Catherine C. Vick

Timing of Surgical Antibiotic Prophylaxis and the Risk of Surgical Site Infection

IMPORTANCE Timing of prophylactic antibiotic administration for surgical procedures is a nationally mandated and publicly reported quality metric sponsored by the Centers for Medicare and Medicaid Services Surgical Care Improvement Project. Numerous studies have failed to demonstrate that adherence to the Surgical Care Improvement Project prophylactic antibiotic timely administration measure is associated with decreased surgical site infection (SSI). OBJECTIVE; To determine whether prophylactic antibiotic timing is associated with SSI occurrence. DESIGN Retrospective cohort study using national Veterans Affairs patient-level data on prophylactic antibiotic timing for orthopedic, colorectal, vascular, and gynecologic procedures from 2005 through 2009. SETTING National Veterans Affairs Surgical Care Improvement Project data from 112 Veterans Affairs hospitals and matched Veterans Affairs Surgical Quality Improvement Program data. PATIENTS Patients undergoing hip or knee arthroplasty, colorectal surgical procedures, arterial vascular surgical procedures, and hysterectomy. INTERVENTION Timing of prophylactic antibiotic administration with respect to surgical incision time. MAIN OUTCOMES AND MEASURES Data for prophylactic antibiotic agent, prophylactic antibiotic timing with respect to surgical incision, and patient and procedure risk variables were assessed for their relationship with the occurrence of a composite superficial or deep incisional SSI within 30 days after the procedure. Nonlinear generalized additive models were used to examine the association between antibiotic timing and SSI. RESULTS Of the 32,459 operations, prophylactic antibiotics were administered at a median of 28 minutes (interquartile range, 17-39 minutes) prior to surgical incision, and 1497 cases (4.6%) developed an SSI. Compared with procedures with antibiotic administration within 60 minutes prior to incision, higher SSI rates were observed for timing more than 60 minutes prior to incision (unadjusted odds ratio [OR] = 1.34; 95% CI, 1.08-1.66) but not after incision (unadjusted OR = 1.26; 95% CI, 0.92-1.72). In unadjusted generalized additive models, we observed a significant nonlinear relationship between prophylactic antibiotic timing and SSI when considering timing as a continuous variable (P = .01). In generalized additive models adjusted for patient, procedure, and antibiotic variables, no significant association between prophylactic antibiotic timing and SSI was observed. Vancomycin hydrochloride was associated with higher SSI occurrence for orthopedic procedures (adjusted OR = 1.75; 95% CI, 1.16-2.65). Cefazolin sodium and quinolone in combination with an anaerobic agent were associated with fewer SSI events (cefazolin: adjusted OR = 0.49; 95% CI, 0.34-0.71; quinolone: adjusted OR = 0.55; 95% CI, 0.35-0.87) for colorectal procedures. CONCLUSIONS AND RELEVANCE The SSI risk varies by patient and procedure factors as well as antibiotic properties but is not significantly associated with prophylactic antibiotic timing. While adherence to the timely prophylactic antibiotic measure is not bad care, there is little evidence to suggest that it is better care.

Preoperative oral antibiotics reduce surgical site infection following elective colorectal resections.

