Despite The Guidelines, Lower Blood Pressure Might Be Unhealthy For Kidney Patients

Main Category: Hypertension
Also Included In: Urology / Nephrology;  Clinical Trials / Drug Trials
Article Date: 25 Jun 2010 - 2:00 PDT

email to a friend   printer friendly   opinions  

Recent guidelines by The National Kidney Foundation Disease Outcomes Quality Initiative (NKF KDOQI)1 call for lower target blood pressure levels in patients with chronic kidney disease (CKD). But in the absence of high-quality scientific evidence, there's a chance this recommendation could do more harm than good, according to a special article appearing in an upcoming issue of the Journal of the American Society Nephrology (JASN).

"The new low blood pressure goals are not definitively supported by data, would be costly to the healthcare system and potentially harmful to patients," according to Julia B. Lewis, MD (Vanderbilt University, Nashville, TN), who performed a critical review of the research evidence.

Issued last year, updated national guidelines for CKD treatment call for a target blood pressure level of less than 130/80 mm Hg (millimeters of mercury) to help preserve kidney function. The recommendation was based on observational studies showing "a continuous benefit of reducing blood pressure to lower and lower levels."

However, Lewis points out several problems with the research behind the new guidelines. Most importantly, since patients in the observational studies were not randomly assigned to different blood pressure goals, the apparent benefit of lower blood pressures could result from other "confounding" factors. "The data supporting the current blood pressure guidelines for patients with CKD do not meet the standard of a primary outcome of a randomized trial," says Lewis.

She explains that, as kidney disease worsens, blood pressure rises and becomes harder to control. So the data may simply reflect the fact that patients with less severe kidney disease have lower blood pressure. In studies where patients were randomly assigned to treatments, the benefits of lower blood pressure were seen only in a subgroup of patients, or several years after the end of treatment.

"Also there is other evidence to bring into question the widespread application of this costly goal of a blood pressure less than 130/80 mm Hg," Lewis adds. Some studies have even suggested that CKD patients with very low blood pressure could be at increased risk of death.

A new trial sponsored by the National Institutes of Health (NIH) will compare the effects of different blood pressure targets in over 10,000 patients with CKD. Until the results are available, Lewis believes that doctors should make individualized decisions about blood pressure control for their patients with kidney disease.

Lewis emphasizes that no firm conclusions can be drawn from her review, since it was based on different types of studies with conflicting results.

The study author is a consultant for Thervance Pharmaceuticals, Covance Pharmaceuticals, and Amira Pharmaceuticals. She also receives research support from Keryx Pharmaceuticals, Nephrogenix, Eli Lilly, and the National Institutes of Diabetes and Digestive and Kidney Diseases (NIDDK).

The article, entitled "Blood Pressure Control in Chronic Kidney Disease: Is Less Really More?" will appear online at http://jasn.asnjournals.org/ on June 24, 2010, doi 10.1681/ASN.2010030236.

The American Society of Nephrology (ASN) does not offer medical advice. All content in ASN publications is for informational purposes only, and is not intended to cover all possible uses, directions, precautions, drug interactions, or adverse effects. This content should not be used during a medical emergency or for the diagnosis or treatment of any medical condition. Please consult your doctor or other qualified health care provider if you have any questions about a medical condition, or before taking any drug, changing your diet or commencing or discontinuing any course of treatment. Do not ignore or delay obtaining professional medical advice because of information accessed through ASN. Call 911 or your doctor for all medical emergencies.

Founded in 1966, the American Society of Nephrology (ASN) is the world's largest professional society devoted to the study of kidney disease. Comprised of 11,000 physicians and scientists, ASN continues to promote expert patient care, to advance medical research, and to educate the renal community. ASN also informs policymakers about issues of importance to kidney doctors and their patients. ASN funds research, and through its world-renowned meetings and first-class publications, disseminates information and educational tools that empower physicians.

1 K/DOQI Clinical Practice Guidelines on Hypertension and Antihypertensive Agents in Chronic Kidney Disease. Guideline 7: Pharmacological therapy: Use of antihypertensive agents in CKD. National Kidney Foundation.

Source: American Society of Nephrology (ASN)

• Additional
• References
• Citations