Head and neck free flap surgical site infections in the era of the Surgical Care Improvement Project

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1 ORIGINAL ARTICLE Head and neck free flap surgical site infections in the era of the Surgical Care Improvement Project Bharat B. Yarlagadda, MD, 1 Daniel G. Deschler, MD, 1 Debbie L. Rich, RN, 2 Derrick T. Lin, MD, 1 Kevin S. Emerick, MD, 1 James W.Rocco, MD, PhD, 1 Marlene L. Durand, MD 3,4 * 1 Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 2 Department of Nursing, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 3 Infectious Disease Service, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 4 Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts. Accepted 6 January 2015 Published online 6 August 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI /hed ABSTRACT: Background. Compliance with Surgical Care Improvement Project (SCIP) parameters regarding antibiotic prophylaxis may affect surgical site infection rates. The purpose of this study was for us to report SCIP compliance, surgical site infection rates, and risk factors in a large series of head and neck free flap surgeries. Methods. A retrospective review of 480 free flap cases was performed. infections occurring within 30 days postoperatively were noted. Results. infection occurred in 13.3% of cases. Prophylaxis was given in 99.8% of cases; ampicillin-sulbactam (83%) and clindamycin (9%) were most common. Prophylaxis was on-time in 92.3% of cases. There were no significant associations between surgical site infection and tumor stage, American Society of Anesthesiologists (ASA) classification, tumor subsite, or flap type. Prior radiation was a risk factor for surgical site infection in patients treated for malignancy. Conclusion. A surgical site infection rate of 13.3% was noted. In this cohort, with a compliance rate with prophylactic antibiotic measures, prior radiation was found to be a risk factor only in patients with cancer. VC 2015 Wiley Periodicals, Inc. Head Neck 38: E392 E398, 2016 KEY WORDS: microvascular reconstruction, free flap, surgical site infection, head and neck cancer, antibiotic prophylaxis INTRODUCTION After the performance of microvascular free tissue transfer for reconstruction of postablative head and neck defects, the development of a surgical site infection can cause considerable morbidity. In this setting, surgical site infection can result in increased hospital length of stay, worsened functional and cosmetic results, and potentially loss of the flap. 1 The need for prophylactic antibiotics for clean-contaminated surgery was established 30 years ago, but the optimal regimen is not well defined. 2 The value of other measures to reduce surgical site infections, such as decolonizing patients who are Staphylococcus aureus carriers or the use of topical oral antiseptics or antibiotics either before or after free flap surgery, is also not known. The reported rates of surgical site infection in head and neck free flap surgery range from 8.1% to 41%. 3 5 The risk of surgical site infection after head and neck reconstruction is postulated to be higher than other anatomic *Corresponding author: M. L. Durand, Infectious Disease Service, Massachusetts Eye and Ear Infirmary, and Department of Medicine, Massachusetts General Hospital, 243 Charles Street, Boston, MA, mdurand@mgh.harvard.edu This work was presented at the proffered papers sessions of the American Head and Neck Society Annual Meeting and International Federation of Head and Neck Oncologic Societies Fifth World Congress, July 28, 2014, New York City, New York. sites because of the creation of communication between the aerodigestive tract and neck, contamination with saliva and respiratory secretions, and postoperative tissue dead space. 3 Various other patient-related factors have been identified in the literature, including immunosuppression and frailty, ischemia of reconstructive tissue, and duration and extent of surgery. 3,6 In 2003, a group of national organizations, including the Centers for Medicare and Medicaid Services (CMS), introduced the Surgical Care Improvement Project (SCIP) in a multiorganizational effort to improve surgical outcomes, including the reduction of the incidence of surgical site infection in acute-care hospitals. The 3 main infection-related SCIP objectives include: (1) start prophylactic antibiotics within 1 hour before surgical incision (within 2 hours for vancomycin or fluoroquinolones); (2) use appropriate prophylactic antibiotics (ie, consistent with published guidelines for a given type of surgery); and (3) stop prophylactic antibiotics within 24 hours after the end of surgery (within 48 hours for cardiac surgery). 7 Compliance with these measures by individual U.S. hospitals for 6 types of surgeries (colon, knee or hip replacement, abdominal or vaginal hysterectomy, cardiac) is reported to the CMS and published on the CMS website Hospital Compare. The implementation and effects of these measures have been widely studied for these 6 types of surgeries, and measures 1 and 2 have been found to be effective in surgical site infection reduction. 8 The application of infection-related E392 HEAD & NECK DOI /HED APRIL 2016

