Table 1.

Sociodemographic characteristics, morbidities and ANA distributions of the study groups (%)

	Augsburg (n = 139)	Bremen (n = 241)	Essen (n = 282)	Hamburg (n = 238)	Hannover (n = 106)	Heidelberg (n = 193)	p valuea	Total (n = 1199)
Sex							0.168
Male	48.2	45.2	39.1	47.9	47.2	38.9		43.8
Female	51.8	54.8	60.9	52.1	52.8	61.1		56.2
Median age (IQR)	55 (47–63)	54 (41–62)	41 (34–50)	48 (30–62)	52 (43–62)	45 (31–59)	<0.0001b	49 (38–60)
Country of birth							<0.0001
Germany	83.5	83.8	21.3	88.7	87.7	40.9		64.0
Other	16.5	16.3	78.7	11.3	12.3	59.1		36.0
BMI							<0.0001
Underweight (<18.50 kg/m2)	0	1.2	0.4	1.7	2.8	2.6		1.3
Normal weight (18.50–24.99 kg/m2)	33.8	43.2	18.5	51.1	46.2	46.9		38.7
Overweight (25.00–29.99 kg/m2)	46.8	39.0	39.9	32.5	35.8	31.3		37.3
Obesity (≥30.00 kg/m2)	19.4	16.6	41.3	14.8	15.1	19.3		22.7
Heart attack							0.18
Yes	5.0	0.8	2.3	1.7	2.8	2.6		2.3
No	95.0	99.2	97.7	98.3	97.2	97.4		97.7
Diabetes							0.40
Yes	7.2	5.4	9.9	5.9	4.7	6.8		6.8
No	92.8	94.6	90.1	94.1	95.3	93.2		93.2
ANA positivity							0.742
Negative (<1:80)	67.6	63.9	66.8	65.1	71.7	68.8		66.7
Positive (≥1:80)	32.4	36.1	33.2	34.9	28.3	31.3		33.3
ANA positivity							0.157
Negative (<1:80)	67.6	63.9	66.8	65.1	71.7	68.8		66.7
Weakly positive (1:80 & 1:160)	25.2	29.0	29.6	32.4	26.4	25.5		28.6
Moderately positive (1:320 & 1:640)	3.6	5.8	2.5	1.3	1.9	4.7		3.3
Strongly positive (≥1:1280)	3.6	1.2	1.1	1.3	0	1.0		1.3

ANA anti-nuclear autoantibody, IQR interquartile range, BMI body mass index

^aChi-square test or Fisher’s exact test for differences across study centers

^bKruskal–Wallis test for differences across study centers