Evaluation of high-risk, comorbid patients undergoing open ventral hernia repair with synthetic mesh

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1 Evaluation of high-risk, comorbid patients undergoing open ventral hernia repair with synthetic mesh David M. Krpata, MD, Jeffrey A. Blatnik, MD, Yuri W. Novitsky, MD, and Michael J. Rosen, MD, FACS, Cleveland, OH Background. The Ventral Hernia Working Group proposed recently a classification system to grade the risk of surgical site occurrence (SSO) during ventral hernia repair (VHR). Accurately predicting the outcomes of synthetic mesh in open VHR for comorbid patients might guide surgeons in appropriate mesh selection in this patient population. Our objective was to determine the incidence of SSO in open, grade II VHR and to examine the use of synthetic mesh in these comorbid patients. Methods. All open, grade II VHR performed by a single surgeon over a 4-year period were reviewed retrospectively. Results. Eighty-eight patients (43 female; mean age, 57 years) with grade II ventral hernias underwent open VHR with synthetic mesh. Associated comorbidities included obesity in 55 (63%), diabetes mellitus in 43 (49%), chronic obstructive pulmonary disease in 27 (31%), smoking in 21 (24%), and immunosuppression in 18 (21%). The mean number of comorbidities per patient was 1.9 (range, 1 4). SSO occurred in 14 (16%) patients and included infection (n = 11), seroma (n = 2), and wound dehiscence (n = 1). Having multiple comorbidities was associated with an increased risk of SSO (P =.02). Three (3%) patients required reoperation or readmission for wound management. With a mean follow-up of 17.8 months, 4 (5%) patients developed a hernia recurrence. Conclusion. Patients with grade II hernias undergoing open VHR are prone to SSO with an incidence of 16%. Although synthetic mesh infections can occur among grade II patients, the majority can be managed conservatively with salvage of the prosthesis, especially if macroporous mesh is used. Given our findings, the use of synthetic mesh in the retrorectus space results in a safe and durable (5% recurrence rate) repair for patients with grade II incisional hernias. (Surgery 2013;153:120-5.) From the Department of Surgery, Case Comprehensive Hernia Center, University Hospitals Case Medical Center, Cleveland, OH UNIQUE PATIENT CHARACTERISTICS, ASSOCIATED COMORBID- ITIES, CHARACTERISTICS OF HERNIA DEFECTS, AND RECON- STRUCTIVE OPTIONS ALL influence the outcome of a hernia repair. One major concern facing all surgeons is the risk of surgical site occurrence (SSO), specifically wound and mesh infection. The rate of wound complications after open ventral hernia repair is reported to be up to 27%. 1-3 Universal application of these results is limited Yuri Novitsky discloses speaker for Lifecell, Davol and consultant for Davol, Kensey Nash. Michael Rosen discloses speaker for Lifecell. Research support from Lifecell, Davol, W.L. Gore, and Cook. Accepted for publication June 4, Reprint requests: David M. Krpata, MD, Department of Surgery, Case Comprehensive Hernia Center, University Hospitals Case Medical Center, Euclid Avenue, Lakeside Rm. 7110, Cleveland, OH david.krpata@uhhospitals.org /$ - see front matter Ó 2013 Mosby, Inc. All rights reserved. because these series represent a heterogeneous group of patients without appropriate stratification for inherent risk factors for SSO, such as smoking, diabetes, immunosuppression, and obesity. 4-6 Recognizing the importance of identifying potential key risk factors for developing a SSO, the Ventral Hernia Working Group (VHWG) established a grading system for management of incisional ventral hernias and the risk of SSO. 7 The VHWG defined SSO as an infection, seroma, wound dehiscence, or the formation of an enterocutaneous fistula after abdominal wall reconstruction. In this grading system, patients were stratified into 1 of 4 groups based on SSO risk: Grade I, low risk; grade II, comorbid patients without a history of wound infection; grade III, potentially contaminated; or grade IV, infected patients. Although a grading system for SSO (such as the one proposed by the VHWG) offers an assessment tool to aid in the management of ventral hernias, this grading system has not been 120 SURGERY

