Potential causal relationship between body mass index (BMI) and acute pancreatitis: a Mendelian randomization study

Abstract

Abstract Objective: To investigate the causal relationship between body mass index (BMI) levels and acute pancreatitis using the two sample Mendelian randomization method (MR). Method: Analyze the aggregated data from the gene wide association study (GWAS). The GWAS summary data used were all sourced from the European population. Using single nucleotide polymorphisms significantly correlated with body mass index levels as instrumental variables, a two sample Mendelian randomization analysis was performed using inverse variance weighted (IVW), MR Egger regression, and weighted median (WM) methods, respectively, to evaluate the causal effect of body mass index and acute pancreatitis using odds ratio (Oddsratio, OR). The body mass index data as an exposure factor was obtained from individuals of European ancestry in the UK Biobank (n=454884). We also used GWAS's publicly aggregated statistical dataset for self-reported non cancer disease codes: acute pancreatitis data included in the UK Biobank (n=463010)（ http://www.nealelab.is/uk-biobank ））as the ending. Result: The IVW results showed that BMI was associated with acute pancreatitis（ β= 0.001969, se=0.0004278, P=0.000004189) showed a significant correlation, and the weighted median results were consistent with the IVW result（ β= 0.001901, se=0.0008264, P=0.02142), also confirming the causal relationship between BMI and acute pancreatitis. The MR Egger regression results confirm that directional pleiotropy is unlikely to bias the results (intercept=4.6E-07; P=0.983), but there is no causal relationship between BMI and acute pancreatitis（ β= 0.001943, se=0.001326, P=0.1442). Cochran's Q-test and funnel plot indicate no evidence of heterogeneity and asymmetry, indicating the absence of directed pleiotropy. Conclusion: The results of MR analysis support a causal relationship between body mass index (BMI) and an increased risk of acute pancreatitis.