Robert W. Krell

Association between sarcopenia and the risk of serious infection among adults undergoing liver transplantation

Although sarcopenia (muscle loss) is associated with increased mortality after liver transplantation, its influence on other complications is less well understood. We examined the association between sarcopenia and the risk of severe posttransplant infections among adult liver transplant recipients. By calculating the total psoas area (TPA) on preoperative computed tomography scans, we assessed sarcopenia among 207 liver transplant recipients. The presence or absence of a severe posttransplant infection was determined by a review of the medical chart. The influence of posttransplant infections on overall survival was also assessed. We identified 196 episodes of severe infections among 111 patients. Fifty‐six patients had more than 1 infection. The median time to the development of an infection was 27 days (interquartile range = 13‐62 days). When the patients were grouped by TPA tertiles, patients in the lowest tertile had a greater than 4‐fold higher chance of developing a severe infection in comparison with patients in the highest tertile (odds ratio = 4.6, 95% confidence interval =  2.25‐9.53). In a multivariate analysis, recipient age (hazard ratio = 1.04, P = 0.02), pretransplant TPA (hazard ratio = 0.38, P < 0.01), and pretransplant total bilirubin level (hazard ratio = 1.05, P = 0.02) were independently associated with the risk of developing severe infections. Patients with severe posttransplant infections had worse 1‐year survival than patients without infections (76% versus 92%, P = 0.003). In conclusion, among patients undergoing liver transplantation, a lower TPA was associated with a heightened risk for posttransplant infectious complications and mortality. Future efforts should focus on approaches for assessing and mitigating vulnerability in patients undergoing transplantation. Liver Transpl 19:1396–1402, 2013.

Effects of Resident Involvement on Complication Rates after Laparoscopic Gastric Bypass

BACKGROUND Although resident involvement has been shown to be safe for most procedures, the impact of residents on outcomes after complex laparoscopic procedures is not well understood. We sought to examine the impact of resident involvement on outcomes after bariatric surgery using a population-based clinical registry. STUDY DESIGN We analyzed 17,057 patients who underwent a primary laparoscopic gastric bypass in the 35-hospital Michigan Bariatric Surgery Collaborative from July 2006 to August 2012. Resident involvement was characterized at the surgeon level. Using hierarchical logistic regression, we examined the influence of resident involvement on 30-day complications, accounting for patient characteristics as well as hospital and surgeon case volume. To evaluate potential mediating factors for specific complications, we also adjusted for operative duration. RESULTS Risk-adjusted 30-day complication rates with and without residents were 13.0% and 8.5%, respectively (p < 0.01). Resident involvement was independently associated with wound infection (odds ratio [OR] = 2.06; 95% CI, 1.24-3.43) and venous thromboembolism (OR = 2.01; 95% CI, 1.19-3.40), but not with any other medical or surgical complications. Operative duration was longer with resident involvement (median duration with residents 129 minutes vs 88 minutes without; p < 0.01). After adjusting for operative duration, resident involvement was still independently associated with wound infection (OR = 1.67; 95% CI, 1.01-2.76), but not venous thromboembolism (OR = 1.73; 95% CI, 0.99-3.04). CONCLUSIONS Resident involvement in laparoscopic gastric bypass is independently associated with wound infections and venous thromboembolism. The effect appears to be mediated in part by longer operative times. These findings highlight the importance of strategies to assess and improve resident technical proficiency outside the operating room.

Reliability of Risk-Adjusted Outcomes for Profiling Hospital Surgical Quality

IMPORTANCE Quality improvement platforms commonly use risk-adjusted morbidity and mortality to profile hospital performance. However, given small hospital caseloads and low event rates for some procedures, it is unclear whether these outcomes reliably reflect hospital performance. OBJECTIVE To determine the reliability of risk-adjusted morbidity and mortality for hospital performance profiling using clinical registry data. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort study was conducted using data from the American College of Surgeons National Surgical Quality Improvement Program, 2009. Participants included all patients (N = 55,466) who underwent colon resection, pancreatic resection, laparoscopic gastric bypass, ventral hernia repair, abdominal aortic aneurysm repair, and lower extremity bypass. MAIN OUTCOMES AND MEASURES Outcomes included risk-adjusted overall morbidity, severe morbidity, and mortality. We assessed reliability (0-1 scale: 0, completely unreliable; and 1, perfectly reliable) for all 3 outcomes. We also quantified the number of hospitals meeting minimum acceptable reliability thresholds (>0.70, good reliability; and >0.50, fair reliability) for each outcome. RESULTS For overall morbidity, the most common outcome studied, the mean reliability depended on sample size (ie, how high the hospital caseload was) and the event rate (ie, how frequently the outcome occurred). For example, mean reliability for overall morbidity was low for abdominal aortic aneurysm repair (reliability, 0.29; sample size, 25 cases per year; and event rate, 18.3%). In contrast, mean reliability for overall morbidity was higher for colon resection (reliability, 0.61; sample size, 114 cases per year; and event rate, 26.8%). Colon resection (37.7% of hospitals), pancreatic resection (7.1% of hospitals), and laparoscopic gastric bypass (11.5% of hospitals) were the only procedures for which any hospitals met a reliability threshold of 0.70 for overall morbidity. Because severe morbidity and mortality are less frequent outcomes, their mean reliability was lower, and even fewer hospitals met the thresholds for minimum reliability. CONCLUSIONS AND RELEVANCE Most commonly reported outcome measures have low reliability for differentiating hospital performance. This is especially important for clinical registries that sample rather than collect 100% of cases, which can limit hospital case accrual. Eliminating sampling to achieve the highest possible caseloads, adjusting for reliability, and using advanced modeling strategies (eg, hierarchical modeling) are necessary for clinical registries to increase their benchmarking reliability.

