Dear Editor,
We read the article by M. Heras et al., which was recently published in your journal, with great interest.1 The authors conclude that having observed a sustained reduction in glomerular filtration (GF) in elderly subjects without proteinuria, it is now possible to reassure these kinds of patients facing the epidemic of chronic kidney disease (CKD).
In this respect, we agree with the authors¿ conclusion, however we would like to highlight some important considerations:
a) In the series studied, the elderly patients with a mortality greater than 24 months presented a higher frequency of episodes of heart failure (HF) compared with those who survived during the follow up (37.5 compared with 15%; p = 0.045 respectively). Of this subgroup of patients with HF, we do not know from the results of this study what the rate of GF (GFR) was, nor do we know the level of proteinuria. Similarly, recent studies, like the CHARM trial, show that over 50% of patients with HF present macroalbuminuria, with a GFR > 60ml/min per 1.73m2. Furthermore, the presence of albuminuria in these subjects was an independent predictor of mortality in this group of patients independent of GFR and creatinine levels.2
b) With regard to the prognostic factors associated with higher mortality, ischaemic heart disease was the determining factor in the logistic regression analysis. Consequently, it is worth highlighting that in the population described by Heras et al., the patients in group 2 (with creatinine levels >1.1mg/dl) were almost three times more likely to have history of ischaemic heart disease than those in group 1 (Cr <1.1) (21.4 versus 7.9%). Similarly, the number of deaths in group 2 was double that in group 1 (12 versus 6). Although these differences were not statistically significant, they suggest a trend that could be analysed more reliably in a larger population sample.
c) From the sample of patients included in this study, 77% of them were hypertensive and practically one third were diabetics. Over 20% of the sample had presented a previous cardiovascular event and therefore, if they were stratified according to the Pulmonary Arterial Hypertension Guidelines published by the European Society of Cardiology (2007), they would be considered high vascular risk patients, independent of their GFR or presence of albuminuria.3 Therefore, although patients preserve their kidney function, the mortality rate continues to be very high; in fact, 22% of patients had a two-year survival outcome in this group.
d) Finally, we would like to highlight that, although the authors¿ conclusion of not referring elderly patients with sustained reduced GF unaccompanied by proteinuria or anaemia, may be correct from a nephrological point of view, it is probably necessary to check for risk factors in this population, given that the global mortality rate is very high.
