Mylan T. Nguyen

Development and Validation of a Risk Stratification Score for Ventral Incisional Hernia after Abdominal Surgery: Hernia Expectation Rates iN Intra-Abdominal Surgery (The HERNIA Project)

BACKGROUND Ventral incisional hernias (VIH) develop in up to 20% of patients after abdominal surgery. No widely applicable preoperative risk-assessment tool exists. We aimed to develop and validate a risk-assessment tool to predict VIH after abdominal surgery. STUDY DESIGN A prospective study of all patients undergoing abdominal surgery was conducted at a single institution from 2008 to 2010. Variables were defined in accordance with the National Surgical Quality Improvement Project, and VIH was determined through clinical and radiographic evaluation. A multivariate Cox proportional hazard model was built from a development cohort (2008 to 2009) to identify predictors of VIH. The HERNIAscore was created by converting the hazards ratios (HR) to points. The predictive accuracy was assessed on the validation cohort (2010) using a receiver operator characteristic curve and calculating the area under the curve (AUC). RESULTS Of 625 patients followed for a median of 41 months (range 0.3 to 64 months), 93 (13.9%) developed a VIH. The training cohort (n = 428, VIH = 70, 16.4%) identified 4 independent predictors: laparotomy (HR 4.77, 95% CI 2.61 to 8.70) or hand-assisted laparoscopy (HAL, HR 4.00, 95% CI 2.08 to 7.70), COPD (HR 2.35; 95% CI 1.44 to 3.83), and BMI ≥ 25 kg/m(2) (HR1.74; 95% CI 1.04 to 2.91). Factors that were not predictive included age, sex, American Society of Anesthesiologists (ASA) score, albumin, immunosuppression, previous surgery, and suture material or technique. The predictive score had an AUC = 0.77 (95% CI 0.68 to 0.86) using the validation cohort (n = 197, VIH = 23, 11.6%). Using the HERNIAscore: HERNIAscore = 4(∗)Laparotomy+3(∗)HAL+1(∗)COPD+1(∗) BMI ≥ 25, 3 classes stratified the risk of VIH: class I (0 to 3 points),5.2%; class II (4 to 5 points),19.6%; and class III (6 points), 55.0%. CONCLUSIONS The HERNIAscore accurately identifies patients at increased risk for VIH. Although external validation is needed, this provides a starting point to counsel patients and guide clinical decisions. Increasing the use of laparoscopy, weight-loss programs, community smoking prevention programs, and incisional reinforcement may help reduce rates of VIH.

Preoperative Glycosylated Hemoglobin and Postoperative Glucose Together Predict Major Complications after Abdominal Surgery

BACKGROUND Glycosylated hemoglobin (HbA1c) is diagnostic of and a measure of the quality of control of diabetes mellitus. Both HbA1c and perioperative hyperglycemia have been targeted as modifiable risk factors for postoperative complications. The HbA1c percent cutoff that best predicts major complications has not been defined. STUDY DESIGN A prospective study of all abdominal operations from a single institution from 2007 to 2010 was performed. All patients with HbA1c within 3 months before surgery were included. The primary end point was major complication, using the Clavien-Dindo complication system, within 30 days of surgery. Stepwise, multivariate analysis was performed including clinically relevant variables chosen a priori. RESULTS Among 438 patients who had a measured HbA1c, 96 (21.9%) experienced a major complication. On multivariate analysis, HbA1c ≥ 6.5% (odds ratio = 1.95; 95% CI, 1.17-3.24; p = 0.01) was found to be the most significant predictor of major complications. Glyosylated hemoglobin and glucose were strongly correlated (correlation coefficient 0.414, p < 0.01). Predicted probabilities demonstrated that both HbA1c and glucose together contributed to major complications; and HbA1c impacted the ability to achieve optimal perioperative glucose control. Patients with a BMI >30 kg/m(2), history of coronary artery disease, and nonwhite race were more likely to have a HbA1c ≥ 6.5%. CONCLUSIONS Elevated HbA1c ≥ 6.5% and perioperative hyperglycemia were associated with an increased rate of major complications after abdominal surgery. Elevated peak postoperative glucose levels were correlated with elevated HbA1c and were independently associated with major complications. More liberal HbA1c testing should be considered in high-risk patients before elective surgery. Safe, feasible, and effective strategies to reduce both HbA1c and perioperative hyperglycemia need to be developed to optimize patient outcomes.

Abdominal reoperation and mesh explantation following open ventral hernia repair with mesh

BACKGROUND This study sought to identify the incidence, indications, and predictors of abdominal reoperation and mesh explantation following open ventral hernia repair with mesh (OVHR). METHODS A retrospective cohort study of all patients at a single institution who underwent an OVHR from 2000 to 2010 was performed. Patients who required subsequent abdominal reoperation or mesh explantation were compared with those who did not. Reasons for reoperation were recorded. The 2 groups were compared using univariate and multivariate analysis (MVA). RESULTS A total of 407 patients were followed for a median (range) of 57 (1 to 143) months. Subsequent abdominal reoperation was required in 69 (17%) patients. The most common reasons for reoperation were recurrence and surgical site infection. Only the number of prior abdominal surgeries was associated with abdominal reoperation on MVA. Twenty-eight patients (6.9%) underwent subsequent mesh explantation. Only the Ventral Hernia Working Group grade was associated with mesh explantation on MVA. CONCLUSIONS Abdominal reoperation and mesh explantation following OVHR are common. Overwhelmingly, surgical complications are themost common causes for reoperation and mesh explantation.

