| Kidney Res Clin Pract > Volume 45(5); 2026 > Article |
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Conflicts of interest
A patent based on this work has been filed (application No. 10-2026-0053087, filed March 24, 2026). All authors have no other conflicts of interest to declare.
Funding
This work was supported by the Seoul National University Hospital Research Fund (grant number: 04-2025-2140).
Acknowledgments
This study used biomedical and research resources, including genetic and health information, provided by the Clinical & Omics Data Archive (CODA) and the Korea Disease Control and Prevention Agency, Republic of Korea (approval number: CODA_S2601596-01).
Data sharing statement
The SNUH data are available from the corresponding author upon reasonable request. The KoGES data are available from the Korea Disease Control and Prevention Agency through CODA (https://coda.nih.go.kr) upon approved application.
Authors’ contributions
Conceptualization: HY, YCK
Investigation: HY, YCK, YSK, KWJ, KHO, DKK, HL, SSH, EK, SP
Data curation, Formal analysis, Validation, Visualization, Software: HY
Funding acquisition: HY, BJ
Methodology: HY, YCK
Resources: YCK, YSK, KWJ, KHO, DKK, HL, SSH, EK, SP
Project administration: BJ, YCK
Supervision: YCK
Writing–original draft: HY
Writing–review & editing: All authors
All authors read and approved the final manuscript.
| Characteristic | SNUH training set (n = 19,746) | SNUH internal validation (n = 8,463) | KoGES external validation (n = 3,960) | p-value (training vs. internal validation) | p-value (SNUH vs. KoGES) |
|---|---|---|---|---|---|
| Demographics | |||||
| Age (yr) | 64.1 ± 15.5 | 64.2 ± 15.5 | 66.9 ± 9.4 | 0.76 | <0.001 |
| Male sex | 12,261 (62.1) | 5,290 (62.5) | 1,672 (40.7) | 0.52 | <0.001 |
| Body mass index (kg/m2) | 23.9 ± 3.9 | 24.0 ± 3.9 | 25.1 ± 3.4 | 0.22 | <0.001 |
| Laboratory measurements | |||||
| eGFR (mL/min/1.73 m2) | 42.2 ± 27.2 | 42.1 ± 27.1 | 56.7 ± 13.9 | 0.73 | <0.001 |
| Hemoglobin (g/dL) | 12.0 ± 2.2 | 12.0 ± 2.2 | 13.3 ± 1.6 | 0.56 | <0.001 |
| HbA1c (%) | 6.3 ± 1.2 | 6.3 ± 1.2 | 6.1 ± 1.2 | 0.80 | <0.001 |
| Serum albumin (g/dL) | 4.1 ± 0.5 | 4.0 ± 0.6 | 4.0 ± 0.2 | 0.03 | <0.001 |
| Glucose (mg/dL) | 118.9 ± 45.7 | 119.0 ± 45.8 | 103.9 ± 33.4 | 0.82 | <0.001 |
| Uric acid (mg/dL) | 6.5 ± 2.0 | 6.5 ± 2.0 | 5.7 ± 1.7 (n = 1,737)a | 0.98 | <0.001 |
| Total cholesterol (mg/dL) | 147.3 ± 50.9 | 147.1 ± 51.6 | 186.9 ± 40.3 | 0.79 | <0.001 |
| Triglycerides (mg/dL) | 135.8 ± 83.7 | 135.5 ± 82.0 | 159.2 ± 108.6 | 0.74 | <0.001 |
