, including rates of statin initiation, discontinuation, and adherence.2

Statin therapy would be recommended for 7.1% of participants by the Australian guidelines and for 24% by the ACC/AHA guidelines. Statin therapy eligibility was expanded to 46% with ACVDR 5‐year risk ≥2% and CAC>0 the criteria, or to 14% when the treatment threshold was ACVDR 5‐year risk ≥2% and CAC ≥100. The respective ICERs were $53028/QALY gained (CAC>0) and $33108/QALY gained (CAC ≥100). Each CAC‐based strategy dominated adoption of the ACC/AHA guidelines. Sensitivity analysis indicated that greater statin adherence in CAC‐guided strategies increased their cost‐effectiveness. Venkataraman and colleagues found that cost‐effectiveness was greatest for people with higher baseline risk (5‐year ACVDR risk ≥5%, men, residents in low socio‐economic status areas),2 consistent with the emerging consensus that not all people with family histories of premature coronary artery disease are at high risk of CVD.

An earlier study in the CAUGHT‐CAD framework found that eligibility based on 5‐year PCE risk ≥2% and CAC>0 was more cost‐effective than the ACC/AHA guidelines (from the perspective of the United States health care sector), with an ICER of $US15014/QALY gained and about $US145 greater total cost per person (CAC scan cost: $US139).3

The findings of Venkataraman and colleagues add to the growing evidence for the cost‐effectiveness of CAC‐enhanced statin allocation strategies. A United States microsimulation study evaluated the cost‐effectiveness from a societal perspective of a CAC‐guided strategy for people at intermediate CVD risk over their lifetime. It found that not prescribing statins for people with zero CAC, moderate intensity statin therapy for people with CAC scores of 1–100, and high intensity statin therapy for those with scores exceeding 100 was more cost‐effective than providing all patients moderate intensity statin therapy (ACC/AHA guidelines), with an ICER of $US8100/QALY gained, (CAC costs: $US100).4 Earlier American studies found that CAC‐guided strategies are more cost‐effective when the cost of statins is high, that of CAC assessment is low, and statin disutility (desire to avoid lifelong statin therapy) is taken into consideration.5,6,7,8

Importantly, however, all these studies were microsimulation modelling studies that include a host of embedded assumptions that may or may not be immediately translatable to clinical practice. Further, Venkataraman and colleagues did not assess a treat‐all strategy, although many authors have advocated such an approach.9,10,11 But in clinical practice, managing CVD risk and initiating lifelong statin therapy is always a shared decision‐making process, rendering any theoretical “treat all” strategy impractical.9 As such, there is inherent value in the personalisation of care that would probably improve further the favourable ICER for CAC‐guided strategies reported by Venkataraman and colleagues.

Despite being a rapid test (less than ten minutes of room time) that requires little technical expertise, the cost of CAC screening varies markedly around the world. In the Danish Cardiovascular Screening trial,12 the incremental cost of a population‐based, free cardiac CT screening program to the Danish health care system was €207 per scan, with an ICER of €9075 per QALY gained. An experimental zero‐cost CAC scanning program in Ohio not only encouraged CAC screening, but also expanded its access to underserved communities, including women, Black people, and people on lower incomes.13

The time has come to eliminate cost and access as barriers to broader adoption of CAC screening by aggressively campaigning for widespread, inexpensive CAC scanning.