BACKGROUND: Surgical site infection is a major cause of morbidity after colorectal resections. Despite evidence that preoperative oral antibiotics with mechanical bowel preparation reduce surgical site infection rates, the use of oral antibiotics is decreasing. Currently, the administration of oral antibiotics is controversial and considered ineffective without mechanical bowel preparation. OBJECTIVE: The aim of this study is to examine the use of mechanical bowel preparation and oral antibiotics and their relationship to surgical site infection rates in a colorectal Surgical Care Improvement Project cohort. DESIGN: This retrospective study used Veterans Affairs Surgical Quality Improvement Program preoperative risk and surgical site infection outcome data linked to Veterans Affairs Surgical Care Improvement Project and Pharmacy Benefits Management data. Univariate and multivariable models were performed to identify factors associated with surgical site infection within 30 days of surgery. SETTINGS: This study was conducted in 112 Veterans Affairs hospitals. PATIENTS: Included were 9940 patients who underwent elective colorectal resections from 2005 to 2009. MAIN OUTCOME MEASURE: The primary outcome measured was the incidence of surgical site infection. RESULTS: Patients receiving oral antibiotics had significantly lower surgical site infection rates. Those receiving no bowel preparation had similar surgical site infection rates to those who had mechanical bowel preparation only (18.1% vs 20%). Those receiving oral antibiotics alone had an surgical site infection rate of 8.3%, and those receiving oral antibiotics plus mechanical bowel preparation had a rate of 9.2%. In adjusted analysis, the use of oral antibiotics alone was associated with a 67% decrease in surgical site infection occurrence (OR=0.33, 95% CI 0.21–0.50). Oral antibiotics plus mechanical bowel preparation was associated with a 57% decrease in surgical site infection occurrence (OR=0.43, 95% CI 0.34–0.55). Timely administration of parenteral antibiotics (Surgical Care Improvement Project-1) had a modest protective effect, with no effect observed for other Surgical Care Improvement Project measures. Hospitals with higher rates of oral antibiotics use had lower surgical site infection rates (R2 = 0.274, p < 0.0001). LIMITATIONS: Determination of the use of oral antibiotics and mechanical bowel preparation is based on retrospective prescription data, and timing of actual administration cannot be determined. CONCLUSIONS: Use and type of preoperative bowel preparation varied widely. These results strongly suggest that preoperative oral antibiotics should be administered for elective colorectal resections. The role of oral antibiotics independent of mechanical bowel preparation should be examined in a prospective randomized trial.

Association of Timely Administration of Prophylactic Antibiotics for Major Surgical Procedures and Surgical Site Infection

BACKGROUND Prophylactic antibiotic (PA) administration 1 to 2 hours before surgical incision (SIP-1) is a publicly reported process measure proposed for performance pay. We performed an analysis of patients undergoing major surgical operations to determine if SIP-1 was associated with surgical site infection (SSI) rates in Department of Veterans Affairs (VA) hospitals. STUDY DESIGN Patients with External Peer Review Program Surgical Care Improvement Project (SCIP)-1 data with matched National Surgical Quality Improvement Program data were included in the study. Patient and facility level analyses comparing SCIP-1 and SSI were performed. We adjusted for clustering effects within hospitals, validated SSI risk score, and procedure type (percentage of colon, vascular, orthopaedic) using generalized estimating equations and linear modeling. RESULTS The study population included 9,195 elective procedures (5,981 orthopaedic, 1,966 colon, and 1,248 vascular) performed in 95 VA hospitals. Timely PA occurred in 86.4% of patients. Untimely PA was associated with a rate of SSI of 5.8%, compared with 4.6% in the timely group (odds ratio = 1.29, 95% CI 0.99, 1.67) in bivariable unadjusted analysis. Patient level risk-adjusted multivariable generalized estimating equation modeling found the SSI risk score was predictive of SSI (p < 0.001); SIP-1 was not associated with SSI. Hospital level multivariable generalized linear modeling found procedure mix (p < 0.0001), but not SIP-1 rate or facility volume, to be associated with facility SSI rate. The study had 80% power to detect a 1.75% difference for patient level SSI rates. CONCLUSIONS Timely PA did not markedly contribute to overall patient or facility SSI rates. These data are important for the ongoing discourse on how to measure and pay for quality of surgical care.