2 SURGICAL SITE INFECTIONS IN FREE FLAP RECONSTRUCTION SCIP measures to clean-contaminated head and neck surgery has not been widely reported. The purpose of this study was to describe the surgical site infection rate and determine risk factors in a cohort of patients undergoing head and neck surgery and free flap microvascular reconstruction at a single institution during a period of uniform implementation of SCIP measures. We also sought to determine predictors of surgical site infection development and assess the appropriateness of the particular SCIP measures utilized. TABLE 1. Demographics of patients undergoing resection and microvascular free flap reconstruction. Variables infection (n 5 64) No surgical site infection (n 5 416) p value Age, y (mean 6 SD) < ASA class I II III IV Tumor/lesion site Oral cavity Oropharynx 6 37 Hypopharynx 7 25 Larynx 5 44 Sinus/maxilla 7 36 Cutaneous/temporal 5 51 Prior surgery Neck/skin surgery No neck/skin surgery Aerodigestive surgery No aerodigestive surgery Prior radiation Radiation No radiation Abbreviation: ASA, American Society of Anesthesiologists. The p values to determine significance of association was performed using chi-square for categorical variables and Student s t test for continuous variables. PATIENTS AND METHODS The medical records of all patients who underwent surgery involving free flap reconstruction in the head and neck between April 1, 2009, and June 30, 2013, at a single specialty hospital (Massachusetts Eye and Ear Infirmary) were retrospectively reviewed. The study was approved by the institutional review board. Eligible patients underwent microvascular free tissue transfer for the reconstruction of defects after ablative head and neck surgery. This included patients undergoing primary and salvage surgery for cancer, laryngectomy for dysfunctional larynges, and secondary reconstruction of postoperative or postradiation defects. One patient had the surgical procedure at an adjacent hospital (same surgical team) and was transferred on the same day to Massachusetts Eye and Ear Infirmary for the remainder of care. The following data were recorded: demographics, surgical duration, tumor stage, location of tumor and defect, nature of surgical resection, nature of reconstruction, incidence of prior surgery or radiation, use of hardware, and perioperative antibiotic regimen. Mandible-sparing oral resections and oral glossectomy were considered in 1 category of resection. Mandibulectomy included marginal and segmental resections. Total glossectomy was considered an oropharyngeal procedure. Designation as laryngectomy/pharyngectomy indicated removal of the larynx with partial or total pharyngectomy. Combination procedures involved more than one of the other resection types. A procedure was considered as clean-contaminated if there was violation of the upper aerodigestive tract. The patient was considered to have had prior surgery regardless of the elapsed timeframe since the previous procedure. Prior neck surgery was considered performance of a clean procedure involving the neck or integument only. Tracheostomy alone was not considered to constitute prior neck surgery. Prior aerodigestive surgery was considered when a prior procedure was performed that opened the mucosa of the oral cavity or pharynx. A surgical site infection was determined by Centers for Disease Control and Prevention (CDC) criteria 9 as occurring within 30 days postoperatively and including one of the following: (1) purulent drainage from the incision; (2) an incision that spontaneously dehisced or was opened by the surgeon because of infection; (3) diagnosis of abscess or other evidence of infection involving a deep incision detected on physical examination, during invasive procedure, or by histopathologic examination or imaging test; or (4) diagnosis by the surgeon of a surgical site infection. infections that were accompanied by the development of an orocutaneous