New Formula for Determining Malnutrition Risk in Elderly
By Rebekah McCallister
Given that normal weight in the elderly can be somewhat difficult to ascertain, identifying older adults at risk of malnutrition using established formulas, such as the Nutritional Risk Index (NRI), can be challenging.
In a new study, Olivier Bouillanne, of the Servicesde Gérontologie, Biologie, and Médecine Gérontologie, and Cometé de Liaison Alimentation et Nutrition, Hôpital Emile-Roux, Assistance Publique -Hôpitaux de Paris, Limeil-Brévannes, France, and colleagues created a modified version of the NRI, the Geriatric Nutritional Risk Index (GNRI), incorporating the Lorentz formula, which considers the patient’s height and weight when estimating ideal body weight (Am J Clin Nutr. 2005;82:777-783).
This prospective study included 181 hospitalized elderly aged ³65 years (144 women, 37 men) in whom nutritional status (ie, albumin, prealbumin, and body mass index [BMI]) and GNRI were assessed (Box). For validation, the GNRI was compared with 2 malnutrition-related factors known to increase risk of morbidity and mortality—[em dash]infections and bedsores.
Six months after the study began, 57% of the patients had returned home, 15% had died (43% of infectious complications), 4% had been moved to an acute care unit, 8% had been transferred to a long-term care unit, and 16% remained in the admission unit. A total of 59 (32.6%) patients had infectious complications (ie, pneumonia, urinary tract infection, septicemia, erysipelas, mucus enteritis, infectious arthritis, and parotitis), bedsores, or both.
There were positive correlations between severity scores (ie, 1 = death; 2 = alive with complications; 3= alive without complications) and both albumin level and GNRI, but there was no correlation with BMI or weight:WLo (which = 1 if weight is higher than WLo). Mortality and morbidity risks were 29 and 4.4 for those with GNRI <82 (“major nutrition-related risk”), 6.6 and 4.9 for those with GNRI 82 to <92 (“moderate nutrition-relation risk”), and 5.6 and 3.3 for those with GNRI 92 to £98 (“low nutrition-related risk”).
During the second phase of the study, which included 2474 patients (1785 women, 689 men) admitted to a geriatric rehabilitation care unit over 3 years, prospective measurement of GNRI showed that 44% of patients were at major or moderate nutrition-related risk.
The authors concluded that GNRI “is a better nutrition-related risk index” than either albumin level or BMI alone.
“We have observed that there is often confusion in published reports between the use of albumin and BMI as a nutrition-related risk index and as an index of malnutrition, which, in fact, are 2 different concepts,” the investigators wrote.
Box.Lorentz equations/GNRI formula
Lorentz equations (WLo) :
Ideal weight for men: H — 100 – [(H – 150)/4]
Ideal weight for women: H — 100 – [(H — 150)/2.5]
where H = [2.02 x knee height (cm)] — (0.04 x age) 64.19 for men and
H= [1.83 x knee height (cm)] — (0.24 x age) 84.88 for women
GNRI = [1.489 x albumin (g/L)] [41.7 x (weight/WLo)]