Jan C. Wille

Impact of postdischarge surveillance on surgical site infection rates for several surgical procedures: results from the nosocomial surveillance network in The Netherlands.

OBJECTIVE To compare the number of surgical site infections (SSIs) registered after hospital discharge with respect to various surgical procedures and to identify the procedures for which postdischarge surveillance (PDS) is most important. DESIGN Prospective SSI surveillance with voluntary PDS. Recommended methods for PDS in the Dutch national nosocomial surveillance network are addition of a special registration card to the outpatient medical record, on which the surgeon notes clinical symptoms and whether a patient developed an SSI according to the definitions; an alternative method is examination of the outpatient medical record. SETTING Hospitals participating in the Dutch national nosocomial surveillance network between 1996 and 2004. RESULTS We collected data on 131,798 surgical procedures performed in 64 of the 98 Dutch hospitals. PDS was performed according to one of the recommended methods for 31,134 operations (24%) and according to another active method for 32,589 operations (25%), and passive PDS was performed for 68,075 operations (52%). Relatively more SSIs were recorded after discharge for cases in which PDS was performed according to a recommended method (43%), compared with cases in which another active PDS method was used (30%) and cases in which passive PDS was used (25%). The highest rate of SSI after discharge was found for appendectomy (79% of operations), followed by knee prosthesis surgery (64%), mastectomy (61%), femoropopliteal or femorotibial bypass (53%), and abdominal hysterectomy (53%). CONCLUSIONS For certain surgical procedures, most SSIs develop after discharge. SSI rates will be underestimated if no PDS is performed. We believe we have found a feasible and sensitive method for PDS that, if patients routinely return to the hospital for a postdischarge follow-up visit, might be suitable for use internationally.

Prevalence of nosocomial infections in The Netherlands, 2007–2008: results of the first four national studies

The PREZIES national network for the surveillance of nosocomial infections (NI) in The Netherlands has organised a national prevalence study twice a year since 2007. This paper presents the results of the first four surveys. Of 95 hospitals in The Netherlands, 41 participated in 92 surveys and 26 937 patients were included. On the survey day 6.2% had an NI (prevalence of infections 7.2%). The prevalence of infections varied from 1.4% to 16.5% between hospitals. The prevalence of surgical site infections was 4.8%, pneumonia 1.1%, primary bloodstream infection 0.5% and symptomatic urinary tract infection 1.7%. On admission to hospital, 3.3% of patients had an NI. On the day of the survey, 30.9% of the patients were receiving antibiotics. The use of antibiotics as well as medical devices differed considerably between hospitals. Both the prevalence of NI in The Netherlands and the use of antibiotics and devices were comparable to other European countries.

Associations between surgical site infection risk and hospital operation volume and surgeon operation volume among hospitals in the Dutch nosocomial infection surveillance network.

OBJECTIVE To examine the association between hospital operation volume and surgeon operation volume and the risk of surgical site infection (SSI). DESIGN Prospective, multicenter cohort study based on surveillance data. METHODS Data were obtained from the Dutch surveillance network for nosocomial infections (Preventie Ziekenhuisinfecties door Surveillance [PREZIES]) on 9 different types of orthopedic surgery, general surgery, and gynecology procedures performed during 1996-2003. Multilevel logistic regression analysis was performed to assess the independent effect of hospital volume and surgeon volume on SSI risk. RESULTS Hospital volume was not significantly associated with SSI risk for any of the selected procedures. Low surgeon volume was associated with an increased risk for an infection for 7 of 9 types of procedures, although this effect was statistically significant only for knee arthroplasty. For 4 procedures, the odds of exceeding the 75th percentile for duration of surgery were greater when the surgeon volume was low than when the surgeon volume was moderate or high. CONCLUSIONS Patients operated on by surgeons with a low operation volume seem to have a higher risk of developing an SSI with some procedures, particularly knee arthroplasty. The higher SSI risk for surgeons with a low operation volume is possibly partly mediated by the longer duration of surgery, a well-known risk factor for development of SSI.

Improved risk adjustment for comparison of surgical site infection rates.

OBJECTIVE To develop prognostic models for improved risk adjustment in surgical site infection surveillance for 5 surgical procedures and to compare these models with the National Nosocomial Infection Surveillance system (NNIS) risk index. DESIGN In a multicenter cohort study, prospective assessment of surgical site infection and risk factors was performed from 1996 to 2000. In addition, risk factors abstracted from patient files, available in a national medical register, were used. The c-index was used to measure the ability of procedure-specific logistic regression models to predict surgical site infection and to compare these models with models based on the NNIS risk index. A c-index of 0.5 indicates no predictive power, and 1.0 indicates perfect predictive power. SETTING Sixty-two acute care hospitals in the Dutch national surveillance network for nosocomial infections. PARTICIPANTS Patients who underwent 1 of 5 procedures for which the predictive ability of the NNIS risk index was moderate: reconstruction of the aorta (n=875), femoropopliteal or femorotibial bypass (n=641), colectomy (n=1,142), primary total hip prosthesis (n=13,770), and cesarean section (n=2,962). RESULTS The predictive power of the new model versus the NNIS index was 0.75 versus 0.62 for reconstruction of the aorta (P<.01), 0.78 versus 0.58 for femoropopliteal or femorotibial bypass (P<.001), 0.69 versus 0.62 for colectomy (P<.001), 0.64 versus 0.56 for primary total hip prosthesis arthroplasty (P<.001), and 0.70 versus 0.54 for cesarean section (P<.001). CONCLUSION Data available from hospital information systems can be used to develop models that are better at predicting the risk of surgical site infection than the NNIS risk index. Additional data collection may be indicated for certain procedures--for example, total hip prosthesis arthroplasty.

