Descriptive statistics
Continuous variables were described using the mean and standard
deviation, or median and interquartile range when variables were not
normally distributed. The independent t-test was used to compare means
of continuous variables by sex while the Mann-Whitney test for
comparison of median values by sex. One way analysis of variance (ANOVA)
was used to compare means of normally distributed continuous variables
by age group or BMI category, while Kruskal Wallis was used for
comparison of medians when variables were not normally distributed.
Pearson’s correlation coefficients determined the association between
age and RA parameters using a statistical significance threshold of
0.05. All statistical analyses were conducted in Stata version 15.