Vitamin D, Hypertension, and Ischemic Stroke: An Unresolved Relationship

The Influence of Different Types of Diabetes on Vascular Complications

The final outcome of diabetes is chronic complications, of which vascular complications are the most serious, which is the main cause of death for diabetic patients and the direct cause of the increase in the cost of diabetes. Type 1 and type 2 diabetes are the main types of diabetes, and their pathogenesis is completely different. Type 1 diabetes is caused by genetics and immunity to destroy a large number of β cells, and insulin secretion is absolutely insufficient, which is more prone to microvascular complications. Type 2 diabetes is dominated by insulin resistance, leading to atherosclerosis, which is more likely to progress to macrovascular complications. This article explores the pathogenesis of two types of diabetes, analyzes the pathogenesis of different vascular complications, and tries to explain the different trends in the progression of different types of diabetes to vascular complications, in order to better prevent diabetes and its vascular complications.

Statistical methods for biomarker data pooled from multiple nested case-control studies

Pooling biomarker data across multiple studies allows for examination of a wider exposure range than generally possible in individual studies, evaluation of population subgroups and disease subtypes with more statistical power, and more precise estimation of biomarker-disease associations. However, circulating biomarker measurements often require calibration to a single reference assay prior to pooling due to assay and laboratory variability across studies. We propose several methods for calibrating and combining biomarker data from nested case-control studies when reference assay data are obtained from a subset of controls in each contributing study. Specifically, we describe a two-stage calibration method and two aggregated calibration methods, named the internalized and full calibration methods, to evaluate the main effect of the biomarker exposure on disease risk and whether that association is modified by a potential covariate. The internalized method uses the reference laboratory measurement in the analysis when available and otherwise uses the estimated value derived from calibration models. The full calibration method uses calibrated biomarker measurements for all subjects, including those with reference laboratory measurements. Under the two-stage method, investigators complete study-specific analyses in the first stage followed by meta-analysis in the second stage. Our results demonstrate that the full calibration method is the preferred aggregated approach to minimize bias in point estimates. We also observe that the two-stage and full calibration methods provide similar effect and variance estimates but that their variance estimates are slightly larger than those from the internalized approach. As an illustrative example, we apply the three methods in a pooling project of nested case-control studies to evaluate (i) the association between circulating vitamin D levels and risk of stroke and (ii) how body mass index modifies the association between circulating vitamin D levels and risk of cardiovascular disease.

The combined presence of hypertension and vitamin D deficiency increased the probability of the occurrence of small vessel disease in China

BACKGROUND

The exact relationship between 25-hydroxyvitamin D [25(OH) D] levels and small vessel disease (SVD) are not clear in China. The aim of this study was to determine such the association between 25(OH) D and SVD in China.

METHODS

We retrospectively enrolled 106 patients with SVD and 115 controls between Jan 2017 and Dec 2017. All the subjects were categorized into three subgroups according to the level of 25 (OH) D: vitamin D deficiency (< 12 ng/ml), insufficiency (12-20 ng/ml) and sufficiency (> 20 ng/ml).

RESULTS

Among 106 SVD patients, 80 (75.5%) were men and the mean age was 61.6 ± 13.2 years. The deficiency of 25(OH) D was observed in 76 (71.7%) of SVD patients and 47 (40.9%) of controls (P = 0.001). Compared with controls, patients with SVD were more likely to be male, a stroke history, smokers, with hyperlipidemia, higher systolic and diastolic blood pressure and low-density lipoprotein, and lower of 25(OH)D level (P < 0.05). Logistic regression analysis revealed the level of 25 (OH) D as an independent predictor of SVD (OR 0.772, 95% CI 0.691-0.862, P = 0.001). Compared with the sufficient 25 (OH) D group, the ORs of SVD in deficient and insufficient 25(OH)D group were 5.609 (95% CI 2.006-15.683) and 1.077 (95% CI: 0.338-3.428) after adjusting for potential confounders, respectively. In hypertensives with vitamin D deficient and insufficient group compared with sufficient group, the ORs of SVD increased to 9.738 (95% CI 2.398-39.540) and 1.108 (95% CI 0.232-5.280), respectively (Pinteraction = 0.001).

CONCLUSION

We found significant associations between SVD and 25(OH)D deficiency. The combined presence of hypertension and vitamin D deficiency increased the probability of developing SVD. Our findings will warrant further prospective studies in the future.