Incidence of surgical site infection surveillance in hysterectomies and related risk factors: a prospective cohort study.

Healthcare-associated infections (HAIs) represent the most common adverse event among hospitalized patients [ 1 – 3 ]. According to the latest research, over 2.5 million HAI episodes occur every year in Europe [ 4 ]. Surgical site infections (SSIs) are the most frequent HAI and are associated with significant morbidity, prolonged hospital stays, and increased healthcare costs [ 5 ]. Reducing these infections may improve both patient outcomes and hospital reimbursements [ 6 ], since SSIs occur in as many as 5% of patients following inpatient surgical procedures and account for up to 17% of all hospital-acquired infections [ 7 ]. Among major surgical procedures performed by gynecologists [ 8 ], hysterectomy ranks highest, with an estimated SSI incidence of around 2% [ 9 ]. Nonmalignant conditions, such as leiomyoma, abnormal bleeding, and endometriosis, account for most cases [ 10 ]. While abdominal hysterectomy (AH) continues to be the most common approach, vaginal hysterectomy (VH) has been associated with fewer complications, a shorter hospital stay, faster recovery, and lower overall costs [ 11 ]. Moreover, laparoscopic hysterectomy has become more feasible in recent years and is frequently performed [ 12 ]. Preventing SSIs post-hysterectomy is a main focus for quality improvement, and surveillance programs are essential tools for preventing their incidence and reducing their adverse effects, thereby reducing patients’ risk of infection [ 13 , 14 ]. As widely reported in the literature, SSIs can be reduced by as much as 55% by the implementation of an effective surveillance strategy [ 15 ]. There is an SSI surveillance program implemented at our hospital, which is used to monitor most surgical procedures, including hysterectomies. The aim of this study was: first, to describe the hospital’s SSI surveillance program; and second, to assess SSI incidence in hysterectomies, its evolution, and the related risk factors for SSI.

The study covered a total of 1,154 women who underwent AH (47.7%) or VH (52.3%). Patients’ overall mean age was 54.7 years (SD=13.2). The mean intervention rate for hysterectomies across the eleven years of follow-up was 105 interventions (SD= 7.1). The most frequent preoperative comorbidities were obesity (10.7%) and DM (8.4%). The most frequent clinical diagnoses were uterine leiomyomas (42%), uterine prolapses (22,5%) and other uterine neoplasms (15%). Table 2 shows the study-population characteristics. Patient characteristics (n=1,154) Standard Deviation, American Society of Anesthesiologists, National Healthcare Safety Network. Overall SSI incidence at the end of follow-up was 2.5% (n=29), 1.9% in abdominal hysterectomies and 3.4% in vaginal hysterectomies (p>0.05). The SSI incidence rate was 0.8 infections per 10,000 patient days; it decreased progressively during the follow-up, and Figure 1 shows the SSI incidence trend over the study period. Trend in incidence (%) of surgical site infection The analysis of infections among infected patients revealed that 48.0% of patients had deep incisional SSIs, 41.0% had superficial SSIs, and 11.0% of patients developed organ-space infection. Analyses by reference to the NHSN risk index showed a continuous increase in SSI incidence, with the rise in the index being 1.0% among patients with an index of 0, 3.0% among patients with an index of 1, 3.4% among patients with an index of 2, and 6.1% among patients with an index of 3 (p=0.03). Laparoscopic procedures accounted for 28.1% of the total amount of hysterectomies and had a shorter duration than hysterectomies carried out by open surgery (p0.05). The mean duration of surgery was 106 minutes (SD=52.7), with the 75 th percentile (P75) for surgical duration being 130 minutes. When duration of surgery was compared between the SSI and non-SSI groups, 24.1% (n=7) of patients in the SSI group had a duration of surgery higher than the P75, as compared