Cardiovascular disease in chronic kidney disease. A clinical update from Kidney Disease: Improving Global Outcomes (KDIGO).

Cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD) is high, and the presence of CKD worsens outcomes of cardiovascular disease (CVD). CKD is associated with specific risk factors. Emerging evidence indicates that the pathology and manifestation of CVD differ in the presence of CKD. During a clinical update conference convened by the Kidney Disease: Improving Global Outcomes (KDIGO), an international group of experts defined the current state of knowledge and the implications for patient care in important topic areas, including coronary artery disease and myocardial infarction, congestive heart failure, cerebrovascular disease, atrial fibrillation, peripheral arterial disease, and sudden cardiac death. Although optimal strategies for prevention, diagnosis, and management of these complications likely should be modified in the presence of CKD, the evidence base for decision making is limited. Trials targeting CVD in patients with CKD have a large potential to improve outcomes.

Can we ameliorate quality of life in chronic kidney disease? The nephrologist's point of view.

Despite admirable technical progress in dialysis procedure, rehabilitation of dialysis patients is far from optimal, in part because of deficiencies in the dialysis modality, in part because of the limited access to kidney transplantation, which is a superior method of treatment, and in part because of demographic reasons, particularly the ageing of the dialysis population. Chronic dialysis treatment creates a particular "microcosmos" in which interpersonal relations and psychological problems carry particular weight.

Intestinal cholesterol absorption, treatment with atorvastatin, and cardiovascular risk in hemodialysis patients.

BACKGROUND: Hemodialysis patients are high absorbers of intestinal cholesterol; they benefit less than other patient groups from statin therapy, which inhibits cholesterol synthesis. OBJECTIVES: This study sought to investigate whether the individual cholesterol absorption rate affects atorvastatin's effectiveness to reduce cardiovascular risk in hemodialysis patients. METHODS: This post-hoc analysis included 1,030 participants in the German Diabetes and Dialysis Study (4D) who were randomized to either 20 mg of atorvastatin (n=519) or placebo (n=511). The primary endpoint was a composite of major cardiovascular events. Secondary endpoints included all-cause mortality and all cardiac events. Tertiles of the cholestanol-to-cholesterol ratio, which is an established biomarker of cholesterol absorption, were used to identify high and low cholesterol absorbers. RESULTS: A total of 454 primary endpoints occurred. On multivariate time-to-event analyses, the interaction term between tertiles and treatment with atorvastatin was significantly associated with the risk of reaching the primary endpoint. Stratified analysis by cholestanol-to-cholesterol ratio tertiles confirmed this effect modification: atorvastatin reduced the risk of reaching the primary endpoint in the first tertile (hazard ratio [HR]: 0.72; p=0.049), but not the second (HR: 0.79; p=0.225) or third tertiles (HR: 1.21; p=0.287). Atorvastatin consistently significantly reduced all-cause mortality and the risk of all cardiac events in only the first tertile. CONCLUSIONS: Intestinal cholesterol absorption, as reflected by cholestanol-to-cholesterol ratios, predicts the effectiveness of atorvastatin to reduce cardiovascular risk in hemodialysis patients. Those with low cholesterol absorption appear to benefit from treatment with atorvastatin, whereas those with high absorption do not benefit.

Clinical manifestation and natural history of diabetic nephropathy.

