Estimation of weight in adults from height: a novel option for a quick bedside technique

In critical care situations, there are often neither the means nor the time to weigh each patient before administering strict weight-based drugs/procedures. A convenient, quick and accurate method is a priority in such circumstances for safety and effectiveness in emergent interventions as none exists in adults while those available are complex and yet to be validated. We aimed to study the correlation and accuracy of a quick bedside method of weight estimation in adults using height.

The technique is estimated body weight-eBW(kg) = (N - 1)100, where 'N' is the measured height in metres. Adult undergraduates were enrolled 10/09/2015. Their heights and weights were measured while the formula was used to obtain the estimated weight. The SPSS version 21.0, Chicago, IL, USA was utilised for data analysis.

We analysed 122 participants aged 21-38 years with height = 1.55 m-1.95 m. The actual body weight range = 48.0 kg-91.0 kg, mean = 65.3 kg ± 9.7 kg and S.E. = 2.0 while eBW = 55 kg-95 kg, mean = 69.1 kg ± 8.4 kg and S.E. = 1.5. On BMI classes, a positive predictive value of 94.7% for the 'normal' category and 95.5% for 'overweight'. Correlation coefficient at 99% confidence interval yielded (r) = + 1, (P = 0.000) while the linear regression coefficient (r²) = + 1 at 95% confidence interval (P = 0.000). The strength of agreement/precision was established by the Bland-Altman plot at 95% ± 2 s (P = 0.000) and kappa statistic with value = 0. 618.

This unprecedented statistical characterisation of the two weight estimate measures to have a good agreement scientifically proposes the utility of our method with the formula eBW(kg) = 100(N-1) in critical care and ATLS protocol.