Low Vitamin D Heralds Worse Outcomes

Deficiency in CKD patients linked to greater mortality and cardiovascular problems, data suggest.

STOCKHOLM—Vitamin D deficiency increases the risk of death and cardiovascular problems in patients with renal disease, according to studies presented here at the European Renal Association-European Dialysis and Transplant Association 2008 congress.

In one study, Pietro Ravani, MD, of the Istituti Ospitalieri in Cremona, Italy, and his colleagues found that plasma 25-hydroxyvitamin D is related directly to glomerular filtration rate (GFR) among patients with moderate to severe CKD and is a strong and independent inverse predictor of mortality. The findings are based on a study of 168 pre-dialysis CKD patients (mean age 70 years; 63% male).

After a mean follow-up of 46.5 months, 78 patients died (66% from cardiovascular causes). Twenty-one of these patients previously had started dialysis. Higher levels of 25-hydroxyvitamin D at baseline predicted both longer renal (dialysis free) and patient survival. Each 1 ng/mL increment in 25-hydroxyvitamin D was associated with a 4% reduced death risk,

Dr. Ravani's team reported. Levels of 25-hydroxyvitamin D higher than the median value (18 ng/mL) in an adjusted model were associated with a significant 44% lower risk for starting dialysis and for death compared with lower values.

Link to cardiovascular risk factors

Researchers presented findings, at the conference, of two Portuguese studies of hemodialysis patients showing that 25-hydroxyvitamin D deficiency (levels below 15 ng/mL) is independently associated with in-creased pulse pressure, increased left ventricular mass index, and vascular calcification, all of which are cardiovascular risk factors.

Additionally, researchers who studied peritoneal dialysis patients in Hong Kong found that low serum 25-hydroxyvitamin D levels are as-sociated with an increased risk of cardiovascular events partly through their relationship with residual renal function, left ventricular hypertrophy, and systolic dysfunction. Each 1-unit increase in hydroxyvitamin D was associated with a 42% reduction in cardiovascular event risk, they reported.