FINE, a novel laboratory-based frailty index for elderly patients: a retrospective descriptive study

ABSTRACT BACKGROUND: Frailty in older adults is a multifactorial geriatric syndrome associated with inflammation, malnutrition, and hematological decline. Objective and easily applicable laboratory-based indices may complement clinical frailty assessment by providing rapid and low-cost screening tools, particularly in primary care and resource-limited settings. OBJECTIVES: To develop a simple laboratory-based frailty screening index (FINE, Frailty Index for the Elderly) using C-reactive protein (CRP), albumin, hemoglobin, and sex, and to evaluate its association with the Clinical Frailty Scale (CFS) in older adults. DESIGN AND SETTING: A retrospective descriptive study conducted using electronic health records of individuals aged 80 years and older. METHODS: Data from 322 older adults were analyzed. Their FINE scores were calculated by assigning 0 or 1 point to CRP, albumin, hemoglobin, and sex based on clinically accepted reference thresholds, yielding a total score ranging from 0 to 4. Frailty was assessed using pre-recorded CFS scores. Associations between FINE scores, CFS, and individual biomarkers were examined. The screening performance was evaluated using receiver operating characteristic (ROC) curve analysis. RESULTS: The mean age of participants was 84.9 ± 4.0 years, and 55.6% were female. The prevalence rate of frailty was 46.6%. FINE scores exhibited a positive correlation with CFS and CRP levels, and a negative correlation with albumin and hemoglobin levels (p < 0.005). ROC analysis demonstrated a statistically significant but moderate discriminatory ability for frailty (area under the curve = 0.642; 95% confidence interval: 0.5820.703). At a cut-off value of ≥ 0.5, FINE scores demonstrated high sensitivity (89.3%) but low specificity (22.1%). CONCLUSION: The FINE score is a simple, rapid, and low-cost laboratory-based frailty screening tool that is significantly associated with clinical frailty and key biological processes underlying frailty. Although low specificity limits its use as a diagnostic instrument, it may serve as a practical first-step screening approach in primary care and resource-limited settings. Further multicenter prospective studies are required to validate these findings.