| HDL cholesterol (mg/dL) | 47.9 ± 15.1 | 48.1 ± 15.3 | 45.4 ± 11.9 | 0.39 | <0.001 |
| Blood urea nitrogen (mg/dL) | 33.0 ± 21.0 | 33.1 ± 21.2 | 19.0 ± 6.7 | 0.60 | <0.001 |
| Serum creatinine (mg/dL) | 2.9 ± 2.9 | 2.9 ± 3.0 | 1.2 ± 0.5 | 0.66 | <0.001 |
| Urine creatinine (mg/dL)b | 103.0 ± 66.0 | 102.4 ± 65.6 | Imputed onlyb | 0.45 | - |
| Urine microalbumin (mg/L)b | 69.6 ± 160.7 | 73.0 ± 164.9 | Imputed onlyb | 0.21 | - |
| UACR (mg/g)b | 407.9 ± 1,207.9 | 405.8 ± 1,187.0 | 29.0 ± 72.3 | 0.92 | <0.001 |
| Sodium (mmol/L) | 139.7 ± 3.3 | 139.8 ± 3.2 | 142.7 ± 2.4 (n = 366)a | 0.71 | <0.001 |
| Potassium (mmol/L) | 4.6 ± 0.6 | 4.6 ± 0.6 | 4.6 ± 0.5 (n = 327)a | 0.73 | 0.007 |
| Calcium (mg/dL) | 9.1 ± 0.7 | 9.1 ± 0.7 | 9.7 ± 0.5 (n = 690)a | 0.17 | <0.001 |
| Phosphorus (mg/dL) | 3.8 ± 1.0 | 3.8 ± 1.0 | Not availablea | 0.35 | - |
| AST (IU/L) | 24.0 ± 28.0 | 24.4 ± 31.8 | 27.2 ± 18.6 | 0.25 | <0.001 |
| ALT (IU/L) | 21.6 ± 25.5 | 21.6 ± 29.6 | 23.2 ± 16.9 | 0.92 | <0.001 |
| GGT (IU/L) | 55.0 ± 100.7 | 56.0 ± 103.2 | 44.7 ± 110.3 (n = 712)a | 0.54 | 0.011 |
| Serum bicarbonate/TCO2 (mEq/L) | 25.4 ± 4.3 | 25.4 ± 4.3 | Not availablea | 0.25 | - |
| Total bilirubin (mg/dL) | 0.68 ± 0.69 | 0.67 ± 0.59 | 0.56 ± 0.29 (n = 361)a | 0.69 | <0.001 |
| Total protein (g/dL) | 7.00 ± 0.71 | 6.98 ± 0.73 | 7.35 ± 0.52 (n = 334)a | 0.01 | <0.001 |
| Medical history | |||||
| RAAS inhibitor use | 14,740 (74.6) | 6,357 (75.1) | 296 (7.2) | 0.42 | <0.001 |
| Statin use | 14,056 (71.2) | 6,008 (71.0) | 439 (10.7) | 0.75 | <0.001 |
| Diagnosis of hypertensionc | 14,740 (74.6) | 6,357 (75.1) | 1,565 (38.1) | 0.42 | <0.001 |
| Diabetes mellitus | 1,708 (8.6) | 739 (8.7) | 1,055 (25.7) | 0.84 | <0.001 |
| Additional comorbiditiesd | |||||
| Cardiovascular diseased | 1,732 (6.1) | 128 (3.2) | - | <0.001 | |
| Cerebrovascular diseased | 480 (1.7) | 86 (2.2) | - | 0.103 | |
| Chronic liver diseased | 1,022 (3.6) | Not available | - | - | |
| Malignancyd | 3,126 (11.1) | 110 (2.8) | - | <0.001 | |
| Polycystic kidney diseased | 1,487 (5.3) | Not available | - | - | |
| Goutd | 199 (0.7) | 406 (10.3) | - | <0.001 | |
| Subgroup: DKD | 1,708/19,746 (8.6) | 739/8,463 (8.7) | Not available | 0.84 | - |
| Subgroup: GN | 637 (3.2) | 316 (3.7) | Not available | 0.03 | - |
| Outcomes | |||||
| Primary outcome (≥40% eGFR decline) | 6,773 (34.3) | 2,903 (34.3) | 69 (1.7) | >0.99 | <0.001 |
| Secondary outcome (≥50% eGFR decline) | 2,429 (12.3) | 1,030 (12.2) | 53 (1.3) | 0.77 | <0.001 |
Data are expressed as mean ± standard deviation or number (%).
