Indication of conservative treatment by antibiotics for uncomplicated and complicated acute appendicitis

Table 1 Patient characteristics and clinical data of patients underwent surgery and improved with conservative treatment

	Surgery group, n = 28	Conservative group, n = 242	P value
Age	41.9 ± 19.8	44.8 ± 20.7	0.495
Time to visit hospital (hour)	38.6 ± 70.0	37.6 ± 66.1	0.453
Body temperature (°C)	37.8 ± 1.0	37.2 ± 0.8	< 0.001
WBC count (/μL)	13440.4 ± 4130.1	12489.8 ± 3986.3	0.325
CRP (mg/dL)	5.9 ± 7.3	4.2 ± 5.3	0.311
Size of appendix (mm)	14.0 ± 3.7	12.3 ± 4.1	0.014

CRP: C-reactive protein; WBC: White blood cell.

Table 2 Area under the curve and optimal cutoff values of clinical data as predictors of resistance to conservative treatment

	Cutoff value	Area under the curve	FPF	TPF
Time to visit hospital (hour)	22	0.5432	0.434	0.571
Body temperature (°C)	37.3	0.6923	0.368	0.679
WBC count (/μL)	15160	0.5568	0.236	0.429
CRP (mg/dL)	4.6	0.5584	0.351	0.500
Size of appendix (mm)	12	0.6409	0.533	0.786

TPF: True-positive fraction; FPF: False-positive fraction; CRP: C-reactive protein; WBC: White blood cell.

Table 3 Univariate and multivariate analysis of risk factors for resistance to conservative treatment, n (%)

	Surgery group, n = 28	Conservative group, n = 242	Univariate analysis, P value	Multivariate analysis, P value	Hazard ration
Age
< 75	26 (10.7)	216 (89.3)	0.554
≥ 75	2 (7.1)	26 (92.9)
Sex
Female	12 (11.1)	96 (88.9)	0.744
Male	16 (9.9)	146 (90.1)
Past history of appendicitis
(-)	25 (11.6)	190 (88.4)	0.180
(+)	3 (5.5)	52 (94.5)
Rebound pain
(-)	9 (7.8)	106 (92.2)	0.238
(+)	19 (12.3)	136 (87.7)
Time to visit hospital (hour)
< 22	12 (8.1)	137 (81.9)	0.166
≥ 22	16 (13.2)	105 (86.8)
Body temperature (°C)
< 37.3	9 (5.6)	153 (94.4)	0.001	0.028	2.945
≥ 37.3	19 (17.6)	89 (82.4)
WBC count (/μL)
< 15160	16 (8.0)	185 (92.0)	0.027	0.138
≥ 15160	12 (17.4)	57 (82.6)
CRP (mg/dL)
< 4.6	14 (8.2)	157 (91.8)	0.122
≥ 4.6	14 (14.1)	85 (85.9)
Size of appendix (mm)
< 12	6 (5.0)	113 (95.0)	0.011	0.600
≥ 12	22 (14.6)	129 (85.4)
Stranding of the adjacent fat
(-)	1 (1.3)	79 (98.7)	0.001	0.162
(+)	27 (16.6)	163 (83.4)
Periappendiceal fluid
(-)	19 (8.4)	206 (91.6)	0.020	0.892
(+)	9 (20.0)	36 (80.0)
Air in appendix
(-)	22 (8.9)	224 (81.1)	0.014	0.164
(+)	6 (25.0)	18 (75.0)
Abscess
(-)	24 (9.4)	230 (80.6)	0.048	0.083
(+)	4 (25.0)	12 (75.0)
Appendicolith
(-)	9 (5.1)	167 (94.9)	< 0.001	0.008	3.746
(+)	19 (20.2)	75 (79.8)
Douglas sinus fluid
(-)	17 (7.7)	203 (92.3)	0.003	0.016	3.580
(+)	11 (22.0)	39 (78.0)
Antibiotics
Second-generation cephems	14 (7.3)	178 (92.7)	0.009	0.260
Broad-spectrum	14 (17.9)	64 (82.1)

CRP: C-reactive protein; WBC: White blood cell.

Table 4 Probability of resistance to conservative treatment by number of risk factors, n (%)

Number of risk factors	Total number	Surgery
0 factor	92	2 (2.2)
1 factor
Body temperature ≥ 37.3 °C	55	4 (7.3)
Douglas sinus fluid	20	2 (10.0)
Appendicolith	38	3 (7.9)
2 factors
Douglas sinus fluid + body temperature ≥ 37.3 °C	9	1 (11.1)
Douglas sinus fluid + appendicolith	12	2 (16.7)
Appendicolith + body temperature ≥ 37.3 °C	35	8 (22.9)
3 factors	9	6 (66.7)