Evaluation of the accuracy of common weight estimation formulae in a Zambian paediatric surgical population

Design and validation of equations for weight estimation in adolescents

INTRODUCTION

Measuring weight is difficult to be carried out in bedridden people, with physical deformity or in emergency units. Under these circumstances, one option is to estimate the weight.

OBJECTIVES

The aim of this study is to propose and validate equations for estimating the weight of Brazilian adolescents based on anthropometric variables related to body weight.

METHODS

The study was developed based on a database created from data collection of a primary project, which had information from 662 Brazilian adolescents (10 to 19 years old). Based on the variables sex, age (days), weight (kg), height (m) and neck circumference (NC) (cm), equations for estimating weight of adolescents were proposed. The formulas were proposed after performing multiple linear regression models and subsequently tested and validated using appropriate statistical tests, considering 99% confidence.

RESULTS

Two formulas were generated, the "Rucco Formulas-Adolescents", one for girls: -131.63091 + (0.00209 × A) + (37.57813 × H) + (3.71482 x NC) and another for boys: - 15.2854 + (-0.00414 × A)+ (14.30315 × H2)+ (0.04888 x NC2). Statistical test (R2) indicated that the proposed formulas are suitable for estimating weight. Low values of REQM and high values of CCI (> 0.8) also reinforce the quality of the proposed formulas.

CONCLUSIONS

The current weight of adolescents can be estimated with adequate accuracy and precision using sex-specific "Rucco Formulas-Adolescents", generated from regression models using only three predictor variables.

A Prospective, Cohort Study of the Effect of Acute and Chronic Malnutrition on Length of Stay in Children Having Surgery in Rwanda

BACKGROUND

Malnutrition is common in pediatric surgical patients, but there are little data from low-income countries that estimate the association of malnutrition with surgical outcomes. We aimed to determine the prevalence of malnutrition and its association with length of stay (LOS) among pediatric surgical patients in Kigali, Rwanda.

METHODS

We conducted a prospective observational cohort study. We enrolled surgical patients between 1 month and 15 years of age. We measured the association of acute malnutrition (wasting) and chronic malnutrition (stunting) with postoperative LOS using log-gamma regression to account for the skewed LOS distribution. Adjustment was made for sex, age, elective versus emergency surgery, household income, and American Society of Anesthesiologists (ASA) classification.

RESULTS

Of 593 children, 124 children (21.2%) had acute malnutrition (wasting) with 39 (6.6%) severely wasted. A total of 160 (26.9%) children had chronic malnutrition (stunting), with 81 (13.7%) severely stunted. Median (interquartile range [IQR]) LOS after surgery was 2 (1-5) days for children with mild/no wasting, 6 (2.5-12.5) days for children with moderate wasting, and 6 (2-15) days with severe wasting. Median (IQR) LOS after surgery was 2 (1-6) days for children with mild/no stunting, 3 (1-3) days for children with moderate stunting, and 5 (2.3-11.8) days with severe stunting malnutrition. After adjustment for confounders, the moderate wasting was associated with increased LOS, with ratio of means (RoM), 1.6; 95% confidence interval [CI], 1.3-2.0; P < .0001. Severe wasting was not associated with increased LOS (RoM, 1.3; 95% CI, 0.9-1.7; P = .12). Severe, but not moderate, stunting was associated with increased LOS (RoM, 1.9; 1.5-2.4; P < .0001).

CONCLUSIONS

Malnutrition is prevalent in >20% of children presenting for surgery and associated with increased LOS after surgery, even after accounting for individual and family-level confounders. Although some aspects of malnutrition may relate to the surgical condition, severe malnutrition may represent a modifiable social risk factor that could be targeted to improve postoperative outcomes and resource use. Severely stunted children should be identified as at risk of having delayed recovery after surgery.

Validation of the Lusaka Formula: A Novel Formula for Weight Estimation in Children Presenting for Surgery in Zambia

BACKGROUND

In children, the use of actual weight or predicted weight from various estimation methods is essential to reduce harm associated with dosing errors. This study aimed to validate the new locally derived Lusaka formula on an independent cohort of children undergoing surgery at the University Teaching Hospital in Lusaka, Zambia, to compare the Lusaka formula's performance to commonly used weight prediction tools and to assess the nutritional status of this population.

