Outcomes/Effectiveness Research

Researchers examine kidney disease progression and dialysis

Patients with diabetes, hypertension, and other medical conditions are at risk of developing chronic kidney disease, a major public health problem in the United States. An estimated 650,000 people are expected to have kidney failure (end-stage renal disease, ESRD) by 2010. People who have ESRD require renal replacement therapy, either ongoing renal dialysis or a kidney transplant; without one of these therapies, ESRD is fatal.

A recent study supported in part by the Agency for Healthcare Research and Quality (HS10064) identifies levels of blood pressure and urine protein excretion that are associated with the lowest risk for kidney disease progression. A second AHRQ-supported study (National Research Service Award training grant T32 HS00079) confirms the negative impact of weight gain between episodes of dialysis on mortality for certain ESRD patients. Both studies are described here.

Jafar, T.H., Stark, P.C., Schmid, C.H., and others (2003, August). "Progression of chronic kidney disease: The role of blood pressure control, proteinuria, and angiotensin-converting enzyme inhibition." Annals of Internal Medicine 139, pp. 244-252.

Hypertension and proteinuria (excess protein in the urine) occur in most patients with chronic kidney disease, and they are risk factors for faster progression of the disease. Blood pressure-lowering agents, such as angiotensin-converting enzyme (ACE) inhibitors, reduce blood pressure and urine protein excretion and slow the progression of kidney disease. This study details the risk of these factors on kidney disease progression. The researchers found that systolic blood pressure of 110 to 129 mm Hg and urine protein excretion of less than 2.0 grams per day were associated with the lowest risk for kidney disease progression.

ACE inhibitors remained beneficial after adjustment for blood pressure and urine protein excretion, reducing the relative risk of disease progression by 33 percent. These findings are based on a meta-analysis of 11 trials comparing the efficacy of antihypertensive regimens with or without ACE inhibitors for 1,860 nondiabetic patients with kidney disease. The investigators analyzed the pooled data to assess the association of systolic and diastolic blood pressure and urine protein excretion with kidney disease progression for 22,610 patient visits. Over a mean followup period of 2.2 years, they documented kidney disease progression in 311 patients, among them 124 in the ACE inhibitor group and 187 in the control group.

Szczech, L.A., Reddan, D.N., Klassen, P.S., and others (2003, August). "Interactions between dialysis-related volume exposures, nutritional surrogates and mortality among ESRD patients." Nephrology, Dialysis, Transplantation 18(8), pp. 1585-1591.

Fluid restriction is prescribed for dialysis patients to limit the amount of fluid that has to be removed during each dialysis treatment, since greater fluid removal during dialysis can precipitate a variety of problems. This study found that a greater percentage of interdialytic weight loss (IDWL%), one measure of weight gain between dialysis treatments, was associated with a greater mortality risk among patients with diabetes mellitus, those with greater post-dialysis weight, greater body mass index, and lower serum sodium measurements.

The researchers retrospectively examined the IDWL% of patients receiving hemodialysis through one insurer in 1998. They defined IDWL% as the difference between the average of pre- and post-dialysis weights from the last 3 months of 1997 expressed as a percentage of post-dialysis weight. Among patients with diabetes, increasing IDWL% was significantly associated with mortality, but it was not associated with increased mortality risk among patients without diabetes. Increasing IDWL% was associated with a greater mortality risk among patients with serum creatinine less than 7.26 mg/dl, but the risk became insignificant at 7.26 mg/dl or greater (a level indicative of better nutrition). The researchers conclude that recommendations for suggested IDWL% should be made in the context of a patient's nutritional status and presence of diabetes.

Return to Contents
Proceed to Next Article