Multicenter Study of the Validity and Reliability of Subjective Global Assessment in the Hemodialysis Population

Abstract

Subjective Global Assessment (SGA) is a nutrition assessment tool recommended by the 2000 NKF K/DOQI Nutrition Guidelines. However, the validity and reliability of this tool have not been established in hemodialysis (HD) patients. The purpose of this observational study was to determine the reliability and validity of SGA in the HD population. Renal dietitians (RD) were recruited to perform SGA (7-point scale version) and collect data on demographics, clinical status, biochemistries, dietary intake, and quality of life (Medical Outcomes Short Form-36) on 3 HD patients at baseline and 6 months later. The 54 participating RDs were trained to perform SGA and collect data via a website created for this study. Interrater reliability for SGA was tested in a subset of 76 patients, via an SGA performed by a second RD at baseline, while intrarater reliability was assessed by the original RD repeating the SGA at 1 month. Data collection occurred at HD facilities in the United States (109 patients), Canada (35 patients), and New Zealand (9 patients). Of the 153 patients, 46% were female, 64% were Caucasian, 6% were Hispanic, 21% were African American, and 6% were Asian. The primary etiologies were hypertension (33%), type 2 diabetes mellitus (DM) (27%), type 1 DM (10%), and glomerular nephritis (10%); 59% had cardiovascular disease. The mean age, body mass index (BMI), serum albumin, and duration on HD were 64 +/- 14 years (mean +/- SD), 28 +/- 7 kg/m(2), 3.7 +/- 0.4 mg/dL, and 41 +/- 34 months, respectively. SGA scores were well nourished (7)-30%; mildly malnourished (MN 6)-41%; moderately MN 5-21%, 4-7%, and 3-2%; and severely MN (2 and 1)-0%. SGA training via the Internet achieved fair interrater reliability (weighted Kappa = 0.5, Spearman's Rho = 0.7) and substantial intrarater reliability (weighted Kappa = 0.7, Spearman's Rho = 0.8) (P < .001). Validity was demonstrated through statistically significant differences in mean BMI and serum albumin across the 5 categories of SGA (7-28 +/- 7, 6-29 +/- 7, 5-28 +/- 8, 4-21 +/- 4, 3-24 +/- 2, P < .05; and 7-3.8 +/- 0.3, 6-3.8 +/- 0.4, 5-37 +/- 0.05, 4-3.4 +/- 0.07, 3-2.9 +/- 1.2, P < .001, respectively). Nutritional status varied by age (P < .05), but not ethnicity or nationality. We conclude that the 7-point scale SGA is a reliable and valid tool for nutritional assessment in adults on HD.