Harald Dobnig

Independent Association of Low Serum 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D Levels With All-Cause and Cardiovascular Mortality

BACKGROUND In cross-sectional studies, low serum levels of 25-hydroxyvitamin D are associated with higher prevalence of cardiovascular risk factors and disease. This study aimed to determine whether endogenous 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels are related to all-cause and cardiovascular mortality. METHODS Prospective cohort study of 3258 consecutive male and female patients (mean [SD] age, 62 [10] years) scheduled for coronary angiography at a single tertiary center. We formed quartiles according to 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels within each month of blood drawings. The main outcome measures were all-cause and cardiovascular deaths. RESULTS During a median follow-up period of 7.7 years, 737 patients (22.6%) died, including 463 deaths from cardiovascular causes. Multivariate-adjusted hazard ratios (HRs) for patients in the lower two 25-hydroxyvitamin D quartiles (median, 7.6 and 13.3 ng/mL [to convert 25-hydroxyvitamin D levels to nanomoles per liter, multiply by 2.496]) were higher for all-cause mortality (HR, 2.08; 95% confidence interval [CI], 1.60-2.70; and HR, 1.53; 95% CI, 1.17-2.01; respectively) and for cardiovascular mortality (HR, 2.22; 95% CI, 1.57-3.13; and HR, 1.82; 95% CI, 1.29-2.58; respectively) compared with patients in the highest 25-hydroxyvitamin D quartile (median, 28.4 ng/mL). Similar results were obtained for patients in the lowest 1,25-dihydroxyvitamin D quartile. These effects were independent of coronary artery disease, physical activity level, Charlson Comorbidity Index, variables of mineral metabolism, and New York Heart Association functional class. Low 25-hydroxyvitamin D levels were significantly correlated with variables of inflammation (C-reactive protein and interleukin 6 levels), oxidative burden (serum phospholipid and glutathione levels), and cell adhesion (vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 levels). CONCLUSIONS Low 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels are independently associated with all-cause and cardiovascular mortality. A causal relationship has yet to be proved by intervention trials using vitamin D.

Association of Vitamin D Deficiency with Heart Failure and Sudden Cardiac Death in a Large Cross-Sectional Study of Patients Referred for Coronary Angiography

CONTEXT Vitamin D has been shown to influence cardiac contractility and myocardial calcium homeostasis. OBJECTIVES We aimed to elucidate whether insufficient vitamin D status is associated with heart failure and sudden cardiac death (SCD). DESIGN, SETTING, AND PARTICIPANTS We measured 25-hydroxyvitamin D [25(OH)D] levels in 3299 Caucasian patients who were routinely referred to coronary angiography at baseline (1997-2000). MAIN OUTCOME MEASURES The main outcome was cross-sectional associations of 25(OH)D levels with measures of heart failure and Cox proportional hazard ratios for deaths due to heart failure and for SCD according to vitamin D status. RESULTS 25(OH)D was negatively correlated with N-terminal pro-B-type natriuretic peptide and was inversely associated with higher New York Heart Association classes and impaired left ventricular function. During a median follow-up time of 7.7 yr, 116 patients died due to heart failure and 188 due to SCD. After adjustment for cardiovascular risk factors, the hazard ratios (with 95% confidence intervals) for death due to heart failure and for SCD were 2.84 (1.20-6.74) and 5.05 (2.13-11.97), respectively, when comparing patients with severe vitamin D deficiency [25(OH)D <25 nmol/liter)] with persons in the optimal range [25(OH)D > or =75 nmol/liter]. In all statistical analyses, we obtained similar results with 25(OH)D and with 1,25-dihydroxyvitamin D. CONCLUSIONS Low levels of 25(OH)D and 1,25-dihydroxyvitamin D are associated with prevalent myocardial dysfunction, deaths due to heart failure, and SCD. Interventional trials are warranted to elucidate whether vitamin D supplementation is useful for treatment and/or prevention of myocardial diseases.

Osteoporosis in Patients With Diabetes Mellitus

Demographic trends with longer life expectancy and a lifestyle characterized by low physical activity and high‐energy food intake contribute to an increasing incidence of diabetes mellitus and osteoporosis. Diabetes mellitus is a risk factor for osteoporotic fractures. Patients with recent onset of type 1 diabetes mellitus may have impaired bone formation because of the absence of the anabolic effects of insulin and amylin, whereas in long‐standing type 1 diabetes mellitus, vascular complications may account for low bone mass and increased fracture risk. Patients with type 2 diabetes mellitus display an increased fracture risk despite a higher BMD, which is mainly attributable to the increased risk of falling. Strategies to improve BMD and to prevent osteoporotic fractures in patients with type 1 diabetes mellitus may include optimal glycemic control and aggressive prevention and treatment of vascular complications. Patients with type 2 diabetes mellitus may additionally benefit from early visual assessment, regular exercise to improve muscle strength and balance, and specific measures for preventing falls.

