Table 1. Demographic data of AS patients and controls.

Sex		Cases (396)	Controls (404)	p-value
	male	354 (89.4%)	364 (90.1%)	0.742
	female	42(10.6%)	40 (9.9%)
Age		29.6±8.5	30.0±9.4	0.518
Duration of diagnosis		11.5±2.1	N/A
BASFI		3.97±1.49	N/A
BASDAI		3.95±1.05	N/A
mSASSS		12.6±13.4	N/A

There is no significant difference in age and sex-distribution between AS patients and controls. Numerical values presented as mean±standard deviation. BASFI : Bath ankylosing spondylitis function index. BASDAI: Bath ankylosing spondylitis disease activity index. mSASSS: modified Stokes ankylosing spondylitis Spine Score.