2 Surgery Volume 153, Number 1 Krpata et al 121 correlated with clinical outcomes of patients undergoing ventral hernia repair. In an attempt to guide surgeons as to the appropriate alloplastic and biologic prosthetic material for abdominal wall reconstruction, the VHWG made the following recommendations. Grade I ventral hernia repairs are managed generally with a synthetic repair material based on surgeon preference. Given the increased risk of SSO associated with grade III and IV ventral hernias, permanent synthetic mesh was generally not recommended by the VHWG. Grade II hernias, however, were more controversial, and no clear recommendations were possible given the lack of objective data regarding outcomes of open ventral hernia repair in this comorbid cohort of patients. We hypothesized that synthetic mesh would be safe and provide a durable repair in this patient population. We reviewed our experience with this specific subgroup of patients to determine the risk of SSO and the influence on outcomes in comorbid patients undergoing open ventral hernia repair with synthetic mesh. METHODS After obtaining institutional review board approval, our prospective database of abdominal wall reconstruction patients was reviewed retrospectively to identify all comorbid patients undergoing open ventral hernia repair with synthetic mesh by a single surgeon (MJR) consecutively from August 2006 to August 2011 at University Hospitals Case Medical Center. Variables analyzed included age, gender, comorbidities, body mass index (BMI), history of prior abdominal operations and hernia repair, characteristics of the hernia defect, and operative technique (Tables I and II). Smoking was defined as active smoking within 3 months of operation. Based on the VHWG classification, obesity was defined as a BMI > 30 kg/m 2. Immunosuppression was not defined clearly by the VHWG, and for our analysis included patients receiving chemotherapy within 3 months of operation, >5 mg/d prednisone therapy, or patients with solid organ transplants. The primary outcome variable of this study was the incidence of SSO, defined based on the ventral hernia working group as infections, clinically relevant seroma requiring intervention, dehiscence, or formation of an enterocutaneous fistula. Surgical site infection (SSI) was defined as those patients requiring antibiotics for wound erythema, opening of postoperative incisions, percutaneous drainage, or operative debridement. Postoperative follow-up was determined through review of the medical record and clinic reports. Hernia Table I. Demographics of open grade II ventral hernia repair (n = 88) Variable Open repair patients Age (yrs) 56.1 ± 10.3 ASA 3.1 ± 4.3 Female gender 43 (48.9%) No. of comorbidities 1.9 ± 0.8 Obese (BMI > 30 kg/m 2 ) 55 (62.5%) BMI (kg/m 2 ) 34.8 ± 6.7 DM 43 (48.9%) COPD 27 (30.7%) Smoker 21 (23.9%) Immunosuppression 18 (20.5%) ASA, American Society of Anesthesiologists score; BMI, body mass index; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus. recurrence was defined as a bulge or hernia present at the repair site and confirmed by an abdominal pelvic computed tomography. Our approach for open abdominal wall reconstruction has been published previously. 8 We prefer to use a retrorectus repair with macroporous synthetic mesh in clean cases, and non crosslinked porcine dermis in contaminated fields. In patients with larger defects, we perform additional myofascial advancement flaps. Although the principles of abdominal wall reconstruction have been maintained throughout the study period (sublay mesh and formal reconstruction of the midline when possible), we have made several modifications to our myofascial advancement techniques that deserve mention. Initially, we performed a standard open, anterior component separation, releasing the external oblique. We then began performing endoscopic releases of the external oblique. 9 Over the past 2 years of the study, we have utilized a posterior component separation. 10,11 A posterior component separation involves releasing the posterior rectus sheath from the rectus muscle to the linea semilunaris. Next, the transversus abdominis muscle is incised just medial to the linea semilunaris, taking care to preserve the intercostal nerves, thereby exposing the peritoneum. This plane is then extended laterally to the psoas muscle if necessary. In patients who have a large pannus, we perform a simultaneous panniculectomy and abdominal wall reconstruction. In these patients, we have reported previously high wound morbidity and prefer a biologic mesh despite the clean nature of the case. 12 For this reason, these panniculectomy patients are excluded from this analysis. Data analysis was performed using SPSS (IBM Corp., Somers, NY). The t-test, chi-square test, and

