High vitamin D levels may prevent death in patients with CKD
Higher serum levels of 25-hydroxyvitamin D (25[OH]D) may likely reduce the risk of all-cause mortality in patients with chronic kidney disease (CKD), reports a study. However, evidence is inconclusive with regard to serum levels of >35 ng/mL.
To investigate the association between different levels of serum 25(OH)D and risk of all-cause mortality, researchers systematically searched Medline and Embase from inception to November 2016 for studies that reported risk estimates of all-cause mortality for three or more categories of serum 25(OH)D in patients with CKD. Also included were those that reported results as continuous.
A total of 1,281 studies were identified, of which 13 prospective cohort studies, two retrospective cohort studies and one nested case-control study were included. These involved 17,053 patients and 7,517 incident deaths.
The authors used a random-effects models to combine reported risk estimates. Summary risk estimates of all-cause mortality were 1.63 (95 percent CI, 1.32 to 1.94) for severe vitamin D deficiency (<10 ng/ml), 1.22 (1.09 to 1.35) for mild deficiency (10 to 20 ng/mL) and 1.12 (1.06 to 1.18) for insufficiency (20 to 30 ng/mL). These findings were more evident in dialysis-dependent patients.
A 10-ng/mL increase in serum 25(OH)D was associated with a 21-percent decrease in the risk of overall mortality (relative risk, 0.79; 0.70 to 0.87). There was also a lower risk of all-cause mortality at a serum 25(OH)D of ∼25 to 30 ng/mL. One of the sources of variation between studies was dialysis treatment.
Patients with CKD have a high prevalence of vitamin D deficiency, according to researchers.