Surveillance and epidemiology of surgical site infections after cardiothoracic surgery in The Netherlands, 2002-2007

OBJECTIVE Surgical site infections after cardiothoracic surgery substantially increase the risk for illness, mortality, and costs. Surveillance of surgical site infections might assist in the prevention of these infections. This study describes the Dutch surveillance methods and results of data collected between 2002 and 2007. METHODS Three cardiothoracic procedures were included: coronary artery bypass graft procedures, valve surgery, and a combination of coronary artery bypass graft procedures with concomitant valve surgery. The surgical site infections were divided into sternal and harvest-site infections. Postdischarge surveillance of surgical site infections was mandatory for sternal wounds and elective for harvest-site wounds, with a follow-up period of 42 postoperative days. Multivariate logistic regression was used for risk factor analysis of coronary artery bypass grafts, with adjustment for random variation among hospitals. RESULTS Eight of the 16 Dutch cardiothoracic centers participated and collected data on 4066 procedures and 183 surgical site infections, revealing a surgical site infection rate of 2.4% for sternal wounds and 3.2% for harvest sites. Sixty-one percent of all surgical site infections were recorded after discharge. For sternal surgical site infections after coronary artery bypass graft procedures, the significant risk factors were rethoracotomy, diabetes, preoperative length of stay, and obesity; for harvest-site infections, the most relevant risk factor was a long time on extracorporeal circulation. Adjusted surgical site infection rates regarding coronary artery bypass graft procedures varied between hospitals from 0.0% to 9.7%. CONCLUSIONS Large differences were found in surgical site infection rates between Dutch hospitals, which indicate room for improvement. The follow-up of patients after hospital discharge reduces underestimation of surgical site infection rates.

Hair removal policies in clean surgery: systematic review of randomized, controlled trials

OBJECTIVE To determine whether certain hair removal policies are better than others to prevent surgical-site infections in patients undergoing clean surgery. METHODS Publications were retrieved by a systematic search of Medline, the Cochrane Library, and EMBASE up to February 2005. Additionally, the reference lists of all identified trials were examined. All randomized trials, quasi-randomized trials, and systematic reviews or meta-analyses of randomized or quasi-randomized trials comparing hair removal policies in clean surgery were selected. Trials involving patients undergoing cranial neurosurgery were excluded. Two reviewers independently assessed trial quality and extracted data. Disagreements were resolved by discussion with a third reviewer. Data from the original publications were used to calculate the relative risk or risk difference of surgical-site infection. Data for similar outcomes were combined in the analysis, where appropriate, with the use of a random effects model. RESULTS Four trials were included in the review. No eligible systematic review or meta-analysis of randomized or quasi-randomized trials was found. The quality of the trials and how they were reported were generally unsatisfactory. Evidence regarding whether preoperative hair removal has any effect was inconclusive. When hair removal was considered necessary, evidence about the best time for removal was inconclusive. There was some evidence that hair removal by clipper is superior to removal by razor. CONCLUSIONS Because of insufficient evidence as a basis for recommendations, the practical consequences for ward management were essential when the Dutch Working Party on Infection Prevention formulated its recommendations for hair removal policies. Large randomized, controlled trials are needed to determine the optimal policy for preoperative hair removal.

Trends in the incidence of surgical site infection in the Netherlands.

OBJECTIVE To evaluate the time trend in the surgical site infection (SSI) rate in relation to the duration of surveillance in The Netherlands. SETTING Forty-two hospitals that participated in the the Dutch national nosocomial surveillance network, which is known as PREZIES (Preventie van Ziekenhuisinfecties door Surveillance), and that registered at least 1 of the following 5 frequently performed surgical procedures for at least 3 years during the period from 1996 through 2006: mastectomy, colectomy, replacement of the head of the femur, total hip arthroplasty, or knee arthroplasty. METHODS Analyses were performed for each surgical procedure. The surveillance time to operation was stratified in consecutive 1-year periods, with the first year as reference. Multivariate logistic regression analysis was performed using a random coefficient model to adjust for random variation among hospitals. All models were adjusted for method of postdischarge surveillance. RESULTS The number of procedures varied from 3,031 for colectomy to 31,407 for total hip arthroplasty, and the SSI rate varied from 1.6% for knee arthroplasty to 12.2% for colectomy. For total hip arthroplasty, the SSI rate decreased significantly by 6% per year of surveillance (odds ratio [OR], 0.94 [95% confidence interval {CI}, 0.90-0.98]), indicating a 60% decrease after 10 years. Nonsignificant but substantial decreasing trends in the rate of SSI were found for replacement of the head of the femur (OR, 0.94 [95% CI, 0.88-1.00]) and for colectomy (OR, 0.92 [95% CI, 0.83-1.02]). CONCLUSIONS Even though most decreasing trends in the SSI rate were not statistically significant, they were encouraging. To use limited resources as efficiently as possible, we would suggest switching the surveillance to another surgical procedure when the SSI rate for that particular procedure has decreased below the target rate.