3 122 Krpata et al Surgery January 2013 Table II. Operative demographics Mean ± SD or n (%) Number of previous abdominal 3.4 ± 2.9 surgeries Number of previous hernia repairs 1.6 ± 2.6 Defect area (cm 2 ) ± <100 7 (8.0%) (67.0%) > (25.0%) Mesh bridging required 5 (5.7%) Component separation 34 (38.6%) Open anterior 4 Endoscopic 6 Open posterior 24 logistic regression were used to perform data analysis where appropriate. RESULTS Eighty-eight patients with grade II ventral hernias underwent open ventral hernia repair with synthetic mesh during the study period. There were 45 males and 43 females with a mean age of 57 years (range, 32 83). The mean American Society of Anesthesiologists score (ASA) was 3.1 (median, 3). The mean number of previous abdominal operations was 3.4 (range, 0 22), with a mean of 1.6 (range, 0 21) previous hernia repairs. Thirty-six (40%) patients were undergoing an initial hernia repair; the remaining patients had $1 prior attempt at hernia repair (1 previous repair [n = 18], 2 [n = 16], 3 [n = 10], 4 [n = 2], 5[n = 3], 6 [n = 1], 8 [n = 1], and 21 [n = 1]). The mean defect size was 419 cm 2 (range, 9 1,920), with an average width of 17 cm (range, 3 40). Seven (8%) patients had defects <100 cm 2, 59 (67%) had defects between 100 and 500 cm 2, and 22 (25%) had defects >500 cm 2. Associated comorbidities for these patients included obesity in 55 (63%), diabetes mellitus in 43 (49%), chronic obstructive pulmonary disease (COPD) in 27 (31%), smoking in 21 (24%), and immunosuppression in 18 (21%). The mean number of comorbidities per patient was 1.9 (range, 1 4). Multiple comorbidities were present in 44 patients: 1 (n = 34), 2 (n = 24), 3 (n = 17), or 4 comorbidities (n = 3). During ventral hernia repair, macroporous synthetic mesh was placed in the retrorectus position in 87 (98%) patients and intraperitoneal in 1 patient (2%). The 1 patient who underwent intraperitoneal mesh placement had undergone bilateral rectus abdominis myocutaneous flaps and had no retrorectus space. This patient had an antiadhesive barrier polyester mesh placed. Component separation was performed in 34 patients (39%). Of these, 4 were anterior components separations, 6 were endoscopic components separation, and 24 were performed as open posterior components separation. Five patients (6%) were unable to have their fascia reapproximated in the midline with a mean defect size of 657 cm 2 (range, ). SSO was identified in 14 (16%) patients as follows: 11 SSIs (13%), 2 seroma (2%), 1 wound dehiscence/skin necrosis (1%), and no enterocutaneous fistulas. Three patients required reoperation or readmission for management of SSOs. The 11 patients who developed a SSI were managed with antibiotics alone (n = 5), antibiotics and bedside/office wound debridement (n = 3), antibiotics and wound debridement in the operating room (n = 1), or partial mesh excision for infected synthetic mesh (n = 2). One patient developed a chronic draining sinus. This occurred 10 months after ventral hernia repair, after which the patient developed a postoperative SSI that required debridement in the operating room and partial mesh excision. Univariate analysis revealed that defect area (P =.05), operative time (P =.01), and COPD (P =.01) were all associated with increased risks of developing a SSO within this cohort of comorbid patients. Operative time (P =.01), ASA score (P =.03), COPD (P =.02), and BMI (P =.04) were all associated with an increased risk of developing a SSI within this cohort (Table III). Multivariate analysis of the 5 comorbidities highlighted by the VHWG for grade II hernias was performed to determine whether either of these variables was more important than the other at predicting SSO in this comorbid group. None of the 5 variables were significant for predicting SSO or SSI, suggesting that all 5 variables in patients with grade II ventral hernias equally contribute to development of SSO and SSI in this cohort of patients. To determine whether having multiple comorbidities increased the chances of a SSO, the effect of compounding comorbidities was also assessed. Having multiple comorbidities resulted in an increased risk of SSO (P =.02; Figure). Mean follow-up was 18 months (range, 1 67). Four (5%) patients developed hernia recurrences. Mean time to development of the hernia recurrence was 27 months (range, 12 35). Of the 4 patients who developed a hernia recurrence, only 1 initially had a SSI. One patient went on to have a laparoscopic repair of the hernia recurrence. The

