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Canadian Journal of Cardiology

SUBOPTIMAL CONTROL OF CHOLESTEROL LEVELS AMONG INDIVIDUALS WITH FAMILIAL HYPERCHOLESTEROLEMIA AND SEVERE HYPERCHOLESTEROLEMIA IN ONTARIO, CANADA

      BACKGROUND

      The contemporary prevalence of familial hypercholesterolemia (FH) in Ontario, Canada is unknown. Using the new Canadian definition that simplified the identification of individuals with FH and severe hypercholesterolemia we evaluated the population prevalence, cholesterol levels, and lipid-lowering treatment of these individuals.

      METHODS AND RESULTS

      The Cardiovascular Health in Ambulatory Care Research Team (CANHEART) database was created through linkage of 19 population-based health databases in Ontario that included lipid testing results, cardiac risk factors and, in those aged 65 and older, lipid-lowering therapies. We identified individuals in the CANHEART cohort aged 20-105 years who were alive as of January 1, 2011 and had at least one lipid measurement. With the Canadian criteria, individuals were categorized as: (i) definite FH (low-density lipoprotein cholesterol [LDL-C] ≥ 8.5 mmol/L), (ii) probable FH (LDL-C 5.0 – 8.4 mmol/L with premature atherosclerotic cardiovascular disease [ASCVD]); (iii) severe hypercholesterolemia (LDL-C 5.0 – 8.4 mmol/L without premature ASCVD); and (iv) general population. We evaluated the prevalence of FH and severe hypercholesteremia and cholesterol levels and lipid-lowering treatment among these individuals at the time of diagnostic LDL-C measurement, and six months and two years later. A baseline lipid profile was available for 4,536,564 individuals in our cohort. Median age was 52 years (interquartile range 41-63); 54.6% were female. A total of 8,740 individuals (0.20% or 1 in 500) met criteria for definite/probable FH and 278,757 individuals (6.14% or ∼1 in 16) met criteria for severe hypercholesterolemia. We report lipid values at index and two-year follow-up (Table). At diagnosis, statin therapy was more likely to be prescribed in elderly patients with definite FH (83%), probable FH (78%) and severe hypercholesterolemia (62%) compared to the general population (43%) (Figure). Prescription rates for statins and other lipid lowering treatments increased in the six months following diagnosis. However, at 2 years follow-up only 63% of definite FH, 67% of probable FH, 57% of severe hypercholesterolemia, and 48% of general population individuals remained on statins. Among treated individuals, 37% of definite FH, 61% of probable FH, and 41% of those with severe hypercholesterolemia reached an LDL-C under 3.5 mmol/L at two-year follow-up. Even fewer attained LDL-C values less than 2.0 mmol/L – 6% (definite FH), 18% (probable FH), 7% (severe hypercholesterolemia).

      CONCLUSION

      Using population-based data we found that FH and severe hypercholesterolemia are common in Ontario and observed suboptimal treatment and cholesterol control. Our study highlights important treatment gaps in these subjects at high risk of ASCVD.
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