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

Cat owners do not provide more reliable weight estimates for cats compared with veterinary professionals in an emergency setting

OBJECTIVES

The aim of the present study was to assess the accuracy of weight estimation in cats provided by pet owners, veterinary technicians, house officers (interns and residents) and attending clinicians in an emergency room (ER). An additional objective was to determine whether carrying the cat contributed to a more accurate weight estimate.

METHODS

A total of 72 cats presented to an ER and were enrolled in the study. Pet owners, veterinary technicians, house officers and attending clinicians were asked to record the cats' estimated weights on individual data collection cards. The actual weights of the cats were then obtained and compared with participants' estimations.

RESULTS

There were no significant differences between weight estimates provided by pet owners, veterinary technicians, house officers and attending clinicians. Similarly, neither the length of experience of the veterinary staff nor carrying the cat had an effect on the provision of a more accurate weight estimate.

CONCLUSIONS AND RELEVANCE

Pet owners are no better at weight estimation of cats in the ER setting compared with veterinary professionals. Carrying the cat did not improve the accuracy of weight estimation among veterinary professionals. The mean cat weight of 4.9 kg could be used as an average cat weight in an emergency situation for an adult cat.

The accuracy of total body weight estimation in adults - A systematic review and meta-analysis

BACKGROUND

Weight estimation is required in adult patients when weight-based medication must be administered during emergency care, as measuring weight is often impossible. Inaccurate estimations may lead to inaccurate drug doses, which may cause patient harm. Little is known about the relative accuracy of different methods of weight estimation that could be used during resuscitative care. The aim of this study was to evaluate the performance and suitability of existing weight estimation methods for use in adult emergency care.

METHODS

A systematic literature search was performed for suitable articles that studied the accuracy of weight estimation systems in adults. The study characteristics, the quality of the studies, the weight estimation methods evaluated, the accuracy data, and any information on the ease-of-use of the method were extracted and evaluated.

RESULTS

A total of 95 studies were included, in which 27 different methods of total body weight estimation were described, with 42 studies included in the meta-analysis. The most accurate methods, determined from the pooled estimates of accuracy (the percentage of estimates within 10% of true weight, with 95% confidence intervals) were 3-D camera estimates (88.8% (85.8 to 91.8%)), patient self-estimates (88.7% (87.7 to 89.7%)), the Lorenz method (77.5% (76.4 to 78.6%)) and family estimates (75.0% (71.5 to 78.6%)). However, no method was without significant potential limitations to use during emergency care.

CONCLUSION

Patient self-estimations of weight were generally very accurate and should be the method of choice during emergency care, when possible. However, since alternative estimation methods must be available when confused, or otherwise incapacitated, patients are unable to provide an estimate, alternative strategies of weight estimation should also be available.

Mid-upper arm circumference as a screening tool for identifying underweight adolescents

Background

Mid-upper arm circumference (MUAC) is a potentially credible alternative method for body mass index (BMI) to assess nutritional status. We aimed to assess the correlation between MUAC and BMI- Z-score and to identify a reliable MUAC cut-off point to detect underweight (BMI- Z-score of < -2 standard deviation) Sudanese adolescents.

Methods

A cross-sectional study was conducted in eastern Sudan. After obtaining adolescents' age and sex, their weight, height, and MUAC were measured using the standard procedures. The MUAC (cm) cut-off corresponding to underweight was calculated using receiver operating characteristic (ROC) curve analysis.

Results

In total, 390 adolescents were enrolled in the study and 205 (52.6%) of them were females. The median (interquartile range, IQR) age was 15.1 (14.0-16.3) years. The medians (IQR) of MUAC and BMI- Z-score were 22.0 (20.0-24.0) cm and - 0.62 (-1.5-0.3), respectively. MUAC was positively correlated with BMI Z-score in all participants (r = 0.534, p < 0.001), in females (r = 0.715, p < 0.001), and in males (r = 0.404, p < 0.001). Of the 390 enrolled adolescents, 61(15.6%) were underweight. The MUAC cut-off for underweight was ≤21.2 cm in all participants (Youden's Index, YI = 0.50; sensitivity = 82.0%; specificity = 68.0%, AUROCC = 0.78), in females (YI = 0.66, sensitivity = 86.0%, specificity = 80.0%, AUROCC = 0.87), and in males (YI = 0.32, sensitivity = 80.0%, specificity = 52.0%, AUROCC = 0.69).

