Proposal for a new classification of anorectal abscesses based on clinical characteristics and postoperative recurrence

Table 1 A univariate analysis of risk factors for postoperative recurrence, n (%)

Variables	Total (n = 525)	Recurrence (n = 205) (39%)	Cured (n = 320) (61%)	χ2 value	P value
New classification
Fistula-prone abscess	142	115 (81.0)	27 (19.0)	143.842	< 0.001
Non-fistula-prone abscess	383	90 (23.5)	293 (76.5)
Gender
Male	464	180 (38.8)	284 (61.2)	0.109	0.742
Female	61	25 (41.0)	36 (59.0)
Age (years)
< 20	7	3 (42.9)	4 (57.1)
20-29	112	41 (36.6)	71 (63.4)
30-39	126	51 (40.5)	75 (59.5)	1.808	0.771
40-49	129	55 (42.6)	74 (57.4)
50-59	120	45 (37.5)	75 (62.5)
> 60	31	10 (32.3)	21 (67.7)
Body mass index (kg/m2)
< 28	436	168 (38.5)	268 (61.5)	0.278	0.592
≥ 28	89	37 (41.6)	52 (58.4)
Time from symptom onset to surgery (days)
< 7	404	117 (29.0)	287 (71.0)	74.940	< 0.001
≥ 7	121	88 (72.7)	33 (27.3)
Smoking status
Smoker	121	46 (38.0)	75 (62.0)	0.070	0.791
Non smoker	404	159 (39.4)	245 (60.6)
Drinking habit
Yes	89	39 (43.8)	50 (56.2)	1.026	0.311
No	436	166 (38.1)	270 (61.9)
Spicy food habit
Yes	149	55 (36.9)	94 (63.1)	0.398	0.528
No	376	150 (39.9)	226 (60.1)
Diabetes mellitus
Yes	58	15 (25.9)	43 (74.1)	4.763	0.029
No	467	190 (40.7)	277 (59.3)
Fever
Yes	122	51 (41.8)	71 (58.2)	0.507	0.476
No	403	154 (38.2)	249 (61.8)
Preoperative antibiotic use
Yes	194	99 (51.0)	95 (49.0)	18.565	< 0.001
No	331	106 (32.0)	225 (68.0)
Constipation
Yes	42	16 (38.1)	26 (61.9)	0.017	0.895
No	483	189 (39.1)	294 (60.9)
Chronic diarrhea
Yes	98	61 (62.2)	37 (37.8)	27.242	< 0.001
No	427	144 (33.7)	283 (66.3)
Insomnia
Yes	84	35 (41.7)	49 (58.3)	0.288	0.591
No	441	170 (38.5)	271 (61.5)
Anesthesia method of perianal abscess
Local	181	74 (40.9)	107 (59.1)	8.305	0.004
Spinal	141	36 (25.5)	105 (74.5)
Abscess site
Anterior	14	4 (28.6)	10 (71.4)	0.537	0.911
Posterior	261	95 (36.4)	166 (63.6)
Left	92	32 (34.8)	60 (65.2)
Right	117	44 (37.6)	73 (62.4)
Anatomic classification
Perianal	322	110 (34.2)	212 (65.8)	43.458	< 0.001
Intersphincteric	94	24 (25.5)	70 (74.5)
Ischiorectal	68	41 (60.3)	27 (39.7)
Horseshoe	38	28 (73.7)	10 (26.3)
Supralevator	3	2 (66.7)	1 (33.3)
Pus volume (mL)
< 5	349	131 (37.5)	218 (62.5)	1.001	0.317
≥ 5	176	74 (42.0)	102 (58.0)
Pus culture
With results	230	99 (43.0)	131 (57.0)	17.214	0.002
Escherichia coli	154	76 (49.4)	78 (50.6)
Klebsiella pneumoniae	37	14 (37.8)	23 (62.2)
Staphylococcus aureus	19	1 (5.3)	18 (94.7)
Others	20	8 (40.0)	12 (60.0)
No growth	295	106 (35.9)	189 (64.1)

Table 2 Variable assignment table of risk factors

Variables	Assignment
Postoperative prognosis	1: Recurrence, 0: Cured
New classification	1: Fistula-prone abscess, 0: Non-fistula-prone abscess
Time from symptom onset to surgery (days)	1: ≥ 7, 0: < 7
Diabetes mellitus	1: Yes, 0 : No
Preoperative antibiotic use	1: Yes, 0: No
Chronic diarrhea	1: Yes, 0: No
Anesthesia method of perianal abscess	1: Local, 0: Spinal
Anatomic classification	1: Perianal, 2: Intersphincteric, 3: Ischiorectal, 4: Horseshoe, 5: Supralevator
Pus culture	1: Escherichia coli, 2: Klebsiella pneumoniae, 3: Staphylococcus aureus, 4: Others, 0: No results

Table 3 A multivariate logistic regression analysis of risk factors for postoperative recurrence

Variables	B value	SE	Wald	P value	Odds ratio	95%CI
New classification	2.035	0.325	39.271	0.000	7.651	4.049-14.458
Time from symptom onset to surgery (days)	0.760	0.343	4.890	0.027	2.137	1.090-4.190
Chronic diarrhea	0.920	0.369	6.203	0.013	2.508	1.216-5.173
Anesthesia method of perianal abscess	0.836	0.288	8.436	0.004	2.308	1.313-4.059