METHODS

The Lusaka formula (weight = [age in months/2] + 3.5 if under 1 year; weight = 2×[age in years] + 7 if older than 1 year) was derived from a previously published data set. We aimed to validate this formula in a new data set. Weights, heights, and ages of 330 children up to 14 years were measured before surgery. Accuracy was examined by comparing the (1) mean percentage error and (2) the percentage of actual weights that fell between 10% and 20% of the estimated weight for the Lusaka formula, and for other existing tools. World Health Organization (WHO) growth charts, mid upper arm circumference (MUAC), and body mass index (BMI) were used to assess nutritional status.

RESULTS

The Lusaka formula had similar precision to the Broselow tape: 160 (48.5%) vs 158 (51.6%) children were within 10% of the estimated weight, 241 (73.0%) vs 245 (79.5%) children were within 20% of the estimated weight. The Lusaka formula slightly underestimated weight (mean bias, -0.5 kg) in contrast to all other predictive tools, which overestimated on average. Twenty-two percent of children had moderate or severe chronic malnutrition (stunting) and 4.7% of children had moderate or severe acute malnutrition (wasting).

CONCLUSIONS

The Lusaka formula is comparable to, or better than, other age-based weight prediction tools in children presenting for surgery at the University Teaching Hospital in Lusaka, Zambia, and has the advantage that it covers a wider age range than tools with comparable accuracy. In this population, commonly used aged-based prediction tools significantly overestimate weights.

Assessment of body weight from percutaneous widths of the bones and joints-Implications in forensic and clinical examinations

BACKGROUND

Estimation of age, stature, sex, and ancestry contributes to the establishment of the biological profile of the deceased in forensic examinations. Assessment of the body weight aids in the approximation of the overall body size of the individual which may help in the forensic identification process. In clinical examinations, body weight assessment assumes importance in cases where body weight measurement is a challenging task due to illness and body deformity.

OBJECTIVE

The present research was conducted to estimate the body weight from the percutaneous width of the bones and joints with the help of prediction equations.

METHODS

The study was carried out on 344 adults (172 Females and 172 Males) aged between 18 and 25 years from the Himachal Pradesh State of North India. Eleven anthropometric measurements including height vertex, mid-arm circumference, humerus bicondylar width, transverse chest breadth, sagittal chest breadth, bi-iliac breadth, handbreadth, femur bicondylar breadth, ankle breadth, foot breadth, and body weight were taken on each individual. The sex differences were evaluated by using independent student t-test and Mann-Whitney U test and the correlation between the body weight and the anthropometric variables was investigated by using both Karl Pearson's correlation coefficient and Spearman's rank correlation coefficient depending upon the normality of the data. Regression models for the estimation of body weight were calculated. Further, a validation study was carried out to check the accuracy and utility of the derived regression models by calculating the mean absolute percent prediction error (MAPPE).

RESULTS

Significant sex differences were observed among all the anthropometric variables. The transverse chest breadth and mid-arm circumference were strongly correlated with the body weight, whereas, a good correlation was also observed in other measurements except for the ankle breadth. The SEE (Standard error of estimate) of the derived linear regression models was compared, and it was found that multiple linear regression models show better accuracy than simple linear regression models. The MAPPE was found to be less in the case of multiple linear regression models than the linear ones.

CONCLUSION

The present investigation concludes that regression models can be used in the estimation of body weight from the percutaneous measurements and joint widths with reasonable accuracy in an Indian population.

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.

The accuracy of the Broselow tape as a weight estimation tool and a drug-dosing guide - A systematic review and meta-analysis

AIMS

The Broselow tape is widely used as a weight-estimation device and drug-dosing guide aid, but concerns about its accuracy and its efficacy have emerged in the last decade. The aim of this study was to systematically review the literature to analyse the accuracy of the Broselow tape as a weight estimation device and review evidence of its utility as a drug-dosing guide.

METHODS

This was a MOOSE-driven systematic review and meta-analysis, which focused on studies evaluating the accuracy of the Broselow tape and studies reviewing its use as a drug-dosing aid.

MAIN RESULTS

The tape has undergone substantial changes over the years, but there was no evidence to show that the changes have improved weight-estimation performance. The weight-estimation accuracy of the tape was suboptimal in all populations, with just over 50% of children receiving an estimation within 10% of their actual weight. The overestimation of weight in low- and middle-income countries was often extreme. This indicated a significant potential for potentially harmful medication errors. The limited available evidence on the value of the tape as a drug-dosing guide indicated that the tape was frequently used incorrectly and contained insufficient information to function without additional resources.

