Table 2. Unadjusted and adjusted odds ratios of association between variables and risk of ankylosing spondylitis.

	Univariate	Multivariate
	OR (95% CI)	aOR (95% CI)
CCI≥1	2.22 (2.15–2.29)	2.14 (2.08–2.21)
Periodontitis	1.42 (1.38–1.45)	1.35 (1.31–1.38)
Appendicitis	1.36 (1.19–1.56)	1.29 (1.13–1.48)
Tonsillitis	1.52 (1.49–1.56)	1.46 (1.43–1.50)

Matched variables include age, sex and year of index date. Abbreviation: OR, odds ratio; CI, confidence interval; CCI, Charlson comorbidity index.