Table 4 A univariate analysis of risk factors for postoperative recurrence in non-fistula-prone abscess subgroup, n (%)

Variables	Total (n = 383)	Recurrence (n = 90) (23.5%)	Cured (n = 293) (76.5%)	χ2	P value
Gender
Male	346	86 (24.9)	260 (75.1)	3.668	0.055
Female	37	4 (10.8)	33 (89.2)
Age (years)
< 20	5	1 (20.0)	4 (80.0)
20-29	88	22 (25.0)	66 (75.0)
30-39	95	24 (25.3)	71 (74.7)	2.580	0.764
40-49	88	22 (25.0)	66 (75.0)
50-59	87	19 (21.8)	68 (78.2)
> 60	20	2 (10.0)	18 (90.0)
Body mass index (kg/m2)
< 28	312	66 (21.2)	246 (78.8)	5.148	0.023
≥ 28	71	24 (33.8)	47 (66.2)
Time from symptom onset to surgery(days)
< 7	342	66 (19.3)	276 (80.7)	31.356	< 0.001
≥ 7	41	24 (58.5)	17 (41.5)
Smoking status
Smoker	93	24 (25.8)	69 (74.2)	0.364	0.546
Non smoker	290	66 (22.8)	224 (77.2)
Drinking habit
Yes	64	20 (31.3)	44 (68.7)	2.568	0.109
No	319	70 (21.9)	249 (78.1)
Spicy food habit
Yes	116	31 (26.7)	85 (73.3)	0.963	0.326
No	267	59 (22.1)	208 (77.9)
Diabetes mellitus
Yes	46	8 (17.4)	38 (82.6)	1.085	0.298
No	337	82 (24.3)	255 (75.7)
Fever
Yes	78	15 (19.2)	63 (80.8)	0.992	0.319
No	305	75 (24.6)	230 (75.4)
Preoperative antibiotic use
Yes	119	24 (20.2)	95 (79.8)	1.065	0.302
No	264	66 (25.0)	198 (75.0)
Constipation
Yes	31	8 (25.8)	23 (74.2)	0.100	0.752
No	352	82 (23.3)	270 (76.7)
Chronic diarrhea
Yes	58	27 (46.6)	31 (53.4)	20.206	< 0.001
No	325	63 (19.4)	262 (80.6)
Insomnia
Yes	59	15 (25.4)	44 (74.6)	0.144	0.705
No	324	75 (23.1)	249 (76.9)
Anesthesia method of perianal abscess
Local	132	36 (27.3)	96 (72.7)	7.191	0.007
Spinal	107	14 (13.1)	93 (86.9)
Abscess site
Anterior	12	2 (16.7)	10 (83.3)	2.062	0.560
Posterior	189	38 (20.1)	151 (79.9)
Left	71	15 (21.1)	56 (78.9)
Right	92	25 (27.2)	67 (72.8)
Anatomic classification
Perianal	239	50 (20.9)	189 (79.1)	40.211	< 0.001
Intersphincteric	73	5 (6.8)	68 (93.2)
Ischiorectal	52	25 (48.1)	27 (51.9)
Horseshoe	18	10 (55.6)	8 (44.4)
Supralevator	1	0 (0.0)	1 (100.0)
Pus volume (mL)
< 5	253	52 (20.6)	201 (79.4)	3.597	0.058
≥ 5	130	38 (29.2)	92 (70.8)
Pus culture
With results	158	36 (22.8)	122 (77.2)	3.760	0.452
Escherichia coli	99	26 (26.3)	73 (73.7)
Klebsiella pneumoniae	26	5 (19.2)	21 (80.8)
Staphylococcus aureus	17	1 (5.9)	16 (94.1)
Others	16	4 (25.0)	12 (75.0)
No growth	225	54 (24.0)	171 (76.0)

Table 5 Variable assignment table of risk factors in non-fistula-prone abscess subgroup

Variables	Assignment
Postoperative prognosis	1: Recurrence, 0: Cured
Body mass index	1: ≥ 28, 0: < 28
Time from symptom onset to surgery(days)	1: ≥ 7, 0: < 7
Pus volume	1: ≥ 5, 0: < 5
Chronic diarrhea	1: Yes, 0: No
Anesthesia method of perianal abscess	1: Local, 0: Spinal
Anatomic classification	1: Perianal, 2: Intersphincteric, 3: Ischiorectal, 4: Horseshoe, 5: Supralevator

Table 6 A multivariate logistic regression analysis of risk factors for postoperative recurrence in non-fistula-prone abscess subgroup

Variables	B value	SE	Wald	P value	Odds ratio	95%CI
Body mass index	1.077	0.455	5.593	0.018	2.935	1.203-7.165
Time from symptom onset to surgery (days)	1.788	0.548	10.659	0.001	5.978	2.043-17.489
Chronic diarrhea	1.229	0.460	7.144	0.008	3.417	1.388-8.412
Anesthesia method of perianal abscess	1.206	0.387	9.721	0.002	3.341	1.565-7.133