Evaluating the impact of childhood BMI on the risk of coronavirus disease 2019: A Mendelian randomization study.

Introduction: Although the correlation between childhood obesity and coronavirus disease 2019 (COVID-19) has been explored, the causality of these remains uncertain. Thus, we conducted a two-sample Mendelian randomization (MR) analysis to identify the causal association. Methods: Instrumental variables of childhood obesity were selected from genome-wide association study involving 61,111 Europeans. Besides, we collected summary statistics of different COVID-19 outcomes (susceptibility, hospitalization, and severity) from genome-wide association study including more than 2 million Europeans. The inverse-variance weighted was applied to assess the causality of childhood obesity with COVID-19. Furthermore, we replicated the above association based on another study. Results: Inverse-variance weighted results suggested that childhood obesity promoted the COVID-19 susceptibility but has not been validated in other approaches. For hospitalization and severity of COVID-19, we found that childhood obesity, respectively, increased 30 and 38% risk ( Discussion: Our study provides evidence for a causal relationship between childhood BMI and COVID-19 which is consistent with previous studies. Though these explanations are biologically plausible, further studies are warranted to elucidate the role of these. Conclusions: Our study suggests the potential causal associations of childhood obesity with COVID-19, especially hospitalization and severity of COVID-19.