Elderly Nutritional Indicators for Geriatric Malnutrition Assessment (ENIGMA): Development and validation of a nutritional prognostic index

Summary Background Few nutritional measurement tools have been validated that predict long-term mortality risks in community-living older persons. Objective To develop and validate a new nutritional prognostic index (ENIGMA) for use in geriatric outpatient or primary care. Design We developed the ENIGMA (four questions: unable to shop, cook or feed one's self, difficulty eating due to oral problem, eat few fruits or vegetables, 3 or more drugs a day, and four blood indicators: low albumin, hemoglobin, total cholesterol and lymphocyte count), and evaluated its predictive validity for 10 years mortality outcome in a development cohort (N = 1550) of community-living older persons, in comparison with the Geriatric Nutritional Risk Index (GNRI), Mini Nutritional Assessment (MNA) and ESPEN Malnutrition (ESPEN-M), and calibrated it externally in a validation cohort (N = 924). Results In the development cohort, ENIGMA component indicators and summary risk score (0–10) were independently associated with significantly increased mortality hazard ratio (HR), adjusted for age, sex, chronic diseases, comorbidity and inflammatory status. Increasing risk categories predicted increasing adjusted HRs (95% CI); low (0–1): reference, moderate (2–3): 1.48 (1.10–2.00), high (4–5): 2.32 (1.52–3.55), very high (6+): 4.97 (2.52–9.77). ENIGMA showed better discriminatory accuracy (C = 0.67, 95% CI = 0.63–0.71) than MNA (C = 0.59, 95% CI = 0.55–0.63), GNRI (C = 0.57, 95% CI = 0.52–0.61), and ESPEN-M (C = 0.52, 95% CI = 0.48–0.56). The predictive accuracy and utility of ENIGMA was supported in the validation cohort (C = 0.68, 95% CI = 0.62–0.74); calibration-at-large, a = 0.00007, p = 0.187; calibration slope = 0.997, 95% CI, 0.997–0.998). Conclusion The ENIGMA is a validated nutritional prognostic tool that strongly predicts long-term mortality risks and is recommended for use in geriatric outpatient and primary care settings.