ALT, alanine aminotransferase; AST, aspartate aminotransferase; DKD, diabetic kidney disease; eGFR, estimated glomerular filtration rate; GGT, gamma-glutamyl transferase; GN, glomerulonephritis; HbA1c, glycated hemoglobin; HDL, high-density lipoprotein; KoGES, Korean Genome and Epidemiology Study; RAAS, renin-angiotensin-aldosterone system; SNUH, Seoul National University Hospital; TCO2, total carbon dioxide; UACR, urine albumin-to-creatinine ratio.
aGGT, total bilirubin, total protein, serum sodium, and serum potassium were measured at baseline only; serum calcium was measured at baseline (n = 366) and the 4th follow-up survey (n = 439) only (total n = 690). Serum uric acid was measured only at the 4th, 6th, 7th, 8th, and 9th follow-up surveys (total n = 1,737). For all other waves, these variables were imputed using SNUH cohort medians (GGT, 27 IU/L; total bilirubin, 0.7 mg/dL; total protein, 7.2 g/dL; sodium, 139.7 mmol/L; potassium, 4.6 mmol/L; calcium, 9.2 mg/dL; uric acid, 5.8 mg/dL). Serum phosphorus and bicarbonate were not measured in any KoGES survey wave and are reported as “Not available.”
bUrine creatinine and urine microalbumin represent spot urine measurements included as independent model features alongside UACR. In the KoGES cohort, these variables were not available at any follow-up wave; all observations were set to SNUH cohort medians (urine creatinine, 102.8 mg/dL; urine microalbumin, 70.6 mg/L) for model inference. UACR was estimated from urine dipstick protein results using a semi-quantitative mapping: negative/trace = 15 mg/g; 1+ = 30 mg/g; 2+ = 100 mg/g; 3+ = 300 mg/g; 4+ = 1,000 mg/g.
cIn the SNUH derivation cohort, hypertension was defined using antihypertensive prescription records as a surrogate marker (RAAS inhibitor duration, >0 days; surrogate-based prevalence, 74.6%–75.1%). In the KoGES cohort, hypertension was defined based on physician diagnosis or current antihypertensive treatment history (prevalence, 38.1%), reflective of the community-based setting.
dAdditional comorbidities were ascertained from ICD-10 diagnosis records (SNUH, n = 28,209) or baseline self-reported medical history questionnaire matched via unique participant ID (KoGES, n = 3,960). These variables were not included as model input features. Chronic liver disease and polycystic kidney disease were not assessed in the KoGES questionnaire (not available).
Model performance in the internal and external validation cohorts. Comparison of discriminative performance metrics (AUROC and AUPRC) among individual ML models (XGBoost, LightGBM, CatBoost, Random Forest), the ensemble ML model, and the KFRE models. In the internal validation (SNUH), the ensemble ML model achieved the highest performance (AUROC, 0.939; 95% CI, 0.934–0.944), significantly outperforming the KFRE 8-variable model (AUROC, 0.884; 95% CI, 0.876–0.893). In the external validation (KoGES), the ensemble ML model maintained robust generalizability (AUROC, 0.859; 95% CI, 0.798–0.914), comparable to the KFRE models (4-variable AUROC, 0.882; 95% CI, 0.818–0.935). AUROC 95% CIs estimated by bootstrap resampling (1,000 iterations).
DeLong test comparing the ensemble ML model with KFRE models showed the following results: in SNUH, ensemble vs. KFRE 4-variable, ΔAUROC, +0.061 (95% CI, +0.055 to +0.067; p < 0.001), and ensemble vs. KFRE 8-variable, ΔAUROC, +0.057 (95% CI, +0.051 to +0.063; p < 0.001); in KoGES, ensemble vs. KFRE 4-variable, ΔAUROC, –0.023 (95% CI, –0.072 to +0.026; p = 0.36), and ensemble vs. KFRE 8-variable, ΔAUROC, –0.023 (95% CI, –0.072 to +0.026; p = 0.35) (Supplementary Table 3, available online).
