Precisão e acurácia na aferição do peso corporal em adultos hospitalizados

Abstract

Objetivo. Verificar a variabilidade entre valores de peso corporal (PC) obtidos por meio de diferentes instrumentos de afericao (balancas). Metodos. Foi realizado estudo transversal que avaliou o PC de 360 adultos, em oito unidades de internacao (UI) de especialidades clinicas e cirurgicas, utilizando tres tipos de balancas: portatil domestica e fixa de plataforma, das UI de origem, e portatil digital, sendo a ultima previamente calibrada e adotada como padrao de referencia. O peso informado (PI) pelos pacientes tambem foi comparado a balanca de referencia. Os valores foram comparados atraves de teste t para amostras pareadas no software estatistico SPSS. Resultados. A diferenca entre a balanca de referencia e o PI foi de 445}3.359g (p=0,015), de -182}2.323g (p=0,140) nas balancas portateis domesticas e de 137}2.412g (p=0,218) com as de plataforma. Tanto PI quanto peso aferido por balanca portatil domestica e de plataforma apresentaram forte correlacao com o valor medio de peso aferido na balanca digital (r=0,973, r=0,987 e r=0,986), respectivamente. Entretanto, considerando a analise de cada paciente, a ocorrencia de erros superiores a 500 g, para mais ou para menos, foi de 78,8% dos pesos informados, 80,6% para as balancas portateis e 40% para as balancas de plataforma. Conclusao. De modo geral, as balancas testadas nao foram acuradas e precisas em estimar o PC dos pacientes avaliados, dado o percentual de erro nas avaliacoes para cada sujeito e a variabilidade observada.

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}3.359g (P=0.015), it was -182}2.323g (P=0.140) for portable domestic scales and 137}2.412g (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 500g 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.