CONCLUSIONS

The Broselow tape lacked sufficient accuracy as a weight estimation and drug-dosing tool when compared to other available techniques. In addition, the Broselow tape contains insufficient drug-dosing information to function as a complete resuscitation aid without additional material. The frequent rate of incorrect usage of the tape indicated that appropriate training with the tape is mandatory to reduce errors.

A systematic review and meta-analysis of the accuracy of weight estimation systems used in paediatric emergency care in developing countries

Introduction

When weight cannot be measured during the management of medical emergencies in children, a convenient, quick and accurate method of weight estimation is required, as many drug doses and other interventions are based on body weight. Many weight estimation methodologies in current use have been shown to be inaccurate, especially in low- and middle-income countries with a high prevalence of underweight children. This meta-analysis evaluated the accuracy of weight estimation systems in children from studies from low- and middle-income countries.

Methods

Articles from low- and middle-income countries were screened for inclusion to evaluate and compare the accuracy of existing systems and the newer dual length- and habitus-based methods, using standard meta-analysis techniques.

Results

The 2D systems and parental estimates performed best overall. The PAWPER tape, parental estimates, the Wozniak method and the Mercy method were the most accurate systems with percentage of weight estimates within 10% of actual weight (PW10) accuracies of 86.9%, 80.4%, 72.1% and 71.4% respectively. The Broselow tape (PW10 47.1%) achieved a moderate accuracy and age-based estimates a very low accuracy (PW10 11.8–47.5%).

Conclusions

The PAWPER tape, the Wozniak method and the Mercy method achieved an acceptable level of accuracy in studies from low- and middle-income countries and should preferentially be used and further advanced for clinical emergency medicine practice. Parental estimates may be considered if the regular caregiver of the child is present and a recent measured weight is known. The Broselow tape and age-based formulas should be abandoned in low- and middle-income country populations as they are potentially dangerously inaccurate.

The accuracy of emergency weight estimation systems in children-a systematic review and meta-analysis

The safe and effective administration of fluids and medications during the management of medical emergencies in children depends on an appropriately determined dose, based on body weight. Weight can often not be measured in these circumstances and a convenient, quick and accurate method of weight estimation is required. Most methods in current use are not accurate enough, but the newer length-based, habitus-modified (two-dimensional) systems have shown significantly higher accuracy. This meta-analysis evaluated the accuracy of weight estimation systems in children. Articles were screened for inclusion into two study arms: to determine an appropriate accuracy target for weight estimation systems; and to evaluate the accuracy of existing systems using standard meta-analysis techniques. There was no evidence found to support any specific goal of accuracy. Based on the findings of this study, a proposed minimum accuracy of 70% of estimations within 10% of actual weight (PW10 > 70%), and 95% within 20% of actual weight (PW20 > 95%) should be demonstrated by a weight estimation system before being considered to be accurate. In the meta-analysis, the two-dimensional systems performed best. The Mercy method (PW10 70.9%, PW20 95.3%), the PAWPER tape (PW10 78.0%, PW20 96.6%) and parental estimates (PW10 69.8%, PW20 87.1%) were the most accurate systems investigated, with the Broselow tape (PW10 55.6%, PW20 81.2%) achieving a lesser accuracy. Age-based estimates achieved a very low accuracy. Age- and length-based systems had a substantial difference in over- and underestimation of weight in high-income and low- and middle-income populations. A benchmark for minimum accuracy is recommended for weight estimation studies and a PW10 > 70% with PW20 > 95% is suggested. The Mercy method, the PAWPER tape and parental estimates were the most accurate weight estimation systems followed by length-based and age-based systems. The use of age-based formulas should be abandoned because of their poor accuracy.

It is time to abandon age-based emergency weight estimation in children! A failed validation of 20 different age-based formulas

AIM

When children's weight cannot be measured during medical emergencies, it must be estimated, as weight is required for many interventions. Age-based formulas are the oldest weight estimation systems in children, but have been shown to be very inaccurate in many studies. This aim of this study was to evaluate the accuracy of age- and length-based formulas and to see if a measure of body habitus could be used to improve the performance of these formulas.

METHODS

This was an analysis of data from a sample of 1085 children aged from 1 month to 16 years, collected from four Emergency Departments in Johannesburg, South Africa. Basic demographic and anthropometric data was collected and each child had a visual assessment of body habitus, quantified as a habitus score. Weight estimates from 20 existing age-based formulas and two length-based formulas were then compared against measured weight to determine their accuracy. Age- and length-based, habitus-modified models were developed and similarly evaluated.