fistula were counted as surgical site infections. A case that developed an orocutaneous fistula within 30 days postoperatively without any other signs or symptoms of infection, as defined by CDC criteria above, was included in the nonsurgical site infection group; there were 7 such cases. Prophylactic intravenous antibiotics were to start within 1 hour before incision and were to be re-dosed intraoperatively as needed, based on surgical duration. The start of surgery was considered to be the time of the first incision, including tracheostomy in those cases that had that procedure first. The surgical field, including the face, neck, chest, and flap donor site, was prepped with povidone-iodine solution at the time of surgery. Data were recorded and analyzed using Excel (Microsoft, Redmond, WA). Descriptive statistics were calculated for the study population. Fisher s exact test or chisquare analysis was used to correlate individual patient and surgical factors with the development of surgical site infection. The Student t test was used for continuous variables. Two-tailed tests were used exclusively. RESULTS Patient and surgical characteristics For the duration of the 4 year and 3 month study period, there were 480 free flap surgical procedures in 461 patients. Nineteen patients had 2 free flap procedures separated by an average of 13 months; these cases were counted separately. The mean age was 63.5 years (range years). Descriptive features are listed in Table 1. Overall, 421 patients (87.7%) underwent reconstruction for cancer defects, 30 cases (6.3%) for defects for benign processes and nonmalignant defects, and 29 HEAD & NECK DOI /HED APRIL 2016 E393

3 YARLAGADDA ET AL. TABLE 2. Indications for surgery and operative details of patients undergoing resection and microvascular free flap reconstruction. Variables infection (n 5 64) No surgical site infection (n 5 416) p value FIGURE 1. Relative frequency of perioperative antibiotic choice used in microvascular reconstruction cases. In 2% of cases, vancomycin was used as the perioperative regimen alone or with other antibiotics (5 of 9 patients). Antibiotics within Other include piperacillin-tazobactam, linezolid, meropenem, metronidazole, or some combination. One patient did not receive perioperative antibiotics. Antibiotics were started within 1 hour before incision in 95.6% of 471 cases in which this data was available. cases (6%) for reconstruction after resection for osteoradionecrosis (ORN). The average surgical duration was 422 minutes or 7 hours (range hours), and in 16 cases (3.3%), the duration of surgery was greater than 10 hours. A total of 58.3% of cases were American Society of Anesthesiologists (ASA) 3 or higher, 45.4% had received prior radiation therapy. Hardware was implanted in 19.2% of patients. Reconstructive donor sites included radial forearm free flap (RFFF; 73.8%), fibula free flap (13.1%), anterolateral thigh (ALT; 11.3%), and other sites, such as scapula or latissimus dorsi (1.9%). Compliance with the Surgical Care Improvement Project Antibiotics were given as surgical prophylaxis in 99.8% of 478 cases; 2 other cases were already receiving antibiotics for treatment of infection at the time of surgery. The choice of antibiotics was considered to be appropriate in all these cases, in compliance with SCIP 2. The antibiotic regimens used are described in Figure 1, with ampicillinsulbactam and clindamycin the most frequent choices. Four hundred seventy cases could be evaluated for compliance with the SCIP measure to start prophylactic antibiotics 0 to 60 minutes before incision (0 120 minutes if vancomycin or a quinolone were used). In 36 cases (7.7%), antibiotic start times were noncompliant with this. However, the amount of time outside the 0 to 60 minute window was <5 minutes in 19% and <15 minutes in 50% of the 36 cases. The surgical site infection rate in noncompliant cases (6 of 36) was not significantly different than the rate in the compliant cases (58 of 434; p >.05). The termination of perioperative prophylactic antibiotics was analyzed for 109 patients during the last 13 months of the study (June 1, 2012 to June 30, 2013). Antibiotics were stopped within 48 hours in 51 patients (46.8%), including 21 patients in whom antibiotics were stopped within 24 hours (19.3%). In the remaining 58 patients, the prophylactic antibiotic was continued beyond 48 hours in some cases and changed to other antibiotics for various reasons, including surgeon preference and treatment of nonsurgical site infections. Indication for surgery Cancer Benign tumor/defect 