4 Surgery Volume 153, Number 1 Krpata et al 123 Table III. Univariate analysis of open grade II risk patients for surgical site occurrence (SSO) and surgical site infection (SSI) SSO (n = 14) SSI (n = 11) P (SSO) P value P (SSI) P value Age (yrs) Gender Female 7/43 (16.3%) 5/43 (11.6%) Male 7/45 (15.6%) 6/45 (23.3%) ASA Defect area Operative time No. of comorbidities BMI (kg/m 2 ) Obese 7/55 (12.7%).30 5/55 (9.1%).22 Smoker 6/21 (28.6%).08 5/21 (23.8%).08 Immunosuppressed 0/18 (0.0%).99 0/18 (0.0%).99 COPD 9/27 (33.3%).01 7/27 (25.9%).02 DM 7/43 (16.3%).08 7/43 (16.3%).32 Number of previous hernia repairs ASA, American Society of Anesthesiologist score; BMI, body mass index; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus. Figure. Probability of wound morbidity based on number of comorbidities present. Black line, SSO; gray line, SSI. 3 other recurrences were small in size and asymptomatic and are being treated conservatively. DISCUSSION This study evaluated a complex group of patients with substantial, clinically relevant associated comorbidities undergoing open abdominal wall reconstruction with synthetic mesh. Several important risk factors for predicting SSO were identified. Patients with obesity, a smoking history, diabetes, and COPD had a16% risk of developing an SSO. SSO was the most common complication in these patients. A reliable classification system of ventral/incisional hernias is needed to guide operative management, predict outcomes of repairs, and allow for a universal terminology when reporting outcomes. Both the European Hernia Society and VHWG have attempted to develop a grading system for abdominal wall hernias. 13 The VHWG utilized a group of experts to develop a consensus opinion as to the risk of SSO based on patient and defect characteristics. The VHWG stratified patients into 4 groups based on presence of contamination at the time of operation and underlying patient comorbidites. 7 This classification system was an important initial step in predicting the risk of SSO; however, no attempt has been made to validate the model to date. Our study evaluated the most controversial group of patients in this classification system: The grade II patients. Although the VHWG felt the presence of comorbidities increased the likelihood of SSO, they were not able to determine either the actual incidence of these events or the ultimate consequence. As predicted, we found that the grade II patients had a high incidence of SSO. Only 3 patients (3%) went on to require operative therapy for their infection. The remainder of the patients retained their mesh and did not have long-term hernia recurrence or prosthetic infections throughout the duration of the study period. Several other investigators have attempted to identify risk factors for postoperative wound morbidity in patients undergoing abdominal wall reconstruction. 1,3,14,15 These studies have particularly evaluated the effect of COPD, diabetes mellitus, obesity, smoking, and immunosuppression on

5 124 Krpata et al Surgery January 2013 SSO. Unlike the current study, there was no attempt to stratify the patients based on underlying comorbidity, complexity of defects, or standardize operative technique. For example, Kaafarani et al 2 report the results of a prospective, randomized trial comparing laparoscopic versus open ventral hernia repair in a much less complex group of patients than reported in the present study. Over 85% of patients in their study were ASA class 1, with a mean BMI of 30.9, and <5% were diabetics. 