Self-reporting of height and weight: valid and reliable identification of malnutrition in preoperative patients

BACKGROUND: Preoperative screening for malnutrition has become mandatory in The Netherlands. A sensitive method to diagnose malnutrition would save time and improve effectiveness. METHODS: A prospective cross-sectional study of 488 adult elective preoperative outpatients was performed. The accuracy of self-reported height and weight was compared with measured data and 3 commonly used malnutrition screening tools. Interobserver agreement was calculated by the intraclass correlation coefficient, studied in Bland and Altman plots, and analyzed by using Cohen's kappa statistic. Accuracy was expressed in sensitivity, specificity, and false-negative rates. RESULTS: Differences between self-reported and measured data were significant, but clinically irrelevant, because only 1 patient was falsely identified as well nourished. Intraclass correlation coefficient for height, weight, and body mass index was high (.97-.99). Bland-Altman plots showed that the mean +/- standard deviation differences and 95% limits of agreement between both methods were as follows: height, .0096 m (+/-.0262, -.0417 to +.0609 m); weight, -1.28 kg (+/- 2.29, -5.76 to +3.20 kg); body mass index, -72 kg/m(2) (+/- 1.11, -2.92 to +1.46 kg/m(2)). The kappa coefficient was .84 (95% confidence interval, .75-.94). Sensitivity was .97 and specificity was .98. Sensitivity and false-negative rates of self-reported data were better overall compared with the screening tools. CONCLUSIONS: Self-reported data provide highly sensitive information to diagnose malnutrition in preoperative outpatients. (c) 2012 Elsevier Inc. All rights reserved