A Checklist-Based Intervention to Improve Surgical Outcomes in Michigan: Evaluation of the Keystone Surgery Program

IMPORTANCE Previous studies of checklist-based quality improvement interventions have reported mixed results. OBJECTIVE To evaluate whether implementation of a checklist-based quality improvement intervention--Keystone Surgery--was associated with improved outcomes in patients in a large statewide population undergoing general surgery. DESIGN, SETTING, AND EXPOSURES A retrospective longitudinal study examined surgical outcomes in 64,891 Michigan patients in 29 hospitals using Michigan Surgical Quality Collaborative clinical registry data from 2006 through 2010. Multivariable logistic regression and difference-in-differences analytic approaches were used to evaluate whether Keystone Surgery program implementation was associated with improved surgical outcomes following general surgery procedures, apart from existing temporal trends toward improved outcomes during the study period. MAIN OUTCOMES AND MEASURES Risk-adjusted rates of superficial surgical site infection, wound complication, any complication, and 30-day mortality. RESULTS Implementation of Keystone Surgery in 14 participating centers was not associated with improvements in surgical outcomes during the study period. Adjusted rates of superficial surgical site infection (3.2% vs 3.2%, P=.91), wound complication (5.9% vs 6.5%, P=.30), any complication (12.4% vs 13.2%, P=.26), and 30-day mortality (2.1% vs 1.9%, P=.32) at participating hospitals were similar before and after implementation. Difference-in-differences analysis accounting for trends in 15 nonparticipating centers and sensitivity analysis excluding patients receiving surgery in the first 6 or 12 months after program implementation yielded similar results. CONCLUSIONS AND RELEVANCE Implementation of a checklist-based quality improvement intervention did not affect rates of adverse surgical outcomes among patients undergoing general surgery in participating Michigan hospitals. Additional research is needed to understand why this program was not successful prior to further dissemination and implementation of this model to other populations.

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

Objective: To determine whether a hospitals ability to rescue patients from major complications underlies variation in outcomes for elderly patients undergoing emergent surgery. Background: Perioperative mortality rates in elderly patients undergoing emergent general/vascular operations are high and vary widely across Michigan hospitals. Methods: We identified 23,224 patients undergoing emergent general/vascular surgical procedures at 41 hospitals within the Michigan Surgical Quality Collaborative between 2006 and 2011. Hospitals were ranked by risk- and reliability-adjusted 30-day mortality rates and grouped into tertiles. We stratified patients by age (<75 and ≥75 years). Risk-adjusted major complication and failure-to-rescue (ie, mortality after major complication) rates were determined for each tertile of hospital mortality. Results: Risk-adjusted mortality rates in elderly patients varied 2-fold across all hospitals. Complication rates correlated poorly with mortality. Failure-to-rescue rates, however, were markedly higher in high-mortality hospitals (29% lowest tertile vs 41% highest tertile; P < 0.01). When compared with younger patients, overall failure-to-rescue rates were almost 2-fold greater in the elderly (36.1% ≥75 vs 18.7% <75; P < 0.01). Conclusions: A hospitals failure to rescue patients from major complications seems to underlie the variation in mortality rates across Michigan hospitals after emergent surgery. Although higher failure-to-rescue rates in the elderly may signify their diminished physiological reserve for surviving critical illness, the wide variation across hospitals also highlights the importance of systems aimed at the early recognition and effective management of major complications in this vulnerable population.

