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Personalized approach to statin allocation benefits older patients
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New data from the BioImage study suggest that personalizing the 2013 American College of Cardiology/American Heart Association guidelines for statin use in older patients will help target treatment to only those who will truly benefit from statins.
Specifically, the researchers found, there may be benefit in withholding statins from patients who would otherwise qualify for them predominantly due to age if they have no evidence of coronary artery calcium or carotid plaque burden.
“With the growing elderly population, the dominant effect of age on eligibility for statin therapy might need reconsideration. All healthy people with optimal [CV] risk factors will automatically, due to age-related risk alone, pass the 7.5% 10-year [atherosclerotic CVD] risk threshold and qualify for ACC/AHA-recommended statin therapy between age 63 and 71 years (depending on sex and ethnicity),” the researchers wrote.
The researchers evaluated whether adding a disease-guided reclassification step after the ACC/AHA-recommended risk assessment would prevent the overtreatment of older patients (men, aged 55-80 years; women, aged 60-80 years).
A more individualized approach
The reclassification approach included the following steps:
To improve specificity, individuals with 7.5% or greater 10-year atherosclerotic CVD risk estimated by pooled-cohort equations are considered ineligible for statins if coronary artery calcium (CAC) or carotid plaque burden are absent.
To prevent undertreatment, individuals considered at intermediate risk (5% to < 7.5% 10-year atherosclerotic CVD risk) are considered eligible if CAC is at least 100 or carotid plaque burden is at least 300 mm2.
Eighty-six percent of the cohort had a 10-year atherosclerotic CVD risk of at least 7.5%, making them eligible for statins. To measure subclinical atherosclerosis, the 5,805 participants (mean age, 69 years; 44% men) received noninvasive imaging. Primary endpoints included CHD and CVD.
During a median follow-up of 2.7 years, 91 participants had a first CHD event and 138 had a first CVD event. A strong association was observed between subclinical atherosclerosis and clinical events. In addition, 10-year atherosclerotic CVD risk was directly correlated with the amount of subclinical atherosclerosis (Spearman correlation coefficient: 0.36 for CAC and 0.31 for carotid plaque burden; P < .0001 for both), the researchers wrote.
According to imaging results, 28% of participants with a 10-year atherosclerotic CVD risk of at least 7.5% had no CAC and 20% did not have any carotid plaque. Overall, the reclassification approach had high sensitivity (96%), but low specificity (15%).
Among the entire cohort, 32% had no evidence of CAC and 23% had no evidence of carotid plaque burden. CAC-guided reclassification improved specificity for CHD events by 22% (P < .0001) with no loss of sensitivity, for a net reclassification index of 0.2 (P < .0001), according to the researchers. Carotid plaque burden-guided reclassification improved specificity 16% (P < .0001) but was associated with a 7% loss in sensitivity for a net reclassification index of 0.09 (P = .001), they wrote.
Net reclassification indexes for CVD were 0.14 for the CAC-guided approach and 0.06 for the carotid plaque burden-guided approach.
“The positive [net reclassification indices] were driven primarily by down-classifying the large subpopulation with CAC = 0 or [carotid plaque burden = 0],” the researchers wrote.
More research needed
In a related editorial, Tasneem Z. Naqvi, MD, MMM, of the department of cardiology at Mayo Clinic in Scottsdale, Arizona, and Vijay Nambi, MD, PhD, from the Michael E. DeBakey Veterans Affairs Hospital in Houston and from the section of cardiovascular research at Baylor College of Medicine, wrote: “Although the study was well done and the authors provided several important pieces of additional information (such as sensitivity analyses excluding those on statins and those with soft endpoints), follow-up was for a mean of only 2.7 years. One should remember that the [pooled-cohort equation] estimates 10-year risk; therefore, an estimated risk of 8% means an annual risk of only [about] 0.8%. Thus, a great majority of the individuals (97.5% if considering the 3 years of follow-up) would not have been expected to have any events.”
According to Naqvi and Nambi, although the study made “a compelling argument to use the absence of subclinical atherosclerosis on imaging as a rationale to withhold statin therapy,” a prospective randomized controlled trial is needed to better identify those at low risk who would not benefit from statin therapy. – by Tracey Romero
Disclosure: The BioImage study was designed by the High-Risk Plaque Initiative, funded by Abbott Vascular, AstraZeneca, BG Medicine, Merck, Philips and Takeda. Mortensen reports no relevant financial disclosures. Please see the full study for list of all other researchers’ financial disclosures. Naqvi reports receiving grants from AtCor Medical, CardioNexus Corp. and Esaote related to carotid ultrasound. Nambi reports being an investigator on a provisional patent filed along with Roche and Baylor College of Medicine on the use of biomarkers in prediction of HF; receiving an honorarium from Siemens; and serving on the regional advisory board of Sanofi.
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