Supplementary Material for: Effect of frail phenotype on cardiorenal risk and healthcare utilization in older patients with chronic kidney disease

Introduction
Limited data have addressed frailty’s role in cardiorenal risk among older adult patients with chronic kidney disease (CKD). We investigated whether frailty could predict major renal and cardiovascular events, healthcare utilization, and mortality in these patients.
Methods
We conducted a prospective cohort enrolling patients ≥ 75 years with a stable estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2. Frailty phenotype consists of shrinking, low activity, exhaustion, weakness, and slowness, scored 0 to 5. The primary composite renal outcome was a ≥ 25 % decrease in eGFR concurrent with CKD stage progression or dialysis initiation. Secondary outcomes included major adverse cardiovascular events (MACE), emergency room (ER) visits, all-cause mortality, and hospitalization. Using multivariate Cox models with/without competing risk analyses, we explored frailty’s impact on these outcomes.
Results
Among 203 older CKD patients (mean age 81.6 ± 5.0 years, female 40.9 %, diabetes 33.0 %, body mass index 24.9 ± 3.7 kg/m2), 67.9% were frail. Over 3.47 years, 38.9% faced composite renal outcomes, 13.3% MACE, 15.3% mortality, and more than half utilized healthcare. Every one-point frailty elevated composite renal outcome risk by 28.0 % (HR: 1.28, 95% CI:1.03–1.59) and significantly increased secondary outcomes (hospitalization [HR: 1.24, 95% CI: 1.06–1.46], unexpected ER visit [HR: 1.20, [95% CI:1.03–1.39], and mortality [HR: 1.51, 95% CI: 1.06–2.16]) but not for MACE [HR: 1.43, 95% CI: 0.99–2.08]. Results were consistent across subgroups and competing risk analysis.
Conclusion
In CKD patients ≥ 75 years, frailty was associated with progressive kidney disease, increased mortality and healthcare utilization.