Table 1. Clinical and Demographic Cohort Characteristics^a.

Characteristic	All Appendectomy (n = 9048)	Nonperforated (n = 7233)	Perforated (n = 1421)	P Value
Male, %	52.0	52.1	55.3	.03
Age, mean (SD), y	39.8 (16.6)	38.2 (15.8)	48.8 (17.6)	<.001
Age distribution, %, y
18-29	34.6	37.5	17.5	<.001
30-39	20.8	22.0	14.2	<.001
40-49	16.3	16.6	17.7	.16
50-59	14.0	12.8	21.3	<.001
60-69	8.9	7.4	17.2	<.001
≥70 (max = 97)	5.4	4.2	12.0	<.001
WBC count, mean (SD)	13.3 (4.8)	13.2 (4.3)	14.5 (4.8)	<.001
Comorbidity index score, %
0	86.1	87.1	80.4	<.001
1	11.3	10.7	14.1	<.001
2	1.8	1.6	3.2	<.001
≥3	0.9	0.6	2.3	<.001
Race, %
White	71.7	71.6	72.4	.52
African American	2.7	2.7	8	.06
Asian	5.3	5.4	4.3	.08
American Indian/Alaskan	0.9	0.8	1.1	.23
Hawaiian/Pacific Islander	0.6	0.7	0.4	8
Unknown	19.0	18.8	20.00	.31
Ethnicity, %
White, non-Hispanic	65.4	65.2	66.7	.26
White, Hispanic	8.0	8.	7.5	.45
Minority, non-Hispanic	9.3	9.5	7.5	.02
Minority, Hispanic	0.1	0.1	0.1	.64
Unknown	17.3	17.2	18.2	.36
Insurance, %
Private	61.8	63.6	54.2	<.001
Medicare	8.	6.4	17.0	<.001
Medicaid	8.4	8.2	8.2	.96
Uninsured, self-pay,  unknown	18.1	18.0	18.0	.97
Other government  program	3.6	3.9	2.7	.03
Preoperation imaging	93.3	93.9	93.9	.97
Negative appendectomy	4.1	NA	NA	NA
Perforation	15.8	NA	NA	NA

Abbreviations: NA, not applicable; WBC, white blood cell.

^aSignificance testing for patient characteristics with more than binomial categories (eg, comorbidity score, race, race and ethnicity, and insurance status) was performed using the Pearson χ² test. The proportion of each strata was compared between those with and without perforation. For example, the percentage of patients with Medicare among those with perforation was compared with the percentage of patients with Medicare among those without perforation. Differences in continuous variables (age and WBC count) were tested for significance using the t test.