The prevalence of diabetes, predominantly of type 2, and the incidence of diabetic nephropathy have dramatically increased worldwide. Diabetic patients constitute the largest proportion of patients with end-stage renal disease (ESRD) requiring dialysis or transplantation; in developed countries, this accounts for up to 50% of ESRD patients, but this proportion has stabilized and possibly somewhat decreased in recent years. Chronic kidney disease in diabetic patients is more heterogeneous than previously thought. The largest proportion suffers from proteinuric diabetic nephropathy with Kimmelstiel-Wilson lesions as the underlying pathology, but reduced glomerular filtration rate in the absence of albuminuria/proteinuria is recognized in an increasing proportion of type 2 diabetic patients. Of particular interest is the recent recognition of vascular lesions in the brain and retina as predictors of nonproteinuric nephropathy with reduced GFR; although currently unproven, such lesions may also be of potential relevance for target blood pressure. Because of the high prevalence of type 2 diabetes in the population, coexisting primary kidney disease and diabetic nephropathy occur in a sizable proportion of type 2 diabetic patients with ESRD. The optimal point to start treatment differs according to target organs. There is no doubt that in proteinuric diabetic patients the earlier the treatment (blood pressure lowering, renin-angiotensin system blockade) is started, the greater is the benefit--at least in patients with proteinuric disease and no major cardiovascular damage. In our opinion, there is no one target blood pressure that fits all patients. Survival of patients with diabetic nephropathy is to a large extent determined by cardiovascular comorbidity. It is currently a matter of debate whether the current definition of type 2 diabetes is appropriate. Some recent findings suggest that minor renal hemodynamic and morphological changes are seen even in (prediabetic) patients who fail to meet the current definition of type 2 diabetes.

The message for World Kidney Day 2009: hypertension and kidney disease: a marriage that should be prevented.

The prevalence of chronic kidney disease (CKD) continues to increase worldwide as does end stage renal disease. The most common, but not only, causes of CKD are hypertension and diabetes. CKD is associated with a significant increase in cardiovascular (CV) risk as most patients with CKD die of a CV cause. Moreover, CV risk increases proportionally as estimated glomerular filtration rate falls below 60 mL/min. CV causes of death in CKD are more prevalent than those from cancer; as a result, the identification and reduction of CKD is a public health priority. High blood pressure is a key pathogenic factor that contributes to the deterioration of kidney function. The presence of kidney disease is a common and underappreciated preexisting medical cause of resistant hypertension. Therefore, treatment of hypertension has become the most important intervention in the management of all forms of CKD. For this reason, World Kidney Day on March 12, 2009 will emphasize the role of hypertension.

Lifestyle modification and progressive renal failure.

There is increasing evidence that lifestyle factors impact on the risk of developing chronic kidney disease (CKD) and the risk of progression of CKD. Equally important is the consideration that patients with CKD are more likely to die from cardiovascular disease than to reach the stage of end-stage renal failure. It is advantageous that manoeuvres that interfere with progression at the same time also reduce the risk of cardiovascular events. Lifestyle factors that aggravate progression include, among others, smoking, obesity and dietary salt intake. Alcohol consumption, according to some preliminary information, has a bimodal relationship to cardiovascular risk and progression, with moderate consumption being protective.

Hyperphosphatemia in renal failure.

The recent recognition that hyperphosphatemia is a strong predictor of survival on dialysis has rekindled interest in the regulation and control of serum phosphate. In incipient renal failure hyperphosphatemia is prevented by increased fractional renal phosphate excretion mediated via an increase in parathyroid hormone and the novel phosphaturic hormone FGF-23 (and possibly others). At a glomerular filtration rate of approximately 30 ml/min this compensatory mechanism fails and hyperphosphatemia ensues. Pre-dialytic serum phosphate concentrations of >6 mg/dl increase cardiac mortality presumably to a large extent, but not exclusively, via promoting vascular calcification. It has recently been recognized that vascular calcification is not only a passive precipitation process following transgression of the critical Ca-x-P product, but is an active process accompanied by expression of osteoblastic bone markers in the vessel wall. Because of the recent recognition of the relation between vascular calcification and serum phosphate as well as serum calcium, there is a need for novel calcium-free phosphate binders. Currently sevelamer and lanthanum carbonate have been introduced and trivalent iron preparations are under development.

Vascular calcification: a stiff challenge for the nephrologist: does preventing bone disease cause arterial disease?

