Incidence and Risk Factors for Surgical Site Infection after Femoral Neck Fracture Surgery: An Observational Cohort Study of 2218 Patients

Table 2

Univariable analyses of risk and prognostic factors.

Variables	Total patients; ()	Non-SSI ()	SSI ()	value
Intraoperative blood loss (mL), (%)				0.198
≤200	1151 (51.9)	1143 (52.0)	8 (36.4)
201-400	716 (32.3)	708 (32.2)	8 (36.4)
401-600	231 (10.4)	229 (10.4)	2 (9.1)
601-800	63 (2.8)	62 (2.8)	1 (4.5)
801-1000	26 (1.2)	24 (1.1)	2 (9.1)
>1000	31 (1.4)	30 (1.4)	1 (4.5)
Age (years), mean (SD)				0.134
Hypertension, (%)	854 (38.5)	848 (38.6)	6 (27.3)	0.277
Diabetes, (%)	369 (16.6)	366 (16.7)	3 (13.6)	0.927
Cerebrovascular disease, (%)	500 (22.5)	495 (22.5)	5 (22.7)	1.000
Cardiovascular disease, (%)	459 (20.7)	453 (20.6)	6 (27.3)	0.616
Concurrent fractures, (%)	262 (11.8)	255 (11.6)	7 (31.8)	0.010
Tumour, (%)	33 (1.5)	32 (1.5)	1 (4.5)	0.760
Renal disease, (%)	64 (2.9)	64 (2.9)	0 (0)	0.863
Urinary tract infection, (%)	14 (0.6)	14 (0.6)	0 (0)	1.000
Residential location (urban), (%)	984 (44.36)	973 (44.3)	11 (50)	0.861
Injury mechanism (high energy), (%)	254 (11.45)	246 (11.2)	8 (36.4)	0.001
Reduction methods (open reduction), (%)	44 (2.0)	42 (1.9)	2 (9.1)	0.069
Preoperative waiting time (≥6 days), (%)	703 (31.7)	690 (31.4)	13 (59.1)	0.006
Type of anesthesia (general), (%)	1009 (45.5)	999 (45.5)	10 (45.5)	0.997
Side (left), (%)	1174 (53.46)	1166 (53.1)	8 (36.4)	0.118
Fixation type, (%)				1.000
Internal fixation	1846 (83.2)	1828 (83.2)	18 (81.8)
External fixation	372 (16.8)	368 (16.8)	4 (18.2)
Operative time (>2.0 hours), (%)	1088 (49.1)	1072 (48.8)	16 (72.7)	0.026
, (%)	803 (36.2)	794 (36.2)	9 (40.9)	0.644
Gender (male), (%)	853 (38.5)	837 (38.1)	16 (72.7)	0.001
BMI, (%)				0.072
<18.5	56 (2.5)	54 (2.5)	2 (9.1)
18.5-23.9	1300 (58.6)	1285 (58.5)	15 (68.2)
24-27.9	565 (25.5)	560 (25.5)	5 (22.7)
28-31.9	280 (12.6)	280 (12.8)	0 (0.0)
≥32	17 (0.8)	17 (0.8)	0 (0.0)
, (%)	1448 (65.3)	1432 (65.2)	16 (72.7)	0.461
, (%)	1017 (45.9)	1002 (45.6)	15 (68.2)	0.035
GLOB (references 20-40 g/L), (%)				0.459
<20	300 (13.5)	295 (13.4)	5 (22.7)	0.167
>40	10 (0.5)	10 (0.5)	0 (0.0)	0.905
A/G (references 1.2-2.4), (%)				0.242
<1.2	370 (16.7)	364 (16.6)	6 (27.3)
>2.4	30 (1.4)	29 (1.3)	1 (4.5)
ALT (references 9-50 U/L), (%)				0.738
<9	193 (8.7)	192 (8.7)	1 (4.5)	0.417
>50	171 (7.7)	169 (7.7)	2 (9.1)	0.515
AST (references 15-40 U/L), n (%)				0.058
<15	463 (20.9)	462 (21.0)	1 (4.5)	0.068
>40	214 (9.6)	210 (9.6)	4 (18.2)	0.156
TBIL (>26 μmol/L), (%)	186 (8.4)	182 (8.3)	4 (18.2)	0.201
DBIL (>6 μmol/L), (%)	688 (31.0)	676 (30.8)	12 (54.5)	0.017
IBIL (>14 μmol/L), (%)	230 (10.4)	227 (10.3)	3 (13.6)	0.878
ALP (references 45-125 U/L), (%)				0.099
<45	266 (12.0)	263 (12.0)	3 (13.6)
>125	71 (3.2)	68 (3.1)	3 (13.6)
GGT (references 10-60 U/L), (%)				0.527
<10	83 (3.7)	81 (3.7)	2 (9.1)
>60	210 (9.5)	208 (9.5)	2 (9.1)
CHE (references 5-12 U/L), (%)				0.020
<5	436 (19.7)	426 (19.4)	10 (45.5)	≤0.001
>12	21 (0.9)	21 (1.0)	0 (0.0)	0.818
TBA (references 1-10 μmol/L), (%)				0.064
<1	284 (12.8)	277 (12.6)	7 (31.8)
>10	164 (7.4)	163 (7.4)	1 (4.5)
HCRP (>8), (%)	1818 (82)	1802 (82.1)	16 (72.7)	0.393
CK (>), (%)	716 (32.3)	708 (32.2)	8 (36.4)	0.681
CKMB (>), (%)	163 (7.3)	160 (7.3)	3 (13.6)	0.468
LDH (>), (%)	638 (28.8)	629 (28.6)	9 (40.9)	0.206
HBDH (>), (%)	618 (27.9)	614 (28.0)	4 (18.2)	0.309
TC (>), (%)	296 (13.3)	294 (13.4)	2 (9.1)	0.784
