Table 2. Features of study groups.

	All patients (n=30)		Non-sacroiliitis group (n=19)		Active sacroiliitis group (n=6)
		n	Mean±SD	n	Mean±SD	n	Mean±SD
Age (year)		44.1±12.5		45.1±13.1		46.5±8.5
Sex
Male	2		2		0
Female	28		17		6
Disease duration (year)		5.9±3.9		6.8±4.5		4.3±1.5
Inflammatory back pain	8*		1		5t
Human leukocyte antigen B27	4**		1 positive		2 positive
	(17 studied)		(10 studied)		(4 studied)
Diagnostic sacroiliitis radiogram	6t		None		4
C-reactive protein (mg/L)		6.7±3.6		5.6±3.0		10.5±4.0t
SD: Standard deviation; * Two patients in chronic sacroiliitis group; ** One patient in chronic sacroiliitis group (three studied); † Two patients in chronic sacroiliitis group; ‡ p<0.05 compared to non-sacroiliitis group.