More Fracture Risk Assessments Needed
SEATTLE—Dialysis patients are at increased risk for fractures, and these fractures are associated with a higher morbidity and mortality compared with fractures in the general population, according to nephrologist Jean Holley, MD, Clinical Professor of Medicine at the University of Illinois at Urbana-Champaign. Still, studies suggest that few dialysis patients receive fracture risk assessment and appropriate preventive therapies.
Clinicians are faced with a quandary when it comes to reducing fractures in dialysis patients, Dr. Holley said. They need to perform risk assessments, review medications, evaluate gait/balance/strength training, and possibly screen for adequate serum levels of vitamin D.
“There are studies suggesting that that lack of vitamin D leads to diminished muscle strength and that diminished muscle strength is associated with increased falls,” Dr. Holley said. “Studies done in non-dialysis patients have shown that vitamin D supplementation of 800 IU a day resulted in decreased falls. If you decrease falls, you decrease fractures.”
A meta-analysis of five randomized trials with a total of 1,237 non-dialysis patients showed that vitamin D supplementation could reduce the risk of falls by 22% compared with placebo. One study included in the meta-analysis showed that 800 IU of vitamin D plus calcium supplementation could reduce falls by 75% (BMJ. 2009; 339:b3692).
The incidence of fractures in end-stage renal disease (ESRD) patients is relatively high, yet there is a not a great deal of published research into the optimal strategies for prevention and treatment in patients with ESRD. Studies suggest that the prevalence of incident fractures among ESRD patients is 10%-40%, with approximately 50% of patients over the age of 50 having had a fracture (Nephrology 2009;14:395-403). Overall, estimates suggest that dialysis patients are four times more likely to suffer a fracture than the general population.
Fractures are also associated with higher morbidity and mortality in the dialysis population compared with the general population. The mortality rates one year after fracture are pegged at 14%-36% in the general population compared with 64% among dialysis patients (Am J Kidney Dis. 2000;36:1115). It is believed that an adverse prognosis after long-bone fracture in dialysis patients may be related to subsequent chronic heart failure, stroke, pulmonary embolism, pneumonia, and septicemia.
Following a fracture, patients experience declines in functional abilities and an increased need for long-term nursing care, she said. Risk factors for fractures in patients with ESRD include female gender, Caucasian race, older age, lower BMI, lower serum albumin, dependence on assistance for ambulation or transfers, coronary artery disease, and peripheral vascular disease, diabetes mellitus, and dialysis vintage. Use of thiazolidinedione (TZDs), such as rosiglitazone and pioglitazone, may be associated with an increased risk for fracture.
Risk factors for falls among dialysis patients include diabetes mellitus, inability to walk 10 meters unassisted, total number of medications and antidepressant use (Am J Kidney Dis. 2005;45:148-153). No studies have linked any one mode of dialysis to falls or risk of fracture.
ESRD patients could have abnormal bone metabolism for a number of reasons, including secondary hyperparathyroidism, abnormal vitamin D metabolism, adynamic bone disease, chronic acidosis, steroid therapy, and hypogonadism. Interestingly, in the general population bone mineral density (BMD) measurements predict fracture risk. However, BMD measurements have not been correlated with fracture risk in dialysis patients. CKD patients tend to have poor bone quality that cannot be measured by absorptometry.
“We clearly need more basic science studies and clinical studies to examine bone in dialysis patients to help us understand the risk for osteoporosis and the risk for adynamic bone disease,” Dr. Holley said in an interview with Renal & Urology News. “Bisphosphonates are actually contraindicated in dialysis patients because of the risk of hypocalcemia. Some nephrologists are using lower doses or spreading out the duration of dose, but there are no data in dialysis patients to show they are effective in reducing fractures in this population.”
For now, the best prevention strategies include reviewing all medications and minimizing the use of psychotropic drugs whenever possible, referring patients to physical therapists for gait/balance/strength training, and referring patients to occupational therapists for safety recommendations.