Are low levels of 25-hydroxyvitamin D a risk factor for cardiovascular diseases or malignancies in renal transplantation?

ABSTRACT

BACKGROUND: Observational studies in healthy people suggest an inverse relationship between 25-hydroxy-vitamin D (25(OH)D levels) and cardiovascular diseases and malignancies. We performed an observational prospective study in renal transplant recipients to investigate the effects of vitamin D deficiency on cardiovascular and malignancy risks. METHODS: From 389 renal transplant recipients, 331 with a functioning graft at 12 months were included in the study. Mineral metabolism parameters were measured at 1, 3, 4 and 12 months. Information regarding the cardiovascular events and malignancies were collected from an electronic database. RESULTS: According to the 1-year mean of 25(OH)D levels, 75 recipients (22.7%) had a normal vitamin D status, 161 (48.6%) had insufficiency and 95 (28.7%) had deficiency in vitamin D levels. During the follow-up, 80 recipients presented at least one cardiovascular event. The total cardiovascular diseases included 27 patients with coronary diseases, 25 with cardiac failure, 18 with arrhythmia, 11 with acute cerebrovascular events and 19 with peripheral vascular disease. Cardiovascular events were not associated with 25(OH)D levels or vitamin D status, and the 10-year cumulative incidence was 29.3% for normal vitamin D status and 31.6% for insufficiency and 51.9% for deficiency (P = 0.216). Furthermore, Cox univariate analysis showed no association between cardiovascular events and vitamin D levels or vitamin D status. In addition, 53 recipients presented at least one malignancy 33 non-melanoma skin malignancies and 20 non-skin malignancies (5 prostate, 3 kidney and urinary tract, 2 colon, 2 lung, 2 lymphoma, 2 breast and 4 from other locations). The cumulative incidence of malignancies was 21.3% for normal vitamin D status, 22.7% for insufficiency and 16.7% for deficiency (P = 0.818). CONCLUSIONS: Our data suggested that low vitamin D levels were not associated with an increased risk of cardiovascular diseases or malignancies. However, due to the small number of patients and events, the results should not be considered as definitive. Additional studies with a higher number of patients are required to elucidate the true impact of vitamin D status on cardiovascular and malignancy risks.