Assessing effectiveness of a novel mid-upper arm circumference Z-score tape in a community setting in Guatemala

Abstract

Background: Mid-Upper Arm Circumference (MUAC) is an independent anthropometric measurement used to identify malnutrition in children. While much research has been dedicated to applying fixed estimates of MUAC to identify cases of malnutrition in children under 5 years of age, far less has been done with age-specific MUAC Z-score values across the continuum of age from birth through adolescence.

Methods: The present study examined the effectiveness of a novel MUAC Z-score tape, in the hands of community health volunteers, to identify children over the age of 5 who would benefit from nutritional rehabilitation. In January of 2019, 112 community health volunteers working within Children International in Guatemala were trained to use the MUAC Z-score tape and asked to collect measurements on children or youth in their communities.

Results: Of the 818 MUAC Z-score tape measurements obtained by volunteers, 88.26% (722/818) were concordant with nutritional risk status as predicted by BMI Z-score, and 90.95% (744/818) were concordant with MUAC Z-score tape measurements made by field medical staff. MUAC Z-scores identified 87.10% (27/31) of the severely or moderately undernourished children as determined by the BMI Z-score who would be candidates for the nutrition rehabilitation program (Z-score ≤ - 2) along with an additional six children that would not have been classified as such with BMI Z-score. A qualitative survey distributed to the volunteers showed moderate rates of understanding of nutritional risk using the tape, and 62.50% reported the tape was easy to use.

Conclusions: These quantitative and qualitative findings suggest that with more in-depth training and education the MUAC Z-score tape is a viable, low-cost, low-burden alternative for community-level nutritional status assessment among the population served by Children International in Guatemala.

Supplementary information: Supplementary information accompanies this paper at (10.1186/s13690-019-0370-0).

Keywords: Acute malnutrition; Community screening of malnutrition; Mid-upper arm circumference.

Fig. 1

Predicted BMI Z-score and MUAC Z-score risk categories as measured by CI staff. The confusion matrix displays the counts in the cells, and color indicates agreement. Negative values on the off diagonals signify disagreement and vary in intensity of blue, whereas positive values on the diagonal represent agreement and vary in intensity of orange. For example, the cell at the intersection of BMI Z-score “Obese” and MUAC-CI Staff “At Risk, Over” is darker blue because there is 50% disagreement (1/2 measurements misclassified at that level). In contrast, BMI Z-score “Normal” and MUAC tape “At Risk, Over” is very light blue because the disagreement at that level is only 1% (4/461 misclassified at that level)

Fig. 2

MUAC Z-score color risk category as measured by staff versus health volunteers. The confusion matrix displays the counts in the cells, and color indicates agreement. Negative values on the off diagonals signify disagreement and vary in intensity of blue, whereas positive values on the diagonal represent agreement and vary in intensity of orange. For example, the cell at the intersection of MUAC-CI Staff “SAM” and MUAC-Volunteer “MAM” is lighter orange because there is 50% disagreement (3/6 measurements misclassified at that level). In contrast, MUAC-CI Staff “Normal” and MUAC-Volunteer “At Risk, Over” is very light blue because the disagreement at that level is only 3% (13/459)

Fig. 3

Predicted BMI Z-score and MUAC Z-score risk categories as measured by volunteers. The confusion matrix displays the counts in the cells, and color indicates agreement. Negative values on the off diagonals signify disagreement and vary in intensity of blue, whereas positive values on the diagonal represent agreement and vary in intensity of orange. For example, the cell at the intersection of BMI Z-score “SAM” and MUAC-Volunteer “MAM” is dark blue because there is 50% disagreement (3/6). In contrast, MUAC-Volunteer “Normal” and BMI Z-score “Overweight” is very light blue because the disagreement at that level is only 1% (1/68)

Fig. 4

Model predicted versus observed probability of disagreement. The figure shows the model results between BMI Z-score and MUAC Z-score measured by volunteers (by BMI Z-score quantiles)