Determination of surgical priorities in appendicitis based on the probability of undetected appendiceal perforation

Table 1 Patient demographics and baseline preoperative characteristics of patients whose initial computed tomography scans suggested nonperforated appendicitis n (%)

	All patients(n = 1236)	No actual appendiceal perforation(n = 1146)	Actual appendiceal perforation(n = 90)	P value
Age (yr)				< 0.001
15-35	556 (45.0)	538 (46.9)	18 (20.0)
35-65	515 (41.7)	471 (41.1)	44 (48.9)
≥ 65	165 (13.3)	137 (12.0)	28 (31.1)
Sex				0.125
Men	612 (49.5)	560 (91.5)	586 (93.9)
Women	624 (50.5)	52 (8.5)	38 (6.1)
Body-mass index (kg/m2)				0.186
< 20	255 (20.6)	239 (20.9)	16 (17.8)
20-25	673 (54.4)	627 (54.7)	46 (51.1)
≥ 25	308 (25.0)	280 (24.4)	28 (31.1)
Comorbidity				0.097
Charlson index = 0	1142 (92.4)	1063 (92.8)	79 (87.8)
Charlson index > 0	94 (7.6)	83 (7.2)	11 (12.2)
Out-of-hospital delay1				0.118
< 72 h	874 (70.7)	817 (71.3)	57 (63.3)
≥ 72 h	362 (29.3)	329 (28.7)	33 (36.7)
Body temperature (°C)				0.003
< 37.6	1029 (83.3)	965 (84.2)	64 (71.1)
≥ 37.6	207 (16.7)	181 (15.8)	26 (28.9)
Presenting symptom				0.640
Abdominal pain	1209 (97.8)	1121 (97.8)	88 (97.8)
Nausea, vomiting	14 (1.1)	13 (1.2)	1 (1.1)
Fever/chill	12 (1.0)	12 (1.0)	0 (0.0)
Indigestion	1 (0.1)	0 (0.0)	1 (1.1)
Lab. findings, median (range)
WBC count (× 103/mm3)	12.0 (1.9-28.7)	11.9(1.9-28.4)	13.8 (4.3-28.7)	0.128
Platelet count (× 103/mm3)	222 (82-587)	223 (82-857)	215 (93-503)	0.102
Neutrophil fraction				0.038
< 65%	244 (19.7)	234 (20.4)	10 (11.1)
≥ 65%	992 (80.3)	912 (79.6)	80 (88.9)
Appendix diameter (CT scan)				0.004
< 8 mm	131 (10.6)	129 (11.3)	2 (2.2)
≥ 8 mm	1105 (89.4)	1017 (88.7)	88 (97.8)
Presence of appendicolith (CT scan)				0.502
No	1086 (87.9)	1009 (88.0)	77 (85.6)
Yes	150 (12.1)	137 (12.0)	13 (14.4)
Time-to-incision (min)2				0.860
mean ± SD	534 ± 498	535 ± 499	521 ± 487
Median (range)	373 (48-4285)	373 (48-4285)	362 (70-3194)

¹Out-of-hospital delay was defined as the time interval between development of initial symptom and the visit to hospital;

²Time-to-incision was defined as the time interval between arrival to the hospital and making incision for operation. CT: Computed tomography; SD: Standard deviation; WBC: White blood cells.

Table 2 Multivariate analysis of factors affecting actual appendiceal perforation

	Hazard ratio	95%CI	P value
Body temperature (°C)			0.011
< 37.6 (standard)	1
≥ 37.6	1.912	1.161-3.149
Out-of-hospital delay (h)			0.006
< 72 (standard)	1
≥ 72	2.454	1.292-4.662
Age (yr)			< 0.001
< 35 (standard)	1
≥ 35	3.358	1.968-5.728
Appendiceal diameter on CT scan(mm)			0.045
< 8 (standard)	1
≥ 8	4.294	1.034-17.832

CT: Computed tomography.

