Chronic kidney disease epidemic: myth and reality.
In recent years, an epidemic of chronic kidney disease (CKD) has emerged as one of the major public health problem. The prevalence of CKD is largely sustained by the inclusion of a substantial proportion of the elderly population within stage 3 CKD, according to the Kidney Disease Outcomes Quality Initiative staging system. However, some clarifications are necessary when interpreting these data. In fact, renal function "normally" declines with age, without bearing any unfavourable outcome; in addition, the Modification of Diet in Renal Disease formula used to calculate glomerular filtration rate (GFR) underestimates kidney function in the elderly and in women. Considerable interest in CKD has been generated by the evidence that predialysis CKD is associated with the increased risk of cardiovascular disease (CVD). Again, potential confounding factors must be ruled out. Age is thought to play a major role in this context. The most common causes of CKD, hypertension and diabetes mellitus, are also known to affect cardiovascular outcomes directly, thus preventing the recognition of an independent effect of kidney dysfunction on mortality by CVD. Taken together, these considerations point for a better definition of CKD. Early identification of patients at risk for accelerated decline in renal function is mandatory to plan strategies for screening and preventing CKD and its complications. At present, detection of CKD in the general population requires a multi-dimensional approach that should include the evaluation of clinical risk conditions, evaluation of albuminuria and sequential monitoring of GFR.