with 23.5% (n=264) in the non-SSI group (p>0.05). The mean hospital stay was 4.5 days (SD=4.6), with a mean length of stay among patients with SSI of 9.3 days (SD=13.8) and 4.3 days (SD=4.1) patients without SSI (p>0.05). Regardless of whether or not the patient had SSI, hospital stay also increased with a rise in the NHSN risk index. Patients with an index of 0 had a mean stay of 3.3 days (SD= 1.9), those with an index of 1 had a mean stay of 4.2 days (SD=3.8), those with an index of 2 had a mean stay of 7.1 days (SD=7.7) and those with an index of 3 had a mean stay as long as 10.0 days (SD=9.6) (p<0.05). Microorganisms most frequently isolated were Escherichia coli (41.0%), Enterococcus faecalis (19.0%), Serratia marcescens (14.0), Proteus mirabilis (7%), Staphyloccocus aureus (7%), and Morganella morganii (7%). Four patients had more than one microorganism isolated from the surgical wound swabs. The univariate analysis showed the risk factors associated with SSI to be cancer (p<0.05), and ASA index ≥2(p<0.05). The risk of SSI was not associated with the rest of the patient-dependent factors (obesity, DM, malnutrition, immunodeficiency, etc.) or with surgery-dependent factors ( Table 3 ). Univariate analysis The adjusted logistic regression analysis showed the following risk factors to be independently associated with SSI incidence: diabetes mellitus (OR: 2.9, 95% CI: 1.1-8.0, p=0.04), cancer (OR: 3.7, 95% CI: 1.4-9.6, p=0.007),and type of hysterectomy (OR: 2.1; 95% CI: 0.95-4.31 p=0.7) at the limit of significance. The risk of SSI was not associated with the rest of patient-dependent factors (obesity, malnutrition, immunodeficiency, etc.) or with surgery-dependent factors ( Table 4 ). Multivariate analysis

Surgical site infection is a hysterectomy complication that leads to increased costs, morbidity, and mortality [ 20 ]. Achieving low SSI rates serves as a good measure for evaluating the surgical practice and the quality of the healthcare provided. In this study, we evaluated the SSI incidence in hysterectomies in a teaching hospital. The hospital has a high-quality inpatient and post-discharge surveillance system that covers all patients undergoing hysterectomy. It showed a continuously decreasing trend in SSI rates during the eleven-year follow-up period. Our study showed an overall SSI rate of 2.5% within the study period from 2013 to 2023. This percentage is consistent with the existing literature, which reports SSI incidence as ranging from 2.1% to 8.2% [ 21 , 22 ]. SSIs are known to affect body tissues, cavities, and organs manipulated during surgery, and they typically occur within 30 days of a surgical procedure. They are categorized by CDC-NHSN as superficial incisional, deep incisional, or organ/space infections [ 23 ]. The microorganisms commonly isolated from SSIs were E. coli, E. faecalis, S. marcescens , and S. aureus , in accordance with other previously published studies [ 24 , 25 ]. Laparoscopic surgeries had a shorter duration in our study and were not associated with a lower SSI incidence, either in univariate or multivariate analysis, although previous studies for patients undergoing hysterectomies have found laparoscopic surgeries to have significantly lower SSI risks than open abdominal approaches [ 26 ]. Although laparoscopy is generally the preferred approach, the traditional abdominal hysterectomy has been more frequently used in our patients. Interestingly, we found a higher percentage of SSI in patients with VH (3.4% in VH versus 1.9% in AH), as reported by Pickett et al. [ 27 ] and other authors, although most authors showed higher incidence in AH [ 28 , 29 ]. Conversely, laparoscopic surgery is known to have many advantages, such as shorter operation time, reduced blood loss during surgery, and minimal incision size. It is important to know that the surgical approach for hysterectomy depends on many factors, including the surgeon’s and/or patient’s choice, the surgeon’s experience and skill, indications for operation, and patient characteristics [ 30 , 31 ]. All the benefits and hazards of the selected approach should be discussed with the patient before a final decision is reached. It is noteworthy that laparoscopic and robotic hysterectomies constitute valuable alternatives for abdominal hysterectomy, especially in obese women [ 32 ]. The risk factors for SSIs include reproductive age, high body mass index (BMI), malnutrition, low socioeconomic status, preoperative anemia, and comorbid diseases such as diabetes mellitus and hypertension [ 33 ]. Accordingly, we found an association between malignant neoplasm and SSI, which remained significant in the multivariate analysis. As far as diabetes mellitus is concerned, we did not find any statistically significant association in the univariate analysis, although it became significant in the multivariate analysis. This may be explained by the fact that multivariate analysis adjusts for the effect of each single variable while controlling for the others, thereby revealing relationships that were previously masked by confounding effects. It is known that modifiable risk factors for SSIs are present during the surgical procedure, and prophylactic antibiotic use is therefore important; accordingly, antibiotic prophylaxis is administered preoperatively in hysterectomy patients in accordance with the recommendations of the American College of Obstetricians and Gynecologists (ACOG). Since many other predictors for SSIs are modifiable, these types of infections can be prevented. Many publications have shown that surgical methods, operating room environment, and preoperative skin preparation affect the risk of SSI [ 34 ]. In line with this, we did not find any relationship either between adequacy of antibiotic prophylaxis or preoperative preparation and incidence of surgical site infection. Based on the CDC guidelines [ 35 ], the following best practices have been defined: a) hair at the incision site should be clipped only if necessary; b) antibiotics should be administered prophylactically less than 30 minutes before the surgical procedure begins, and repeated if blood loss reaches 1.5 liters or if the duration of the operation extends beyond 3 hours; c) skin should be prepared with chlorhexidine; d) the surgical team should wash their hands and forearms; e) comorbidities, such as diabetes, should be controlled appropriately; f) the wound should be sutured if the subcutaneous tissue layer is greater than 2 cm in depth; and g) BMI should be appropriate. Furthermore, a diet with appropriate caloric intake is important for optimal wound healing [ 36 – 38 ]. However, no single intervention has been identified as the most effective method for reducing SSI rates, and all of them should be considered. We are aware that not all potential risk factors implicated in SSI, such as nasal decolonization, rheumatoid arthritis, coagulopathy, wound dehiscence, and others, were assessed in our study. This should be considered a limitation of this study. However, our study also has strengths, as it is based on prospective data collection and the use of an internationally accepted definition of SSIs, as well as a defined follow-up, according to the guidelines [ 19 ] enables a reliable comparability of our results. There was a low number of events (SSI) that could have made the stability of the multivariate model debatable, although it showed a high accuracy. In conclusion, hospital-based infection surveillance systems providing indicators of improvement and infection control practices based on characterizing risk factors seem to be critical for reducing infection rates. In this prospective study, we identified cancer and diabetes mellitus as independent risk factors for SSI in hysterectomies. These risk factors are susceptible to change, showing the necessity to follow strict compliance with patient preparation protocols and wound decontamination, reduction of surgical time, and identification of patients at risk who require comprehensive monitoring and epidemiological surveillance programs.

