Determining a global mid-upper arm circumference cut-off to assess underweight in adults (men and non-pregnant women)

Objective: To determine if a global mid-upper arm circumference (MUAC) cut-off can be established to classify underweight in adults (men and non-pregnant women). Design: We conducted an individual participant data meta-analysis (IPDMA) to explore the sensitivity (SENS) and specificity (SPEC) of various MUAC cut-offs for identifying underweight among adults (defined as BMI < 18 center dot 5 kg/m(2)). Measures of diagnostic accuracy were determined every 0 center dot 5 cm across MUAC values from 19 center dot 0 to 26 center dot 5 cm. A bivariate random effects model was used to jointly estimate SENS and SPEC while accounting for heterogeneity between studies. Various subgroup analyses were performed. Setting: Twenty datasets from Africa, South Asia, Southeast Asia, North America and South America were included. Participants: All eligible participants from the original datasets were included. Results: The total sample size was 13 835. Mean age was 32 center dot 6 years and 65 % of participants were female. Mean MUAC was 25 center dot 7 cm, and 28 % of all participants had low BMI (<18 center dot 5 kg/m(2)). The area under the receiver operating characteristic curve for the pooled dataset was 0 center dot 91 (range across studies 0 center dot 61-0 center dot 98). Results showed that MUAC cut-offs in the range of <= 23 center dot 5 to <= 25 center dot 0 cm could serve as an appropriate screening indicator for underweight. Conclusions: MUAC is highly discriminatory in its ability to distinguish adults with BMI above and below 18 center dot 5 kg/m(2). This IPDMA is the first step towards determining a global MUAC cut-off for adults. Validation studies are needed to determine whether the proposed MUAC cut-off of 24 cm is associated with poor functional outcomes.