AUPRC, area under the precision-recall curve; AUROC, area under the receiver operating characteristic curve; CI, confidence interval; KFRE, Kidney Failure Risk Equation; KoGES, Korean Genome and Epidemiology Study; ML, machine learning; SNUH, Seoul National University Hospital.
| Variable | DKD (n = 739) | GN (n = 316) | HTN (n = 660) | Proteinuria-dominant (n = 1,063) |
|---|---|---|---|---|
| Demographics | ||||
| Age (yr) | 65.4 ± 13.2 | 50.5 ± 16.8 | 68.0 ± 14.4 | 62.4 ± 15.9 |
| Body mass index (kg/m2) | 24.5 ± 4.3 | 23.4 ± 3.7 | 24.4 ± 3.5 | 24.2 ± 4.5 |
| Male sex | 467 (64.6) | 140 (48.1) | 353 (61.6) | 633 (62.7) |
| Laboratory measurements | ||||
| eGFR (mL/min/1.73 m2) | 38.6 ± 26.1 | 32.9 ± 31.7 | 40.2 ± 23.6 | 33.8 ± 24.9 |
| eGFR slope (mL/min/1.73 m2/yr) | –2.1 ± 5.7 | –0.9 ± 4.8 | –1.7 ± 4.0 | –2.6 ± 4.7 |
| Hemoglobin (g/dL) | 11.7 ± 2.1 | 11.5 ± 2.2 | 12.2 ± 2.2 | 11.5 ± 2.3 |
| HbA1c (%) | 7.1 ± 1.3 | 5.6 ± 0.7 | 6.3 ± 1.0 | 6.5 ± 1.3 |
| Serum albumin (g/dL) | 4.0 ± 0.6 | 3.9 ± 0.5 | 4.1 ± 0.5 | 3.9 ± 0.6 |
| Glucose (mg/dL) | 143.8 ± 65.0 | 101.2 ± 25.2 | 120.4 ± 51.6 | 127.7 ± 58.4 |
| Uric acid (mg/dL) | 6.5 ± 2.0 | 6.8 ± 2.1 | 6.7 ± 2.0 | 6.8 ± 2.1 |
| Total cholesterol (mg/dL) | 135.4 ± 50.6 | 166.4 ± 62.1 | 142.5 ± 48.3 | 150.8 ± 54.7 |
| Triglycerides (mg/dL) | 149.6 ± 89.2 | 144.3 ± 90.7 | 141.4 ± 89.0 | 149.1 ± 87.5 |
| HDL cholesterol (mg/dL) | 43.8 ± 13.7 | 53.5 ± 18.2 | 47.3 ± 14.7 | 46.8 ± 14.9 |
| Blood urea nitrogen (mg/dL) | 35.8 ± 21.6 | 43.3 ± 28.0 | 32.6 ± 19.5 | 40.1 ± 24.8 |
| Serum creatinine (mg/dL) | 3.2 ± 3.0 | 4.6 ± 4.3 | 2.6 ± 2.6 | 3.4 ± 2.9 |
| UACR (mg/g) | 660.2 ± 1,813.9 | 623.5 ± 1,245.2 | 334.7 ± 989.8 | 1,753.1 ± 2,115.2 |
| Sodium (mmol/L) | 139.5 ± 3.4 | 139.9 ± 3.0 | 140.0 ± 3.2 | 139.5 ± 3.4 |
| Potassium (mmol/L) | 4.7 ± 0.6 | 4.7 ± 0.7 | 4.7 ± 0.6 | 4.7 ± 0.6 |
| Calcium (mg/dL) | 9.1 ± 0.7 | 9.0 ± 0.7 | 9.1 ± 0.7 | 8.9 ± 0.7 |
| Phosphorus (mg/dL) | 3.9 ± 1.1 | 4.3 ± 1.3 | 3.7 ± 0.9 | 4.0 ± 1.2 |
| AST (IU/L) | 22.2 ± 11.0 | 21.8 ± 20.2 | 22.3 ± 11.2 | 22.8 ± 15.2 |
| ALT (IU/L) | 21.0 ± 16.3 | 19.0 ± 20.7 | 20.7 ± 15.2 | 20.7 ± 21.9 |
| GGT (IU/L) | 45.5 ± 80.5 | 34.6 ± 51.2 | 45.6 ± 66.6 | 58.6 ± 100.2 |
| Serum bicarbonate/TCO2 (mmol/L) | 25.0 ± 4.4 | 24.0 ± 4.3 | 25.0 ± 4.2 | 24.4 ± 4.6 |
| Total bilirubin (mg/dL) | 0.6 ± 0.3 | 0.6 ± 0.3 | 0.7 ± 0.3 | 0.6 ± 0.4 |
| Total protein (g/dL) | 6.9 ± 0.7 | 6.8 ± 0.8 | 7.0 ± 0.6 | 6.8 ± 0.8 |
| Medical history | ||||
| RAAS inhibitor use | 617 (85.3) | 275 (94.5) | 526 (91.8) | 912 (90.4) |
| Statin use | 592 (81.9) | 244 (83.8) | 465 (81.2) | 830 (82.3) |
| HTNa | 140 (19.4) | 275 (94.5) | 660 (100) | 68 (6.7) |
| Diabetes mellitus | 739 (100) | 14 (4.8) | 140 (24.4) | 134 (13.3) |
| Outcomes | ||||
