Background: Body weight (BW) is widely used to evaluate and manage clinical situations therefore assessment errors can influence the ichosen therapies.
Objective: To assess the variability in values of BW obtained by using different equipment (weight scales).
Methods: A cross sectional study was performed to assess BW of 360 adult patients in eight units including clinical and surgical specialties Three types of scales were used: a portable domestic model and a fixed platform model, both from the units and a portable digital model previously calibrated and used as standard reference equipment. Self-reported weight (SRW) was also compared to weight assessed with the reference equipment. The values were compared trough paired-samples t-test using SPSS software.
Results: The difference between weights assessed by the reference equipment and SRW was 445+/-3.359 g (P=0.015), it was -182+/-2.323 g (P=0.140) for portable domestic scales and 137+/-2.412 g (P=0.218) for platform fixed scales. Values obtained from SRW, portable domestic scales and fixed platform scales were strongly correlated to the mean value of weight assessed by the reference equipment (r=0.973, r=0.987 and r=0.986, respectively). Nevertheless, considering analyses of each patient, errors of magnitude greater than 500 g occurred in 78.8% of SRW, 80.6% of the portable domestic scales and 40% of the fixed platform scales.
Conclusion: In general, the scales tested were neither accurate nor precise for measuring BW, considering the percentage of error in the evaluation of each patient and the variability observed.