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

BackgroundPreoperative screening for malnutrition has become mandatory in The Netherlands. A sensitive method to diagnose malnutrition would save time and improve effectiveness.MethodsA 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 κ statistic. Accuracy was expressed in sensitivity, specificity, and false-negative rates.ResultsDifferences 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/m2 (±1.11, −2.92 to +1.46 kg/m2). The κ 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.ConclusionsSelf-reported data provide highly sensitive information to diagnose malnutrition in preoperative outpatients.