Vitamin D Deficiency and Cardiovascular Mortality: Retrospective Analysis "Siena Osteoporosis" Cohort

Abstract

Vitamin D is a fat-soluble vitamin that plays a key role in bone metabolism, particularly concerning the regulation of calcium and phosphate homeostasis. Cardiovascular disease (CVD) is the main cause of morbidity and mortality in Western countries. Knowledge of the role of vitamin D in CVD arose from evidence of the vitamin D receptor (VDR) inside the cardiovascular system. In this retrospective analysis, we investigated the relationships between vitamin D status and hospitalization for heart failure (HF), overall mortality and cardiovascular mortality. Between 2004 and 2009, age-stratified, random sampling of elderly men and postmenopausal women in the primary care registers of Siena residents was performed. In total, 174 males (mean ± SD, 65.9 ± 6 years) and 975 females (62.5 ± 6 years) were enrolled in the study. We investigated the association between 25OHD status and hospitalization for HF or causes of mortality. A total of 51 subjects (12 males and 39 females) had been hospitalized for acute HF. At the end of the survey, 931 individuals were alive, while 187 had died (43 males and 144 females). A greater proportion of deceased patients showed low 25OHD (particularly patients with levels below 20 ng/mL). A similar trend was observed concerning the prevalence of patients with 25OHD levels below 20 ng/mL who died from stroke (RR = 2.15; 95% CIs 0.98-4.69; p = 0.06). Low 25OHD levels may be predictive of cardiovascular mortality. Whether vitamin deficiency represents a primitive cause or is a simple bystander in increased cardiovascular mortality should be further investigated in prospective large cohort studies specifically designed to assess CVD risk, including a detailed assessment of cardiac dysfunction and the characterization of atherosclerotic lesions.

Keywords: cardiovascular diseases; heart failure; mortality; vitamin D status.

Figure 1

25OHD status in different groups analyzed. Heart failure patients present lower levels of vitamin D than controls, without significance. No significant differences were found between living and deceased groups.

Figure 2

Levels of 25OHD levels between control group and heart failure group. In the control group, no particular differences were found in vitamin D levels. Patients hospitalized for heart failure presented 25OHD levels below 20 ng/mL compared to non-hospitalized patients, but without statistical significance (p = 0.2).

Figure 3

Number of events stratified by vitamin D status. Deceased subjects presented lower vitamin D levels compared to living subjects. Patients who were deceased due to cardiovascular diseases, including stroke, presented lower 25OHD levels than subjects who were deceased due to all the other causes. Most of these subjects were representative of group 3 and 4, with vitamin D levels below 20 ng/mL.

Figure 4

Number of events stratified by vitamin D status above or below 20 ng/mL. Patients who were deceased due to CVD and stroke were both representative of group 3 and 4 of vitamin D levels. Levels of vitamin D in living individuals were homogeneous.