Long-Term Follow-Up of Technical Outcomes for Incisional Hernia Repair

BACKGROUND Incisional hernia repair (IHR) is plagued by high recurrence rates and lack of long-term outcomes data to guide repair technique. Mesh repair reduces recurrence rates but lacks standardization of technique. We investigated long-term outcomes of elective IHR, focusing on technical predictors of recurrence. STUDY DESIGN This retrospective multicenter cohort study included elective IHR performed at 16 Veterans Affairs hospitals between 1997 and 2002. Hernia characteristics and operative details were abstracted from operative notes, and chart review was performed to identify recurrence and complications. Kaplan-Meier curves and Cox regression models were used to evaluate the effects of hernia characteristics and operative technique on recurrence. RESULTS There were 1,346 elective IHRs, of which 22% were recurrent hernias. Repair technique was primary suture in 31%, open inlay or onlay mesh in 30%, open underlay in 30%, and laparoscopic in 9%. At median follow-up of 73.4 months, there were 383 recurrences (28.5%), 23 mesh removals (1.7%), and 7 enterocutaneous fistulas (ECF) (0.5%). On Cox regression modeling with adjustment for hernia and Veterans Affairs site characteristics, the effectiveness of mesh varied by position. Compared with suture repair, laparoscopic (hazard ratio = 0.49; 95% CI, 0.28-0.84) and open underlay mesh repair (hazard ratio = 0.72; 95% CI, 0.53-0.98) substantially reduced the recurrence risk, but onlay or inlay mesh repair did not. Mesh position did not affect mesh removal or ECF rates. CONCLUSIONS Underlay technique, either laparoscopic or open, for mesh implantation during elective IHR substantially reduces the risk of recurrence, without increasing the risk of serious mesh infection or ECF.

Elective surgical case cancellation in the Veterans Health Administration system: identifying areas for improvement

BACKGROUND This study evaluated elective surgical case cancellation (CC) rates, reasons for these cancellations, and identified areas for improvement within the Veterans Health Administration (VA) system. METHODS CC data for 2006 were collected from the scheduling software for 123 VA facilities. Surveys were distributed to 40 facilities (10 highest and 10 lowest CC rates for high- and low-volume facilities). CC reasons were standardized and piloted at 5 facilities. RESULTS Of 329,784 cases scheduled by 9 surgical specialties, 40,988 (12.4%) were cancelled. CC reasons (9,528) were placed into 6 broad categories: patient (35%), work-up/medical condition change (28%), facility (20%), surgeon (8%), anesthesia (1%), and miscellaneous (8%). Survey results show areas for improvement at the facility level and a standardized list of 28 CC reasons was comprehensive. CONCLUSIONS Interventions that decrease cancellations caused by patient factors, inadequate work-up, and facility factors are needed to reduce overall elective surgical case cancellations.

Fibroblast-derived MT1-MMP promotes tumor progression in vitro and in vivo

BackgroundIdentification of fibroblast derived factors in tumor progression has the potential to provide novel molecular targets for modulating tumor cell growth and metastasis. Multiple matrix metalloproteases (MMPs) are expressed by both mesenchymal and epithelial cells within head and neck squamous cell carcinomas (HNSCCs), but the relative importance of these enzymes and the cell source is the subject of controversy.MethodsThe invasive potential of HNSCC tumor cells were assessed in vitro atop type I collagen gels in coculture with wild-type (WT), MMP-2 null, MMP-9 null or MT1-MMP null fibroblasts. A floor of mouth mouse model of HNSCC was used to assess in vivo growth after co-injection of FaDu tumor cells with MMP null fibroblasts.ResultsHere we report changes in tumor phenotype when FaDu HNSCCs cells are cocultured with WT, MMP-2 null, MMP-9 null or MT1-MMP null fibroblasts in vitro and in vivo. WT, MMP-2 null and MMP-9 null fibroblasts, but not MT1-MMP null fibroblasts, spontaneously invaded into type I collagen gels. WT fibroblasts stimulated FaDu tumor cell invasion in coculture. This invasive phenotype was unaffected by combination with MMP-9 null fibroblasts, reduced with MMP-2 null fibroblasts (50%) and abrogated in MT1-MMP null fibroblasts. Co-injection of FaDu tumor cells with fibroblasts in an orthotopic oral cavity SCID mouse model demonstrated a reduction of tumor volume using MMP-9 and MMP-2 null fibroblasts (48% and 49%, respectively) compared to WT fibroblasts. Consistent with in vitro studies, MT1-MMP null fibroblasts when co-injected with FaDu cells resulted in a 90% reduction in tumor volume compared to FaDu cells injected with WT fibroblasts.ConclusionThese data suggest a role for fibroblast-derived MMP-2 and MT1-MMP in HNSCC tumor invasion in vitro and tumor growth in vivo.