| Primary outcome (≥40% eGFR decline or ESRD) | 303 (41.9) | 163 (56.0) | 171 (29.8) | 524 (51.9) |
| Secondary outcome (≥50% eGFR decline or ESRD) | 111 (15.4) | 54 (18.6) | 60 (10.5) | 215 (21.3) |
Data are expressed as mean ± standard deviation or number (%). Groups are not mutually exclusive; patients may appear in multiple columns. Demographic and laboratory characteristics stratified by four clinically distinct subgroups: DKD, GN, HTN, and proteinuria-dominant disease (UACR ≥ 300 mg/g). The GN and proteinuria groups exhibited the most severe phenotypes, characterized by lower mean eGFR (32.9 and 33.8 mL/min/1.73 m2, respectively) and elevated serum creatinine, reflecting the high-risk nature of these etiologies in a tertiary care setting. Clinical subgroups were defined as follows based on the internal validation set: DKD, patients with a recorded diagnosis of diabetes mellitus (International Classification of Diseases, 10th Revision [ICD-10]: E10–E14; n = 739); GN, patients with a GN-specific ICD-10 subgroup code (N00–N08; n = 316); HTN, patients with an ICD-10 coded HTN diagnosis (I10–I15; n = 660); and proteinuria-dominant disease, patients with UACR ≥300 mg/g (n = 1,063).
ALT, alanine aminotransferase; AST, aspartate aminotransferase; DKD, diabetic kidney disease; eGFR, estimated glomerular filtration rate; ESRD, end-stage renal disease; GGT, gamma-glutamyl transferase; GN, glomerulonephritis; HbA1c, glycated hemoglobin; HDL, high-density lipoprotein; HTN, hypertension; RAAS, renin-angiotensin-aldosterone system; TCm2, total carbon dioxide; UACR, urine albumin-to-creatinine ratio.
AUROC, area under the receiver operating characteristic curve; CI, confidence interval; DKD, diabetes mellitus; GN, glomerulonephritis; HTN, hypertension; KFRE, Kidney Failure Risk Equation; UACR, urine albumin-to-creatinine ratio.
95% CIs were estimated by bootstrap resampling (1,000 iterations). Ensemble denotes the soft-voting ensemble of XGBoost, LightGBM, CatBoost, and Random Forest. Subgroups are not mutually exclusive and were defined as follows: DKD, International Classification of Diseases, 10th Revision [ICD-10]: E10–E14; GN, ICD-10: N00–N08; HTN, ICD-10: I10–I15; proteinuria-dominant, UACR ≥300 mg/g.
Hojun Yu
https://orcid.org/0000-0003-0410-1231
Yon Su Kim
https://orcid.org/0000-0003-3091-2388
Kwon Wook Joo
https://orcid.org/0000-0001-9941-7858
Kook-Hwan Oh
https://orcid.org/0000-0001-9525-2179
Dong Ki Kim
https://orcid.org/0000-0002-5195-7852
Hajeong Lee
https://orcid.org/0000-0002-1873-1587
Seung Seok Han
https://orcid.org/0000-0003-0137-5261
Eunjeong Kang
https://orcid.org/0000-0002-2191-2784
Sehoon Park
https://orcid.org/0000-0002-4221-2453
Byoungjun Jeon
https://orcid.org/0000-0003-0127-6490
Yong Chul Kim
https://orcid.org/0000-0003-3215-8681
