The epidemic of chronic kidney disease: looking at ageing and cardiovascular disease through kidney-shaped lenses

In recent years, a 'silent' chronic kidney disease (CKD) epidemic has been proposed by many authors. The 'outbreak' is because of the inclusion of a large proportion of the elderly population within stage 3 CKD according to the Kidney Disease Outcomes Quality Initiative staging system. Unfortunately, this does not take into account the fact that renal function normally declines with age; in addition, the Modification of Diet in Renal Disease formula used to calculate glomerular filtration rate underestimates renal function in the elderly. Because population preventive strategies need a precise definition of the target for screening, a more accurate tool to detect CKD in the general population is required. Considerable interest in CKD has been generated by the evidence that predialysis CKD is associated with increased risk of cardiovascular disease (CVD). Such an association per se does not imply that CKD is a causal determinant of CVD. As CKD has been detected particularly in elderly individuals, it is tempting to speculate that an association may exist between age and cardiovascular outcomes in patients with CKD. Furthermore, the definition of CKD is a nosographic simplification that includes diseases with different causes and pathogenetic mechanisms. The aetiologies of renal diseases can affect cardiovascular outcomes, and the two major causes of end-stage renal disease, diabetes mellitus and hypertension, indeed do so. These findings point to a need for a better definition of CKD to optimize the allocation of healthcare resources and to clarify the nature of the association between CKD and CVD.