Risk of complications from enterotomy or unplanned bowel resection during elective hernia repair

HYPOTHESIS Enterotomy or unplanned bowel resection (EBR) may occur during elective incisional hernia repair (IHR) and significantly affects surgical outcomes and hospital resource use. DESIGN Retrospective review of patients undergoing IHR between January 1998 and December 2002. SETTING Sixteen tertiary care Veterans Affairs medical centers. PATIENTS A total of 1124 elective incisional hernia repairs identified in the National Surgical Quality Improvement Program data set. INTERVENTION Elective IHR. MAIN OUTCOME MEASURES Thirty-day postoperative complication rate, return to operating room, length of stay, and operative time. RESULTS Of the 1124 elective procedures, 74.1% were primary IHR, 13.3% were recurrent prior mesh IHR, and 12.6% were recurrent prior suture. Overall, 7.3% had an EBR. The incidence of EBR was increased in patients with prior repair: 5.3% for primary repair, 5.7% for recurrent prior suture, and 20.3% for prior mesh repair (P < .001). The occurrence of EBR was associated with increased postoperative complications (31.7% vs 9.5%; P < .001), rate of reoperation within 30 days (14.6% vs 3.6%; P < .001), and development of enterocutaneous fistula (7.3% vs 0.7%; P < .001). After adjusting for procedure type, age, and American Society of Anesthesiologists class, EBR was associated with an increase in median operative time (1.7 to 3.5 hours; P < .001) and mean length of stay (4.0 to 6.0 days; P < .001). CONCLUSIONS Enterotomy or unplanned bowel resection is more likely to complicate recurrent IHR with prior mesh. The occurrence of EBR is associated with increased postoperative complications, return to the operating room, risk of enterocutaneous fistula, length of hospitalization, and operative time.

Predictors of mesh explantation after incisional hernia repair

BACKGROUND Prosthetic mesh used for incisional hernia repair (IHR) reduces hernia recurrence. Mesh infection results in significant morbidity and challenges for subsequent abdominal wall reconstruction. The risk factors that lead to mesh explantation are not well known. METHODS This is a multisite cohort study of patients undergoing IHR at 16 Veterans Affairs hospitals from 1998 to 2002. RESULTS Of the 1,071 mesh repairs, 55 (5.1%) had subsequent mesh explantation at a median of 7.3 months (interquartile range 1.4-22.2) after IHR with permanent mesh prosthesis. Infection was the most common reason for explantation (69%). No differences were observed by the type of repair. Adjusting for covariates, same-site concomitant surgery (hazard ratio [HR] = 6.3) and postoperative surgical site infection (HR = 6.5) were associated with mesh explantation. CONCLUSIONS Patients undergoing IHR with concomitant intra-abdominal procedures have a greater than 6-fold increased hazard of subsequent mesh explantation. Permanent prosthetic mesh should be used with caution in this setting.

