Identification of optimal cutoffs for obesity and lipid-related indices in screening activities of daily living disability in Chinese middle-aged and elderly adults

Abstract

Objective: The aim of this study was to investigate the efficacy of 13 obesity- and lipid-related indices in screening and predicting activities of daily living (ADL) disability, as well as to determine the optimal cutoffs for these indices in the middle-aged and elderly population in China.

Methods: This study was based on cross-sectional data from the China Health and Retirement Longitudinal Study (CHARLS), which included 4,784 participants aged 45 years and older. Thirteen obesity- and lipid-related indices, including body mass index (BMI), waist circumference (WC), the waist-height ratio (WHtR), the visceral adiposity index (VAI), the body shape index (ABSI), the body roundness index (BRI), the lipid accumulation product (LAP), the conicity index (CI), the Chinese visceral adiposity index (CVAI), the triglyceride-glucose (TyG) index and its correlation index (TyG-BMI, TyG-WC, TyG-WHtR), were analyzed. Unadjusted and adjusted correlations between these indices and ADL disability were assessed via logistic regression analyses, and the area under the curve (AUC) of each index as a predictor of ADL ability was calculated via receiver operating characteristic (ROC) curves to compare the predictive efficacy and determine the optimal cutoff value.

Results: After adjustment for confounders, all 13 obesity- and lipid-related indices were independently associated with the risk of ADL disability (p < 0.05). All 13 indices had predictive value for ADL disability according to the ROC analysis (all AUCs > 0.7). The LAP index exhibited the highest predictive efficacy in men (AUC = 0.793, 95% CI: 0.704-0.882, and optimal cutoff = 35.669), and BMI was optimal in women (AUC = 0.721, 95% CI: 0.678-0.765, and optimal cutoff = 26.142). The TyG-BMI performed well in both sexes (men AUC = 0.790, female AUC = 0.720). The risk of ADL disability increased significantly with each unit increase in obesity and lipid indices.

Conclusion: All 13 obesity- and lipid-related indices were effective predictors of ADL disability risk in Chinese middle-aged and older adults. LAP and BMI emerged as the best predictors of ADL disability in men and women, respectively. These indices can serve as simple screening tools to identify the risk of ADL disability and facilitate early intervention.

Keywords: CHARLS database; activities of daily living; cross-sectional studies; obesity and lipid-related measurement indices; receiver operating characteristic curve.

Figure 1

Flowchart of data screening for this study.

Figure 2

The ROC curves of each indicator in the prediction of ADL risk in males. (A) ROC for BMI; (B) ROC for WC; (C) ROC for WHtR; (D) ROC for CVAI; (E) ROC for VAI; (F) ROC for ABSI; (G) ROC for BRI; (H) ROC for LAP; (I) ROC for CI; (J) ROC for TYG; (K) ROC for TYG_BMI; (L) ROC for TYG_WC; (M) ROC for WHtR. WC, waist circumference; BMI, body mass index; WHtR, waist to height ratio; VAI, visceral adiposity index; ABSI, A body shape index; BRI, body roundness index; LAP, lipid accumulation product; CVAI, Chinese visceral adiposity index; CI, conicity index; TyG index, triglyceride-glucose index; TyG-BMI, TyG related to BMI; TyG-WC, TyG related to WC; TyG-WHtR, TyG related to WHtR.

Figure 3

The ROC curves of each indicator in the prediction of ADL risk in females. (A) ROC for BMI; (B) ROC for WC; (C) ROC for WHtR; (D) ROC for CVAI; (E) ROC for VAI; (F) ROC for ABSI; (G) ROC for BRI; (H) ROC for LAP; (I) ROC for CI; (J) ROC for TYG; (K) ROC for TYG_BMI; (L) ROC for TYG_WC; (M) ROC for WHtR. WC, waist circumference; BMI, body mass index; WHtR, waist to height ratio; VAI, visceral adiposity index; ABSI, A body shape index; BRI, body roundness index; LAP, lipid accumulation product; CVAI, Chinese visceral adiposity index; CI, conicity index; TyG index, triglyceride-glucose index; TyG-BMI, TyG related to BMI; TyG-WC, TyG related to WC; TyG-WHtR, TyG related to WHtR.