Clinical characteristics of adult and paediatric patients with familial hypercholesterolemia: A real-life cross-sectional study from the Turkish National Database

Background and aims: Familial hypercholesterolemia (FH) is the most common cause of premature atherosclerotic cardiovascular disease (ASCVD). Türkiye is among the countries with the highest rate of ASCVD. However, no population-based study has been published so far on the prevalence of FH, demographic and clinical characteristics, burden of ASCVD, treatment compliance, and attainment of low-density lipoprotein cholesterol (LDL-C) targets. Methods: We performed a study using the Turkish Ministry of Health's national electronic health records involving 83,063,515 citizens as of December 2021 dating back 2016. Adults fulfilling the diagnostic criteria of definite or probable FH according to the Dutch Lipid Network Criteria (DLNC), and children and adolescents fulfilling the criteria of probable FH according to the European Atherosclerosis Society (EAS) Consensus Panel report formed the study population (n = 157,790). The primary endpoint was the prevalence of FH. Results: Probable or definite FH was detected in 0.63% (1 in 158) of the adults and 0.61% (1 in 164) of the total population. The proportion of adults with LDL-C levels >4.9 mmol/L (190 mg/dL) was 4.56% (1 in 22). The prevalence of FH among children and adolescents was 0.37% (1 in 270). Less than one-third of the children and adolescents, and two-thirds of young adults (aged 18–29) with FH were already diagnosed with dyslipidaemia. The proportion of adults and children and adolescents on lipid-lowering treatment (LLT) was 32.1% and 1.5%, respectively. The overall discontinuation rate of LLT was 65.8% among adults and 77.9% among children and adolescents. Almost no subjects on LLT were found to attain the target LDL-C levels. Conclusions: This nationwide study showed a very high prevalence of FH in Türkiye. Patients with FH are diagnosed late and treated sub-optimally. Whether these findings may explain the high rates of premature ASCVD in Türkiye needs further investigation. These results denote the urgent need for country-wide initiatives for early diagnosis and effective management of FH patients.