Estimating children's weight in a Rwandan emergency centre

Validation study on a prediction formula to estimate the weight of children & adolescents with special needs aged 2-18 years old

BACKGROUND

This study aims to validate two predictive formulas of weight estimating strategies in children with special needs, namely the Cattermole formula and the Mercy formula.

METHODOLOGY

A cross-sectional study with a universal sampling of children and adolescents with special needs aged 2-18 years old, diagnosed with cerebral palsy, down syndrome, autism and attention-deficit/hyperactivity disorder was conducted at Community-Based Rehabilitation in Central Zone Malaysia. Socio-demographic data were obtained from files, and medical reports and anthropometric measurements (body weight, height, humeral length, and mid-upper arm circumference) were collected using standard procedures. Data were analysed using IBM SPSS version 26. The accuracy of the formula was determined by intraclass correlation, prediction at 20% of actual body weight, residual error (RE) and root mean square error (RMSE).

RESULT

A total of 502 children with a median age of 7 (6) years were enrolled in this study. The results showed that the Mercy formula demonstrated a smaller degree of bias than the Cattermole formula (PE = 1.97 ± 15.99% and 21.13 ± 27.76%, respectively). The Mercy formula showed the highest intraclass correlation coefficient (0.936 vs. 0.858) and predicted weight within 20% of the actual value in the largest proportion of participants (84% vs. 48%). The Mercy formula also demonstrated lower RE (0.3 vs. 3.6) and RMSE (3.84 vs. 6.56) compared to the Cattermole formula. Mercy offered the best option for weight estimation in children with special needs in our study population.

Weight estimation in two groups of Ghanaian children with chronic diseases using Broselow, Mercy, PAWPER XL and PAWPER XL-MAC tapes

Introduction

The performance of various weight estimation methods in children with sickle cell disease (SCD) and heart disease (HD) has not been studied. We aimed to determine and compare the accuracies of the Broselow, Mercy, PAWPER XL and PAWPER XL-MAC tapes in Ghanaian children with no known chronic diseases (controls), SCD and HD.

Methods

We prospectively recruited 631 children (199 with HD, 209 SCD and 223 controls) from the Komfo Anokye Teaching Hospital (KATH). Their weights were estimated using the Broselow, Mercy, PAWPER XL and PAWPER XL-MAC tapes. These estimated weights were compared to measured weight using mean percentage error (MPE), the proportion of weight estimates within ±10% (P10) and ±20% (P20) of measured weight. Bland-Altman limits of agreement (LOA) were determined to assess the precision of weight estimation and agreement with measured weight.

Results

The PAWPER XL, Mercy and PAWPER XL-MAC were the most accurate in all groups of children studied. All methods except the Broselow tape (BT), which performed best in the control group, had their best performance among children with SCD with negligible critical error rates (proportion of children with weight estimates > 20% of their actual weight). The P20 in the various groups of children using the BT were 88.36%, 80.21% and 51.10% respectively in the control, SCD and HD groups. The Mercy, PAWPER XL and PAWPER XL MAC tapes were generally above 90% in all groups.

Discussion

The Mercy, PAWPER XL and PAWPER XL-MAC tapes performed significantly better than the BT in all groups of children studied. These methods of weight estimation performed best in children with SCD with very little critical error.

Accuracy of Weight Estimation in Children Using the Broselow, PAWPER XL, PAWPER XL-MAC, and Mercy Tapes

OBJECTIVES

Quick and accurate estimate of a child's weight is often required for medical interventions like drug dose calculation when scale measured weights cannot be obtained safely. Length-based methods of weight estimation are more accurate than age-based methods, with the most accurate being the length-based, habitus-modified methods. This study sought to determine and compare the accuracies of the 2017 Broselow tape, Paediatric Advanced Weight Prediction in the Emergency Room Extra-Long (PAWPER XL) tape, Paediatric Advanced Weight Prediction in the Emergency Room Extra-Long Mid-Arm Circumference (PAWPER XL-MAC) tape, and the 2-dimensional (2D) Mercy tape in Ghanaian children.

METHODS

A cross-sectional study was conducted at the Tamale Teaching Hospital in Ghana. Eight hundred forty children between 2 months and 13 years had their weights estimated by the 2017 Broselow, PAWPER XL, PAWPER XL-MAC, and 2D Mercy tapes. Accuracy of the methods was determined by percentage of weight estimated to within 10% and 20% of actual weight. Mean percentage error and the Bland-Altman analysis were used to assess bias and precision.