Table 3 Risk estimation of developing actual appendiceal perforation

Groups	No. of risk factors1	Ratio of patients with perforation vs total population	Hazard ratio of perforation	95%CI	P value
Control group	0-1		1
Intermediate risk group	2	52/581 (9.0%)	4.8	2.416-9.563	< 0.001
High risk group	3-4	28/156 (17.9%)	10.7	5.064-22.596	< 0.001

¹The risk factors are (1) patient age ≥ 65 years; (2) body temperature ≥ 37.8 years; (3) body temperature n≥ 8 mm; and (4) out-of-hospital symptom duration ≥ 72 h.

Table 4 Comparison of intraoperative and postoperative variables according to the presence of actual appendiceal perforation n (%)

	All patients(n = 1236)	No actual appendiceal perforation(n = 1146)	Actual appendiceal perforation(n = 90)	P value
Surgical technique				0.111
Open appendectomy	6 (0.5)	5 (0.5)	1 (1.1)
Lap. appendectomy
Multiport	930 (75.3)	857 (74.8)	73 (81.1)
Single-port	299 (24.2)	283 (24.7)	16 (17.8)
Operation time (min)				< 0.001
Mean ± SD	61.8 ± 25.0	61.1 ± 24.4	71.2 ± 30.1
Median (range)	55 (15-230)	55.0 (15-230)	65.0 (35-200)
Drain insertion				< 0.001
No	1110 (89.8)	1041 (90.8)	69 (76.7)
Yes	126 (10.2)	105 (9.2)	21 (23.3)
Duration prior free oral fluids				0.001
Mean ± SD	1.3 ± 0.7	1.2 ± 0.6	1.6 ± 0.6
Median (range)	1 (1-7)	1 (1-7)	1 (1-6)
Duration prior soft diet				< 0.001
Mean ± SD	1.5 ± 0.9	1.47 ± 0.9	1.92 ± 1.1
Median (range)	1 (1-8)	1 (1-8)	2 (1-8)
Dosage of analgesics				0.054
Mean ± SD	1.58 ± 3.8	1.48 ± 3.5	2.83 ± 6.5
Median (range)	1 (0-70)	1 (0-70)	1 (0-50)
Analgesics duration, median (d)				0.007
Mean ± SD	0.77 ± 1.8	0.72 ± 1.7	1.4 ± 2.2
Median (range)	0.0 (0-42)	0.0 (0-42)	1 (0-15)
Postoperative complications
Severe complications (grade 3-4)	16 (1.3)	14 (1.2)	7 (7.8)	< 0.001
Total complications	94 (7.6)	113 (9.9)	20 (22.2)	0.014
Postoperative hospital stay (d)				< 0.001
Mean ± SD	4.02 ± 2.3	3.92 ± 2.3	5.2 ± 2.9
Median (range)	4 (1-48)	3 (1-48)	4 (2-17)
Readmissions				0.714
No	1210 (97.9)	1122 (97.9)	88 (97.8)
Yes	26 (2.1)	24 (2.1)	2 (2.2)

Table 5 Comparison of postoperative complications n (%)

	No actual appendiceal perforation (n = 1146)	Actual appendiceal perforation (n = 90)	P value
Grade 1, n (%)	5 (0.8)	0 (0.0)	1.000
Renal dysfunction	1	0
Hepatitis	1	0
Hyperamylasemia	3	0
Grade 2, n (%)	94 (8.2)	13 (14.4)	0.051
Wound infection	72	8
Urinary retention	11	1
Delayed gastric emptying	6	2
Pneumonia	2	0
Pleural effusion	2	2
Renal dysfunction	1	0
Grade 3, n (%)	14 (1.2)	7 (7.8)
Intra-abdominal abscess	9	5
Intestinal obstruction (ileus)	4	2
Intra-abdominal hemorrhage	1	0
Severe complications (grade 3-4), n (%)	14 (1.2)	7 (7.8)	< 0.001
Total complications, n (%)	113 (9.9)	20 (22.2)	0.014

Postoperative complications were classified as described by Clavien: grade 1 = deviation from the normal postoperative course without the need for pharmacological or any other intervention; grade 2 = requiring pharmacological treatment with drugs; grade 3 = requiring surgical, endoscopic, or radiological intervention; and grade 4 = life-threatening complication requiring intensive care unit management.