To the Editor,

We have read with interest the article “Connection Between the Early Phases of Kidney Disease and the Metabolic Syndrome” recently published in Revista Española de Cardiologia. The authors describe the association of the metabolic syndrome (MS) and early kidney disease (EKD) with carotid intima-media thickening (CIMT).1 Interestingly, although they assessed the relationship between a group of risk factors and the presence of subclinical and early vascular lesions, they did not discuss its actual implications regarding prevention or the treatment of these patients. In fact, it remains to be clarified whether these lesions should be considered to be the 2 diagnostic criteria of the MS; this has already been proposed for C-reactive protein, which, besides presenting higher levels in subjects with the MS, improves risk prediction of cardiovascular disease.2

In addition, EKD and CIMT are 2 disorders that can be stabilized but are only resolved with difficulty, especially when the values are close to normal; the mean glomerular filtration rate was 87mL/min/1.73 m2 and CIMT ranged between 0.6mm and 0.7mm. Moreover, clinical trials that have investigated CIMT regression or changes in EKD have not found a correlation with improved cardiovascular prognosis3, 4 suggesting that they behave as markers of vascular injury rather than as risk factors. In contrast, studies based on the MESYAS (Metabolic Syndrome in Active Subjects) registry have shown that the lipid components of the MS, as measured by the ratio of triglyceride to high-density lipoprotein (HDL), are very specific markers for the presence of other components of the MS5 and, more importantly, one of the major risk factors for myocardial infarction.6 This association has also been described both for the presence of the MS and for the additive effect of its components.7

Finally, the authors considered high blood pressure and diabetes as exclusion criteria in the study,1 when it has been reported that these are 2 of the main factors associated with the presence of the MS in the Spanish workforce.8 Furthermore, they state that they are unaware of the existence of previous data that associate the MS with EKD. Nevertheless, in 2004 and 2005, respectively, data from the NHANES III (National Adult Health Examination Survey) registry9 and the MESYAS registry10 were published regarding this association and coincided regarding the lack of an association between HDL and kidney damage.

We believe that the authors describe an association with few implications for cardiovascular risk stratification, while the actual implication of the MS in patients with established cardiovascular disease remains to be elucidated. During the last decade, the MS has given rise to great interest due to its relevance in the prevention of diabetes mellitus and cardiovascular disease; however, its relevance in patients with established cardiovascular disease remains undefined and unaccepted.

Corresponding author: acorderofort@gmail.com