2 28 ORN 2 27 Extent of resection Oral cavity Oropharyngeal 9 30 Mandibulectomy Maxilla/skull base 8 38 Lateral skull base/ 4 47 cutaneous Laryngectomy/ pharyngectomy Combination 3 31 Type of flap RFFF FFF ALT Other 1 8 Wound classification Clean Clean-contaminated Hardware Hardware implanted No hardware Operative duration, min, mean 6 SD Abbreviations: ORN, osteoradionecrosis; RFFF, radial forearm free flap; FFF, fibula free flap; ALT, anterolateral thigh. The p values to determine significance of association were performed using chi-square for categorical variables and Student s t test for continuous variables. infection and risk factors Of 480 patients, 64 (13.3%) developed a head and neck site surgical site infection, with average onset 12.3 days postoperatively (range days). There was no statistically significant association between the development of head and neck surgical site infection and the following variables: prior radiation therapy; stage IV cancer versus lower stages; ASA classification 3 or 4 versus lower; tumor subsite; type of resection; type of flap reconstruction; the presence of hardware; and prior surgery either in the neck or aerodigestive tract (Tables 1 and 2). There was no significant difference in duration of surgery in patients who did and did not develop a surgical site infection. The average age of those who developed surgical site infection was approximately 4 years younger than those who did not (mean of 59.8 years of age vs 64 years; p <.01). There was no difference in the surgical site infection rate in patients age 65 years or older (24 of 225 patients; 10.6%) versus patients younger than 65 years (p >.05). Twenty-two of the 64 patients (34.4%) with surgical site infection developed late-onset surgical site infections (days postoperatively), but there was no significant difference in any of the patient or operative characteristics noted above when comparing this group with the E394 HEAD & NECK DOI /HED APRIL 2016

4 SURGICAL SITE INFECTIONS IN FREE FLAP RECONSTRUCTION TABLE 3. Characteristics and association with development of surgical site infection for patients undergoing resection and free flap reconstruction for malignancy. Variables infection (n 5 60) No surgical site infection (n 5 361) p value Tumor/lesion site Oral cavity Oropharynx 6 35 Hypopharynx 7 22 Larynx 5 36 Sinus/maxilla 7 26 Cutaneous/temporal 4 49 Stage I III IV ASA class I II III IV Prior radiation Radiation No radiation Abbreviation: ASA, American Society of Anesthesiologists. Patients undergoing surgery for benign lesions and for osteoradionecrosis without active malignancy are excluded for this subgroup analysis. There is a statistically significant association of preoperative radiation with development of surgical site infection in this group. early onset (days 1 14 postoperatively) surgical site infection group (p >.05; chi-square for categorical variables; Student s t test for continuous variables). We have previously described the time course and microbiology of surgical site infections in a cohort that included the 64 surgical site infections described in this study. 10 Forty-four patients (9.2%) underwent clean surgery, without violation of the mucosa of the aerodigestive tract. This included reconstructions for cutaneous defects for benign and malignant indications. The remainder of the patients underwent clean-contaminated procedures. The rate of surgical site infection in clean procedures was 6.8%, but there was no significant difference in the rate of surgical site infection development between those who underwent clean versus clean-contaminated procedures (p >.05). Subgroup analysis was performed to account for the presence of patients with ORN and benign disease. Within the group of 29 patients undergoing resection and reconstruction for ORN, the incidence of surgical site infection was 6.9%. In addition, another 30 patients underwent reconstruction for benign disease, including benign tumors, postoperative mandible fracture, soft tissue radionecrosis, laryngeal dysfunction, and traumatic defect, with a 6.7% surgical site infection rate in this group as well. There were no statistically significant associations between the studied independent variables and surgical site infections in these subgroups. When only the group who had surgery for cancer is considered (421 cases), the surgical site infection rate was 14.3% (60 cases; Table 3). Forty percent of these 421 patients had received prior radiation therapy, and this nearly doubled the rate of surgical site infection (19.6% vs 10.6%; p 5.015). Other