2 Alternatively, our study population consisted of comorbid patients with a median ASA of 3 with >60% of the patients being obese (mean BMI, 34.8 kg/m 2 ), and nearly 50% were diabetic. Prior studies have evaluated much less complex hernias, limiting the applicability of their results to comorbid patients with complex defects. Over 70% of patients in prior studies were undergoing an initial hernia repair of relatively small defects. Our series reports the repair of large hernias with a mean defect size of 419 cm 2 with the majority being recurrent hernia repairs. Most series have also reported a wide range of open repairs with some series allowing a multitude of open approaches to be evaluated as a single group. Our series was performed by a single surgeon with a standardized technique. Although there were some technical modifications of components separations performed during the study period, the general concept of sublay mesh and fascial reconstruction remained constant. As the complexity of patients presenting for ventral hernia repair continues to expand, it is very important to appropriately stratify the risk of SSO to provide reasonable levels of expectation for postoperative outcomes. The implications of operative technique must also be addressed when interpreting our results. The role of laparoscopy in abdominal wall reconstruction should always be considered in the evaluation of grade II patients. Laparoscopic ventral hernia repair has been shown clearly in prospective, randomized trials to result in a significantly lower incidence of SSO. 16 Not all defects, however, are amenable to a laparoscopic approach. In fact, in the study from Itani et al, 16 the mean sizes of the defects were only and 68.1 cm 2 for laparoscopic and open repairs, respectively. In our series, the average defect size was >3 times greater than their series for laparoscopic repair, and would not likely have been amendable to laparoscopy. We have reserved laparoscopy for those patients with small- to medium-sized defects with associated comorbidities. Likewise, a variety of open ventral hernia repair procedures have been described. In this series, a standard retrorectus repair was performed in nearly all patients allowing a macroporous synthetic mesh to be utilized. The choice of prosthetic material must be considered carefully in this patient population based on our results and the recommendation of the VHWG. Despite the relatively high incidence of SSIs in our series, we were able to manage the majority of these SSIs with conservative wound measures without long-term mesh complications. Macroporous synthetic meshes compared with the expanded polytetrafluoroethylene-based microporous prostheses have long been shown to be relatively resistant to infection and can often be salvaged if infection does occur. 17 One patient in our series did develop a chronic draining sinus that has been difficult to manage. Our results might not be generalizable to all types of synthetic mesh and all approaches to abdominal wall reconstruction. Microporous mesh has less resistance to infection and almost always must be explanted after infection. 18 Likewise, a composite macroporous mesh coated with an anti-adhesive barrier might not be as resistant to bacterial contamination. Thus, if a surgeon preferred an intraperitoneal position of the prosthetic, greater rates of mesh infection and excision might occur. To our knowledge, no studies have evaluated systematically the resistance of various synthetic materials to bacterial contamination. Overall hernia recurrence rate for this cohort was 5% with a mean follow-up time of nearly 1.5 years. We believe this relatively low recurrence rate for such complex patients with comorbidities and a mean defect size of over 400 cm 2 is most likely attributable to the technique. The placement of macroporous synthetic mesh between the rectus muscle and posterior rectus fascia allows for maximal mesh incorporation and durability. Our findings are consistent with Iqbal et al, 19 who reviewed 254 patients who had undergone abdominal wall reconstruction with a modified Rives Stoppa technique. 19 This group found an overall recurrence rate of 5% with a mean follow-up time of 5 years. Other groups have also reported recurrence rates of <5% after a similar retromuscular preperitoneal approach. 20 This study has several limitations. First, our practice includes a tertiary and quaternary referral practice of complex ventral hernias. Whether our results can be generalized to other practices is unknown; however, the complex nature of our referral practice has enabled us to amass a large experience with comorbid patients undergoing ventral hernia repair. Second, although our initial intent was to provide guidance as to mesh selection in this patient population, the fact that we do not