Choice of Intravenous Antibiotic Prophylaxis for Colorectal Surgery Does Matter

BACKGROUND The Surgical Care Improvement Program endorses mandatory compliance with approved intravenous prophylactic antibiotics; however, oral antibiotics are optional. We hypothesized that surgical site infection (SSI) rates may vary depending on the choice of antibiotic prophylaxis. STUDY DESIGN A retrospective cohort study of elective colorectal procedures using Veterans Affairs Surgical Quality Improvement Program (VASQIP) and SSI outcomes data was linked to the Office of Informatics and Analytics (OIA) and Pharmacy Benefits Management (PBM) antibiotic data from 2005 to 2009. Surgical site infection rates by type of IV antibiotic agent alone (IV) or in combination with oral antibiotic (IV + OA) were determined. Generalized estimating equations were used to examine the association between type of antibiotic prophylaxis and SSI for the entire cohort and stratified by use of oral antibiotics. RESULTS After 5,750 elective colorectal procedures, 709 SSIs (12.3%) developed within 30 days. Oral antibiotic + IV (n = 2,426) had a lower SSI rate than IV alone (n = 3,324) (6.3% vs 16.7%, p < 0.0001). There was a significant difference in the SSI rate based on type of preoperative IV antibiotic given (p ≤ 0.0001). Generalized estimating equations adjusting for significant covariates of age, body mass index, procedure work relative value units, and operation duration demonstrated an independent protective effect of oral antibiotics (odds ratio [OR] 0.37, 95% CI 0.29 to 0.46), as well as increased rates of SSI associated with ampicillin/sulbactam (OR 2.21, 95% CI 1.37 to 3.56) and second generation cephalosporins (cefoxitin, OR 2.50, 95% CI 1.83 to 3.42; cefotetan, OR 2.70, 95% CI 1.72 to 4.22) when compared with first generation cephalosporin/metronidazole. CONCLUSIONS The choice of IV antibiotic was related to the SSI rate; however, oral antibiotics were associated with reduced SSI rate for every antibiotic class.

Surgical Site Infection After Arthroplasty: Comparative Effectiveness of Prophylactic Antibiotics: Do Surgical Care Improvement Project Guidelines Need to Be Updated?

BACKGROUND Prophylactic antibiotics decrease surgical site infection (SSI) rates, and their timing, choice, and discontinuation are measured and reported as part of the Surgical Care Improvement Project (SCIP). The aim of this study was to assess the comparative effectiveness of the SCIP-approved antibiotics for SSI prevention. METHODS This retrospective cohort study utilized national Veterans Affairs (VA) data on patients undergoing elective hip or knee arthroplasty from 2005 to 2009. Data on prophylactic antibiotics were merged with VA Surgical Quality Improvement Program data to identify patient and procedure-related risk factors for SSI. Patients were stratified by documented penicillin allergy. Chi-square and Wilcoxon rank-sum tests were used to compare SSI rates among patients receiving SCIP-approved prophylactic antibiotics. RESULTS A total of 18,830 elective primary arthroplasties (12,823 knee and 6007 hip) were included. Most patients received prophylactic cefazolin as the sole agent (81.9%), followed by vancomycin as the sole agent (8.0%), vancomycin plus cefazolin (5.6%), and clindamycin (4.5%). Documented penicillin allergy accounted for 54.1% of cases involving vancomycin administration compared with 94.6% of cases involving clindamycin. The overall thirty-day SSI rate was 1.4%, and the unadjusted rate was 2.3% with vancomycin only, 1.5% with vancomycin plus cefazolin, 1.3% with cefazolin only, and 1.1% with clindamycin. Unadjusted analysis of penicillin-allergic patients revealed an SSI rate of 2.0% with vancomycin only compared with 1.0% with clindamycin (p = 0.18). For patients without penicillin allergy, the SSI rate was 2.6% with vancomycin only compared with 1.6% with vancomycin plus cefazolin (p = 0.17) and 1.3% with cefazolin only (p < 0.01). CONCLUSIONS Current SCIP guidelines address antibiotic timing but not antibiotic dosage. (The generally accepted recommendation for vancomycin is 15 mg/kg.) Although vancomycin is a narrower-spectrum antibiotic than either cefazolin or clindamycin, our finding of higher SSI rates following prophylaxis with vancomycin only may suggest a failure to use an appropriate dosage rather than an inequality of antibiotic effectiveness. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.