Comparing the validity of anthropometric measurements in identifying malnutrition status of older age people in Borena district, North Central Ethiopia: a cross_sectional study

Background Malnutrition among older age people is becoming significantly higher in spite of improvements in the health care system. Life expectancy of Ethiopian elders is increasing; but reliable and valid tools for screening and diagnosis of malnutrition in this subgroup are limited. This study aimed to assess the validity of anthropometric measurements: Mid Upper Arm Circumference (MUAC), Body Mass Index (BMI), and Calf Circumference (CC) in detecting malnutrition status of older age people in Ethiopia. Methods A community based cross-sectional study was conducted in Borena District from January to March, 2020. A total of 421 participants aged were systematically included in the study. To test reliability and validity of the measurements,Cronbach's [alpha] coefficient and Pearson's correlations were used, respectively. The full Mini-Nutritional Assessment (MNA) tool was used to diagnosis malnutrition. Overall accuracy, sensitivity and specificity of BMI, MUAC and CC were estimated using Receiver Operating Characteristic curves. The Youden Index was used to determine the best cut-off point. Results The reliability of BMI, MUAC and CC by Cronbach's alpha was found 0.847. Significant positive correlations between MNA, BMI(r = 0.56, p < 0.01); MNA, MUAC(r = 0.43, p < 0.01; and MNA, CC(r = 0.52, p < 0.01) revealed. The area under the curve (AUC) of BMI, MUAC and CC were found: 0.98(95% CI, 0.96-0.99, p < 0.001), 0.94(95% CI, 0.89-0.98, p < 0.001) and 0.96(95% CI, 0.94-0.98, p < 0.001) indicating the overall accuracy respectively. The sensitivity and specificity of BMI, MUAC and CC using established cut off points were found: 90%, 96%; 78%, 94% and 84%, 95% respectively. However, using the Youden index the best cut-off point, the sensitivity and specificity of MUAC and CC were 88%, 86%; 92% and 89% respectively and adjusted for age and sex. Conclusions The current study demonstrated that BMI was a reliable and valid method to identify the malnutrition status of older age people. A MUAC value of 19 cm and CC of 30 cm were simple and efficient cut-off points for the determination of malnutrition in the older age people. A future study is needed to validate the validity of BMI, MUAC and CC against biochemical tests as gold standard. Keywords: Anthropometric indices, Older age, Malnutrition, MNA, Reliability, Validity