ESRD

Chronic kidney disease (CKD) is an insidious disease that gradually impairs kidney function. In its earliest stages, patients may be unaware they have the disease, but over a period ranging from several years to several decades, CKD will often progress to end-stage renal disease (ESRD), requiring renal replacement therapy (dialysis or kidney transplantation) to sustain life.

CKD arises as a consequence of diabetes mellitus, hypertensive nephrosclerosis, chronic glomerulonephritis, polycystic kidney disease, and a host of other disorders.1 Diabetes and hypertension are the two leading causes of end-stage renal disease ESRD, accounting for approximately 43% and 27% of all new end-stage renal disease ESRD cases, respectively.

ESRD

Staging and Prevalence of CKD

While the terminology of the formal literature has been inconsistent and confusing, this monograph has adopted the CKD staging terminology recently proposed by the National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) and uses the term chronic kidney disease to encompass the entire spectrum of kidney disease, from its earliest stages through end-stage renal disease ESRD.

As serum creatinine (SCr) levels are an imperfect indicator of the severity of kidney disease, the NKF-K/DOQI staging and prevalence estimates are based on glomerular filtration rates (GFRs) derived using a formula developed by Levey and colleagues5 from data in the Modification of Diet in Renal Disease Study.

The resulting estimated total of 19.5 million people in the United States who have CKD marks the disease as a major public health concern, affecting more than the number of Americans with diabetes (estimated at 17 million)8 and nearly half the number of those with hypertension (estimated at 50 million).9 Because CKD typically progresses to its most severe form, ESRD, the public health concern is underscored by the most recent data from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDKD). The combined 1995 to 1999 prevalence of ESRD patients was 392,847 on dialysis and 8,287 with transplants.2 Expecting this alarming trend to continue, the NIDDKD has estimated that the prevalence of ESRD will reach over half a million by 2010.10

The NKF-K/DOQI prevalence estimates, together with the high costs associated with CKD, prompted the National Institutes of Health to establish the National Kidney Disease Education Program (NKDEP), an aggressive public education campaign currently underway. The NKDEP initiative likely will recommend interventions based on this K/DOQI staging. For patients first diagnosed with CKD, a primary goal will be to slow progression through the use of angiotensin-converting enzyme inhibitors, blood pressure control, and, in patients with diabetes, blood sugar control. Emphasis will be given to preventive and therapeutic approaches related to uremic complications, malnutrition, anemia, bone disease, acidosis, and medical comorbidities, such as cardiovascular disease.

esrd

One frequently cited paper that sheds light on the prevalence of anemia in CKD patients prior to ESRD—and the quality of their care—is a retrospective analysis by Obrador and colleagues21 of more than 130,000 US patients initiating dialysis between April 1995 and June 1997. Sixty-eight percent of these patients had a Hct value <30%, considered to indicate severe anemia, and 51% had a Hct value <28% immediately before starting dialysis. Of those with Hct <28%, epoetin had not been prescribed for 80%.

Concerned by the facts that anemia develops early in CKD and worsens as the disease progresses, a panel of nephrologists developed a concept called the Renal Anemia Management Period (RAMP). The RAMP model emphasizes the progressive nature of CKD and the need for timely and appropriate treatment—well before the development of ESRD —to prevent anemia and other comorbidities that can potentially lead to irreversible, physiological damage, such as LVH.40 Rather than representing data from a specific study, the RAMP model notes trends identified in many studies.

Of all new end-stage renal disease (ESRD) cases from 1994 through 1998, about 43% were attributed to diabetic nephropathy, making diabetes the leading cause of ESRD in the United States.

Recently, Shoji and colleagues demonstrated that diabetes increases aortic stiffness and is an independent predictor of mortality in patients with ESRD.19 Since many patients with diabetes develop both anemia and eventually ESRD, they are at an even greater risk for the development of cardiac complications than either group alone.

In ESRD, severe impairment of QOL may occur in as many as 31% of patients.