Kyle H. Sheetz

Analytic morphomics, core muscle size, and surgical outcomes.

Objective:Assess the relationship between lean core muscle size, measured on preoperative cross-sectional images, and surgical outcomes. Background:Novel measures of preoperative risk are needed. Analytic morphomic analysis of cross-sectional diagnostic images may elucidate vast amounts of patient-specific data, which are never assessed by clinicians. Methods:The study population included all patients within the Michigan Surgical Quality Collaborative database with a computerized tomography(CT) scan before major, elective general or vascular surgery (N = 1453). The lean core muscle size was calculated using analytic morphomic techniques. The primary outcome measure was survival, whereas secondary outcomes included surgical complications and costs. Covariate adjusted outcomes were assessed using Kaplan-Meier analysis, multivariate cox regression, multivariate logistic regression, and generalized estimating equation methods. Results:The mean follow-up was 2.3 years and 214 patients died during the observation period. The covariate-adjusted hazard ratio for lean core muscle area was 1.45 (P = 0.028), indicating that mortality increased by 45% per 1000 mm2 decrease in lean core muscle area. When stratified into tertiles of core muscle size, the 1-year survival was 87% versus 95% for the smallest versus largest tertile, whereas the 3-year survival was 75% versus 91%, respectively (P < 0.003 for both comparisons). The estimated average risk of complications significantly differed and was 20.9%, 15.0%, and 12.3% in the lower, middle, and upper tertiles of lean core muscle area, respectively. Covariate-adjusted cost increased significantly by an estimated

Surgical Site Infection and Analytic Morphometric Assessment of Body Composition in Patients Undergoing Midline Laparotomy

10,110 per 1000 mm2 decrease in core muscle size (P = 0.003). Conclusions:Core muscle size is an independent and potentially important preoperative risk factor. The techniques used to assess preoperative CT scans, namely analytic morphomics, may represent a novel approach to better understanding patient risk.

A statewide colectomy experience: the role of full bowel preparation in preventing surgical site infection.

BACKGROUND Obesity is a known risk factor for surgical site infection (SSI). Our hypothesis is that morphometric measures of midline subcutaneous fat will be associated with increased risk of SSI and will predict SSI better than conventional measures of obesity. STUDY DESIGN We identified 655 patients who underwent midline laparotomy (2006 to 2009) using the Michigan Surgical Quality Collaborative database. Using novel, semiautomated analytic morphometric techniques, the thickness of subcutaneous fat along the linea alba was measured between T12 and L4. To adjust for variations in patient size, subcutaneous fat was normalized to the distance between the vertebrae and anterior skin. Logistic regression analyses were used to identify factors independently associated with the incidence of SSI. RESULTS Overall, SSIs were observed in 12.5% (n = 82) of the population. Logistic regression revealed that patients with increased subcutaneous fat had significantly greater odds of developing a superficial incisional SSI (odds ratio [OR] = 1.76 per 10% increase, 95% CI 1.10 to 2.83, p = 0.019). Smoking, steroid use, American Society of Anesthesiologists (ASA) classification, and incision-to-close operative time were also significant independent risk factors for superficial incisional SSI. When comparing subcutaneous fat and body mass index (BMI) as the only model variables, subcutaneous fat significantly improved model predictions of superficial incisional SSI (area under the receiver operating characteristic curve [AUC] 0.60, p = 0.023); BMI did not (AUC 0.52, p = 0.73). CONCLUSIONS Abdominal subcutaneous fat is an independent predictor of superficial incisional SSI after midline laparotomy. Novel morphometric measures may improve risk stratification and help elucidate the pathophysiology of surgical complications.

Decreased core muscle size is associated with worse patient survival following esophagectomy for cancer

Objective:To assess the utility of full bowel preparation with oral nonabsorbable antibiotics in preventing infectious complications after elective colectomy. Background:Bowel preparation before elective colectomy remains controversial. We hypothesize that mechanical bowel preparation with nonabsorbable oral antibiotics is associated with a decreased rate of postoperative infectious complications when compared with no bowel preparation. Methods:Patient and clinical data were obtained from the Michigan Surgical Quality Collaborative–Colectomy Best Practices Project. Propensity score analysis was used to match elective colectomy cases based on primary exposure variable—full bowel preparation (mechanical bowel preparation with nonabsorbable oral antibiotics) or no bowel preparation (neither mechanical bowel preparation given nor nonabsorbable oral antibiotic given). The primary outcomes for this study were occurrence of surgical site infection and Clostridium difficile colitis. Results:In total, 2475 cases met the study criteria. Propensity analysis created 957 paired cases (n = 1914) differing only by the type of bowel preparation. Patients receiving full preparation were less likely to have any surgical site infection (5.0% vs 9.7%; P = 0.0001), organ space infection (1.6% vs 3.1%; P = 0.024), and superficial surgical site infection (3.0% vs 6.0%; P = 0.001). Patients receiving full preparation were also less likely to develop postoperative C difficile colitis (0.5% vs 1.8%, P = 0.01). Conclusions:In the state of Michigan, full bowel preparation is associated with decreased infectious complications after elective colectomy. Within this context, the Michigan Surgical Quality Collaborative recommends full bowel preparation before elective colectomy.