risk factors for this group (ASA class, tumor location, and tumor staging) are shown in Table 3, but were not found to be statistically significant. Fistulae Salivary fistulae (orocutaneous or pharyngocutaneous) developed within 30 days postoperatively in 13 patients, but 6 were in association with surgical site infections so they were included in the surgical site infection group of 64 patients noted above. Eight of 13 total fistula cases were in the laryngectomy/pharyngectomy resection category (3 surgical site infection-related, and 5 uninfected fistulae), therefore, 9.5% of all 84 laryngectomy/pharyngectomy cases were complicated by fistulae. Seven patients (1.5%) developed fistulae but had no evidence of infection, so these cases were not considered to be surgical site infections. The onset of these fistulae occurred before discharge in 4 patients (postoperative days 5, 9, and before day 24 in 2 patients in whom exact onset date was unavailable), and after discharge in 3 patients (postoperative days 15, 16, and 18). The fistula was characterized as peristomal in 5, submental in 1, and neck in 1. Surgery was clean-contaminated and performed for cancer in all 7 patients, classified as ASA 2 or 3 (3 and 4 patients, respectively), and used RFFF (6 patients) or ALT (1 patient) for reconstruction. Four of the 7 patients had prior radiation therapy. The average age (65 years) and operating room time (420 minutes) were similar to the other nonsurgical site infection cases. Including versus excluding these 7 uninfected fistulae cases in the surgical site infection group does not significantly change the overall surgical site infection rate (14.8% vs 13.3%; p 5.6). Inclusion of these 7 patients in univariate analysis did not change the significance of any associations between the development of surgical site infection and the patient or operative variables previously described. Donor site infections A total of 22 surgical site infections were noted at the donor site, comprising 4.6% of all donor sites. This included 14 forearms, 6 thighs, and 2 fibula sites. There were no skin graft harvest site surgical site infections noted. A mean 15 day interval was noted (range days) before diagnosis of donor site surgical site infection was made. We have previously described the time of onset and microbiology of these donor surgical site infections. 10 No statistically significant associations were noted between the development of donor site surgical infection and the flap harvest site or applicable as previously described independent variables, including ASA, age, and surgical duration. DISCUSSION Although microvascular free tissue transfer is a reliable and effective method of reconstruction of major head and neck defects, complications, such as surgical site infection, can result in considerable morbidity and poor outcomes. The current study demonstrates a surgical site infection rate of 13.3%, which compares favorably with the literature (Table 4). 3,11 18 It should be noted that comparison between studies is difficult because many studies HEAD & NECK DOI /HED APRIL 2016 E395

5 YARLAGADDA ET AL. TABLE 4. Literature review of surgical site infection and risk factors in head and neck free flap reconstruction. XRT as surgical site infection risk Surgical time Follow-up, d infection risk factors Prior XRT infection definition infection rate Cleancontaminated Author, ref Flaps Cohort Karakida Cancer 100% 40.6% CDC ASA, surgical duration NR NR Kamizono Cancer 100% 19% CDC Malnutrition, ASA, XRT, bone flap 17.3% Univariate only NR NR NR NR Flap type, duration of hospital stay, need for flap revision M ucke Cancer NR (40.4%) Purulence discharge Suh All defects 92% 2.8% NR NR NR NR NR 30 Jones All defects NR 10% NR NR 42% NR 672 NR Bourget All defects NR 28% Frank Dehiscence, partial flap failure 100% NR NR 120 purulence Yang Cancer 100% 28.3% CDC NR 16% No risk NR Hospital d/c Dassonville All defects 96.4% 10% NR NR 31% NR 480 NR Benatar All defects NR 17% NR XRT 32% Yes NR Hospital d/c Present study 479 All defects 91% 13.3% CDC None 45.30% No, except cancer subgroup Abbreviations: XRT, external radiation therapy; CDC, Center for Disease Control and Prevention, in reference to the definition of surgical site infection 9 ; ASA, American Society of Anesthesiology classification; NR, not reported; Hospital d/c, hospital discharge. In the Cohort column, designation of All defects denotes inclusion of reconstruction for benign tumors, trauma, and posttreatment defects with no active malignancy. Surgical time is listed in minutes; the duration