Skip to main content

Table 1 Characteristics of all included studies

From: Beyond the operating room: do hospital characteristics have an impact on surgical site infections after colorectal surgery? A systematic review

First author, year, country Description Study design and PICO Study results
Abbas 2019 [26]
Multiple countries
English
Large-scale international study to determine the time-trend of surgical site infection (SSI) incidence in SSI surveillance networks. Networks identified through systematic literature review were provided with standardized data template Cohort
Population
Colorectal surgery (no source)
Intervention
Surveillance over time
1) One-year increase in surveillance time
2) X years of surveillance
Comparison
1) Year One in surveillance time
2) X-1 years of surveillance
Outcome
SSI rate (no source)
STROBE Score
25 in 29
Study size: 320 123
10 networks included
8.5 (IQR 7–11) median years of surveillance
Relative Risk
Intervention 1)
1) 2 years 0.92 (0.89–0.96)
2) 3 years 0.90 (0.87–0.94)
3) 4 years 0.91 (0.87–0.95)
4) 5 years 0.86 (0.83–0.90)
5) 6 years 0.92 (0.87–0.96)
6) 7 years 0.84 (0.79–0.89)
7) 8 years 0.86 (0.80–0.92)
Intervention 2)
1) X = 3 - 0.98 (0.94–1.02)
2) X = 4 − 1.00 (0.96–1.05)
3) X = 5–0.95 (0.91–0.99)
4) X = 6–1.06 (1.01–1.12)
5) X = 7–0.92 (0.86–0.98)
6) X = 8–1.02 (0.04–1.11)
Angel García 2020 [17]
Spain
English
Study data from nine public hospitals in Murcia, Spain, from January 2006 to December 2015. The study developed two risk-adjustment models based on multiple logistic regression, without considering hospital bed size as a candidate variable Cohort
Population
Colorectal surgery (ICD-9)
Exposure
1) Bed size > 500
2) Bed size 250–500
Comparison
Bed size < 250
Outcome
SSI (ICD-9 codes)
STROBE score
17 in 24
Study size 6 325
423 SSIs (7.32%)
Odds ratio (OR) (overall SSI, univariate analysis)
1) 0.54 (0,41–0,72)
2) 0.95 (0.74–1.23)
Du 2019 [16]
China
English
Multicenter surveillance of radical resection of colon and rectal carcinoma in 26 tertiary hospitals in 14 cities, from January 2015 to June 2016
Surveillance made by infection control professionals until discharge, using a
real-time nosocomial infection surveillance system, and by telephone 30 days postoperatively
Cohort
Population
Radical resection of colon and rectal carcinomas (ICD-9)
Exposure
Beds < 2500
Comparison
Beds ≥ 2500
Outcome
SSI (CDC 1992)
STROBE score
11 in 30
Study size 5 729
3 406 radical resection of colon carcinoma
2 323 radical resection of rectal carcinoma
206 SSIs (3.60%)
87 SSIs after colon resection (2.55%)
• 32 superficial (0.94%)
• 19 deep (0.56%)
• 36 organ space (1.06%)
119 SSIs after rectal resection (5.12%)
• 53 superficial (2.28%)
• 26 deep (1.11%)
• 40 organ space (1.72%)
OR (Multivariable analysis for overall SSI)
0.644 (0.451–0.921) resection of colon carcinoma
0.513 (0.356–0.739) resection of rectal carcinoma
El Aziz 2020 [25]
United States
English
Six-year longitudinal study using the American College of Surgeons—National Surgical Quality Improvement Program (ACS-NSQIP) database, an American quality improvement program gathering abstract patient information through predesigned data extraction sheets manage by trained data abstractors from all participating institutions
SSIs assessed in-hospital before discharge and after discharge until post-operative day 30
ORs adjusted for age > 80 years old, gender, race, body mass index, diabetes mellitus, current smoker within one year, dyspnea, functional health status prior to surgery, history of severe chronic obstructive pulmonary disease, ascites, congestive heart failure in 30 days before surgery, hypertension requiring medication, dialysis, disseminated cancer, open wound infection, steroid use for chronic condition, > 10% loss bodyweight in the last six months, bleeding disorders, transfusion > 1 unit red blood cells 72 h before surgery, pre-operative albumin and hematocrit, diagnosis, extent of resection, operative approach, diversion, operation time, any surgical complication before discharge, any medical complication before discharge, days from operation to discharge
