Objective To explore the relationship between body mass index (BMI), weight-adjusted waist circumference index (WWI), body roundness index (BRI), and relative fat mass index (RFM) and the risk of diabetic foot ulcer (DFU) and all-cause mortality, and to provide a basis for risk stratification in diabetic patients.
Methods Based on the data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2004, 1,487 diabetic patients aged ≥35 years were included. Weighted logistic regression was used to analyze the association between BMI, WWI, BRI, and RFM and DFU and the pre-DFU state. ROC curves and restricted cubic splines were used to analyze the discriminatory ability of each index for DFU and its non-linear relationship. By linking to the National Death Index database, the patients were followed up until December 31, 2019, and weighted Cox proportional hazards regression was used to analyze the relationship between each index and all-cause mortality.
Results A total of 1,487 diabetic patients were included, among whom 100 (6.7%) had DFU and 733 (49.3%) were in the pre-DFU state. After fully adjusting for confounding factors, BMI, WWI, BRI, and RFM were all significantly associated with an increased risk of DFU, with OR values of 1.07, 1.95, 1.47, and 1.13, respectively; however, these indices were not significantly associated with the pre-DFU state. All four indices had moderate discriminatory power for DFU, with AUCs of approximately 0.71 to 0.72. RCS analysis showed a non-linear relationship between WWI and the risk of DFU. The analysis of all-cause mortality revealed that WWI, BRI, and RFM were significantly associated with an increased risk of death, while the association of BMI was relatively weak. Among them, WWI and BRI performed more prominently in the stratification of mortality risk.
Conclusion Multiple obesity-related anthropometric indices are significantly associated with an increased risk of DFU in diabetic patients, and WWI and BRI are also associated with an increased risk of all-cause mortality. Simple and non-invasive anthropometric indices are promising for identifying high-risk populations for DFU and providing references for early prevention and risk stratification.