given by Dassonville et al 17 is the median; all others list mean duration. For M ucke et al, 12 surgical site infection rate was not reported separately but included in delayed healing along with dehiscence, and that rate was 40.4% for neck or oral sites. Kamizono et al 11 reported on 182 free flap cases and 15 pedicled flap cases; overall surgical site infection rate was 21.3% but 19% in the free flap group. In the present study, prior XRT was found to be a risk factor for surgical site infection only in patients undergoing surgery for active malignancy. do not list their criteria for surgical site infection, or the interval postoperatively for including surgical site infections. Our study followed CDC guidelines and included all surgical site infections occurring within 30 days postoperatively, longer than many other studies. There are conflicting reports in the literature regarding predictors of surgical site infection development after free flap surgery. Patient characteristics previously noted to be surgical site infection risk factors include active tobacco use, prior radiation, length of surgery, operative blood loss, ASA classification, and tumor stage, among others. 3,18,19 Shuman et al 19 noted a higher incidence of surgical site infection in head and neck surgical patients with advanced ASA classification, higher operative blood loss, and those requiring operative takeback. Karakida et al 3 noted surgical site infection risk factors of advanced ASA, advanced T classification, increased surgical duration, performance of bilateral neck dissection, and increased estimated blood loss on univariate analysis; only the associations with ASA score and duration of surgery remained significant after multivariate analysis was performed. The presence of malnutrition as measured by hypoalbuminemia has been found as a surgical site infection risk factor in some studies. 11,20 Conversely, other studies of exclusively free flap procedures did not find these parameters to be statistically significant risk factors ,16,17 We did not find any association between length of surgery, ASA classification, and tumor stage. In our study, the average age of patients who developed a surgical site infection was 4 years less than those who did not (59.8 vs 64 years), although the significance of this finding is unclear. Although Haughey et al 21 found age >55 years to be a risk factor for major medical complications after free flap surgery, other analyses did not find age to be a predictor of wound complications after these procedures. 22 Johnson et al 6 have previously considered the development of a mucocutaneous fistula as having a wound infection. Subsequently, studies have varied in their interpretation of the development of fistula, although several authors have followed the criteria set forth by Johnson et al. 4,6,11,17,20 Some have separated the development of fistula without other signs of infection; for instance, Penel et al 4 reported that 23% of infections were, in fact, fistula without purulent drainage. Multiple other reports follow the CDC criteria as we have interpreted them, and do not include the development of an uninfected fistula as evidence of surgical site infection unless there are other criteria for infection present. 12,15,16,18,23,27 Although reported separately, Benatar et al 18 did not classify fistula and infection as mutually exclusive, and noted rates of 15.2% and 17.1%, respectively. Bozikov and Arnez 23 reported fistula rates of 6.2% and infection rates of 5.7%. Consistent with these more recent reports, our study excludes patients with fistula and no other signs of infection from the surgical site infection cohort. However, for the sake of completion, when the 7 patients (1.5%) in our study with fistula and no infection are included in analysis, the surgical site infection rate was 14.8%, not significantly different from 13.3%. Preoperative radiation therapy is traditionally held as a risk factor for wound healing complications, including E396 HEAD & NECK DOI /HED APRIL 2016