Study design and population. We conducted a prospective cohort study on patients undergoing VH or AH at the Alcorcón Foundation University Hospital ( Hospital Universitario Fundación Alcorcón/UHFA ) from January 1, 2013 through December 31, 2023, to ascertain the incidence of SSI. The aim of this study was to describe the hospital’s SSI surveillance program and SSI incidence of hysterectomies, its evolution, and the associated risk factors for SSI. The Hospital Ethics & Research Committee approved the study under document dossier no. 9/14, and it was carried out according to the Declaration of Helsinki and national and institutional standards. A sample size was estimated on the basis of a 95% confidence level (CI), an expected SSI incidence of 3% [ 9 ], a precision of 1.5%, and losses to follow-up of 1%. Accordingly, a study population of 1002 subjects (501 for each type of hysterectomy) was considered necessary to ensure an appropriate sample. Hysterectomies were chosen and included consecutively according to surgical programming across the study period. The International Classification of Diseases-9-Clinical Modification (ICD-9-CM) hysterectomies surgical procedures included are shown in Table 1 . Hysterectomies ICD-9-CM a procedure codes International Classification of Diseases-9-Clinical Modification. Definitions. A case of surgical site infection was defined as any woman aged at least 18 years who was diagnosed with SSI within 30 days post-hysterectomy and was identified through the hospital’s active surveillance system for nosocomial infections. We defined SSI as superficial, deep, or organ space infections according to the Centers for Disease Control and Prevention (CDC) criteria [ 16 ]. Patients with suspected or confirmed infection on the date of surgery were excluded. The SSI surveillance system includes at least one surgical procedure from all surgical specialties and holds regular meetings at which yearly reports of SSI incidence and events are discussed. Data collection and ethics. All data were collected by applying the SSI surveillance protocol in line with the NHSN (National Healthcare Safety Network) surveillance procedure and using the software developed by INCLIMECC [ 17 ]. Briefly, all patients referred to hysterectomy surgery were actively monitored from the time of admission to discharge, including any in-hospital readmissions and outpatient examinations, at both the hospital and primary health-care level, within a follow-up period of 30 days after the operative procedure [ 18 ]. Detailed patient characteristics were collected, including: sex; age; comorbidity [kidney failure, coma, diabetes mellitus (DM), obesity (BMI >30 kg/m 2 ), malnutrition (BMI <18.5 kg/m 2 ), neoplasm, chronic obstructive pulmonary disease (COPD), immunosuppression, cirrhosis, injection drug abuse, neutropenia]; the American Society of Anesthesiologists (ASA) score; clinical diagnosis according to ICD-9-CM; pre-operative in-hospital stay; wound class (clean, clean-contaminated, contaminated, and dirty); administration and appropriateness of antibiotic prophylaxis (choice, time of initiation, application method, dosage, and duration) according to the antibiotic guidelines issued by the hospital infection prevention committee (cefazolin 2g. iv. 30 min prior to induction of anesthesia and 24 h postoperatively; vancomycin 1g. iv. 30-60 min prior to induction of anesthesia in case of allergy); preoperative preparation adequacy (antiseptic showering, antiseptic skin preparation, and antiseptic mouth rinses); hair removal; use of drains; blood transfusion; duration of operative procedure; and identified microorganisms. The sample was categorized according to the NHSN risk index, estimated by the sum of three major risk factors: ASA score (1 point if >2); wound class (1 point if contaminated or dirty); and duration of surgery (1 point if higher than the 75 th percentile), with values ranging from 0 to 3. Outcome measures. The primary endpoint was SSI incidence according to CDC/NHSN criteria, namely: (i) superficial incisional SSI; (ii) deep incisional SSI; and (iii) organ/space SSI. SSI rates and their 95% confidence intervals (95% CI) were calculated. Secondary endpoints examined post-surgery in-hospital stay and the incidence trend of SSI over the study period. Statistical analysis. Patients’ demographic and clinical characteristics were described. Categorical variables were analyzed using Pearson’s chi-square test or Fisher’s exact test. The Student t-test or one-way ANOVA, as appropriate, was used to compare continuous variables. The nonparametric Mann-Whitney U test or the Kruskal-Wallis test, as appropriate, was used for non-normally distributed data, and the Shapiro-Wilk test was used to assess the normality of the distribution. The association between risk factors and SSI incidence was assessed by reference to the odds ratio (OR). We also performed both univariate and multivariate analyses to study independently associated risk factors for SSI. An adjusted multivariate logistic regression model was built by backward stepwise selection; this procedure allows for a large number of associated risk factors to be screened quickly and efficiently [ 19 ]. The cutoff points for adding and removing variables were 0.2 and 0.05, respectively. Statistical analyses were performed using SPSS v.27, with hypothesis testing based on a two-tailed test of significance (p<0.05).