Exploring the Causality Between Body Mass Index and Sepsis: A Two-Sample Mendelian Randomization Study

Abstract

<b>Objective:</b> Observational epidemiological studies have shown a link between obesity and sepsis, but any causal relationship is not clear. Our study aimed to explore the correlation and causal relationship between body mass index and sepsis by a two-sample Mendelian randomization (MR). <b>Methods:</b> In large sample genome-wide association studies, single-nucleotide polymorphisms related to body mass index were screened as instrumental variables. Three MR methods, MR-Egger regression, weighted median estimator, and inverse variance-weighted, were used to evaluate the causal relationship between body mass index and sepsis. Odds ratio (OR) and 95% confidence interval (CI) were used as the evaluation index of causality, and sensitivity analyses were conducted to assess pleiotropy and instrument validity. <b>Results:</b> By two-sample MR, the inverse variance weighting method results suggested that increased body mass index was associated with an increased risk of sepsis (odds ratio 1.32; 95% CI 1.21-1.44; <i>p</i> = 1.37 × 10^-9) and streptococcal septicemia (OR 1.46; 95% CI 1.11-1.91; <i>p</i> = 0.007), but there was no causal relationship with puerperal sepsis (OR, 1.06; 95% CI, 0.87-1.28; <i>p</i> = 0.577). Sensitivity analysis was consistent with the results, and there was no heterogeneity and level of pleiotropy. <b>Conclusion:</b> Our study supports a causal relationship between body mass index and sepsis. Proper control of body mass index may prevent sepsis.