Vitamin d deficiency and metabolic syndrome: The joint effect on cardiovascular and all-cause mortality in the United States adults

Figure 1 Participant flowchart (A) and the analysis conceptual model (B) in the study. Serum 25(OH)D: Serum 25 hydroxyvitamin D (a marker of vitamin D level in blood); MetS: Metabolic syndrome; CART: Classification and regression tree; HD: Heart disease; CBVD: Cerebrovascular disease; CVD: Cardiovascular disease.

Figure 2 Joint effect of serum 25 hydroxyvitamin D and metabolic syndrome on the risk of cardiovascular disease (A) and all-cause mortality (B). Serum 25(OH)D: Serum 25-hydroxyvitamin D; MetS: Metabolic syndrome; CVD: Cardiovascular disease; HR: Hazard ratio.

Figure 3 Example of classification and regression trees with serum 25 hydroxyvitamin D ≥ 20 vs < 20 ng/dL in both sexes. A: Decision tree. Node 1: is the “root” node. Nodes 2 to 5 are the “leaves”. Node 5 is also called as the terminal node, including five sub-nodes (5a – 5e). Each “leaf” is a classification labeled for the output variable {serum 25-hydroxyvitamin D [25(OH)D]}, showing in each oval-shaped box. Under each box, the values listed on right indicates the % of total sample size, and the value listed on the left indicates the % of those with serum 25(OH)D concentration ≥ 20 ng/mL. If the value on the left-listed is > 0.5 then the corresponding oval-shaped box is labeled as 25(OH) ≥ 20 ng/mL, otherwise labeled as < 20 ng/mL; B: An example of top 10 important variables presented by their mean decrease in Gini (MDG) index, a higher MDG indicates a stronger predictor for the output variable. 25(OH)D: 25-hydroxyvitamin D; RACEGP: Race group, coded as racegp = 1 for non-Hispanic White, racegp = 2 for non-Hispanic Black, and racegp = 3 for all the other race groups; Sex = 1 for male, and sex = 2 for female; FOP: Serum folate level; MDG: Mean decrease in Gini index.

Figure 4 Mean Serum 25-hydroxyvitamin D concentrations (ng/mL) by race/ethnicity and sex (A), and by age (B), and serum folate levels (C). Serum 25(OH)D: Serum 25-hydroxyvitamin D; NHW: Non-Hispanic White; NHB: Non-Hispanic Black; Other: All other race/ethnicity.