Mid-upper arm circumference cut-offs identifying malnourishment and risk of mortality among patients with tuberculosis

Using Mid-Upper Arm Circumference (MUAC) in place of Body Mass Index (BMI) may be preferable for identifying malnutrition in various situations, especially in resource-poor settings. The primary objective of this study was to determine MUAC cut-offs corresponding to BMI < 20 kg/m2, < 18.5 kg/m2, < 17 kg/m2 and < 16 kg/m2 in a cohort of patients with tuberculosis from West Africa. The secondary objective was to examine the prognostic value of MUAC cut-offs in predicting mortality at two months of tuberculosis treatment. The aim was to propose unisex MUAC cut-offs that could be used to identify malnutrition and to identify patients at increased risk of dying. This prospective, observational cohort study was conducted from 2003 to 2022. Diagnostic accuracy of MUAC to identify BMI cut-offs was assessed for every 0.5 cm in the range < 20.0 cm to < 27.0 cm. Area under the receiver operating characteristic curves (AUROCCs), sensitivity (SENS), specificity (SPEC), false negative and false positive were determined. Cox proportional hazard model was used to examine the association between MUAC cut-offs and mortality. Data from 2,098 patients were included. MUAC was found to be excellent in its ability to identify BMI cut-offs with AUROCCs close to 0.9. The MUAC cut-offs that best corresponded to BMI < 20 kg/m2, < 18.5 kg/m2, < 17 kg/m2 and < 16 kg/m2 were < 25 cm (SENS 75.1%, SPEC 83.0%), < 24 cm (SENS 75.1%, SPEC 80.0%), < 23 cm (SENS 77.9%, SPEC 83.2%) and < 22.5 cm (SENS 80.3%, SPEC 81.9%). Mortality risk significantly increased with MUAC values < 22 cm. MUAC cut-off < 25 cm was proposed to be used in place of BMI < 20 kg/m2 to identify malnourishment and MUAC cut-off < 22 cm was proposed to identify patients at increased risk of dying and thus in need of further attention.