CAC score may refine statin use in elderly
medwireNews: Noninvasive imaging identifies patients who can be spared statin therapy despite advanced age, shows an analysis of the BioImage cohort.
The 5805 participants included in the study were aged an average of 68.9 years and 86% were theoretically eligible for statin treatment, under the 2013 American College of Cardiology/American Heart Association (ACC/AHA) guidelines.
These guidelines lowered the threshold for statin therapy to include all patients with a 10-year cardiovascular disease (CVD) risk of at least 7.5% according to the Pooled Cohort Equations (PCE), meaning that everyone will eventually become eligible based purely on age.
Of the eligible BioImage participants, 28% had a coronary artery calcium (CAC) score of 0. And over a median follow-up of 2.7 years, the coronary heart disease (CHD) event rate per 1000 person–years was 0.85 among these people, rising to 4.11 and 11.73 for those with a score of 1–99 and 100 or more, respectively.
Likewise, rates per 1000 person–years were 1.74 for the 20% of participants with no carotid plaque, rising to 4.63 and 9.94 for those with scores of 1–299 and 300 or more, respectively. CHD rates were significantly increased in the two higher versus the lowest groups for CAC and in the highest versus and lowest groups for carotid plaque score after accounting for confounders including age, gender, hypertension and diabetes.
The sensitivity of PCE for CHD events was 96%, but the specificity was just 15%, report Erling Falk (Aarhus University Hospital, Denmark) and co-researchers in the Journal of the American College of Cardiology.
Among patients with a PCE risk of at least 7.5% but less than 15%, accounting for a CAC score of 0 barely changed the sensitivity (97%), but significantly improved the specificity to 25%.
Accounting for the absence of carotid plaque (but not for CAC score) reduced sensitivity somewhat, to 91%, but improved specificity to 21%. Accounting for either CAC or carotid plaque also significantly improved the classification of patients in the cohort overall, irrespective of PCE risk.
In a linked editorial, Tasneem Naqvi (Mayo Clinic, Scottsdale, Arizona, USA) and Vijay Nambi (Michael E DeBakey Veterans Affairs Hospital, Houston, Texas, USA) highlight the relatively short follow-up, but note that other studies support the long-term low CVD risk associated with a CAC score of 0.
They call the findings a “compelling argument” for incorporating imaging in the risk assessment of asymptomatic elderly people, and say that “given that imaging might identify up to one-third of the statin-eligible population who could do well without chronic lipid-lowering therapy, physicians may consider incorporating such a strategy in their discussion with patients about reducing CVD risk.”
The editorialists advise an integrated approach towards statin prescription in elderly people, to include discussions of lifestyle modification, drug interactions and adverse effects, and patient preference.
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