Sensitivity and specificity of the body mass index in the diagnosis of obesity in patients with non-dialysis chronic kidney disease: a comparison between gold standard methods and the cut-off value purpose

espanolIntroduccion: el estado nutricional es un importante predictor de pronostico en la enfermedad renal cronica (ERC), incluso en la fase de predialisis. Las medidas antropometricas universalmente usadas para el diagnostico de la obesidad en la poblacion general pueden no presentar el mismo desempeno en individuos con ERC. Objetivo: verificar la sensibilidad y especificidad del indice de masa corporal (IMC) en relacion con el porcentaje de grasa corporal (%GC), obtenido por la absorciometria con rayos X de doble energia (DEXA) y pletismografia de desplazamiento aereo (PDA) de pacientes renales cronicos no dialiticos. Metodos: se obtuvo el IMC. La DEXA y la PDA se utilizaron para determinar el porcentaje de GC y se consideraron metodos patron-oro. Resultados: se evaluaron 78 pacientes con una media de edad de 54,4 ± 13,9 anos. Se observo una elevada prevalencia de sobrepeso/obesidad (55,2%), segun el IMC, y de porcentaje de GC alto, de acuerdo con la DEXA (69,2%) y la PDA (53,8%). El IMC presento una correlacion estadisticamente significativa con el porcentaje de GC obtenido por los dos metodos y en ambos sexos (p Conclusion: la prevalencia de pacientes con exceso de grasa corporal fue elevada. Los puntos de corte convencionales para el IMC no fueron adecuados en esos pacientes y esto sugiere que los valores de IMC ≥ 25 kg/m2 presentan mayor exactitud para el diagnostico de obesidad. EnglishIntroduction: nutritional status is an important predictor of prognosis in chronic kidney disease (CKD), including pre-dialysis. Anthropometric measures universally used for the diagnosis of obesity in the general population may not present the same performance in individuals with CKD. Objective: to verify the sensitivity and specificity of body mass index (BMI) in relation to the percentage of body fat (%BF) obtained by dual energy X-ray absorptiometry (DEXA) and air displacement plethysmography (PDA) for patients with non-dialysis chronic kidney disease. Methods: BMI was obtained. DEXA and ADP were used to determine %BF and they were considered as gold standard methods. Results: a total of 78 patients were evaluated, with a mean age of 54.4 ± 13.9 years old. There was a higher prevalence of overweight/obesity (55.2%), according to BMI, and high %BF, according to DEXA (69.2%) and ADP (53.8%). BMI showed a statistically significant correlation with the %BF obtained by both methods and in both sexes (p Conclusion: the prevalence of patients with excess body fat was high. The conventional cut-off points for BMI were not adequate in these patients and suggested that BMI ≥ 25 kg/m2 were more accurate for diagnosing obesity.