Table 1.

Characteristics of patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis (PsA) and the general population (healthy controls)

	Rheumatoid arthritis (n = 469)	Ankylosing spondylitis (n = 164)	Peripheral psoriatic arthritis (n = 101)	Axial psoriatic arthritis (n = 65)	General population (n = 1579)
Women (%)	71.8	18.9	61.4	50.7	50.2
Age (years)
- mean (± SD)	57.5 (14.3)	51.7 (9.2)	60.7 (11.6)	58.2 (10.3)	55.2 (19.2)
Disease duration
- mean (± SD)	6.1 (4.2)	8.2 (4.6)	7.5 (5.3)	8.4 (4.3)	NA
Educational level, n (%)
- primary school	240 (51.2)	70 (42.7)	45 (44.6)	30 (46.1)	928 (58.8)
- secondary school	149 (31.8)	65 (39.6)	43 (42.6)	25 (38.5)	418 (26.5)
- high school/university	80 (17.0)	29 (17.7)	13 (12.8)	10 (14.4)	233 (14.7)
No of comorbid conditions, n (%)
- none	217 (46.3)	73 (44.5)	45 (44.6)	19 (29.3)	548 (34.7)
- 1	131 (27.9)	37 (22.6)	26 (25.7)	12 (18.5)	334 (33.5)
- 2	47 (10.0)	30 (18.3)	13 (12.9)	21 (32.3)	112 (7.1)
- 3	20 (4.3)	15 (9.1)	15 (14.8)	10 (15.4)	69 (4.4)
- 4	25 (5.3)	6 (3.7)	2 (2.0)	2 (3.0)	21 (1.3)
- 5 or more	29 (6.2)	3 (1.8)	0 (0)	1 (1.5)	12 (0.8)
Comorbidity score by SCQ	4.35 (3.1)	2.48 (1.9)	3.75 (2.5)	3.34 (2.1)	1.95 (1.9)
- mean (± SD)
DAS
- mean (± SD)	4.5 (0.8)	--	4.4 (0.9)	--	NA
BASDAI	--	54.7 (17.2)	--	53.8 (14.4)	NA
- mean (± SD)
Rx Sharp score	59.4 (32.9)	--	62.1 (39.1)	--	NA
- mean (± SD)
mSASSS
- mean (± SD)	--	14.7 (5.2)	--	13.7 (5.1)	NA
PASI
- mean (± SD)	--	--	7.1 (3.3)	6.7 (2.9)	NA

NA = non applicable

Abbreviations: DAS = Disease Activity Score; BASDAI = Bath Ankylosing Spondylitis Disease Activity index; mSASSS = modified Stoke Ankylosing Spondylitis Spine Score; PASI = Psoriasis Area and Severity Index