Cost of Major Surgery in the Sarcopenic Patient

Preoperative risk assessment, particularly for patient frailty, remains largely subjective. This study evaluated the relationship between core muscle size and patient outcomes following esophagectomy for malignancy. Using preoperative computed tomography scans in 230 subjects who had undergone transhiatal esophagectomy for cancer between 2001 and 2010, lean psoas area (LPA), measured at the fourth lumbar vertebra, was determined. Cox proportional hazards regression was employed to analyze overall survival (OS) and disease-free survival (DFS) adjusted for age, gender, and stage, and the Akaike information criterion was used to determine each covariate contribution to OS and DFS. Univariate analysis demonstrated that increasing LPA correlated with both OS (P = 0.017) and DFS (P = 0.038). In multivariate analysis controlling for patient and tumor characteristics, LPA correlated with OS and DFS in patients who had not received neoadjuvant treatment (n = 64), with higher LPA associated with improved OS and DFS. Moreover, LPA was of equivalent, or slightly higher importance than pathologic stage. These measures were not predictive among patients (n = 166) receiving neoadjuvant chemoradiation. Core muscle size appears to be an independent predictor of both OS and DFS, as significant as tumor stage, in patients following transhiatal esophagectomy. Changes in muscle mass related to preoperative treatment may confound this effect. Assessment of core muscle size may provide an additional objective measure for risk stratification prior to undergoing esophagectomy.

Impact of Hospital Characteristics on Failure to Rescue Following Major Surgery.

BACKGROUND Sarcopenia is associated with poor outcomes after major surgery. There are currently no data regarding the financial implications of providing care for these high-risk patients. STUDY DESIGN We identified 1,593 patients within the Michigan Surgical Quality Collaborative (MSQC) who underwent elective major general or vascular surgery at a single institution between 2006 and 2011. Patient sarcopenia, determined by lean psoas area (LPA), was derived from preoperative CT scans using validated analytic morphomic methods. Financial data including hospital revenue and direct costs were acquired for each patient through the hospitals finance department. Financial data were adjusted for patient and procedural factors using multiple linear regression methods, and Mann-Whitney U test was used for significance testing. RESULTS After controlling for patient and procedural factors, decreasing LPA was independently associated with increasing payer costs (

Improving mortality following emergent surgery in older patients requires focus on complication rescue.

6,989.17 per 1,000 mm(2) LPA, p < 0.001). The influence of LPA on payer costs increased to

Morphometric Age and Mortality After Liver Transplant

26,988.41 per 1,000 mm(2) decrease in LPA (p < 0.001) in patients who experienced a postoperative complication. Further, the covariate-adjusted hospital margin decreased by

Failure to rescue and mortality following repair of abdominal aortic aneurysm

2,620 per 1,000 mm(2) decrease in LPA (p < 0.001) such that average negative margins were observed in the third of patients with the smallest LPA. CONCLUSIONS Sarcopenia is associated with high payer costs and negative margins after major surgery. Although postoperative complications are universally expensive to payers and providers, sarcopenic patients represent a uniquely costly patient demographic. Given that sarcopenia may be remediable, efforts to attenuate costs associated with major surgery should focus on targeted preoperative interventions to optimize these high risk patients for surgery.

Geographic variation in use of laparoscopic colectomy for colon cancer

Objective:To determine the effect of hospital characteristics on failure to rescue after high-risk surgery in Medicare beneficiaries. Summary Background Data:Reducing failure to rescue events is a common quality target for US hospitals. Little is known about which hospital characteristics influence this phenomenon and more importantly by how much. Methods:We identified 1,945,802 Medicare beneficiaries undergoing 1 of six high-risk general or vascular operations between 2007 and 2010. Using multilevel mixed-effects logistic regression modeling, we evaluated how failure to rescue rates were influenced by specific hospital characteristics previously associated with postsurgical outcomes. We used variance partitioning to determine the relative influence of patient and hospital characteristics on the between-hospital variability in failure to rescue rates. Results:Failure to rescue rates varied up to 11-fold between very high and very low mortality hospitals. Comparing the highest and lowest mortality hospitals, we observed that teaching status (range: odds ratio [OR] 1.08–1.54), high hospital technology (range: OR 1.08–1.58), increasing nurse-to-patient ratio (range: OR 1.02–1.14), and presence of >20 intensive care unit (ICU) beds (range: OR 1.09–1.62) significantly influenced failure to rescue rates for all procedures. When taken together, hospital and patient characteristics accounted for 12% (lower extremity revascularization) to 57% (esophagectomy) of the observed variation in failure to rescue rates across hospitals. Conclusions:Although several hospital characteristics are associated with lower failure to rescue rates, these macrosystem factors explain a small proportion of the variability between hospitals. This suggests that microsystem characteristics, such as hospital culture and safety climate, may play a larger role in improving a hospitals ability to manage postoperative complications.