Cohort
Population
Elective surgery for colon or rectal cancer, using Current Procedural Terminology (CPT) codes
Exposure
1) Discharge to skilled facility
2) Discharge to rehabilitation center
3) Discharge to separate acute care
Comparison
Discharged home
Outcome
SSI (ACS-NSQIP 2016)
STROBE score
21 in 27
Study size 108 617
3476 total SSIs (3.2%)
  1396 superficial SSIs (1.3%)
  349 Deep SSIs (0.3%)
  1915 organ space SSIs (1.8%)
ORs (overall SSIs, adjusted)
1) 1.02 (0.87–1.20)
2) 1.03 (0.81–1.31)
3) 1.25 (0.74–2.09)
Furuya-Kanamori 2017 [20]
Australia
English
New South Wales Admitted Patient Data Collection contains data on all admitted patient services provided by public and private hospitals in the region
Subset population of adult patients who underwent colorectal surgery between January 2002 and December 2013
The annual volume of colorectal surgery in public hospitals was categorized into tertiles, per surgical procedure: low-volume hospitals performed < 45procedures/year, mid-volume performed 45–115 procedures/year and high-volume performed > 115 procedures/year
Outcome includes in-hospital infection only
Cohort
Population
Colorectal surgery (ICD-10, Australian Modification)
Exposure
1) Mid-Hospital Volume
2) High-Hospital Volume
Comparison
Low-Hospital Volume
Outcome
Surgical site infection (ICD-10)
STROBE score
20.5 in 28
Study size 58 096 cases from 59 hospitals
Incidence: 9.64% (9.40–9.88%)
OR (overall SSI, crude analysis)
1) 1.23 (1.08–1.40)
2) 1.50 (1.34–1.69)
When risk-adjusted SSI rates per 1000 admissions were examined, low-volume hospitals performed better for colorectal procedures (91.7 for low, 96.7 for mid and 96.7 for high-volume public hospitals)
Manilich 2013 [23]
United States
English
Single-center study, with exclusion of outpatient surgical cases. 30-day follow-up by letter or phone call
Surgeon volume determined by the number of procedures in each major category that a surgeon performed in 2 years—colorectal surgical procedure as the unit of analysis
Cohort
Population
Major abdominal or transanal colorectal surgery (no source)
Exposure
Surgeon volume < 20 procedures
Comparison
Surgeon volume ≥ 20 procedures
Outcome
SSI (ACS-NSQIP)
STROBE score
23 in 29
Study size 3 552 cases by 15 surgeons
300 incisional SSIs (8.4%)
OR (overall SSI, adjusted OR)
1.38 (1.06–1.79)
Mannien 2008 [28]
Netherlands
English
Data from 1996 to 2006 from the Dutch National Nosocomial Surveillance Network. Hospital participation is voluntary. Hospitals can annually decide which surgical procedures to include, and post-discharge surveillance is strongly recommended
OR adjusted for post-discharge surveillance, American Society of Anesthesiologists (ASA) classification, wound contamination class, duration of surgery, duration of preoperative hospitalization and emergency procedure
Cohort
Population
Colectomy (no source)
Intervention
Surveillance
1) 1-year increase in surveillance time to operation
Comparison
1-less year in surveillance time to operation
Outcome
SSI (CDC 1992)
STROBE score
18.5 in 27
Study size 3 031
370 SSIs (12.2%)
OR (overall SSI, adjusted)
1) 0.92 (0.83–1.02)
Merkow 2013 [19]
United States
English
Multicenter study using centers participating in the ACS-NSQIP, that collects comprehensive data from > 500 hospitals, including 51 National Cancer Institutes
Age, race, ASA class, functional status, preoperative albumin level, hypertension, chronic obstructive pulmonary disease, chemoradiation, disseminated cancer and case complexity were all significantly different at baseline. Adjustment for differences in patient demographics and risk factors, as well as surgical complexity
Cohort
Population
Colorectal cancer surgery (CPT)
Exposure
Oncological Hospital
1) National Cancer Institute
Comparison
Non-oncological hospital
Outcome
SSI (ACS NSQIP)
STROBE score
18.5 in 28
Study size 52,265 from 310 hospitals
Incidence
7.7% superficial SSIs
4.8% deep or organ/space SSIs
OR (adjusted)
Superficial: 1.35 (1.08–1.70)
Deep or organ/space: 1.17 (0.98–1.40)
Schröder 2018 [18]
Germany
English
