Evaluation of the Mercy weight estimation method in Ouelessebougou, Mali

Alassane Dicko,Moussa Traoré,Mohamed Lamine Alhousseini,Bouran Sidibé,Susan M Abdel-Rahman

doi:10.1186/1471-2458-14-270

Abstract

BackgroundThis study evaluated the performance of a new weight estimation strategy (Mercy Method) with four existing weight-estimation methods (APLS, ARC, Broselow, and Nelson) in children from Ouelessebougou, Mali.MethodsOtherwise healthy children, 2 mos to 16 yrs, were enrolled and weight, height, humeral length (HL) and mid-upper arm circumference (MUAC) obtained by trained raters. Weight estimation was performed as described for each method. Predicted weights were regressed against actual weights. Agreement between estimated and actual weight was determined using Bland-Altman plots with log-transformation. Predictive performance of each method was assessed using residual error (RE), percentage error (PE), root mean square error (RMSE), and percent predicted within 10, 20 and 30% of actual weight.Results473 children (8.1 ± 4.8 yr, 25.1 ± 14.5 kg, 120.9 ± 29.5 cm) participated in this study. The Mercy Method (MM) offered the best correlation between actual and estimated weight when compared with the other methods (r2 = 0.97 vs. 0.80-0.94). The MM also demonstrated the lowest ME (0.06 vs. 0.92-4.1 kg), MPE (1.6 vs. 7.8-19.8%) and RMSE (2.6 vs. 3.0-6.7). Finally, the MM estimated weight within 20% of actual for nearly all children (97%) as opposed to the other methods for which these values ranged from 50-69%.ConclusionsThe MM performed extremely well in Malian children with performance characteristics comparable to those observed for U.S and India and could be used in sub-Saharan African children without modification extending the utility of this weight estimation strategy.

Highlights

This study evaluated the performance of a new weight estimation strategy (Mercy Method) with four existing weight-estimation methods (APLS, Australian Resuscitation Council (ARC), Broselow, and Nelson) in children from Ouelessebougou, Mali
All the children presenting to the research center and for whom informed consent and assent (7– 17 years) were obtained were enrolled unless they presented with any of the following exclusion criteria: 1) known or apparent limb deformities, 2) unable to be positioned for height/length measurements, 3) underlying pathological condition that would produce abnormal body composition for age
The Mercy method performed extremely well, demonstrating performance characteristics comparable to those observed for the method when applied to children in the Agreement within: 10%

Summary

Introduction

This study evaluated the performance of a new weight estimation strategy (Mercy Method) with four existing weight-estimation methods (APLS, ARC, Broselow, and Nelson) in children from Ouelessebougou, Mali. Weight is essential for evaluating normal growth and development, examining the adequacy of nutrition, and delivering proper medication doses when children fall ill. Assessing weight is especially important in African settings where an estimated one in four children are nutritionally compromised [1,2,3]. Though there exist numerous published strategies for pediatric weight estimation, they remain less than ideal for use in African settings. Most methods were developed using Western standards for growth and development and few have been validated for use in African populations [10,11,12,13,14,15]. Most fail to account for the extremes of body composition and stature that are observed in children of the same age, some require multiple or complex formulae, others require subjective determinations of habitus, and essentially all of them have restrictions on the age or length of children for whom they are designed [15,16,17,18,19,20]

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Results

Conclusion