Disease-Guided Initiation of Statin Therapy in the Elderly
Does coronary artery calcium (CAC) or carotid artery plaque burden (cPB) improve the identification of adults who benefit from statin therapy?
Data from the BioImage Study, a prospective observational cohort, were used for the present analysis. Participants were men ages 55-80 years of age and women 60-80 years of age, without known atherosclerotic cardiovascular disease (ASCVD) at baseline examination completed between January 2008 and June 2009. American College of Cardiology (ACC)/American Heart Association (AHA) lipid guideline recommendations were used to group participants into three statin benefit groups: 1) individuals without ASCVD or diabetes, 40-75 years of age with a low-density lipoprotein cholesterol (LDL-C) of 70-189 mg/dl, and estimated 10-year ASCVD risk of ≥7.5%; 2) individuals with diabetes, 40-75 years of age, and LDL-C 70-189 mg/dl; and 3) individuals with primary elevations of LDL-C ≥190 mg/dl. Presence of CAC or cPB was used to up- or down-classify participants for statin eligibility groups. Participants were classified from statin eligibility of optional to clear statin eligibility if CAC was ≥100 (or equivalent cPB). Participants were down-classified from statin-eligible to statin-ineligible if imaging revealed no CAC or cPB.
A total of 5,805 participants (mean age 69 years, 56% female) were included in this study. The majority of the cohort (86%) was statin-eligible because of an estimated 10-year ASCVD risk ≥7.5%; risk was ≥15% in 55% of participants. Over a median follow-up of 2.7 years, 91 participants were diagnosed with clinical coronary heart disease (CHD) and 138 experienced a cardiovascular event. CAC or cPB scores of 0 were common (32% and 23%, respectively) and associated with low event rates. With CAC-guided reclassification, specificity for CHD events improved 22% (p < 0.0001) without any significant loss in sensitivity, yielding a binary net reclassification index (NRI) of 0.20 (p < 0.0001). With cPB-guided reclassification, specificity improved 16% (p < 0.0001) with a minor loss in sensitivity (7%), yielding a NRI of 0.09 (p = 0.001). For cardiovascular events, NRI was 0.14 (CAC-guided) and 0.06 (cPB-guided). The positive NRIs were driven primarily by down-classifying the large subpopulation with CAC = 0 or cPB = 0.
The investigators concluded that withholding statins in individuals without CAC or cPB could spare a significant proportion of elderly people from taking a pill that would benefit only a few. This individualized disease-guided approach is simple and easy to implement in routine clinical practice.
These data suggest that information on CAC or carotid arterial plaque may assist clinicians and their patients in determining whether to initiate statin therapy.
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