Causal Association Between Childhood Body Mass Index and Phlebitis and Thrombophlebitis: An Analysis Using Mendelian Randomization.

Background: Research has indicated a link between obesity and a greater likelihood of venous disorders. However, the specific relationship between obesity in children and conditions such as phlebitis and thrombophlebitis remains undetermined. To explore this, we undertook a two-sample Mendelian randomization (MR) study to investigate the possible causal impact of childhood body mass index (BMI) on the development of phlebitis and thrombophlebitis. Methods: This study utilized genome-wide association studies data from European populations. Childhood BMI was assessed in a sample of 39,620 individuals, while data on phlebitis and thrombophlebitis were obtained from 1613 cases and 335,586 controls. We selected 16 single nucleotide polymorphisms significantly associated with childhood BMI as instrumental variables (IVs). The inverse variance weighting (IVW) method was applied as the primary approach, with weighted median, MR-Egger regression, and weighted mode methods used as complementary analyses. Results: The IVW analysis indicates a significant causal link between childhood BMI and the occurrence of phlebitis and thrombophlebitis (Beta = 0.002739, Standard error (SE) = 0.000740, p = 0.0002147). Results from the weighted median method (Beta = 0.002446, SE = 0.001046, p = 0.01933) aligned with the IVW findings. However, the MR-Egger and weighted mode analyses did not show a significant association (p = 0.1051 and p = 0.2525, respectively). Leave-one-out sensitivity tests and heterogeneity assessments were performed, revealing no evidence of horizontal pleiotropy. Conclusion: The findings from the MR analysis suggest a potential causal relationship between childhood BMI and an elevated risk of phlebitis and thrombophlebitis. This study provides new insights into the impact of childhood obesity on venous health, emphasizing the need for early intervention and prevention strategies.