Introduction:
Heterozygous familial hypercholesterolemia (heFH) is characterized by high levels of low-density lipoprotein cholesterol (LDL-C) and increased risk for premature coronary artery disease (CAD) and death. Reduction of CAD and mortality by statins has not been properly quantified in heFH. The aim of the current study is to determine the effect of statins on CAD and mortality in heFH.
Methods:
All adult heFH patients identified by the Dutch FH screening program between 1994 and 2014 and registered in the PHARMO Database Network were eligible. Of these patients we obtained hospital, pharmacy (in- and outpatient), and mortality records in the period between 1995 and 2015. The effect of statins (time-varying) on CAD and all-cause mortality was determined using a Cox proportional hazard model, while correcting for the use of other lipid-lowering therapy, thrombocyte aggregation inhibitors, antihypertensive and antidiabetic medication (all time-varying). Furthermore, we used inverse probability for treatment weighting (IPTW) to account for differences between statin-treated and untreated patients regarding history of CAD before follow-up, age at start of follow-up and age of screening, as well as body mass index, LDL-C and triglycerides.
Results:
Of the 25,479 identified heFH patients, 11,021 gave informed consent to obtain their medical records, of whom 2,447 could be retrieved. We excluded 766 patients younger than 18. The remaining 1,681 heFH patients comprised our study population and these had very similar characteristics as compared to the 23,798 excluded FH patients, e.g. mean (SD) LDL-C levels were 214 (74) vs. 203 (77) mg/dL. Among 1,151 statin users, there were 133 CAD events and 15 deaths during 10,115 statin treated person-years, compared to 17 CAD events and 9 deaths during 4,965 person-years in 530 never statin users (combined rate: 14.6 vs. 5.2, respectively, p<0.001). After applying IPTW to account for indication bias and correcting for use of other medications, the hazard ratio of statin use for CAD and all-cause mortality was 0.61 (0.40 - 0.93).
Conclusions:
In heFH patients, statins lower the risk for CAD and mortality by 39%.
A case of familial hypercholesterolemia with premature coronary artery disease
