Abstract: FR-PO1130
Serum Creatinine- and Cystatin C-Based Skeletal Muscle Mass Surrogates Predict Mortality in Nondialysis-Dependent CKD: Results from the Fukuoka Kidney Disease Registry (FKR) Study
Session Information
- CKD: Screening, Diagnosis, Serum and Urine Biomarkers, and Scoring Indices
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 2301 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention
Authors
- Yamada, Shunsuke, Kyushu Daigaku, Fukuoka, Fukuoka Prefecture, Japan
- Tanaka, Shigeru, Kyushu Daigaku, Fukuoka, Fukuoka Prefecture, Japan
- Suenaga, Tatsuya, Kyushu Daigaku, Fukuoka, Fukuoka Prefecture, Japan
- Okamura, Kazuhiro, Kyushu Daigaku, Fukuoka, Fukuoka Prefecture, Japan
- Tsuruya, Kazuhiko, Nara Kenritsu Ika Daigaku, Kashihara, Nara Prefecture, Japan
- Ago, Tetsuro, Kyushu Daigaku, Fukuoka, Fukuoka Prefecture, Japan
- Nakano, Toshiaki, Kyushu Daigaku, Fukuoka, Fukuoka Prefecture, Japan
Background
Reduced skeletal muscle mass (SMM), strength, and sarcopenia are common in patients with non-dialysis chronic kidney disease (CKD). Surrogate markers based on serum creatinine (SCr) and serum cystatin C (SCystC) have been shown to correlate with SMM measured by DEXA and BIA methods. However, limited evidence exists regarding the predictive value of these SMM surrogates for all-cause mortality in non-dialysis CKD patients. Furthermore, it remains unclear which SCr- and SCystC-based index provides superior prognostic accuracy.
Methods
We analyzed data from 4,216 patients enrolled in the FKR Study, a prospective observational cohort of non-dialysis CKD patients in Japan. SMM surrogates included the SCr/SCystC ratio, the ratio of SCr-based eGFR to SCystC-based eGFR, the product of SCr and SCystC-based eGFR, and estimated SMM values derived from published formulas (Sunayama et al., 2023; Yamada et al., 2022; Kim et al., 2016). Participants were divided into quartiles (Q1–Q4) based on each surrogate. All-cause mortality risk was assessed using multivariable Cox proportional hazards models adjusted for potential confounders. Discriminative ability for all-cause mortality was assessed using time-dependent ROC analysis over the 5-year follow-up. Time-dependent AUROCs were calculated and compared among surrogates to determine the most accurate prognostic marker.
Results
Over a median follow-up of 5 years, 411 deaths were recorded. Across all SMM surrogates, patients in the lowest quartile (Q1) had a significantly higher risk of all-cause mortality compared to those in the highest quartile (Q4); HR of Q1 ranged from 1.43 to 2.64 depending on SMM surrogates. This association remained robust in models using restricted cubic splines to account for non-linearity. Among the markers examined, the eGFR ratio and SCystC-eGFR × SCr demonstrated better predictive performance based on time-dependent AUROC.
Conclusion
Lower levels of SMM, as estimated by SCr- and SCystC-based surrogates, are independently associated with increased risk of all-cause mortality in non-dialysis CKD patients. These simple, routinely available biomarkers may be useful for identifying sarcopenia and stratifying mortality risk in this population.