. Author manuscript; available in PMC: 2010 May 26.

Published in final edited form as: Arthritis Care Res (Hoboken). 2010 Mar;62(3):418–424. doi: 10.1002/acr.20096

Table 2. Association between birth order and SSc prevalence^*.

Birth order	SSc probands (n = 987)	Unaffected siblings (controls) (n = 3,086)	OR	P	95% CI
1 (n = 974)	257	717	1 (ref.)
2–5 (n = 2,560)	635	1,925	1.25	0.010	1.06–1.50
6–9 (n = 469)	82	387	2.22	< 0.001	1.57–3.15
10–15 (n = 72)	15	57	3.53	0.001	1.68–7.45

SSc = systemic sclerosis; OR = odds ratio; 95% CI = 95% confidence interval.

Table 2. Association between birth order and SSc prevalence*.