Environmental risk factors differ between rheumatoid arthritis with and without auto-antibodies against cyclic citrullinated peptides

Table 5 Self-reported health conditions and risk of rheumatoid arthritis, Denmark 1998 to 2003

	Women		Men		Both genders
	Number of patients/controls	OR^a (95% CI)	Number of patients/controls	OR^a (95% CI)	OR^a (95% CI)
Mononucleosis	12/24	0.74 (0.35 to 1.56)	3/12	0.48 (0.13 to 1.84)	0.63 (0.33 to 1.20)^b
Hay fever ^c	61/63	1.32 (0.89 to 1.97)	14/36	0.56 (0.27 to 1.17)	1.13 (0.81 to 1.58)
Atopic dermatitis	19/24	0.99 (0.51 to 1.90)	7/10	1.46 (0.51 to 4.20)	1.12 (0.65 to 1.94)
Asthma ^c,d	24/40	0.74 (0.43 to 1.28)	4/28	0.22 (0.07 to 0.67)	0.58 (0.36 to 0.93)^e
Stomach or duodenal ulcer	20/32	0.70 (0.38 to 1.27)	12/30	0.70 (0.33 to 1.47)	0.73 (0.47 to 1.16)^b
Diarrhea	49/84	0.72 (0.48 to 1.07)	27/53	1.01 (0.58 to 1.75)	0.81 (0.59 to 1.12)
Type I diabetes ^c	2/1	2.84 (0.22 to 36.05)	3/6	1.15 (0.26 to 5.00)	1.30 (0.39 to 4.34)
Thyroid disease ^c	38/34	1.45 (0.87 to 2.40)	3/2	2.32 (0.35 to 15.44)	1.52 (0.94 to 2.46)^b
Periodontal disease	83/118	0.95 (0.67 to 1.33)	41/88	0.92 (0.57 to 1.47)	0.91 (0.70 to 1.19)
Urinary tract infection	171/256	0.76 (0.57 to 1.01)	13/40	0.57 (0.28 to 1.14)	0.73 (0.57 to 0.95)^e
Cancer	12/19	0.70 (0.33 to 1.49)	4/2	5.51 (0.89 to 34.19)	1.01 (0.51 to 1.99)
Blood transfusion	51/66	0.99 (0.65 to 1.51)	12/26	0.84 (0.39 to 1.79)	0.98 (0.68 to 1.40)
Tonsillectomy, adenoidectomy, appendectomy, or splenectomy	163/214	0.97 (0.73 to 1.29)	63/124	1.00 (0.65 to 1.55)	0.98 (0.78 to 1.24)
Schizophrenia among first-degree relatives	6/5	2.19 (0.62 to 7.77)	6/6	1.77 (0.51 to 6.11)	2.08 (0.88 to 4.93)^b

Numbers of patients and controls refer to participants who ever had the health condition in question. ^aORs represent comparisons between 'ever' versus 'never' (= reference) for each presented disease, with adjustment for birth year, year or pseudo-year of RA diagnosis, and (when combined) gender. ^bTest for homogeneity 0.05 < p < 0.20. ^cPhysician-verified diagnosis. ^dAsthma before age 45 years. ^eTest for homogeneity p < 0.05. CI, confidence interval; OR, odds ratio.

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