Table 3.

Multivariable analysis of risk factors for complicated appendicitis.

Potential risk factors (model N = 62,756)	Adjusted odds ratio for complicated appendicitis	95% confidence interval		p value∗
Age groups (ref = 0–5 years)				—
6–10 years	0.42	0.39	0.44	<0.001
11–15 years	0.34	0.32	0.36	<0.001
16–20 years	0.21	0.19	0.22	<0.001
Race/ethnicity (ref = White)				—
African American	1.08	1.02	1.15	0.02
Hispanic	1.07	1.03	1.11	<0.001
Others	1.17	1.12	1.23	<0.001
Female (ref = male)	0.92	0.89	0.95	<0.001
Household income quartiles (ref = 1st quartile)
2nd quartile	1.02	0.98	1.06	0.33
3rd quartile	0.99	0.95	1.04	0.79
4th quartile	0.90	0.86	0.95	<0.001
Transfer-in (ref = not a transfer)
Transferred from another acute care hospital	1.39	1.32	1.47	<0.001
Transferred in from other types of facility	1.00	0.90	1.12	0.94
Hospital region (ref = Northeast)				—
Midwest	1.58	1.50	1.67	<0.001
South	1.31	1.25	1.37	<0.001
West	1.15	1.10	1.20	<0.001
Urban/rural (ref = urban)	0.99	0.94	1.03	0.61
Season (ref = summer)				—
Spring	1.10	1.06	1.14	<0.001
Fall	1.09	1.04	1.14	<0.001
Winter	1.08	1.04	1.13	<0.001
Insurance (ref = Govt insurance)
Private insurance	0.94	0.91	0.97	<0.001
Others	1.02	0.97	1.08	0.35
Hospital type (ref = non-children's hospital)	1.70	1.64	1.77	<0.001

^∗ p values calculated from Binary regression.