[Heritability of body mass index based on twin studies: a Meta-analysis]

Objective: To use Meta analysis to understand the prevalence of the heritability of body mass index (BMI) in twins. Methods: All studies on the heritability of the twins' BMI published before December 31, 2020 were retrieved through the China National Knowledge Network, Wanfang, VIP, PubMed and Web of Science databases. The literature quality was evaluated by using Joanna Briggs Institute Critical Appraisal tools. Stata 16.0 was used to perform subgroup analysis on the outcome indicators (heritability, 95%CI) to explore the source of heterogeneity. The local weighted regression method was used to fit the trend of heritability with age. The publication bias test and the sensitivity analysis of included literatures were also performed by using Stata 16.0. Results: A total of 10 articles meeting the inclusion and exclusion criteria were included with 79 twins' independent estimates of heritability for BMI. Meta-analysis showed that the combined value of BMI heritability was 0.69 (95%CI: 0.65-0.71), the combined value of BMI (0.68, 95%CI: 0.65-0.70) in males was lower than that (0.70, 95%CI: 0.68-0.72) in females. The heritability of BMI (0.72, 95%CI: 0.68-0.76) in childhood and adolescence was higher than that (0.68, 95%CI: 0.66-0.70) in adulthood. The gender specific difference in BMI heritability in twins ≤18 years old was even greater, which was lower in males (0.68, 95%CI: 0.61-0.76) than in females (0.75, 95%CI: 0.69-0.81). The heritability increased with age in childhood, reached peak at about 18 years old, and then slowly decreased with age. Conclusions: The heritability of BMI varied with population characteristics, especially age and gender. In view of the high estimated value of BMI heritability in female children and adolescents, more attention should be paid to the start time of health intervention.