6 SURGICAL SITE INFECTIONS IN FREE FLAP RECONSTRUCTION surgical site infection. Current literature provides mixed findings in this regard. Kamizono et al 11 noted that preoperative radiation therapy, along with advanced ASA, malnutrition, and the use of a bone flap, to be a surgical site infection risk factor on univariate analysis only; this association did not hold on multivariate analysis. Likewise, other retrospective studies by multiple authors did not find radiation therapy to predict wound complications after free tissue transfer. 21,24 Conversely, a large study of 728 free flap reconstructive procedures did note preoperative radiation therapy to be a predictor of wound complications postoperatively. 25 In a report of 429 cases, Benatar et al 18 likewise noted an association of surgical site infection with preoperative radiation therapy. Higher doses of radiation, >60 gray, was a greater risk factor than lower doses or no radiation. When all free flap cases were considered, the present study did not find an association between surgical site infection and preoperative radiation. However, radiation was found to be a risk factor for surgical site infection when patients with active malignancy were considered alone. The low rate of surgical site infection in the present study is likely a result of multiple factors in addition to surgical technique and high compliance with on-time antibiotic administration. Although no difference in operative times was noted between those patients who did and did not develop surgical site infection (p >.05), our study demonstrates a lower average operative time, an average of 422 minutes, than previously described in the literature for similar procedures in which the average surgical times ranged from 480 to 672 minutes. 3,11,12,17 Previous work has shown that reduced operating room times are associated with reduced rates of overall postoperative complications in head and neck reconstruction as well as decreased rates of surgical site infection. 3,14,26 Decreasing operative times can reduce the chance for incidental wound contamination, tissue damage, and other factors predisposing to surgical site infection, as shown in studies of procedures within and outside of the head and neck. 25,28 The present study notes a high rate of compliance with the first 2 SCIP parameters regarding antibiotic prophylaxis. Although the SCIP guidelines offer concrete parameters for prophylactic antibiotic administration, similar, but not universal, practices have been described in the head and neck literature previously. Although a few studies list in their methods section that prophylactic antibiotics were started within 1 hour before incision as part of the study protocol, almost none list the actual compliance rate with that objective. 6,29 Lofti et al 26 state, for example, a rate of 80% received antibiotics before skin incision, but there is no mention of start of antibiotics within 60 minutes before cut-time. Many other studies do not mention this objective, and it is possible that a low rate of compliance with on-time administration of prophylactic antibiotics influences surgical site infection rates. A lower rate of compliance was noted with the parameter of antibiotic cessation postoperatively. Surveys of microvascular surgeons report a wide variance in practice regarding termination of prophylactic antibiotics. 30 Retrospective studies cannot answer the question of whether short versus long course prophylaxis is indicated, but several randomized prospective trials have found no benefit to extending prophylactic antibiotics more than 24 hours postoperatively. 2,20,29 CONCLUSIONS This series represents a large cohort of patients undergoing microvascular reconstruction for head and neck defects. The overall rate of surgical site infection of 13.3% compares favorably to the current literature, even though we included all surgical site infection cases occurring within 30 days postoperatively, a longer inclusion period than many studies. In the overall cohort, no operative or oncologic parameters were found to be significant risk factors for the development of surgical site infection. For the subgroup that had free flap surgery for active malignancy, prior radiation therapy was a risk factor for surgical site infection. This low rate of surgical site infection development occurred in a setting of high documented compliance with on-time antibiotic administration. REFERENCES 1. Kruse AL, Luebbers HT, Gr atz KW, Obwegeser JA. Factors influencing survival of free-flap in reconstruction for cancer of the head and neck: literature review. Microsurgery 2010;30: Johnson JT, Schuller DE, Silver F, et al. Antibiotic prophylaxis in high-risk head and neck surgery: one-day vs. five-day therapy. Otolaryngol Head Neck Surg 1986;95: Karakida K, Aoki T, Ota Y, et al. Analysis of risk factors for surgical-site infections in 276 oral cancer surgeries with microvascular free-flap reconstructions at a single university hospital. J Infect Chemother 2010;16: Penel N, Fournier C, Lefebvre D, Lefebvre JL. 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