Table 4.

Association of serum IgG levels with isolated ileal disease.

Serum IgG	Crude	Model 1a	Model 2b
Elevated serum IgG	0.27 (0.175–0.42)	0.29 (0.185–0.45)	0.37 (0.23–0.61)
Quartile 1 of serum IgG	Reference	Reference	Reference
Quartile 2 of serum IgG	0.83 (0.53–1.31)	0.835 (0.53–1.32)	1 (0.61–1.63)
Quartile 3 of serum IgG	0.44 (0.28–0.7)	0.46 (0.29–0.74)	0.55 (0.33–0.92)
Quartile 4 of serum IgG	0.2 (0.12–0.33)	0.21 (0.13–0.355)	0.3 (0.165–0.53)
P for trend	<0.001	<0.001	<0.001
Per-SD increase	0.485 (0.4–0.59)	0.5 (0.41–0.61)	0.55 (0.43–0.7)

Data are odds ratio (95% confidence interval).

^aAdjusted for gender, age at diagnosis.

^bAdjusted for gender, age at diagnosis, history of appendectomy and intestinal surgery, serum IgA, and IgM, perianal disease, complicated disease, and disease activity.