Conclusion

MUAC has good accuracy results and can be adopted for community-based screening of underweight adolescents.

Weight Estimation for Drug Dose Calculations in the Prehospital Setting - A Systematic Review

BACKGROUND

Weight estimation is required to enable dose calculations for weight-based drugs administered during emergency care. The accuracy of the estimation will determine the accuracy of the administered dose. This is an important matter of patient safety. The objective of this systematic review was to collect, review, evaluate, and create a synthesis of the current literature focusing on the accuracy of weight estimation in the prehospital environment.

METHODS

This systematic review followed the PRISMA guidelines. Studies were identified and included if they were peer reviewed, full length, published in English, and contained original data. Studies utilizing any form of weight estimation methodology in the prehospital setting (in children or adults) were included. Data on the quality of the studies and accuracy of the weight estimation systems were extracted. Common themes were also identified.

RESULTS

Twenty-five studies met the inclusion criteria, with only nine studies (36.0%) containing useful weight estimation accuracy data. The overall quality of the studies was poor. The Broselow tape and paramedic estimates were the most studied methods of weight estimation, but there was insufficient evidence to support conclusions about accuracy. The major themes identified included the importance of accurate weight estimation and drug dosing as critical matters of patient safety, and the need for training to ensure these processes are performed accurately.

CONCLUSIONS

There were limited robust data identified on the accuracy of different weight estimation methods used in the prehospital setting. Future high-quality clinical research in this area is of critical importance to ensure patient safety in the prehospital environment.

Development and Validation of a Length- and Habitus-Based Method of Ideal and Lean Body Weight Estimation for Adults Requiring Urgent Weight-Based Medical Intervention

BACKGROUND AND OBJECTIVE

Accurate drug dosing in obese patients requires an estimation of ideal body weight (IBW) or lean body weight (LBW) for dosing hydrophilic medications. Erroneous weight estimates during the management of adults requiring weight-based treatment may contribute to poor outcomes. Existing methods of IBW and LBW estimation or measurement are very difficult to use during emergency care. A new point-of-care model would be useful to provide rapid estimates of IBW and LBW for this purpose.

METHODS

A model was derived based on the PAWPER XL-MAC tape, a pediatric weight estimation system which uses recumbent length and mid-arm circumference to estimate IBW and LBW. The new adult model was used to generate IBW and LBW estimations for a derivation sample (n = 33155) and a validation sample (n = 5926) from National Health and Nutrition Examination Survey (NHANES) datasets. The model was developed in two steps, with calibration at each step, before being validated on an unused dataset. The outcome measure was to achieve >95% of IBW and LBW estimations within 20% of recognized reference standards (P20 > 95%) and >70% of estimations within 10% of these standards (P10 > 70%).

RESULTS

The new model achieved a P20 of 100% and a P10 of 99.9% for IBW and a P20 of 98.3% and a P10 of 78.3% for LBW. This accuracy was maintained in both sexes, all ages, all ethnic groups, all lengths, and in all habitus types, except for the severely obese female subgroup.

CONCLUSIONS

The modified PAWPER XL-MAC model proved to be an accurate method of IBW and LBW estimation. It could, therefore, have an important role in facilitating emergency drug dose calculations in obese adult patients.