Validation of surgical site infection surveillance in the Netherlands.

OBJECTIVES To describe how continuous validation of data on surgical site infection (SSI) is being performed in the Dutch National Nosocomial Infection Surveillance System (Preventie Ziekenhuisinfecties door Surveillance [PREZIES]), to assess the quality and accuracy of the PREZIES data, and to present the corresponding outcomes of the assessment. DESIGN Mandatory, 1-day on-site validation visit to participating hospitals every 3 years. The process of surveillance, including the quality of the method of data collection, is validated by means of a structured interview. The use of SSI criteria is validated by review of medical records, with the judgment of the validation team as the criterion standard. SETTING Hospitals participating in PREZIES. RESULTS During 1999-2004, the validation team visited 40 hospitals and reviewed 859 medical charts. There was no deviation between reports of SSI by infection control professionals and findings by the PREZIES validation team at 30 hospitals and 1 deviation in each of 10 hospitals; the positive predictive value was 0.97, and the negative predictive value was 0.99. The validation team often gave advice to the hospital, aimed at perfecting the process of surveillance. On 2 occasions, data were removed from the PREZIES database after the validation visit revealed deviations from the SSI surveillance protocol that could have resulted in nonrepresentative SSI rate data. CONCLUSIONS PREZIES is confident that the assembled Dutch SSI surveillance data are reliable and robust and are sufficiently accurate to be used as a reference for interhospital comparison. PREZIES will continue performing on-site validation visits, to improve the process of surveillance and ensure the reliability of the surveillance data.

Hospital-related determinants for surgical-site infection following hip arthroplasty.

OBJECTIVE To determine hospital-related risk factors for surgical-site infection (SSI) following hip arthroplasty. DESIGN Prospective, multicenter cohort study based on surveillance data and data collected through a structured telephone interview. With the use of multilevel logistic regression, the independent effect of hospital-related characteristics on SSI was assessed. SETTING Thirty-six acute care hospitals in the Dutch surveillance network for nosocomial infections (PREZIES), from 1996 to 2000. PATIENTS Thirteen thousand six hundred eighty patients who underwent total or partial hip arthroplasty. RESULTS A high annual volume of operations was associated with a reduced risk of SSI (risk-adjusted risk ratio [RR] per 50 extra operations, 0.85; 95% confidence interval [CI95], 0.74-0.97). With each extra full-time-equivalent infection control staff member per 250 beds available for prevention of SSI, the risk for SSI was decreased (RR, 0.48; CI95, 0.16-1.44), although the decrease was not statistically significant. Hospital size, teaching status, university affiliation, and number of surgeons and their years of experience showed no important association with the risk of SSI. CONCLUSION Undergoing surgery in a hospital with a low volume of operations increases a patients risk of SSI.

Effect of optimized antibiotic prophylaxis on the incidence of surgical site infection.

OBJECTIVE To compare the rate of surgical site infection (SSI) before and after an intervention period in which an optimized policy for antibiotic prophylaxis was implemented. To demonstrate that a more prudent, restrictive policy would not have a detrimental effect on patient outcomes. DESIGN Before-after trial with prospective SSI surveillance in the Dutch nosocomial surveillance network (Preventie Ziekenhuisinfecties door Surveillance [PREZIES]), using the criteria of the Centers for Disease Control, including postdischarge surveillance for up to 1 year. METHODS During a preintervention period and a postintervention period (both 6-13 months), 12 Dutch hospitals collected data on antimicrobial prophylaxis and SSI rates. The study was limited to commonly performed surgical procedures in 4 specialties: vascular, intestinal, gynecological and orthopedic surgery. Selected risk factors for analysis were sex, age, American Society of Anesthesiologists classification, wound contamination class, duration of surgery, length of hospital stay before surgery, and urgency of surgery (elective or acute). RESULTS A total of 3,621 procedures were included in the study, of which 1,668 were performed before the intervention and 1,953 after. The overall SSI rate decreased from 5.4% to 4.5% (P=.22). Among the procedures included in the study, the largest proportion (55%) were total hip arthroplasty, and the smallest proportion (2%) were replacement of the head of the femur. SSI rates varied from 0% for vaginal hysterectomy to 21.1% for femoropopliteal or femorotibial bypass surgery. Crude and adjusted odds ratios showed that there were no significant changes in procedure-specific SSI rates after the intervention (P>.1). CONCLUSIONS An optimized and restrictive antibiotic prophylaxis policy had no detrimental effect on the outcome of clean and clean contaminated surgery, as measured by SSI rate.