The role of obesity in mortality from digestive diseases in UK Biobank

Abstract Most current studies use body mass index (BMI) or waist circumference (WC) to define obesity, and BMI, which reflects subcutaneous fat independent of visceral fat, is the most commonly used indicator of obesity. WC reflects subcutaneous and visceral fat. This research aims to investigate the effect of obesity on mortality in people with digestive diseases. According to BMI and WC, we divided patients with obesity into the following four groups: general obesity, abdominal obesity, combined obesity, and non-obese. The effects of different obesity types on mortality in a population with digestive diseases were analysed via Cox regression and inverse probability-weighted Cox regression. Our research employed multivariate imputation via the chained equations method to interpolate missing values. A total of 254,445 participants, with a mean age of 57.8 ± 7.8 years, were included in the analysis. Of these participants, 227,111 (89.3%) participants were censored, and 27,334 (10.7%) participants died. Abdominal obesity and combined obesity were independent predictors of mortality in patients with digestive diseases. The combination of BMI and WC was valuable and significant for considering the type of obesity. In addition, our study revealed that sex, socioeconomic status, lifestyle habits, and physical activity were also associated with death in people with digestive disorders. Combined obesity, which is determined by both BMI and WC, is an important factor that influences mortality in a population with digestive diseases, and it plays a stronger role than abdominal obesity alone. These modifiable risk factors for mortality can provide guidance to populations with digestive diseases to avoid poor lifestyles and prolong survival time.