Statistical analysis
The distribution of the included variables of our study was tested via
Shapiro- Wilk method. Normal distribution data was presented as mean ±
standard variance, otherwise median and (interquartile range) was
presented. Correspondingly, student’s t test or Mann-Whitney U test were
used to test the between group difference of the mean or mean rank,
respectively. Spearman’s rank correlation efficiency was test to
evaluate the association between ERAP1 methylation level and
other continuous or hierarchical variables. Univariate
logistic
regression analysis was used to calculate the odds ratio (OR). Odds
ratio (OR) with 95% confidence interval (CI) and forest plot were used
to evaluated association of individual methylation site and AS
visualized. Multiple logistic regression analysis was used to establish
a regression model. Receiver operating characteristic (ROC) curve and
area under curve (AUC) were applied to assess the predictive value of
the ERAP1 methylation as a biomarker of AS. All these data
analysis diagram
plotting
were accomplished by SPSS 23.0 software (SPSS Inc., Chicago, IL, USA),
GraphPad Prism 7.00 (GraphPad Software Inc., CA, USA) and R software. A
two-tailed P < 0.05 was taken as statistically
significant, and multiple comparisons were adjusted through Bonferroni
method.