6 Surgery Volume 153, Number 1 Krpata et al 125 have a control group in this study prevents us from reaching any of these conclusions. Our data do, however, provide a reasonable guide to counsel patients and surgeons as to reasonable expectations of SSO and SSI in comorbid patients undergoing open ventral hernia repairs. These data might provide some insight into mesh selection as well. Because a cm piece of macroporous synthetic mesh costs approximately $150 in our hospital, it seems unlikely that anyone would prefer a $10,000 biologic mesh of a similar size based on our favorable results. Finally, the fact that we did not find any variable based on the VHWG classification system that contributed more to SSO than any other variable might be due to the fact that all these comorbidities contribute equally, poorly defined terms such as immunosuppression, or the fact that this study was underpowered to determine that difference. In conclusion, patients with grade II hernias undergoing open VHR are prone to SSO with an incidence of 16%. We identified a correlation between multiple comorbidities and increasing rates of SSO. All efforts should be made in preoperative optimization of all comorbidities in patients undergoing open abdominal wall reconstruction. Although synthetic mesh infections can occur in grade II patients, the majority can be managed conservatively with salvage of the prosthetic, especially if macroporous mesh is used. Given our findings, the use of synthetic mesh in the retrorectus space results in a safe and durable (5% recurrence rate) repair for grade II patients undergoing abdominal wall reconstruction. REFERENCES 1. Finan KR, Vick CC, Kiefe CI, Neumayer L, Hawn MT. Predictors of wound infection in ventral hernia repair. Am J Surg 2005;190: Kaafarani HM, Kaufman D, Reda D, Itani KM. Predictors of surgical site infection in laparoscopic and open ventral incisional herniorrhaphy. J Surg Res 2010;163: Dunne JR, Malone DL, Tracy JK, Napolitano LM. Abdominal wall hernias: risk factors for infection and resource utilization. J Surg Res 2003;111: Candage R, Jones K, Luchette FA, et al. Use of human acellular dermal matrix for hernia repair: friend or foe? Surgery 2008;144: Diaz JJ Jr, Conquest AM, Ferzoco SJ, et al. Multi-institutional experience using human acellular dermal matrix for ventral hernia repair in a compromised surgical field. Arch Surg 2009;144: Kim H, Bruen K, Vargo D. Acellular dermal matrix in the management of high-risk abdominal wall defects. Am J Surg 2006;192: Breuing K, Butler CE, Ferzoco S, et al. Incisional ventral hernias: review of the literature and recommendations regarding the grading and technique of repair. Surgery 2010;148: Rosen MJ, Fatima J, Sarr MG. Repair of abdominal wall hernias with restoration of abdominal wall function. J Gastrointest Surg 2010;14: Harth KC, Rosen MJ. Endoscopic versus open component separation in complex abdominal wall reconstruction. Am J Surg 2010;199: Krpata DM, Blatnik JA, Novitsky YW, Rosen MJ. Posterior and open anterior components separations: a comparative analysis. Am J Surg 2012;203: Carbonell AM, Cobb WS, Chen SM. Posterior components separation during retromuscular hernia repair. Hernia 2008;12: Harth KC, Blatnik JA, Rosen MJ. Optimum repair for massive ventral hernias in the morbidly obese patient: is panniculectomy helpful? Am J Surg 2011;201: Muysoms FE, Miserez M, Berrevoet F, et al. Classification of primary and incisional abdominal wall hernias. Hernia 2009;13: Pessaux P, Lermite E, Blezel E, et al. Predictive risk score for infection after inguinal hernia repair. Am J Surg 2006;192: Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for prevention of surgical site infection, Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee. Am J Infect Control 1999;27: Itani KM, Hur K, Kim LT, et al. Comparison of laparoscopic and open repair with mesh for the treatment of ventral incisional hernia: a randomized trial. Arch Surg 2010;145: Stoppa R, Petit J, Abourachid H, et al. [Original procedure of groin hernia repair: interposition without fixation of Dacron tulle prosthesis by subperitoneal median approach]. Chirurgie 1973;99: Cobb WS, Carbonell AM, Kalbaugh CL, Jones Y, Lokey JS. Infection risk of open placement of intraperitoneal composite mesh. Am Surg 2009;75: Iqbal CW, Pham TH, Joseph A, et al. Long-term outcome of 254 complex incisional hernia repairs using the modified Rives-Stoppa technique. World J Surg 2007;31: Novitsky YW, Porter JR, Rucho ZC, et al. Open preperitoneal retrofascial mesh repair for multiply recurrent ventral incisional hernias. J Am Coll Surg 2006;203: