Nutritional Status as Predictor for Mortality in Older Adults With Acute Kidney Injury

Older adults (OA) exhibit the highest incidence of acute kidney injury (AKI), with outcomes influenced by comorbidities, frailty, and malnutrition. Nutritional status, a potentially modifiable factor, has not been extensively evaluated as a mortality predictor in hospitalized OA with AKI. Our purpose was to report on the mortality risk provided by the nutritional status, comorbidities, and biochemical parameters in OA with AKI. Methods: In this prospective cohort study (July 2024–July 2025) conducted at a tertiary geriatric unit, hospitalized OA with AKI, diagnosed according to KDIGO criteria, underwent a comprehensive nutritional assessment within 48 hours of admission. The Geriatric Nutritional Risk Index (GNRI), Mini Nutritional Assessment, anthropometric measurements, and biochemical markers were recorded. The primary outcome was in-hospital all-cause mortality; secondary outcomes included the analysis of all-cause mortality according to nutritional and clinical factors, such as dysphagia, hyporexia, and GNRI quartiles (Q1–Q4). Logistic regression models were used to identify independent predictors of mortality, and all models were adjusted for AKI severity. Results: Of 742 admissions, 187 patients met the inclusion criteria. The median age was 76.8 years, and 50% were male. GNRI quartile analysis demonstrated a progressive deterioration in anthropometric and biochemical markers from Q4 to Q1. Mortality was higher in the high-risk GNRI group (42.2% vs 30.1%); however, this difference did not reach statistical significance (p = 0.098). In adjusted analyses, dysphagia (adjusted odds ratio [aOR] 6.11; 95% CI 1.82–20.51; p = 0.003), hyporexia (aOR 2.24; 95% CI 1.02–4.92; p = 0.044), and lower GNRI (aOR 1.07 per unit decrease; 95% CI 1.02–1.13; p = 0.004) were independently associated with increased mortality. In contrast, a higher mid-upper arm circumference was independently associated with a protective effect (aOR 0.78; 95% CI 0.67–0.91; p = 0.001). Conclusions: In OA hospitalized with AKI, poor nutritional status, particularly dysphagia, hyporexia, and lower GNRI, was independently associated with increased in-hospital mortality, whereas preserved muscle mass was protective. Early, simple, bedside nutritional assessments may help guide targeted interventions to improve outcomes in this high-risk population.