Geriatric Nutritional Risk Index independently predicts mortality beyond frailty and sarcopenia screening in older adults: a retrospective cohort study

BACKGROUND: Malnutrition drives adverse outcomes in older adults, but routine screening is often hindered by time constraints and reliance on subjective data. The Geriatric Nutritional Risk Index (GNRI), derived from serum albumin and body weight, offers an objective alternative. However, its prognostic value relative to brief frailty and sarcopenia screens in outpatient settings remains unclear. METHODS: This retrospective cohort study included 1,288 patients aged ≥ 60 years from a tertiary geriatric outpatient clinic in Türkiye. The primary outcome was all-cause mortality. Multivariable Cox proportional hazards regression was used to estimate adjusted hazard ratios (aHRs), controlling for age, sex, and estimated glomerular filtration rate (eGFR). Discriminative performance and incremental prognostic value were compared against the FRAIL scale, SARC-F questionnaire, and Mini Nutritional Assessment-Short Form (MNA-SF) at a primary 3-year landmark. RESULTS: During a median follow-up of 581 days, 134 deaths (10.4%) occurred among 1,288 participants (median age 70 years; 67.5% female). Each one-unit increase in the GNRI was associated with an 8% lower mortality risk (aHR 0.92; 95% CI 0.90-0.95; p < 0.001). This association remained significant when the GNRI was evaluated simultaneously with the MNA-SF, FRAIL, and SARC-F. At the 3-year landmark (n = 367), the GNRI achieved the highest numerical discrimination among all screening tools (AUC 0.701; 95% CI 0.636-0.766), though pairwise differences did not reach statistical significance after Holm adjustment. Adding the GNRI to the base clinical model yielded a statistically significant incremental value (ΔC-statistic = 0.044; p < 0.001), representing the study's most robust discriminative finding. Results were consistent across age, sex, and renal function subgroups. CONCLUSIONS: In geriatric outpatients, the GNRI independently predicts all-cause mortality and provides significant incremental value beyond a base clinical model. While it showed the highest numerical discrimination among frailty and sarcopenia screens, this standalone advantage did not reach statistical significance, supporting its integration as a complementary tool in routine geriatric assessment. A data-driven threshold of ≤ 105 for screening and the established cutoff of ≤ 98 for rule-in support a tiered approach to nutritional risk stratification. Prospective, multicentre validation is warranted before widespread clinical adoption of these specific cutoffs.