Índice cintura-talla: prueba para valoración de riesgo cardiovascular y diagnóstico del síndrome metabólico Translated title: Waist-Length Index: Test for Cardiovascular Risk Assessment and Diagnosis of Metabolic Syndrome

The metabolic characteristics of type 2 diabetes, insulin resistance, and diminished insulin secretion are costly to measure directly. To evaluate the utility of several simple indices derived from insulin and glucose measurements, the indices were examined from 1982 to 1997 with respect to correlation with more sophisticated measures of insulin sensitivity and secretion in Pima Indians in the Gila River Indian Community of Arizona. Ability to predict the incidence of diabetes in 1,731 persons was also examined. Indices were calculated from fasting and 2-hour glucose (G0, G120) and insulin (I0, I120) concentrations obtained during an oral glucose tolerance test. Fasting serum insulin concentration and the insulin sensitivity index (10(4)/(I0 x G0)) each showed a moderate correlation with the estimate of insulin sensitivity derived from the hyperinsulinemic-euglycemic clamp (absolute value r approximately 0.60). They also strongly predicted the incidence of diabetes (incidence rate ratio comparing the most and least insulin-resistant tertile groups approximately 3.0). Corrected insulin response (I120/(G120 x (G120 - 70))) was modestly correlated with insulin secretion as measured by an intravenous glucose tolerance test (r = 0.35). Impaired insulin secretion assessed by this index predicted incidence of diabetes, particularly after control for insulin sensitivity index (incidence rate ratio = 1.6). Thus, simple indices of insulin sensitivity and secretion may be reasonable surrogates for more sophisticated measures in epidemiologic studies. Show more

Visceral obesity is associated with metabolic abnormalities that increase the risk of type 2 diabetes and coronary heart disease. Obese patients with a substantial accumulation of visceral adipose tissue are characterized by higher insulinaemic and glycaemic responses during an oral glucose challenge as well as by a deteriorated plasma lipoprotein-lipid profile compared with individuals with normal body weights or obese subjects with low levels of visceral adipose tissue. Results of the Quebec Cardiovascular Study have shown that the cluster of metabolic disturbances observed among subjects with visceral obesity (hyperinsulinaemia, hyperapolipoprotein B and small, dense low-density lipoprotein (LDL) particles) is associated with a 20-fold increase in the risk of coronary heart disease in a sample of middle-aged men followed over 5 years. Therefore, we have developed a simple screening approach in order to help physicians and health professionals identify at low cost individuals who would be characterized by this cluster of atherogenic abnormalities. We found that the simultaneous presence of an elevated waist girth combined with moderate hypertriglyceridaemia ('hypertriglyceridaemic waist') could adequately identify a large proportion (approximately 80%) of carriers of the above triad of atherogenic metabolic abnormalities (hyperinsulinaemia, hyperapolipoprotein B and small, dense LDL particles). Finally, there is evidence suggesting that the risk of an acute coronary syndrome in these viscerally obese patients may not always be related to the extent of coronary artery stenosis, providing further support to the notion that additional markers of thrombosis/inflammation should be considered. Thus, the stabilization of the atherosclerotic plaque, rather than its regression may even become a more legitimate and feasible therapeutic objective for the management of the coronary heart disease risk in the viscerally obese patient. Although these notions are based on a plausible metabolic rationale, randomized trials with proper end-points will be needed to determine the clinical benefits associated with the management of visceral obesity and related metabolic complications. Show more

En este estudio se enfatiza la importancia de efectuar una estimación del tamaño muestral al emprender una investigación biomédica. Los escenarios más comúnmente encontrados son analizados y se discuten los procedimientos apropiados para establecer tamaños muestrales en estudios de prevalencia, promedios, proporciones, pruebas diagnósticas, concordancia, cohortes y caso-control Show more