There has been an explosion of interest in vascular calcification in the last 5 years. Four key "germinal" findings have fallen onto very fertile soil. First, on the background of an increasing cardiovascular disease burden it has been found that at least cross-sectionally, and in a limited fashion prospectively, achieved dialysis plasma phosphate levels are linked to all-cause and cardiovascular mortality. Second, there are increasing reports of calcific uremic arteriolopathy in Australia and the United States. Third, we know know that the mechanical properties of the carotid artery, and the aorta, have a profound influence on survival for dialysis patients. Vascular calcification itself (as assessed by x-ray films and ultrasound) has been linked to aortic stiffness. Fourth, increasing numbers of studies are showing extremely extensive coronary artery calcification (CAC) in dialysis patients, even at a young age. From these apparently unlinked observations the following assertion has been posited-that in the widespread (over) use of calcium-containing oral phosphate binders (OPB) to prevent uremic osteodystrophy in our dialysis population we have unwittingly accelerated widespread uremic vasculopathy and thereby contributed to premature cardiovascular mortality. It is the purpose of this article to discuss vascular calcification (and particularly CAC) in dialysis patients as we understand it today. We will review the published series, with special reference to the Sevelamer Treat to Goal trial and also discuss the new Kidney Disease Outcome Quality Initiative (K-DOQI) guidelines on the use of phosphate binders in chronic kidney disease.

Management of disturbances of calcium and phosphate metabolism in chronic renal insufficiency, with emphasis on the control of hyperphosphataemia.

BACKGROUND: Disturbances of calcium-phosphate (Ca-P) metabolism in chronic renal insufficiency (CRI) play an important role not only in bone disease (renal osteodystrophy) but also in soft tissue calcification, with an increased risk of vascular calcification, arterial stiffness, and worsening of atherosclerosis. METHODS: Discussion in order to achieve a consensus on key points relating to pathogenesis, clinical assessment, and management of renal osteodystrophy in dialysis patients. RESULTS: Secondary hyperparathyroidism develops primarily as a consequence of reduced active vitamin D production by the kidneys and phosphate retention, with the development of hyperphosphataemia, hypocalcaemia, and increased parathyroid hormone (PTH) levels. The same factors over the long term cause parathyroid gland hyperplasia and autonomous PTH production (tertiary hyperparathyroidism). As hyperphosphataemia and increased CaxP product have been associated with increased mortality in dialysis patients, hyperparathyroidism should be prevented and managed, starting in the pre-dialysis period, by calcium/vitamin D supplementation. Hyperphosphataemia is usually treated by means of intestinal phosphate binders, but different types of binders have been used. The traditional aluminium-based phosphate binders are certainly effective, but have the drawback of side effects due to aluminium absorption (osteomalacia, encephalopathy, microcytic anaemia). Calcium-containing phosphate binders (calcium carbonate or calcium acetate) have mainly been used for the last 10-15 years. However, they aggravate metastatic calcification, particularly if they are taken together with vitamin D analogues and a high calcium dialysate concentration. New calcium- and aluminium-free phosphate binders have recently been developed and may be useful, particularly in patients with metastatic calcification and/or hypercalcaemic episodes, in order to reduce the phosphate burden in the absence of an additional calcium load. New vitamin D analogues and calcimimetic drugs are also being developed for PTH suppression, with the goal to minimize or even entirely avoid hypercalcaemia and/or hyperphosphataemia. A suitable dialysate calcium concentration is important and must take into consideration the medical therapy and the calcium balance on an individual patient basis. Surgical parathyroidectomy is the ultimate means of treating hypercalcaemic hyperparathyroidism, when medical therapy has failed. CONCLUSION: Achieving an evidence-based consensus can give clinicians a useful tool for the treatment of disturbances of Ca-P metabolism in CRI: this has become an important objective in nephrological care, particularly as ageing and increased risk of atherosclerosis have become major issues in the dialysis population.