Influence of median surgeon operative duration on adverse outcomes in bariatric surgery

BACKGROUND Evidence suggests that prolonged operative time adversely affects surgical outcomes. However, whether faster surgeons have better outcomes is unclear, as a surgeon׳s speed could reflect skill and efficiency, but may alternatively reflect haste. This study evaluates whether median surgeon operative time is associated with adverse surgical outcomes after laparoscopic Roux-en-Y gastric bypass. METHODS We performed a retrospective cohort study using statewide clinical registry data from the years 2006 to 2012. Surgeons were ranked by their median operative time and grouped into terciles. Multivariable logistic regression with robust standard errors was used to evaluate the influence of median surgeon operative time on 30-day surgical outcomes, adjusting for patient and surgeon characteristics, trainee involvement, concurrent procedures, and the complex interaction between these variables. RESULTS A total of 16,344 patients underwent surgery during the study period. Compared to surgeons in the fastest tercile, slow surgeons required 53 additional minutes to complete a gastric bypass procedure (median [interquartile range] 139 [133-150] versus 86 [69-91], P<.001). After adjustment for patient characteristic only, slow surgeons had significantly higher adjusted rates of any complication, prolonged length of stay, emergency department visits or readmissions, and venous thromboembolism (VTE). After further adjustment for surgeon characteristics, resident involvement, and the interaction between these variables, slow surgeons had higher rates of any complication (10.5% versus 7.1%, P=.039), prolonged length of stay (14.0% versus 4.4%, P=.002), and VTE (0.39% versus .22%, P<.001). CONCLUSION Median surgeon operative duration is independently associated with adjusted rates of certain adverse outcomes after laparoscopic Roux-en-Y gastric bypass. Improving surgeon efficiency while operating may reduce operative time and improve the safety of bariatric surgery.

Postoperative burden of hospital-acquired Clostridium difficile infection

OBJECTIVE Clostridium difficile infection (CDI) is a common hospital-acquired infection. Previous reports on the incidence, risk factors, and impact of CDI on resources in the surgical population are limited. In this context, we study CDI across diverse surgical settings. METHODS We prospectively identified patients with laboratory-confirmed postoperative CDI after 40 different general, vascular, or gynecologic surgeries at 52 academic and community hospitals between July 2012 and September 2013. We used multivariable regression models to identify CDI risk factors and to determine the impact of CDI on resource utilization. RESULTS Of 35,363 patients, 179 (0.51%) developed postoperative CDI. The highest rates of CDI occurred after lower-extremity amputation (2.6%), followed by bowel resection or repair (0.9%) and gastric or esophageal operations (0.7%). Gynecologic and endocrine operations had the lowest rates (0.1% and 0%, respectively). By multivariable analyses, older age, chronic immunosuppression, hypoalbuminemia (≤3.5 g/dL), and preoperative sepsis were associated with CDI. Use of prophylactic antibiotics was not independently associated with CDI, neither was sex, body mass index (BMI), surgical priority, weight loss, or comorbid conditions. Three procedure groups had higher odds of postoperative CDI: lower-extremity amputations (adjusted odds ratio [aOR], 3.5; P=.03), gastric or esophageal operations (aOR, 2.1; P=.04), and bowel resection or repair (aOR, 2; P=.04). Postoperative CDI was independently associated with increased length of stay (mean, 13.7 d vs 4.5 d), emergency department presentations (18.9 vs 9.1%) and readmissions (38.9% vs 7.2%, all P<.001). CONCLUSIONS Incidence of postoperative CDI varies by surgical procedure. Postoperative CDI is also associated with higher rates of extended length of stay, emergency room presentations, and readmissions, which places a potentially preventable burden on hospital resources.

Abdominal aortic calcification and surgical outcomes in patients with no known cardiovascular risk factors.

Introduction:In the setting of cardiovascular (CV) risk evaluation before major elective surgery, current risk assessment tools are relatively poor for discriminating among patients. For example, patients with clinical CV risk factors can be clearly identified; but among those without appreciated clinical CV risk, there may be a subset with stigmata of CV disease noted during the preoperative radiographic evaluation. Our study evaluated the relationship between abdominal aortic (AA) calcification measured on preoperative computed tomography (CT) imaging and surgical complications in patients undergoing general elective and vascular surgery. We hypothesized that patients with no known CV risk factors but significant aortic calcification on preoperative imaging will have inferior surgical outcomes. Methods:The study group included 1180 patients from the Michigan Surgical Quality Collaborative (MSQC) database who underwent major general or vascular elective surgery between 2006 and 2009 and who had a CT scan of the abdomen specifically for preoperative planning. AA calcification was measured using novel analytic morphomic techniques and reported as a percentage of the total wall area containing calcification. Patients were divided into cohorts by clinical CV risk and extent of AA calcification. Univariate analysis was used to compare postoperative morbidity between patient cohorts. Multivariate logistic regression analysis was used to compare continuous AA calcification with overall morbidity in patients with no clinical CV risk factors. Results:AA calcification was strongly skewed to the right (53.5% had no AA calcification) and was significantly correlated with age (&rgr; = 0.43, P < 0.001). Unadjusted univariate analysis of morbidity showed no significant differences in complication rates between patients in the clinical CV risk and significant AA calcification (no known CV risk factor) categories. The clinical CV risk (P < 0.001) and significant AA calcification without CV risk factors (P = 0.009) populations both had significantly more infectious and overall complications than patients with no AA calcification and no clinical CV risk. Multivariate logistic regression confirmed that AA calcification was a significant predictor of morbidity in patients with no clinical CV risk factors (odds ratio = 1.35, P = 0.017). Discussion:This study suggests that AA calcification may be related to progression of CV disease and surgical outcomes. A better understanding of the complex interaction of patient physiology with overall ability to recover from major surgery, using novel approaches such as analytic morphomics, has great potential to improve risk stratification and patient selection.