Data from surgical site infection module of the German national nosocomial infection surveillance system, the component for surgical site infections, which is patient based and voluntary. SSI following laparoscopic colon resection from 145 hospitals (44 public, 65 non-profit and 36 private) and following open colon resection in 159 (45, 67 and 37, respectively) Cohort
Population
Colon procedures (national codes)
Exposure
Public ownership
Non-profit ownership
Bed size < 400
Comparison
Private ownership
Bed size < 400
Outcome
SSI
STROBE score
19 in 29
Study size 28,291
• 19 453 open colon procedures
• 8838 laparoscopic colon procedures
ORs (overall SSIs, multivariate analysis)
1.12 (0.86–1.47) for public ownership
0.85 (0.66–1.09) for non-profit ownership
0.81 (0.51–1.29) for bed size < 400
Serra-Aracil 2011 [15]
Spain
English
Multicenter study of 19 public hospitals in Catalonia, Spain, between June 2007 and March 2008
Colon operation defined as any resection above the peritoneal reflection. Rectal operation defined as any resection below the same point. Inclusion criteria were the application of all preventive measures and rectal cancer operations with oncologic resections. Outpatient visit after 30 days
Cohort
Population
Elective operations for colon or rectal cancer
Exposure
1) > 500 beds
2) 250–500 beds
Comparison
< 250 beds
Outcome
SSI (CDC 1992)
STROBE score
18 in 29
Study Size: 611
383 colon cancer operation
89 total SSIs (23.2%)
• 49 superficial SSIs (12.8%)
• 8 deep SSIs (2.1%)
• 32 organ space SSIs (8.4%)
228 rectal cancer operation
63 SSIs (27.6%)
• 31 superficial SSIs (13.6%)
• 13 deep SSIs (5.7%)
• 19 organ space SSIs (8.3%)
OR (univariate analysis)
Colon cancer operations
Overall SSI
1) 0.48 (0.25–0.95)
2) 0.41 (0.17–0.95)
Incisional SSI
1) 0.36 (0.18–0.76)
2) 0.26 (0.09–0.68)
Organ/space SSI
1) 1.25 (0.41–5.68)
2) 1.52 (0.39–7.80)
Rectal cancer operations
Overall SSI
1) 0.69 (0.30–1.67)
2) 0.68 (0.24–1.94)
Incisional SSI
1) 0.89 (0.35–2.63)
2) 0.90 (0.27–3.13)
Organ/space SSI
1) 0.51 (0.16-2.00)
2) 0.49 (0.08–2.54)
Spolverato 2019 [21]
Italy
English
Data from National Italian Hospital Discharge Dataset, from January 2002 to November 2014
Adult patients only
Hospital volume calculated as the average annual number of rectal cancer procedures performed at each hospital, during study period, divided into tertiles (respectively 1–12, 13–31, > 31 surgeries/year)
Main outcome is failure to rescue, defined as the mortality rate among patients with complications, which is why there is no adjusted analysis specifically for SSI; however, low-volume hospitals, in multivariable analysis, are associated with higher rate of failure to rescue and any complication, when compared with high volume hospitals
Cohort
Population
Major surgical procedure for primary rectal cancer (ICD-9)
Exposure
1) High-volume hospital
2) Intermediate-volume hospital
Comparison
Low-volume hospital
Outcome
SSI (ICD-9)
STROBE score
20.5 in 30
Study size 75 280
3.9% SSI incidence
OR (overall SSI, crude analysis)
1) 0.99 (0.90–1.08)
2) 0.95 (0.87–1.04)
Staszewicz 2014 [29]
Switzerland
English
Data collected from 1998 to 2010 from the Swissnoso consortium, a voluntary participation surveillance network of Swiss public hospitals
OR adjusted for age, sex, ASA Score ≥ 3, delay from admission to operation > 2 days, emergency, antibiotic prophylaxis, contamination class ≥ 3, multiple procedures, laparoscopy, duration > T, re-intervention for non-infectious complications
Cohort
Population
Colectomy (no source)
Intervention
Surveillance
1) time to operation
Outcome
SSI (CDC 1992)
STROBE score
18 in 28
Study size 7411
1349 SSIs (18.2%)
555 superficial SSIs (7.5%)
308 deep SSIs (4.2%)
486 organ/space SSIs (6.6%)
OR (overall SSI, adjusted)
1.05 (1.03–1.07)
Tserenpuntsag 2014 [11]
United States
English
Multicenter study of 174 New York State hospitals, with mandatory surveillance of SSIs following colon procedures through the NHSN, including post-discharge detection of SSI. Authors used 2009–2010 data of an audit of the surveillance program, performed by trained program staff certified in infection control
