Validation of the Broca index as the most practical method to calculate the ideal body weight

Abstract

Ideal body weight (IBW) calculation is useful in clinical practice, but most of the formulas to calculate it are complicated. Broca index (BI) is still a simple and effective method to determine IBW although seems to be abandoned. Our objective is to verify validity of BI compared with Hammond and Robinson formulas, and with IBW calculated from ideal body mass index (BMI) (22.5kg/m 2) in a population. We made a correlational study from 400 patients of nutrition and surgery consult, from 2010 to 2015. Patients were classified according to their BMI in group A <30kg/m 2 and B ≥30kg/m 2. Age, sex, height and weight, were recorded to calculate IBW with Hammond, Robinson and BI formulas and the IBW calculated from ideal BMI. we analyzed, statistical significance with student's t test, Pearson coefficient and linear regression. Of the 400 patients, 221 were group A, 49.7% men, and 50.3% women. Average age, height, actual weight and actual BMI were 38.9years-old, 167cm, 67.6kg, and 24.1kg/m 2 respectively; and group B, 179 patients; 44.6% men, 55.4% women. Average age, height and actual weight, and actual BMI were 38.4years-old, 168cm, 112.3kg and 39.7kg/m 2 respectively. Both groups showed normal distribution. When comparing IBW using BI, with the other formulas analysed with t-test, result was significant in all (p 0.000). Utilizing Pearson coefficient also all showed significance (p 0.000) for both groups. Linear regression with Hammond, Robinson formulas and weight calculated from ideal BMI showed relationship of 95.7%, 96.5% and 99.8% respectively and between the 4 IBW formulas together, 100% relationship for both groups. BI seems to offer the same accuracy as other more complex formulas for the calculation of the IBW. BI continues to have validity and utility in clinical practice, so we promote it as a useful clinical tool because of its simplicity.