Profiling hospitals on bariatric surgery quality: which outcomes are most reliable?

BACKGROUND Under the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program, hospitals will receive risk-adjusted outcomes feedback for peer comparisons and benchmarking. It remains uncertain whether bariatric outcomes have adequate reliability to identify outlying performance, especially for hospitals with low caseloads that will be included in the program. We explored the ability of risk-adjusted outcomes to identify outlying hospital performance with bariatric surgery for a range of hospital caseloads. STUDY DESIGN We used the 2010 State Inpatient Databases for 12 states (N = 31,240 patients) to assess different outcomes (eg, complications, reoperation, and mortality) after bariatric stapling procedures. We first quantified outcomes reliability on a 0 (no reliability) to 1 (perfect reliability) scale. We then assessed whether risk- and reliability-adjusted outcomes could identify outlying performance among hospitals with different annual caseloads. RESULTS Overall and serious complications had the highest overall reliability, but this was heavily dependent on caseload. For example, among hospitals with the lowest caseloads (mean 56 cases/year), reliability for overall complications was 0.49 and 6.0% of hospitals had outlying performance. For hospitals with the highest caseloads (mean 298 cases/year), reliability for overall complications was 0.79 and 30.3% of hospitals had outlying performance. Reoperation had adequate reliability for hospitals with caseloads higher than 120 cases/year. Mortality had unacceptably low reliability regardless of hospital caseloads. CONCLUSIONS Overall complications and serious complications have adequate reliability for distinguishing outlying performance with bariatric surgery, even for hospitals with low annual caseloads. Rare outcomes, such as reoperations, have inadequate reliability to inform peer-based comparisons for hospitals with low annual caseloads, and mortality has unacceptably low reliability for bariatric performance profiling.

Complication Rates of Ostomy Surgery Are High and Vary Significantly Between Hospitals

BACKGROUND: Ostomy surgery is common and has traditionally been associated with high rates of morbidity and mortality, suggesting an important target for quality improvement. OBJECTIVE: The purpose of this work was to evaluate the variation in outcomes after ostomy creation surgery within Michigan to identify targets for quality improvement. DESIGN: This was a retrospective cohort study. SETTINGS: The study took place within the 34-hospital Michigan Surgical Quality Collaborative. PATIENTS: Patients included were those undergoing ostomy creation surgery between 2006 and 2011. MAIN OUTCOME MEASURES: We evaluated hospital morbidity and mortality rates after risk adjustment (age, comorbidities, emergency vs elective, and procedure type). RESULTS: A total of 4250 patients underwent ostomy creation surgery; 3866 procedures (91.0%) were open and 384 (9.0%) were laparoscopic. Unadjusted morbidity and mortality rates were 43.9% and 10.7%. Unadjusted morbidity rates for specific procedures ranged from 32.7% for ostomy-creation-only procedures to 47.8% for Hartmann procedures. Risk-adjusted morbidity rates varied significantly between hospitals, ranging from 31.2% (95% CI, 18.4–43.9) to 60.8% (95% CI, 48.9–72.6). There were 5 statistically significant high-outlier hospitals and 3 statistically significant low-outlier hospitals for risk-adjusted morbidity. The pattern of complication types was similar between high- and low-outlier hospitals. Case volume, operative duration, and use of laparoscopic surgery did not explain the variation in morbidity rates across hospitals. LIMITATIONS: This work was limited by its retrospective study design, by unmeasured variation in case severity, and by our inability to differentiate between colostomies and ileostomies because of the use of Current Procedural Terminology codes. CONCLUSIONS: Morbidity and mortality rates for modern ostomy surgery are high. Although this type of surgery has received little attention in healthcare policy, these data reveal that it is both common and uncommonly morbid. Variation in hospital performance provides an opportunity to identify quality improvement practices that could be disseminated among hospitals.