Key factors associated with postoperative complications in patients undergoing colorectal surgery.

BACKGROUND: Surgical outcomes are determined by complex interactions among a variety of factors including patient characteristics, diagnosis, and type of procedure. OBJECTIVE: The aim of this study was to prioritize the effect and relative importance of the surgeon (in terms of identity of a surgeon and surgeon volume), patient characteristics, and the intraoperative details on complications of colorectal surgery including readmission, reoperation, sepsis, anastomotic leak, small-bowel obstruction, surgical site infection, abscess, need for transfusion, and portal and deep vein thrombosis. DESIGN: This study uses a novel classification methodology to measure the influence of various risk factors on postoperative complications in a large outcomes database. METHODS: Using prospectively collected information from the departmental outcomes database from 2010 to 2011, we examined the records of 3552 patients who underwent colorectal surgery. Instead of traditional statistical methods, we used a family of 7000 bootstrap classification models to examine and quantify the impact of various factors on the most common serious surgical complications. For each complication, an ensemble of multivariate classification models was designed to determine the relative importance of potential factors that may influence outcomes of surgery. This is a new technique for analyzing outcomes data that produces more accurate results and a more reliable ranking of study variables in order of their importance in producing complications. PATIENTS: Patients who underwent colorectal surgery in 2010 and 2011 were included. SETTINGS: This study was conducted at a tertiary referral department at a major medical center. MAIN OUTCOME: Postoperative complications were the primary outcomes measured. RESULTS: Factors sorted themselves into 2 groups: a highly important group (operative time, BMI, age, identity of the surgeon, type of surgery) and a group of low importance (sex, comorbidity, laparoscopy, and emergency). ASA score and diagnosis were of intermediate importance. The outcomes most influenced by variations in the highly important factors included readmission, transfusion, surgical site infection, and abscesses. LIMITATIONS: This study was limited by the use of data from a single tertiary referral department at a major medical center. CONCLUSIONS: Body mass index, operative time, and the surgeon who performed the operation are the 3 most important factors influencing readmission rates, rates of transfusions, and surgical site infection. Identification of these contributing factors can help minimize complications.

Prognostic modeling of preoperative risk factors of pouch failure.

BACKGROUND: The prospect of pouch failure needs to be considered when evaluating the management strategy for patients who may be candidates for an ileo anal pouch. An ability to predict the likelihood and timing of failure preoperatively may influence surgical decision making. OBJECTIVE: The aim of this study was to define a preoperative prognostic model for ileoanal pouch failure. DESIGN: A novel random forest methodology was used to evaluate the prognostic significance of 21 preoperative potential risk factors for pouch failure. A forest of 3000 random survival trees was grown to estimate pouch failure for each patient and to identify important risk factors that maximize survival prediction. SETTINGS: This study took place at a tertiary referral department at a major academic medical center. PATIENTS: Patients undergoing an ileoanal pouch at this institution between 1983 and 2008 were included. MAIN OUTCOME MEASURES: The primary outcome measured was pouch survival. RESULTS: Between 1983 and 2008, 3754 patients underwent ileoanal pouch. Type of resection (total proctocolectomy vs completion proctectomy), type of anastomosis (stapled vs mucosectomy), patient diagnosis (mucosal ulcerative colitis and others vs Crohn's disease) and diagnosis of diabetes had the strongest effect on pouch survival. Predicted survival was worse for completion proctectomy (HR, 1.44; 95% CI, 1.08-1.93), Crohn's disease (HR, 2.37; 95% CI, 1.48-3.79), handsewn anastomosis (HR, 1.72; 95% CI, 1.23-2.42), and diabetes (HR, 2.31; 95% CI, 1.25-4.24). Pouch survival was worse for the oldest group of patients. LIMITATIONS: This study was limited by its retrospective nature. CONCLUSION: Random forest techniques applied to a large number of patients undergoing the ileoanal pouch identify factors associated with pouch failure. Attention directed at these factors may improve outcomes for these patients.

Genetic and epigenetic classifications define clinical phenotypes and determine patient outcomes in colorectal cancer.

BACKGROUND: A molecular classification of colorectal cancer has been proposed based on microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and mutations in the KRAS and BRAF oncogenes. This study examined the prevalence of these molecular classes, and differences in clinical presentation and outcome. METHODS: Demographics, tumour characteristics and survival were recorded for 391 subjects with colorectal cancer. Tumour DNA was analysed for MSI (high (MSI-H) or microsatellite stable (MSS)), CIMP (high (CIMP-H) or no (CIMP-neg)) and BRAF and KRAS mutations. Clinical differences between four phenotypes were examined. RESULTS: Most tumours were MSS/CIMP-neg (69.8 per cent), with a nearly equal distribution of MSI-H/CIMP-H, MSI-H/CIMP-neg and MSS/CIMP-H types. MSS/CIMP-neg tumours were less likely to be poorly differentiated (P = 0.009). CIMP-H tumours were more common in older patients (P < 0.001). MSI-H/CIMP-H tumours had a high frequency of BRAF mutation and a low rate of KRAS mutation; the opposite was true for MSS/CIMP-neg tumours (P < 0.001). The four molecular phenotypes tended towards divergent survival (P = 0.067 for stages 1-III). MSI-H cancers were associated with better disease-free survival (hazard ratio 2.00 (95 per cent confidence interval 1.03 to 3.91); P = 0.040). CONCLUSION: Colorectal cancers are molecularly and clinically heterogeneous. These different molecular phenotypes may reflect variable prognosis.

Risk factors associated with ileal pouch-related fistula following restorative proctocolectomy.

INTRODUCTION: Pouch-related fistula occurs in 5-10 per cent of patients after restorative proctocolectomy. The present study identified risk factors associated with the development of such fistulas. METHODS: Data on preoperative and postoperative risk factors were recorded from 1965 patients who underwent restorative proctocolectomy in a single tertiary centre between 1983 and 2001. Cox regression analysis was used to identify independent predictors of pouch-perineal, pouch-abdominal wall and pouch-vaginal fistula during follow-up. RESULTS: Median patient follow-up was 4.1 (range 0-19) years. By 15 years' follow-up, pouch-vaginal fistulas had occurred in 44 women (5.2 per cent). The prevalence of ileal pouch-perineal and pouch-abdominal wall fistula was 3.6 per cent (70 patients) and 1.5 per cent (30 patients) respectively. Independent predictors of pouch-related fistula identified by multivariate analysis were diagnosis of indeterminate colitis or Crohn's disease (hazard ratio (HR) 1.28 (95 per cent confidence interval (c.i.) 1.00 to 1.65) and 1.73 (95 per cent c.i. 1.07 to 3.48) respectively versus ulcerative colitis or familial adenomatous polyposis), previous anal pathology (HR 3.43 (95 per cent c.i. 2.43 to 4.84) and 4.02 (95 per cent c.i. 1.27 to 12.77) respectively for perineal abscess and fistula in ano versus no previous anal pathology), abnormal anal manometry (HR 4.29 (95 per cent c.i. 2.33 to 7.91)), patient sex (HR 0.74 (95 per cent c.i. 0.58 to 0.95) for men versus women) and pelvic sepsis (HR 3.79 (95 per cent c.i. 2.48 to 5.79)). CONCLUSION: This study suggests that Crohn's disease and the clinical signs that favour the diagnosis of Crohn's disease may contribute to the development of pouch-related fistula.