The burden of severe hypercholesterolemia and familial hypercholesterolemia in a population-based setting in the US

Contemporary prevalence, awareness, and control of severe hypercholesterolemia (SH) and familial hypercholesterolemia (FH) and the associated atherosclerotic cardiovascular disease risk in the US are unknown.

Using electronic health records, we assessed the burden of SH and FH in Olmsted County, Minnesota, US, between 2004 and 2015. We defined SH as low-density lipoprotein cholesterol (LDL-C) level ≥190 mg/dl without secondary causes of hypercholesterolemia and FH as a Dutch Lipid Clinic Network score ≥6. Controls were age- and sex-matched individuals with LDL-C level <190 mg/dl.

The age- and sex-adjusted point and period prevalence (age-recursive method) of SH was 4.44% and 8.95%, respectively; 1 in 21 had FH (∼1:233 adults), and 46.2% had a recorded diagnosis. Guideline recommended targets (LDL-C <100 mg/dl and <70 mg/dl in the primary and secondary prevention settings, respectively) were achieved in 33.1% and 21.2% of SH cases, with less women overall achieving the target than men (18.6% vs. 23.7%, p=0.022). After adjustment for conventional risk factors, the hazard ratio for incident coronary heart disease (CHD) in those with SH was 1.21 (1.05-1.39; p=0.010), in those with SH and a family history of CHD was 2.16 (1.57-2.96; p<0.001) and in those with FH was 4.61 (2.66-7.97; p<0.001). The association of SH with CHD was modified by age (p-interaction = 0.015), such that the risk was greater at younger ages.

SH was prevalent and an independent risk factor for incident CHD. Awareness and control were low, highlighting a treatment gap (more prominent in women) that needs to be addressed.