RESULTS

The proportion of weight estimates within 10% and 20% of actual weight for Broselow tape were 47.5% and 82.3%, for 2D Mercy tape were 73.1% and 96.3%, for PAWPER XL-MAC were 77.6% and 97.5%, and for PAWPER XL were 81.7% and 96.8%, respectively. The Broselow tape had the greatest bias and least precision among the 4 methods. The Mercy, PAWPER XL-MAC, and PAWPER XL tapes had similar performance, but all performed significantly better than the Broselow tape in pairwise comparison. The best weight estimation method overall was the PAWPER XL tape as it also had the least bias and greatest precision.

CONCLUSIONS

The Mercy, PAWPER XL-MAC, and PAWPER XL tapes were more accurate than the 2017 Broselow tape and should be used in preference in Ghana and countries with similar population structure.

Comparison of paediatric weight estimation methods at a tertiary hospital in Ghana

Introduction

Weight estimation in children is critical in paediatric emergencies. The Broselow Tape (BT) and most age-based formulae for weight estimation were derived in high-income countries and are thought to overestimate the weight of children in low-income countries. This study sought to validate the 2017 BT, and eight age-based weight estimation formulae among Ghanaian children and to derive a weight estimation formula using this data.

Methods

A cross-sectional study was conducted in the Tamale Teaching Hospital (TTH) in Ghana. Children aged between 2 months and 13 years had their weights estimated by the 2017 BT and eight age-based formulae. These estimated weights were compared to the weight of the children measured by a calibrated Seca scale using mean percentage error (MPE) and the percentage of weight estimates within 10% and 20% of actual weight. Bland-Altman method was used to assess agreement between estimated and actual weight of the children. A new formula was derived by linear regression.

Results

Seven hundred and seventy-five children took part in the study. The 2017 BT, Original APLS (APLS1) and Nelson's formulae performed best with proportion of weight estimates within 10% of actual weight being 47.5%, 51.1% and 47.5% respectively. The formula developed in this study was: W_E = 3Am / 10 + 5 (for infants <12 months), W_E = 2A + 7 (1 to 4 years) and W_E = 2A + 9 (5 to 13 years), where W_E is estimated weight, A_m is age in completed months and A is age in completed years. The new formula had similar accuracy as the three best performing methods in this study.

Conclusion

The Broselow Tape, APLS1 and the Nelson's formula were the most accurate in this study. APLS1 and the Broselow Tape can be used for weight estimation in Ghanaian children when no other better method is available.

Accuracy of weight estimation methods in adults, adolescents and children: a prospective study

INTRODUCTION

Weight estimation of both adult and paediatric patients is often necessary in emergency or low-resource settings when it is not possible to weigh the patient. There are many methods for paediatric weight estimation, but no standard methods for adults. PAWPER and Mercy tapes are used in children, but have not been assessed in adults. The primary aim of this study was to assess weight estimation methods in patients of all ages.

METHODS

Patients were prospectively recruited from emergency and outpatient departments in Kigali, Rwanda. Participants (or guardians) were asked to estimate weight. Investigators collected weight, height, mid-arm circumference (MAC) and humeral-length data. In all participants, estimates of weight were calculated from height and MAC (PAWPER methods), MAC and humeral length (Mercy method). In children, Broselow measurements and age-based formulae were also used. The primary outcome measure was the proportion of estimates within 20% of actual weight (p20).

RESULTS

We recruited 947 participants: 307 children, 309 adolescents and 331 adults. For p20, the best methods were: in children, guardian estimate (90.2%) and PAWPER XL-MAC (89.3%); in adolescents, PAWPER XL-MAC (91.3%) and guardian estimate (90.9%); in adults, participant estimate (98.5%) and PAWPER XL-MAC (83.7%). In all age groups, there was a trend of decreasing weight estimation with increasing actual weight.

CONCLUSION

This prospective study of weight estimation methods across all age groups is the first adult study of PAWPER and Mercy methods. In children, age-based rules performed poorly. In patients of all ages, the PAWPER XL-MAC and guardian/participant estimates of weight were the most reliable and we would recommend their use in this setting.