BMD, Modifiable Risk Factors Linked to Poor Outcomes in Chronic Kidney Disease

By Marilynn Larkin

July 22, 2020

NEW YORK (Reuters Health) - In patients with chronic kidney disease (CKD) who are not on dialysis, modifiable lifestyle factors, including low physical activity and a high dietary sodium/potassium ratio, are associated with and may predict poor renal outcomes, researchers in Korea suggest.

Dr. K-B Lee of Sungkyunkwan University School of Medicine in Seoul analyzed data from the KNOW-CKD cohort study ( Bone mineral density (BMD) of the lumbar spine, hip, or femoral neck were measured by dual-energy x-ray absorptiometry and classified by T score: normal (T score − 1.0 or more); osteopenia (− 1.0 > T score > − 2.5); and osteoporosis (− 2.5 or less) of the lumbar spine, hip, or femoral neck.

As reported in Osteoporosis International, among 2,128 adults with CKD (mean age 54; 61% men), 33% had osteopenia and 8%, osteoporosis. Over a median follow-up of 4.3 years, there were 521 cases of incident end-stage renal disease (ESRD).

Lower BMD was associated with female sex, older age, low eGFR, low BMI, low physical activity (odds ratio = 0.62) and high dietary Na/K ratio (1.07).

After adjustment, low BMD was associated with increased incident ESRD (HR = 1.14 for osteopenia and 1.43 for osteoporosis). The association was similar according to T score discordance classification.

The authors state, "We showed that modifiable lifestyle factors of physical activity and dietary Na/K intake are associated with BMD in CKD. Patients with low BMD have higher incident ESRD than those with normal BMD in CKD."

Dr. Lee did not respond to requests for a comment, but two US nephrologists commented in emails to Reuters Health.

Dr. Uday Nori, Program Director, Nephrology Fellowship at The Ohio State University Wexner Medical Center in Columbus said, "It is well known that CKD causes low BMD and other systemic complications such as anemia, metabolic acidosis, fluid overload, hyperkalemia, etc."

"There has been a long-standing interest in figuring out if these complications influence the progression of CKD in turn," he noted. "Many studies have supported the idea that diligent treatment of these complications has slowed down the rate of progression of CKD but the quality of these studies is low. We treat the complications anyway to improve morbidity and mortality overall, not knowing if it is improving CKD progression."

"It is a logical conclusion that patients who progressed to ESRD would have had worse BMD. Posing the counter argument that low BMD is associated with a higher rate of ESRD is intriguing," he added. "The authors never explained the rationale for this argument. In my opinion, the only basis for this argument would have been a specific intervention that improved the BMD and ergo, the ESRD is lower; (however), this study is observational."

"A prospective, randomized clinical trial with a specific intervention to improve the BMD in one arm of the trial would be one way to add to the current practice/research," Dr. Nori concluded.

Dr. Mary Ellen Dean, assistant clinical professor at the Touro College of Osteopathic Medicine in New York City said that while it is interesting to consider the thought that low BMD might predict CKD progression, "one would have to tease out many more variables in these patients."

"Risk factors which are modifiable are important to stress no matter what," she said. "Educating the patient in understanding the impact of low BMD and potential other bone diseases from renal critical to success in this endeavor. If patients understand how these factors all interplay, they are more likely to comply with recommendations."

SOURCE: Osteoporosis International, online July 8, 2020.