Higher levels of serum 25-hydroxyvitamin D were linked with a decreased risk for mortality among patients with chronic kidney disease, according to researchers in Iran.
“Vitamin D, as a versatile and scarce nutrient, plays an important role in human health,” Ahmad Jayedi, of the department of community nutrition at the School of Nutritional Science and Dietetics at Tehran University of Medical Science, and colleagues wrote. “Results from interventional studies indicated that supplementation with vitamin D was significantly associated with decrement in the risk of mortality both in general population and [chronic kidney disease] patients.”
The researchers added that the optimum 25-(OH)D level for patients with chronic kidney disease was unclear.
Jayedi and colleagues performed a systematic review and dose-response meta-analysis of studies reporting risk estimates of all-cause mortality for at least three categories of 25-(OH)D among patients with chronic kidney disease. They ultimately reviewed two retrospective cohort studies, 13 prospective cohort studies and one nested case-control study. The studies included 17,053 patients with chronic kidney disease and 7,517 incident deaths.
The risk for all-cause mortality was 63% higher in patients with severe 25-(OH)D deficiency (< 10 ng/mL; RR = 1.63; 95% CI, 1.32-1.94); 22% higher in mild 25-(OH)D deficiency (10-20 ng/mL; RR = 1.22; 95% CI, 1.09-1.35) and 12% higher in 25-(OH)D insufficiency (20-30 ng/mL; RR = 1.12; 95% CI, 1.06-1.18). The risk for mortality was lower among patients who did not need dialysis.
A 10-ng/mL increase in 25-(OH)D was linked with a 21% decrease in overall mortality risk (RR = 0.79; 95% CI, 0.7-0.87), Jayedi and colleagues reported. Patients with 25-(OH)D between 25 ng/mL and 30 ng/mL had a lower risk for all-cause mortality.
“Our findings put an emphasis on the importance of measurement and correction of serum [vitamin D] in [patients with chronic kidney disease],” the researchers wrote. “However, it seems necessary to conduct well-designed, placebo-controlled trials to examine the survival effects of [vitamin D] supplementation. Additionally, concerning health outcomes of serum [vitamin D] levels more than 35 ng/mL in [patients with chronic kidney disease], we have no clear evidence.” – by Andy Polhamus
Disclosure: The researchers report no relevant financial disclosures.