The Association of 25-Hydroxyvitamin D Levels with Late Cytomegalovirus Infection in Kidney Transplant Recipients: The Wisconsin Allograft Recipient Database

Background. Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality in kidney transplant recipients. Vitamin D has an integral role in proper immune function, and deficiency is common among kidney transplant recipients. It remains unclear whether 25-hydroxyvitamin D [25(OH)D] level is associated with CMV infection in kidney transplant recipients. Methods. We examined the relationship between 25(OH)D levels, measured at least 6 months posttransplant, and subsequent CMV infection in 1976 recipients free of prior CMV infection. Results. Of 1976 recipients, 251 (12.7%) were vitamin D deficient [25(OH)D <20 ng/mL] and 548 (27.7%) were insufficient (20-29 ng/mL) at the time of the first 25(OH)D measurement. A total of 107 recipients had a CMV infection within 1 year of a 25(OH)D measurement. Vitamin D deficiency was associated with a 1.81-fold higher risk (relative hazard = 1.81; 95% confidence interval [CI], 1.06-3.09) than vitamin D sufficiency after adjustment for baseline characteristics and concurrent graft function and blood calcineurin inhibitor concentration. Each 1 ng/mL lower 25(OH)D was associated with a 2% higher risk of infection (95% CI, 0%-4%) in continuous analyses after adjustment. Conclusions. Low 25(OH)D is common in kidney transplant recipients and associated with late CMV infection. These results highlight the need for interventional trials to assess the potential for vitamin D supplementation to reduce infectious complications in kidney transplant recipients.