Management of Children with Heterozygous Familial Hypercholesterolemia Worldwide: A Meta-Analysis.

Heterozygous familial hypercholesterolemia (HeFH) is one of the most frequent monogenic disorders in the world, leading to premature atherosclerotic cardiovascular diseases (ASCVD). The aim of this meta-analysis was to evaluate the efficacy and safety of lipid lowering therapy (LLT) and achievement of low-density lipoprotein cholesterol (LDL-C) goal in children with HeFH. The main endpoint was efficacy of goal achievement for LDL-C and other lipid parameters: total cholesterol [TC], triglycerides [TG], high density lipoprotein cholesterol [HDL-C], apolipoprotein B [apo B] and lipoprotein(a) [Lp(a)]), and the LLT safety (adverse events [AEs], including endocrine function, and growth indices). The secondary endpoint was an effect of LLT on attainment of LDL-C goal treatment (<3.5 mmol/L/130 mg/dL). A total of 41 studies with 4667 pediatric patients at mean age 12.08±2.4 years were included. 17 reported the efficacy and safety of LLT therapy compared to control, while the remaining assessed LLT through pre- and post-treatment. At median follow-up of 18.8 months, the group on LLT had significantly higher mean reductions of TC, LDL-C, TG, and increased HDL-C compared to control (-1.75 [-67,7 mg/dl], -1.84 [-71.2 mg/dl], -0.11 [-9.74 mg/dl], 0.08 mmol/L [3.1 mg/dl], respectively, p<0.001 for all). In the subgroup analysis according to different types of LLT we observed a significantly higher mean reduction of LDL-C by statin combined with ezetimibe treatment, followed by PCSK9 inhibitors, statins in monotherapy, and monotherapy with ezetimibe (-2.48 [-95.9 mg/dl], -2.16 [-83.5 mg/dl], -2.03 [-78.5 mg/dl], and -1.50 mmol/L [-58 mg/dl], respectively, test for overall effect: p<0.001). The pooled LDL-C was reduced by 33.44% (-2.14 mmol/L [-82.8 mg/dl], p <0.001) and failed to reach the goal treatment (<3.5 mmol/L) by 12.6% (95%CI, 12.4 – 12.9%). 38.7% of children achieved the LDL-C goal, 23.9% fell short by up to 10%, 10.7% experienced moderate failure (were over the LDL-C target between >10-20%), and 26.7% failed by more than 20% to reach the LDL-C target. When comparing different regions, only Sweden and Greece achieved the LDL-C goal <3.5 mmol/L in the follow-up, followed by the Netherlands, Norway, Poland, USA, UK, France, Spain, Belgium, and Austria (with the following additional required LDL-C reduction to be on the goal: 2.2%, 3.4%, 3.5%, 8.9%, 10.2%, 11.2%, 11.2%, 15%, 19.4%, respectively). For other investigated countries over 20% mean LDL-C reduction was required. All parameters related to endocrine function and demographic indices were unaffected by LLT therapy ( p >0.05). The adverse events were not reported significantly higher when compared to the control and the prevalence of therapy discontinuation was only 0.8%. In conclusion, despite the efficacy of LLT in children with HeFH and the low occurrence of discontinuation-related adverse events, achieving LDL-C treatment goals was relatively rare, with large differences between the investigated countries. These results underscore the importance of considering early combination therapy of statins and ezetimibe, and PCSK9 inhibitors (if available) to attain LDL-C goals effectively.