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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Trainee Research Award Finalist — Clinical Science
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© 2021 Published by Elsevier Inc.