Background: The extent to which relevant confounding variables influence the recognized association between renal insufficiency and malnutrition is not known. This study examined whether renal insufficiency was associated with malnutrition, independent of relevant demographic, social, and medical conditions in noninstitutionalized adults 60 years of age and older.
Methods: Participants (5248) in the United States Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1994), a cross-sectional study, were examined in a multivariate logistic regression model. Participants were stratified into three groups of glomerular filtration rate (GFR) by serum creatinine. Dietary and nutritional factors were estimated from 24-hour dietary recall, biochemistry measurements, anthropometry, and bioelectrical impedance. Participants were malnourished if they demonstrated at least three of the following five criteria: (1) serum albumin < or =37 g/L, (2) male weight < or =63.9 kg, female weight < or =51.8 kg, (3) serum cholesterol <4.1 mmol/L, (4) energy intake <15 kcal/kg/day, and (5) protein intake <0.5 g/kg/day.
Results: A GFR <30 mL/min/1.73 m(2) was present in 2.3% of men and 2.6% of women; these participants demonstrated low energy and protein intake and higher serum markers of inflammation. Thirty-one percent of individuals with malnutrition demonstrated a GFR <60 mL/min/1.73 m(2). In multivariate analysis, a GFR <30 mL/min/1.73 m(2) was independently associated with malnutrition [odds ratio 3.6 (2.0 to 6.6)] after adjustment for relevant demographic, social and medical conditions.
Conclusions: It is probable that renal insufficiency is an important independent risk factor for malnutrition in older adults. Malnutrition should be considered, prevented, and treated as possible in persons with clinically important renal insufficiency. These results should be confirmed in a prospective longitudinal cohort study.