Stage-specific utility of obesity indices across the chronic kidney disease continuum.

TyG-ABSI demonstrated superior performance for identifying prevalent CKD compared to ABSI.

• Study utilized NHANES data from 1999-2018 with n=14,175 participants.
• The highest quartile (Q4) of TyG-ABSI showed significantly increased CKD risk after full adjustment (OR = 1.58, 95% CI: 1.23-2.03).
• TyG-ABSI captures metabolic dysregulation, incorporating triglyceride-glucose index with body shape measures.
• This association was identified through logistic regression with full covariate adjustment.

ABSI emerged as a stronger, nonlinear predictor of all-cause mortality in established CKD patients.

• Restricted cubic splines identified a significant ABSI z-score threshold of z=0.624, above which all-cause mortality risk increased steeply (HR = 1.44, 95% CI: 1.17-1.77).
• After full adjustment, ABSI Q4 remained significantly associated with all-cause mortality (HR = 1.50).
• TyG-ABSI associations with mortality attenuated after full adjustment.
• ABSI demonstrated superior discriminative accuracy for all-cause mortality (AUC = 0.68) compared to TyG-ABSI (AUC = 0.66).

ABSI was a stronger predictor of cardiovascular disease (CVD) mortality in established CKD patients than TyG-ABSI.

• Restricted cubic splines identified a significant ABSI z-score threshold of z=0.416 for CVD mortality risk (HR = 1.35, 95% CI: 1.09-1.83).
• After full adjustment, ABSI Q4 was significantly associated with CVD mortality (HR = 2.40).
• ABSI demonstrated superior discriminative accuracy for CVD mortality (AUC = 0.64) compared to TyG-ABSI (AUC = 0.59).
• The nonlinear relationship between ABSI and CVD mortality was identified using restricted cubic splines analysis.

ABSI z-score thresholds for mortality risk were identified as distinct inflection points for all-cause and CVD mortality.

• All-cause mortality risk increased steeply above ABSI z-score = 0.624.
• CVD mortality risk increased above a lower threshold of ABSI z-score = 0.416.
• These thresholds were identified through restricted cubic splines analysis.
• The differential thresholds suggest CVD mortality risk elevates at a lower level of body shape abnormality than all-cause mortality.

Subgroup analyses confirmed the robustness of ABSI for mortality prediction in established CKD patients.

• Subgroup analyses were conducted to test consistency of the ABSI-mortality association.
• Results confirmed robustness across subgroups, supporting the generalizability of findings.
• TyG-ABSI associations with mortality did not demonstrate the same robustness after full adjustment.
• These findings support stage-specific risk stratification strategies in CKD management.

The study identified a stage-specific shift in the primary driver of adverse outcomes across the CKD continuum.

• TyG-ABSI, capturing metabolic dysregulation, is optimal for identifying CKD risk in the general population.
• ABSI, reflecting anatomical fat distribution, becomes the superior predictor of mortality in established CKD.
• The large-scale cohort comprised n=14,175 participants from NHANES 1999-2018.
• This differential utility supports obesity phenotyping for cardiovascular risk assessment, metabolic disease screening, and geriatric prognosis.