Outcomes with Porcine Acellular Dermal Matrix versus Synthetic Mesh and Suture in Complicated Open Ventral Hernia Repair

BACKGROUND Mesh reinforcement as part of open ventral hernia repair (OVHR) has become the standard of care. However, there is no consensus on the ideal type of mesh to use. In many clinical situations, surgeons are reluctant to use synthetic mesh. Options in these complicated OVHRs include suture repair or the use of biologic mesh such as porcine acellular dermal matrix (PADM). There has been a paucity of controlled studies reporting long-term outcomes with biologic meshes. We hypothesized that compared with synthetic mesh in OVHR, PADM is associated with fewer surgical site infections (SSI) but more seromas and recurrences. Additionally, compared with suture repair, we hypothesized that PADM is associated with fewer recurrences but more SSIs and seromas. METHODS A retrospective study was performed of all complicated OVHRs performed at a single institution from 2000-2011. All data were captured from the electronic medical records of the service network. Data were compared in two ways. First, patients who had OVHR with PADM were case-matched with patients having synthetic mesh repairs on the basis of incision class, Ventral Hernia Working Group (VHWG) grade, hernia size, American Society of Anesthesiologists (ASA) class, and emergency status. The PADM cases were also matched with suture repairs on the basis of incision class, hernia grade, duration of the operation, ASA class, and emergency status. Second, we developed a propensity score-adjusted multi-variable logistic regression model utilizing internal resampling to identify predictors of primary outcomes of the overall cohort. The U.S. Centers for Disease Control and Prevention (CDC) definition of SSI was utilized; seromas and recurrences were defined and tracked similarly for all patients. Data were analyzed using the McNemar, X(2), paired two-tailed Student t, or Mann-Whitney U test as appropriate. RESULTS A total of 449 complicated OVHR cases were reviewed for a median follow up of 61 mos (range 1-143 mos): 94 patients had PADM repairs, whereas 154 patients underwent synthetic mesh repairs, and 201 had suture repairs. The 40 PADM repairs were matched to synthetic repairs and 59 were matched to suture repairs. The PADM repairs that could not be well matched (n=54 unmatched for synthetic repairs, 35 unmatched for suture repairs) were characterized generally by larger hernias, VHWG grades of 3 or 4, and incision class 3 or 4 with longer operative durations and more ASA class 4 cases. The patients were well matched. Comparing PADM with synthetic mesh, there was no difference in SSI (20% vs. 35%; p=0.29), seromas (32.5% vs. 15%; p=0.17), mesh explantations (5% vs. 15%, p=0.28), readmissions within 90 d (37.5% vs. 45%; p=1.00), or recurrence (8.5% vs. 22.5%; p=0.15). Compared with suture repair, patients with PADM had fewer recurrences (11.9% vs. 33.9%; p<0.01) and more seromas (32.2% vs. 10.2%; p=0.02), but a similar number of SSIs (23.7% vs. 39.0%; p=0.19) and 90-d readmissions (35.6% vs. 39.0%; p=0.88). Propensity score-adjusted multi-variable logistic regression of the entire cohort corroborated the results of the case-matched patients. CONCLUSIONS The PADM repair of complicated OVHR resulted in fewer recurrences, more seromas, and no difference in SSI compared with suture repair. Although no reduction in SSI was identified with the use of PADM rather than synthetic mesh or suture for OVHR, the meaning of this finding is unclear, as this case-controlled study was underpowered and limited by selection bias. According to our data, 280 patients would have been needed to identify a clinically significant difference in the primary outcome of SSI as well as secondary outcomes of mesh explantation and recurrence (α=0.05; β=0.20). A randomized trial is warranted to compare PADM with synthetic mesh in complicated OVHR.

Review of stoma site and midline incisional hernias after stoma reversal

BACKGROUND The incidence of incisional hernias after stoma reversal is not well reported. The aim of this study was to systematically review the literature reporting data on incisional hernias after stoma reversal. We evaluated both the incidence of stoma site and midline incisional hernias. METHODS A systematic review identified studies published between January 1, 1980, and December 31, 2012, reporting the incidence of incisional hernia after stoma reversal at either the stoma site or at the midline incision (in cases requiring laparotomy). Pediatric studies were excluded. Assessment of risk of bias, detection method, and essential study-specific characteristics (follow-up duration, stoma type, age, body mass index, and so forth) was done. RESULTS Sixteen studies were included in the analysis; 1613 patients had 1613 stomas formed. Fifteen studies assessed stoma site hernias and five studies assessed midline incisional hernias. The median (range) incidence of stoma site incisional hernias was 8.3% (range 0%-33.9%) and for midline incisional hernias was 44.1% (range 8.7%-58.1%). When evaluating only studies with a low risk of bias, the incidence for stoma site incisional hernias is closer to one in three and for midline incisional hernias is closer to one in two. CONCLUSION Stoma site and midline incisional hernias are significant clinical complications of stoma reversals. The quality of studies available is poor and heterogeneous. Future prospective randomized controlled trials or observational studies with standardized follow-up and outcome definitions/measurements are needed.