If a small bowel procedure, kidney transplant, liver transplant, or bile duct, liver pancreatic or rectal procedure was performed through the same incision, and it was not clear which procedure was associated with infection, the SSI was attributed to 1 of the above listed procedures
Case-control
Population
Colon procedures, using ICD-9 codes
Exposures
Teaching hospitals
Bed size > 500
Comparison
Nonteaching hospitals
Bed size ≤ 500
Outcome:
SSI (CDC 1992)
STROBE Score:
18.5 in 28
Study Size: 2 656 cases from 175 hospitals
698 SSIs identified
• 355 superficial incisional
• 343 deep incisional and organ space
ORs (overall SSI, bivariable analysis):
Teaching hospitals:
1.88 (1.55–2.95) for superficial
1.86 (1.45–2.39) for deep incisional and organ space
Bed size:
2.32 (1.82–2.95) for superficial incisional and 2.08 (1.54–2.80) for deep and organ space
Vicentini 2019 [27]
Italy
English
32 Piedmont hospitals (primary, secondary and tertiary) participating in the voluntary Italian surveillance system for SSIs, using data from January 2009 to December 2015
Surveillance must be performed at least 6 months/year or a minimum of 50 procedures must be monitored
Surveillance time is equivalent to the number of years of participation in a surveillance program
Cohort
Population
Colon surgery (ICD-9)
Intervention
Surveillance
1) Participating in surveillance program for over 5 years
2) 1-unit increase in the number of monitored procedures
3) 1-year increase in surveillance time
Comparison
1) No participation in surveillance network
Outcome
SSI (ECDC)
STROBE score
16 in 27
Study size 6 060
595 SSIs (9.83%), 172 post-discharge
370 incisional SSIs (6.13%)
96 deep SSIs (1.59%)
97 organ/space SSI (1.60%)
RR (overall SSI)
1) 0.64 (0.46–0.90)
2) 0.99 (0.98-1.00)
3) 0.93 (0.89–0.97)
Wang 2021 [22]
United States
English
Safety-net hospitals are mandated to treat patients regardless of their ability to pay, and consequently carry a high safety-net burden (SNB), defined as the proportion of patients who are either uninsured or Medicaid-insured. Hospitals were stratified into tertiles of low, medium and high SNB
Data from State Inpatient Databases (2009–2014)
Hospital volume stratified into quartiles by colectomy case volume
Adult patients only
Cohort
Population
Colectomy (ICD-9)
Exposure
1. High safety-net burden
2. Medium safety-net burden
3. Hospital volume—4th quartile
4. Hospital volume—3rd quartile
5. Hospital volume—2nd quartile
Comparison
1. Low safety-net burden (1–2)
2. Hospital volume—1st quartile (3–5)
Outcome
SSI (ICD-9)
STROBE score
21.5 in 30
Study size 459 568
29 117 SSIs (6.3%)
OR (overall SSI, crude analysis)
1. 1.35 (1.31–1.40)
2. 0.97 (0.94-1.00)
3. 0.51 (0.50–0.53)
4. 0.64 (0.62–0.66)
5. 0.70 (0.68–0.73)
Yi 2018 [24]
United States
English
Administrative databases used for colorectal surgical patients discharged in years 2013 and 2014, in a hybrid tertiary referral central with 8 campuses and 2247 beds. Over 80% of study patients were from campuses with high colorectal surgery volume
Volume of surgery determined by the actual number of patients operated on per surgeon. High volume surgeon with case volume of more than 34 cases in the last 2 years, medium volume with case volume between 14 and 34, and low volume with fewer than 14 cases
Cohort study
Population
Colorectal procedures (ICD-9)
Exposure
Medium-volume Surgeon
Low-volume Surgeon
Comparison
High-volume Surgeon
Outcome
SSI (no source provided)
STROBE Score
16,5 in 27
Study size 1 190 cases by 44 surgeons
ORs (overall SSI, adjusted)
0.23 (0.08–0.65) for medium-volume surgeons
0.39 (0.09–1.71) for low-volume surgeons
  1. ACS-NSQIP, American College of Surgeons-National Surgical Quality Improvement Program; ASA, American Society of Anesthesiologists; CDC, Centers for Disease Control and Prevention; CPT, Current Procedural Terminology; ECDC, European Centre for Disease Prevention and Control; ICD, International Statistical Classification of Diseases and Related Health Problems; IQR, interquartile range; NHSN, National Healthcare Safety Network; OR, odds ratio; SNB, safety-net burden; SSI, surgical site infection