Value of the conicity index as an indicator of abdominal obesity in predicting cardiovascular disease and all-cause mortality risk in patients with diabetes based on NHANES data from 1999-2018

Abstract

Objective

The mortality risk among patients with diabetes is increasingly severe, yet the relationship between obesity and mortality risk in these patients remains controversial. This study evaluated the Conicity index (C-index), an indicator of abdominal obesity, to determine its value in predicting cardiovascular disease (CVD) and all-cause mortality in patients with diabetes.

Methods

This cross-sectional study utilized NHANES 1999–2018 data. Patients were grouped into quartiles based on the C-index. The relationship between the C-index and mortality risk was assessed using Cox proportional hazards regression models and restricted cubic spline (RCS) analysis.

Results

A total of 7694 patients with diabetes were included in the study. The obesity rate was 55.7 %, with an average follow-up duration of 88 months. During this period, 588 CVD deaths and 2094 all-cause deaths occurred. Higher C-index quartiles were associated with increased mortality risks, with hazard ratios for all-cause mortality ranging from 1.00 to 2.29 and for CVD mortality from 1.00 to 2.23. Unadjusted RCS analysis showed a linear positive correlation between the C-index and mortality risks. After adjusting for confounding factors, a non-linear positive correlation was observed between the C-index and all-cause mortality risk, particularly when the C-index exceeded 1.40. Subgroup analysis revealed that the relationship between the C-index and all-cause mortality was more significant in men and nonobese patients.

Conclusions

The C-index is a valuable predictor of mortality in patients with diabetes. A C-index above 1.40, being male, and being nonobese are associated with a more significant risk of all-cause mortality.