Estimating Lean Body Weight in Adults With the PAWPER XL-MAC Tape Using Actual Measured Weight as an Input Variable

Introduction

Accurate drug dose calculation in obese patients requires an estimation of lean body weight (LBW) for dosing hydrophilic medications. Inaccurate weight estimates during the management of critically ill obese adults may contribute to inaccurate drug doses and consequential poor outcomes. Existing methods of LBW estimation or measurement may be very difficult or impossible to use during emergency care. A point-of-care model that could provide rapid, accurate estimates of LBW would, therefore, be of significant clinical value.

Methods

A model was derived based using the adult version of the PAWPER XL-MAC tape. This derived model used recumbent length and measured total body weight (TBW) to estimate LBW. The derived model was used to generate LBW estimations in a random sample from National Health and Nutrition Examination Survey (NHANES) datasets (n=33,215). The benchmark outcome measure was to achieve >95% of LBW estimations within 20% of DXA-measured fat-free mass (P20>95%) and >70% of estimations within 10% of DXA-measured fat-free mass (P10>70%).

Results

The new model achieved a P20 of 99.7% and a P10 of 86.4% for LBW in the pooled sample and exceeded the minimum accuracy standards. This accuracy was maintained in both sexes, all ages, all ethnic groups, all lengths and in all habitus types.

Conclusions

The modified PAWPER XL-MAC model, using TBW as an input variable, proved to be an accurate method of LBW estimation. It could potentially have an important role in facilitating emergency drug dose calculations in critically ill or injured obese adult patients.

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.

Preclinical trial of noncontact anthropometric measurement using IR-UWB radar

Anthropometric profiles are important indices for assessing medical conditions, including malnutrition, obesity, and growth disorders. Noncontact methods for estimating those parameters could have considerable value in many practical situations, such as the assessment of young, uncooperative infants or children and the prevention of infectious disease transmission. The purpose of this study was to investigate the feasibility of obtaining noncontact anthropometric measurements using the impulse-radio ultrawideband (IR-UWB) radar sensor technique. A total of 45 healthy adults were enrolled, and a convolutional neural network (CNN) algorithm was implemented to analyze data extracted from IR-UWB radar. The differences (root-mean-square error, RMSE) between values from the radar and bioelectrical impedance analysis (BIA) as a reference in the measurement of height, weight, and body mass index (BMI) were 2.78, 5.31, and 2.25, respectively; predicted data from the radar highly agreed with those from the BIA. The intraclass correlation coefficients (ICCs) were 0.93, 0.94, and 0.83. In conclusion, IR-UWB radar can provide accurate estimates of anthropometric parameters in a noncontact manner; this study is the first to support the radar sensor as an applicable method in clinical situations.

Comparison of adult weight estimation methods for use during emergency medical care

OBJECTIVE

Many emergency drug and fluid doses are weight dependent in adults, but in resuscitation and low-resource settings it can be impractical or impossible to weigh a patient. It is especially important to obtain accurate weight estimation for dose calculations for emergency drugs with narrow therapeutic ranges. Several weight estimation methods have been proposed for use in adults, but none is widely established. The aim of this study was to compare the accuracy of adult weight estimation methods.

METHODS

Demographic and body measurement data were obtained from the US National Health and Nutrition Examination Survey (NHANES), and 7 previously published weight estimation methods were used to estimate the weight for each individual. The primary outcomes were the proportions of estimates within 10% and 20% of actual weight (P10, P20). An acceptable accuracy was predetermined to be P10 = 70% and P20 = 95%.

RESULTS

The data set included 5158 adults (51.2% women) with sufficient data to calculate all weight estimation methods. The Lorenz method performed best (P10 = 86.8%, P20 = 99.4%) and met the standard of acceptability across sex and body mass index subgroups. The Mercy and PAWPER XL-MAC methods performed acceptably in non-obese adults.

CONCLUSION

The ideal weight estimation method should be accurate, rapid, simple, and feasible. This study has demonstrated the accuracy of 7 methods. The Lorenz method performed best but is complex and likely to be difficult to apply in resuscitation settings. Other simpler and quicker methods are at least as accurate as the best methods widely used in children, and there is potential for further calibrating these for use in adults before validation in real-world studies.

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.