Low Vitamin D Levels Predict Stroke in Patients Referred to Coronary Angiography

Background and Purpose— Vitamin D deficiency is common among the elderly and may contribute to cerebrovascular diseases. We aimed to elucidate whether low vitamin D levels are predictive for fatal stroke. Methods— The LUdwigshafen RIsk and Cardiovascular Health (LURIC) study includes 3316 patients who were referred to coronary angiography at baseline between 1997 and 2000. 25-Hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] were measured in 3299 and 3315 study participants, respectively. To account for the seasonal variation of vitamin D metabolites, we calculated z values for the 25(OH)D and 1,25(OH)2D concentrations within each month of blood draw. Results— During a median follow-up time of 7.75 years, 769 patients died, including 42 fatal (ischemic and hemorrhagic) strokes. When compared with survivors in binary logistic-regression analyses, the odds ratios (with 95% CIs) for fatal stroke were 0.58 (0.43 to 0.78; P<0.001) per z value of 25(OH)D and 0.62 (0.47 to 0.81; P<0.001) per z value of 1,25(OH)2D. After adjustment for several possible confounders, these odds ratios remained significant for 25(OH)D at 0.67 (0.46 to 0.97; P=0.032) and for 1,25(OH)2D at 0.72 (0.52 to 0.99; P=0.047). Z values of 25(OH)D and 1,25(OH)2D were also reduced in the 274 patients who had a history of previous cerebrovascular disease events at baseline. Conclusions— Low levels of 25(OH)D and 1,25(OH)2D are independently predictive for fatal strokes, suggesting that vitamin D supplementation is a promising approach in the prevention of strokes.

Vascular calcification and osteoporosis—from clinical observation towards molecular understanding

Patients with osteoporosis frequently suffer from vascular calcification, which was shown to predict both cardiovascular morbidity/mortality and osteoporotic fractures. Various common risk factors and mechanisms have been suggested to cause both bone loss and vascular calcification, including aging, estrogen deficiency, vitamin D and K abnormalities, chronic inflammation and oxidative stress. Major breakthroughs in molecular and cellular biology of bone metabolism and the characterization of knockout animals with deletion of bone-related genes have led to the concept that common signaling pathways, transcription factors and extracellular matrix interactions may account for both skeletal and vascular abnormalities. For example, mice that lack the cytokine decoy receptor osteoprotegerin or the hormone Klotho display a combined osteoporosis-arterial calcification phenotype. In this review, we summarize the current data and evaluate potential mechanisms of the osteoporosis-arterial calcification syndrome. We propose a unifying hypothesis of vascular calcification that combines both active and passive mechanisms of vascular mineralization with aspects of bone resorption and age-related changes.

Vitamin D and mortality in older men and women.

Objective  Vitamin D deficiency is common among the elderly and may contribute to cardiovascular disease. The aim of our study was to elucidate whether low serum levels of 25‐hydroxyvitamin D [25(OH)D] are associated with an increased risk of all‐cause and cardiovascular mortality.

Sclerostin and its association with physical activity, age, gender, body composition, and bone mineral content in healthy adults.

CONTEXT Sclerostin is produced by osteocytes and inhibits bone formation through the Wnt/β-catenin-signaling pathway. Only limited data are available on circulating sclerostin levels in healthy subjects. OBJECTIVE We aimed to evaluate the correlation between sclerostin and physical activity, anthropometric, and biochemical variables. DESIGN, SETTING, AND PARTICIPANTS We conducted a cross-sectional observational study in 161 healthy adult men and premenopausal women aged 19 to 64 yr (mean age, 44 ± 10). INTERVENTION(S) There were no interventions. MAIN OUTCOME MEASURE(S) Serum sclerostin levels were associated with body composition, bone mineral density, physical activity, and various biochemical parameters. RESULTS A positive correlation between age and sclerostin in both men (r = 0.37; P < 0.001) and premenopausal women (r = 0.66; P < 0.001) was found. Men had significantly higher sclerostin levels than women (49.8 ± 17.6 vs. 37.2 ± 15.2 pmol/liter; P < 0.001). However, after adjustment for age, bone mineral content (BMC), physical activity, body mass index (BMI), and renal function, sclerostin levels did not differ (P = 0.543). Partial correlation analysis adjusted for age, gender, and kidney function revealed a significant positive correlation between sclerostin levels and BMC, bone mineral density, BMI, and android/gynoid fat and a significant negative correlation with serum osteocalcin and calcium. The most physically active quartile had significantly lower sclerostin levels compared to the least active quartile in a univariate analysis. CONCLUSIONS In healthy adults, sclerostin serum levels correlate positively with age, BMI, and BMC and negatively with osteocalcin and calcium. Further studies in larger populations are needed to confirm our findings and to better understand their clinical implications.

Effect of high-dose vitamin D3 on hospital length of stay in critically ill patients with vitamin D deficiency: the VITdAL-ICU randomized clinical trial.