TG (>), (%)	186 (8.4)	183 (8.3)	3 (13.6)	0.613
Sodium (references 137-147 mmol/L), (%)				0.131
<137	851 (38.4)	838 (38.2)	13 (59.1)
>147	8 (0.4)	8 (0.4)	0 (0.0)
K (references 3.5-5.3 mmol/L), (%)				0.736
<3.5	247 (11.1)	245 (11.2)	2 (9.1)	0.549
>5.3	25 (1.1)	25 (1.1)	0 (0.0)	0.778
CL (references 99-110 mmol/L), (%)				0.400
<99	295 (13.3)	291 (13.3)	4 (18.2)	0.334
>110	84 (3.8)	82 (3.7)	2 (9.1)	0.202
TCO2 (references 20–30 mmol/L), n (%)				0.263
<20	101 (4.6)	99 (4.5)	2 (9.1)	0.265
>30	95 (4.3)	95 (4.3)	0 (0.0)	0.380
GLU (>6.1), (%)	982 (44.3)	974 (44.4)	8 (36.4)	0.453
UREA (>8), (%)	322 (14.5)	319 (14.5)	3 (13.6)	1.000
CREA (references 57-97 mmol/L), (%)				0.242
<57	1003 (45.2)	994 (45.3)	9 (40.9)	0.426
>97	118 (5.3)	118 (5.4)	0 (0.0)	0.376
UA (references 208-428 mmol/L), (%)				0.446
<208	939 (42.3)	932 (42.4)	7 (31.8)	0.316
>428	98 (4.4)	96 (4.4)	2 (9.1)	0.254
WBC (references 3.5-9.5 10^9/L), (%)				0.825
<3.5	14 (0.6)	14 (0.6)	0 (0.0)	0.869
>9.5	773 (34.9)	766 (34.9)	7 (31.8)	0.764
NEU (references 1.8-6.3 10^9/L), (%)				0.516
<1.8	9 (0.4)	9 (0.4)	0 (0.0)	0.914
>6.3	1163 (52.4)	1154 (52.6)	9 (40.9)	0.277
LYM (references 1.1-3.2 10^9/L), (%)				0.326
<1.1	1037 (46.8)	1030 (46.9)	7 (31.8)	0.158
>3.2	15 (0.7)	15 (0.7)	0 (0.0)	0.861
MON (references 0.1-0.6 10^9/L), (%)				0.865
<0.1	0 (0.0)	0 (0.0)	0 (0.0)	—
>0.6	1271 (57.3)	1258 (57.3)	13 (59.1)	0.865
EOS (references 0.02-0.52 10^9/L), (%)				0.077
<0.02	686 (30.9)	684 (31.1)	2 (9.1)
>0.52	10 (0.5)	10 (0.5)	0 (0.0)
BAS (>0.06), (%)	167 (7.5)	163 (7.4)	4 (18.2)	0.134
RBC (>5.8), (%)	2 (0.1)	2 (0.10)	0 (0.00)	1.000
HGB (<110/120), (%)	843 (38)	833 (37.9)	10 (45.5)	0.470
HCT (references 40%-50%), (%)				0.530
<40	1781 (80.3)	1765 (80.4)	16 (72.7)	0.255
>50	437 (19.7)	431 (19.6)	6 (27.3)	0.255
MCV (references 82-100 fL), (%)				0.221
<82	67 (3.0)	66 (3.0)	1 (4.5)	0.492
>100	141 (6.4)	141 (6.4)	0 (0.0)	0.234
MCH (references 22-34 pg), (%)				0.247
<27	66 (3.0)	65 (3.0)	1 (4.5)	0.487
>34	130 (5.9)	130 (5.9)	0 (0.00)	0.263
MCHC (references 316-354 g/L), (%)				0.237
<316	45 (2.0)	45 (2.0)	0 (0.00)	0.636
>354	95 (4.3)	95 (4.3)	0 (0.00)	0.380
PLT (references 125-350 10^9/L), (%)				0.735
<125	165 (7.4)	164 (7.5)	1 (4.5)	0.504
>250	572 (25.8)	565 (25.7)	7 (31.8)	0.516
MPV (references 7.4-11.0 fL), (%)				0.265
<7.4	295 (13.3)	290 (13.2)	5 (22.7)	0.158
>11.0	66 (3.0)	66 (3.0)	0 (0.00)	0.513

ASA: American Society of Anesthesiologists grade; BMI: body mass index; TP: total protein; ALB: albumin; GLOB: globulin; A/G: albumin/globulin; ALT: alanine transaminase; AST: aspartate aminotransferase; TBIL: total bilirubin; DBIL: direct bilirubin; IBIL: indirect bilirubin; ALP: alkaline phosphatase; GGT: γ-glutamyl transpeptidase; CHE: cholinesterase; TBA: total bile acid; HCRP: hypersensitive C-reactive protein; CK: creatine kinase; CKMB: creatine kinase isoenzyme; LDH: lactic dehydrogenase; HBDH: hydroxybutyrate dehydrogenase; TC: total cholesterol; TG: triglyceride; GLU: glucose; UREA: serum urea; CREA: creatinine; UA: uric acid; WBC: white blood cell; NEU: neutrophile; LYM: lymphocyte; MON: mononuclear cell; EOS: eosinophilic granulocyte; BAS: basophilic granulocyte; RBC: red blood cell; HGB: hemoglobin; HCT: hematocrit; MCV: mean corpuscular volume; MCH: mean corpuscular hemoglobin; MCHC: mean corpuscular hemoglobin concentration; PLT: platelet; MPV: mean platelet volume. Significant variables.