Figure 3.

Adjusted associations of vitamin D level (nmol/L). (A) age (reference value = 37 years); (B) median household income (reference value = $CDN 73,264, the median); (C) percentage of individuals who were not born in Canada (reference value = 22%, the median); (D) percentage of Aboriginal people (reference value = 2%, the median); (E) percentage of individuals ≥25 years old who had at least some post-secondary education (reference value = 56%, the median). Age, median household income, percentage of immigrants, and percentage of subjects with some post-secondary education were coded using restricted cubic spline (RCS) functions with five knots located at the 5th, 25th, 50th, 75th, and 95th percentiles of their distribution, and percentage of aboriginal people was coded using the 5th, 50th and 95th percentiles of its distribution. Y-axis represents the difference in mean vitamin D level between individuals with any value of the continuous predictor (as indicated on the x-axis) and individuals with the reference value (as indicated by the vertical dashed line). Shaded area represents the 95% confidence band. Horizontal dashed line indicates the zero difference in mean 25 hydroxyvitamin D level.