Risk stratification model for diabetic kidney disease progression based on metabolic and inflammatory biomarkers

Table 1 Risk stratification and Kaplan-Meier survival outcomes by nomogram score category

Parameter	Low-risk (0-120 points), n = 156	Intermediate-risk (121-200 points), n = 152	High-risk (> 200 points), n = 150
3-year progression rate	8.7%	28.4%	62.3%
HR vs low-risk (95%CI)	Reference	4.1 (2.3-7.3)	12.8 (7.3-22.4)
P value vs low-risk	-	< 0.001	< 0.001
Log-rank P (overall)	< 0.001
Subgroup C-index range	0.821-0.856 (age, sex, diabetes duration subgroups; all interaction P > 0.10)
DCA net benefit superiority	Superior vs “treat all”/“treat none” at 10%-70% threshold probability (most evident at 20%-50%)

Subgroup analyses included age (< 60 years vs ≥ 60 years), sex (male vs female), and diabetes duration (< 10 years vs ≥ 10 years). DCA: Decision curve analysis; HR: Hazard ratio.

Table 2 Baseline characteristics of the study population, mean ± SD/median (interquartile range)/n (%)

Characteristic	Total (n = 458)	Progression (n = 142)	Non-progression (n = 316)
Age (years)	56.8 ± 11.2	61.4 ± 10.1	54.5 ± 11.2
Male sex	267 (58.3)	89 (62.7)	178 (56.3)
Diabetes duration (years)	9.7 ± 6.4	12.3 ± 6.8	8.4 ± 5.9
BMI (kg/m2)	26.3 ± 3.8	27.2 ± 3.9	25.9 ± 3.7
eGFR (mL/minute/1.73 m2)	78.6 ± 24.3	62.3 ± 22.1	86.7 ± 21.5
UACR (mg/g)	85 (32-268)	348 (126-856)	52 (18-142)
HbA1c (%)	8.0 ± 1.5	8.9 ± 1.6	7.6 ± 1.3
SUA (μmol/L)	378 ± 84	425 ± 89	356 ± 76
hs-CRP (mg/L)	2.4 (1.2-4.6)	4.2 (2.1-7.8)	1.8 (0.9-3.2)
TyG index	8.9 ± 0.7	9.4 ± 0.7	8.7 ± 0.6
NLR	2.5 (1.8-3.6)	3.6 (2.4-5.2)	2.1 (1.6-2.9)
Diabetic retinopathy	71 (15.5)	41 (28.9)	30 (9.5)

BMI: Body mass index; eGFR: Estimated glomerular filtration rate; UACR: Urinary albumin-to-creatinine ratio; HbA1c: Hemoglobin A1c; SUA: Serum uric acid; hs-CRP: High-sensitivity C-reactive protein; TyG: Triglyceride-glucose; NLR: Neutrophil-to-lymphocyte ratio.

Table 3 External validation cohort performance metrics (n = 215)

Metric	Value	95%CI
Discrimination
Overall C-index	0.826	0.779-0.873
Time-dependent AUC at 1 year	0.845	0.798-0.892
Time-dependent AUC at 2 years	0.833	0.783-0.883
Time-dependent AUC at 3 years	0.821	0.769-0.873
Calibration
Calibration slope at 1 year	1.02
Calibration slope at 2 years	0.99
Calibration slope at 3 years	0.97
Risk stratification (3-year progression rate)
Low-risk group	9.3%
Intermediate-risk group	26.7%
High-risk group	61.8%

Calibration intercepts were close to zero at all time points. Risk stratification results closely mirror the derivation cohort findings. AUC: Area under the curve.

Table 4 Comparison with established risk prediction models

Model	Derivation C-index	Validation C-index	Calibration slope	NRI
Our nomogram	0.843 (0.807-0.879)	0.826 (0.779-0.873)	0.96	Reference
KFRE	0.781 (0.738-0.824)	0.768 (0.716-0.820)	0.89	23.6%
KDIGO model	0.765 (0.721-0.809)	0.752 (0.698-0.806)	0.87	26.8%
CKD Progression score	0.748 (0.703-0.793)	0.735 (0.680-0.790)	0.84	29.3%

Values are presented with 95%CIs where applicable. All comparisons with our nomogram: P < 0.05. KFRE: Kidney Failure Risk Equation; KDIGO: Kidney Disease: Improving Global Outcomes; NRI: Net reclassification improvement; CKD: Chronic kidney disease.