High or normal serum levels of 25-hydroxyvitamin D and the use of vitamin D supplements are associated with a lower risk of infection in patients on long-term dialysis, a new systematic review and meta-analysis concluded.
Among patients with high or normal levels of 25-hydroxyvitamin D [25(OH)D], the pooled adjusted risk of any infection was 39% lower compared with those who have low levels, a team led by Guobin Su, MD, of Karolinska Institutet in Stockholm, Sweden, and Xusheng Liu, MD, of Guangdong Provincial Hospital of Chinese Medicine, reported online ahead of print in Nephrology Dialysis Transplantation.
In addition, among patients with vitamin D deficiency, those who took vitamin D supplements—either a nutritional supplements or vitamin D receptor activator (VDRA)—had a significant 41% decreased pooled adjusted risk of infection than those who did not. The risk of infection did not differ significant among users and non-users of nutritional vitamin D, but VDRA users had a significant 48% lower pooled adjusted risk of infection compared with non-users.
The meta-analysis included 17 studies, including 6 cohort studies evaluating 25(OH)D serum levels (5714 patients) and 11 evaluating the use of vitamin D supplements (92,309). The threshold for defining high or normal vitamin D levels varied among the studies, as did the type of vitamin D supplements used and mode of delivery.
In a discussion of study limitations, the authors noted that they selected the most adjusted relative risks presented in each study, “which may have resulted in outcome reporting bias despite representing the most conservative risk estimation.” In addition, they pointed out that the meta-analysis was based mostly on observational studies, so their data “cannot prove causality, and residual and unmeasured confounding could not be eliminated.”
Su G, Liu Z, Qin X, et al. Vitamin D deficiency and treatment versus risk of infection in end-stage renal disease patients under dialysis: a systematic review and meta-analysis. Nephrol Dial Transplant. 2018; published online ahead of print.