Is It Valid to Compare Surgical Site Infections Rates Between Countries? Insights From a Study of English and Norwegian Surveillance Systems

Worldwide incidence of surgical site infections in general surgical patients: A systematic review and meta-analysis of 488,594 patients

BACKGROUND

Establishing worldwide incidence of general surgical site infections (SSI) is imperative to understand the extent of the condition to assist decision-makers to improve the planning and delivery of surgical care. This systematic review and meta-analysis aimed to estimate the worldwide incidence of SSI and identify associated factors in adult general surgical patients.

MATERIALS AND METHODS

A systematic review was undertaken using MEDLINE (Ovid), CINAHL (EBSCO), EMBASE (Elsevier) and the Cochrane Library to identify cross-sectional, cohort and observational studies reporting SSI incidence or prevalence. Studies of less than 50 participants were excluded. Data extraction and quality appraisal were undertaken independently by two review authors. The primary outcome was cumulative incidence of SSI occurring up to 30 days postoperative. The secondary outcome was the severity/depth of SSI. The I² statistic was used to explore heterogeneity. Random effects models were used in the presence of substantial heterogeneity. Subgroup, meta-regression sensitivity analyses were used to explore the sources of heterogeneity. Publication bias was assessed using Hunter's plots and Egger's regression test.

RESULTS

Of 2091 publications retrieved, 62 studies were included. Of these, 57 were included in the meta-analysis across six anatomical locations with 488,594 patients. The pooled 30-day cumulative incidence of SSI was 11% (95% CI 10%-13%). No prevalence data were identified. SSI rates varied across anatomical location, surgical approach, and priority (i.e., planned, emergency). Multivariable meta-regression showed SSI is significantly associated with duration of surgery (estimate 1.01, 95% CI 1.00-1.02, P = .014).

CONCLUSIONS

and Relevance: 11 out of 100 general surgical patients are likely to develop an infection 30 days after surgery. Given the imperative to reduce the burden of harm caused by SSI, high-quality studies are warranted to better understand the patient and related risk factors associated with SSI.

Surgical Site Infection after Digestive Surgery: Diagnosis and Treatment in a Context of Limited Resources

Background: Surgical site infections (SSIs) are responsible for substantial morbidity in patients who undergo digestive surgery. However, very little is known about the aspects of SSIs in sub-Saharan Africa. Methods: The purpose of this study was to assess the prevalence and identify the risk factors of SSI in patients who were treated in the Department of Digestive Surgery of Tenkodogo Hospital in Burkina Faso. We performed a prospective study from January 1, 2016 to December 31, 2016. All patients who underwent digestive tract surgery during this period were included and followed. Patients whose post-operative surgical sites were complicated by infection were identified. Surgical site infection was diagnosed according to the U.S. Centers for Disease Control and Prevention (CDC) definition. Bacteriologic sampling was performed in all included patients. Results: A total 964 patients underwent surgery during the study period and were included in the study. Seven hundred thirty-seven were females (76.4%), and 227 were males. The mean age of the included patients was 47.5 years (standard deviation [SD] = 9 years). One hundred fourteen patients presented with SSI, the incidence of which was 11.8%. The incidence of SSI was substantially higher in females than in males (63.2 vs. 36.8%, p < 0.05). The incidence was also higher in patients living below the poverty line (71.1 vs. 28.9%, p < 0.05). Clinically, the incidence of SSI was higher in emergency surgery than in scheduled surgery (84.2 vs. 15.8%, p < 0.05). Contaminated or dirty surgery was more risky than clean surgery (p < 0.05). With respect to bacteria, the most commonly isolated microbes were Escherichia coli (66.7%) and Staphylococcus aureus (15%). Treatment mainly consisted of appropriate antibiotic therapy and local care. Three deaths were recorded for a mortality rate of 2.6%. Conclusions: Surgical site infections are frequent in sub-Saharan environments. The risk factors seem to be clinical and social.

Performance of surgical site infection risk prediction models in colorectal surgery: external validity assessment from three European national surveillance networks

OBJECTIVE

To assess the validity of multivariable models for predicting risk of surgical site infection (SSI) after colorectal surgery based on routinely collected data in national surveillance networks.

DESIGN

Retrospective analysis performed on 3 validation cohorts.

PATIENTS

Colorectal surgery patients in Switzerland, France, and England, 2007-2017.

METHODS

We determined calibration and discrimination (ie, area under the curve, AUC) of the COLA (contamination class, obesity, laparoscopy, American Society of Anesthesiologists [ASA]) multivariable risk model and the National Healthcare Safety Network (NHSN) multivariable risk model in each cohort. A new score was constructed based on multivariable analysis of the Swiss cohort following colorectal surgery, then based on colon and rectal surgery separately.

RESULTS

We included 40,813 patients who had undergone elective or emergency colorectal surgery to validate the COLA score, 45,216 patients to validate the NHSN colon and rectal surgery risk models, and 46,320 patients in the construction of a new predictive model. The COLA score's predictive ability was poor, with AUC values of 0.64 (95% confidence interval [CI], 0.63-0.65), 0.62 (95% CI, 0.58-0.67), 0.60 (95% CI, 0.58-0.61) in the Swiss, French, and English cohorts, respectively. The NHSN colon-specific model (AUC, 0.61; 95% CI, 0.61-0.62) and the rectal surgery-specific model (AUC, 0.57; 95% CI, 0.53-0.61) showed limited predictive ability. The new predictive score showed poor predictive accuracy for colorectal surgery overall (AUC, 0.65; 95% CI, 0.64-0.66), for colon surgery (AUC, 0.65; 95% CI, 0.65-0.66), and for rectal surgery (AUC, 0.63; 95% CI, 0.60-0.66).

CONCLUSION

Models based on routinely collected data in SSI surveillance networks poorly predict individual risk of SSI following colorectal surgery. Further models that include other more predictive variables could be developed and validated.

Impact of participation in a surgical site infection surveillance network: results from a large international cohort study

BACKGROUND

Surveillance of surgical site infections (SSIs) is a core component of effective infection control practices, though its impact has not been quantified on a large scale.

AIM

To determine the time-trend of SSI rates in surveillance networks.

METHODS

SSI surveillance networks provided procedure-specific data on numbers of SSIs and operations, stratified by hospitals' year of participation in the surveillance, to capture length of participation as an exposure. Pooled and procedure-specific random-effects Poisson regression was performed to obtain yearly rate ratios (RRs) with 95% confidence intervals (CIs), and including surveillance network as random intercept.

FINDINGS

Of 36 invited networks, 17 networks from 15 high-income countries across Asia, Australia and Europe participated in the study. Aggregated data on 17 surgical procedures (cardiovascular, digestive, gynaecological-obstetrical, neurosurgical, and orthopaedic) were collected, resulting in data concerning 5,831,737 operations and 113,166 SSIs. There was a significant decrease in overall SSI rates over surveillance time, resulting in a 35% reduction at the ninth (final) included year of surveillance (RR: 0.65; 95% CI: 0.63-0.67). There were large variations across procedure-specific trends, but strong consistent decreases were observed for colorectal surgery, herniorrhaphy, caesarean section, hip prosthesis, and knee prosthesis.

CONCLUSION

In this large, international cohort study, pooled SSI rates were associated with a stable and sustainable decrease after joining an SSI surveillance network; a causal relationship is possible, although unproven. There was heterogeneity in procedure-specific trends. These findings support the pivotal role of surveillance in reducing infection rates and call for widespread implementation of hospital-based SSI surveillance in high-income countries.