Cardiovascular disease and compliance with lipid-lowering therapy among young individuals with familial hypercholesterolemia in Norway - A register study.

Aims: Investigation of cardiovascular disease (CVD), all-cause death and use of statins and ezetimibe among young Norwegian individuals with heterozygous Familial hypercholesterolemia (FH). Methods: We included subjects with genetically verified FH born 1988-2008 and twenty controls per FH subject, with linkage to prescription data, hospitalization data and cause of death from national Norwegian health registries. Data on CHD and death during 2008-2018, and for dispensed prescriptions during 2004-2018, were collected. Results: 1351 subjects with FH and 27,015 controls were included. Mean age (SD) at start of follow-up was 12.3 (5.4) years. There was one Coronary Heart Disease (CHD) event and 6 deaths in the FH-group and 3 CHD events and 53 deaths in the control group. CHD and all-cause death were non-significantly increased in the FH-group, hazard ratios (95 % confidence intervals) 6.68 (0.69-64.20) and 2.26 (0.98-5.28), respectively. None of the deaths in the FH-group were related to cardiovascular disease. 83 % of subjects with FH had been prescribed a statin, and 21 % ezetimibe. During the first year after the first prescription, 18.5 % of subjects did not refill their prescription within 180 days after the end date of the previous prescription. 69 % and 60 % of subjects with a prescription had >80 % of days covered with statins and ezetimibe, respectively. After 8 years, around 70 % of subjects were covered with statins. Conclusions: Results suggest increased risk of CHD in FH relative to controls, but measures are imprecise because of low absolute risks. Compliance with lipid lowering therapy was moderate.