To the Editor,
As Cordero et al. state in the current issue of Revista Española de Cardiología, our research group describes the association between the cluster of vascular risk factors known as the metabolic syndrome (MS)1 and the presence of subclinical and early vascular lesions that, once established, hardly ever return to normal.
The importance of this relationship lies in the fact that we know that MS doubles the risk of cardiovascular (CV) disease and triples the risk of CV death2; that it significantly increases the risk of advanced kidney disease3; and that patients with advanced kidney disease have an increased risk of death that can be almost 6-fold greater than that of patients with normal clearing.4 In fact, when signs of kidney disease appear, the structural lesion is already established and, as prevention is considered the best strategy in managing these patients, it is crucial to detect the earliest abnormalities so as to design specific interventions.5 Our findings confirm that MS is significantly associated with incipient deterioration of kidney function and increased intima-media thickness, but we cannot conclude these markers should be included in MS diagnostic criteria.
We coincide with other authors6 in our belief that management of these patients requires that we perform studies aimed at clarifying this marker's possible role in prognosis and in determining the most effective treatment.
We are fully aware of NHANES registry data for 20043 and cite the aforementioned study.1 Its authors evaluate advanced stages of kidney disease and the presence of microalbuminuria independently of the glomerular filtration rate. Therefore, in our opinion, our results complement and confirm these findings. We did not consider the 2005 MESYAS registry7 because it took account of the glomerular filtration rate in isolation, whereas our study looked at this in combination with the presence of microalbuminuria, in accordance with current American Society of Nephrology recommendations.8
Finally, we wish to make it clear that given diabetes and high blood pressure are well-known factors contributing to kidney damage, we excluded patients presenting these in order to study the real value of MS in evaluating subclinical CV disease.
Corresponding author: mflandecho@unav.es