IMPORTANCE Low vitamin D status is linked to increased mortality and morbidity in patients who are critically ill. It is unknown if this association is causal. OBJECTIVE To investigate whether a vitamin D3 treatment regimen intended to restore and maintain normal vitamin D status over 6 months is of health benefit for patients in ICUs. DESIGN, SETTING, AND PARTICIPANTS A randomized double-blind, placebo-controlled, single-center trial, conducted from May 2010 through September 2012 at 5 ICUs that included a medical and surgical population of 492 critically ill adult white patients with vitamin D deficiency (≤20 ng/mL) assigned to receive either vitamin D3 (n = 249) or a placebo (n = 243). INTERVENTIONS Vitamin D3 or placebo was given orally or via nasogastric tube once at a dose of 540,000 IU followed by monthly maintenance doses of 90,000 IU for 5 months. MAIN OUTCOMES AND MEASURES The primary outcome was hospital length of stay. Secondary outcomes included, among others, length of ICU stay, the percentage of patients with 25-hydroxyvitamin D levels higher than 30 ng/mL at day 7, hospital mortality, and 6-month mortality. A predefined severe vitamin D deficiency (≤12 ng/mL) subgroup analysis was specified before data unblinding and analysis. RESULTS A total of 475 patients were included in the final analysis (237 in the vitamin D3 group and 238 in the placebo group). The median (IQR) length of hospital stay was not significantly different between groups (20.1 days [IQR, 11.1-33.3] for vitamin D3 vs 19.3 days [IQR, 11.1-34.9] for placebo; P = .98). Hospital mortality and 6-month mortality were also not significantly different (hospital mortality: 28.3% [95% CI, 22.6%-34.5%] for vitamin D3 vs 35.3% [95% CI, 29.2%-41.7%] for placebo; hazard ratio [HR], 0.81 [95% CI, 0.58-1.11]; P = .18; 6-month mortality: 35.0% [95% CI, 29.0%-41.5%] for vitamin D3 vs 42.9% [95% CI, 36.5%-49.4%] for placebo; HR, 0.78 [95% CI, 0.58-1.04]; P = .09). For the severe vitamin D deficiency subgroup analysis (n = 200), length of hospital stay was not significantly different between the 2 study groups: 20.1 days (IQR, 12.9-39.1) for vitamin D3 vs 19.0 days (IQR, 11.6-33.8) for placebo. Hospital mortality was significantly lower with 28 deaths among 98 patients (28.6% [95% CI, 19.9%-38.6%]) for vitamin D3 compared with 47 deaths among 102 patients (46.1% [95% CI, 36.2%-56.2%]) for placebo (HR, 0.56 [95% CI, 0.35-0.90], P for interaction = .04), but not 6-month mortality (34.7% [95% CI, 25.4%-45.0%] for vitamin D3 vs 50.0% [95% CI, 39.9%-60.1%] for placebo; HR, 0.60 [95% CI, 0.39-0.93], P for interaction = .12). CONCLUSIONS AND RELEVANCE Among critically ill patients with vitamin D deficiency, administration of high-dose vitamin D3 compared with placebo did not reduce hospital length of stay, hospital mortality, or 6-month mortality. Lower hospital mortality was observed in the severe vitamin D deficiency subgroup, but this finding should be considered hypothesis generating and requires further study. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01130181.

Genetic predisposition for adult lactose intolerance and relation to diet, bone density, and bone fractures

Evidence that genetic disposition for adult lactose intolerance significantly affects calcium intake, bone density, and fractures in postmenopausal women is presented. PCR‐based genotyping of lactase gene polymorphisms may complement diagnostic procedures to identify persons at risk for both lactose malabsorption and osteoporosis.

Low Serum Levels of 25-Hydroxyvitamin D Predict Fatal Cancer in Patients Referred to Coronary Angiography

Accumulating evidence suggests that vitamin D may protect against cancer, but results from epidemiologic studies are inconclusive so far, and other studies looking into the prospective association of total cancer mortality and serum 25-hydroxyvitamin D [25(OH)D] levels, which are considered to be the best indicator of vitamin D status, are scarce. We measured 25(OH)D and 1,25-dihydroxyvitamin D in 3,299 patients from the Ludwigshafen Risk and Cardiovascular Health study. The baseline examination was done between July 1997 and January 2000 and included a fasting blood sampling in the morning before coronary angiography. During a median follow-up period of 7.75 years, 95 patients died due to cancer. After adjustment for possible confounders, the Cox proportional hazard ratio (95% confidence interval) of the fourth 25(OH)D quartile was 0.45 (0.22-0.93) when compared with the first quartile and the hazard ratio per increase of 25 nmol/L in serum 25(OH)D concentrations was 0.66 (0.49-0.89). We found no association between serum 1,25-dihydroxyvitamin D levels and fatal cancer. In summary, our data suggest that low levels of 25(OH)D are associated with increased risk of fatal cancer in patients referred to coronary angiography and that the maintenance of a sufficient vitamin D status might therefore be a promising approach for the prevention and/or treatment of cancer. (Cancer Epidemiol Biomarkers Prev 2008;17(5):1228–33)