William G. Henderson

Impact of Body Mass Index on Perioperative Outcomes in Patients Undergoing Major Intra-abdominal Cancer Surgery

BackgroundObesity is an increasingly common serious chronic health condition. We sought to determine the impact of body mass index (BMI) on perioperative outcomes in patients undergoing major intra-abdominal cancer surgery.MethodsA prospective, multi-institutional, risk-adjusted cohort study of patients undergoing major intra-abdominal cancer surgery was performed from the 14 university hospitals participating in the Patient Safety in Surgery Study of the National Surgical Quality Improvement Program (NSQIP). Demographic, clinical, and intraoperative variables and 30-day morbidity and mortality were prospectively collected in standardized fashion. Analysis of variance, Bonferroni multiple comparisons of means tests, and multivariable logistic regression analysis were performed.ResultsWe identified 2258 patients who underwent esophagectomy (nxa0=xa029), gastrectomy (nxa0=xa0223), hepatectomy (nxa0=xa0554), pancreatectomy (nxa0=xa0699), or low anterior resection/proctectomy (nxa0=xa0753). Patients were stratified by National Institutes of Health (NIH)-defined BMI obesity class, with 573 (25.4%) patients classified as obese (BMIxa0>xa030xa0kg/m2). There were no differences in mean work relative value units, total time of operation, or length of stay amongst the BMI classes. After adjusting for other risk factors, obesity was not a risk factor for death or major complications but was a risk factor for wound complications. The risk of postoperative death was greatest in underweight patients (odds ratio [OR] 5.24; 95% confidence interval [CI] 1.7–16.2).ConclusionIn patients undergoing major intra-abdominal cancer surgery, obesity is not a risk factor for postoperative mortality or major complications. Importantly, underweight patients have a fivefold increased risk of postoperative mortality, perhaps a consequence of their underlying nutritional status.

Risk of Major Adverse Cardiac Events Following Noncardiac Surgery in Patients With Coronary Stents

IMPORTANCEnGuidelines recommend delaying noncardiac surgery in patients after coronary stent procedures for 1 year after drug-eluting stents (DES) and for 6 weeks after bare metal stents (BMS). The evidence underlying these recommendations is limited and conflicting.nnnOBJECTIVEnTo determine risk factors for adverse cardiac events in patients undergoing noncardiac surgery following coronary stent implantation.nnnDESIGN, SETTING, AND PARTICIPANTSnA national, retrospective cohort study of 41,989 Veterans Affairs (VA) and non-VA operations occurring in the 24 months after a coronary stent implantation between 2000 and 2010. Nonlinear generalized additive models examined the association between timing of surgery and stent type with major adverse cardiac events (MACE) adjusting for patient, surgery, and cardiac risk factors. A nested case-control study assessed the association between perioperative antiplatelet cessation and MACE.nnnMAIN OUTCOMES AND MEASURESnA composite 30-day MACE rate of all-cause mortality, myocardial infarction, and cardiac revascularization.nnnRESULTSnWithin 24 months of 124,844 coronary stent implantations (47.6% DES, 52.4% BMS), 28,029 patients (22.5%; 95% CI, 22.2%-22.7%) underwent noncardiac operations resulting in 1980 MACE (4.7%; 95% CI, 4.5%-4.9%). Time between stent and surgery was associated with MACE (<6 weeks, 11.6%; 6 weeks to <6 months, 6.4%; 6-12 months, 4.2%; >12-24 months, 3.5%; Pu2009<u2009.001). MACE rate by stent type was 5.1% for BMS and 4.3% for DES (Pu2009<u2009.001). After adjustment, the 3 factors most strongly associated with MACE were nonelective surgical admission (adjusted odds ratio [AOR], 4.77; 95% CI, 4.07-5.59), history of myocardial infarction in the 6 months preceding surgery (AOR, 2.63; 95% CI, 2.32-2.98), and revised cardiac risk index greater than 2 (AOR, 2.13; 95% CI, 1.85-2.44). Of the 12 variables in the model, timing of surgery ranked fifth in explanatory importance measured by partial effects analysis. Stent type ranked last, and DES was not significantly associated with MACE (AOR, 0.91; 95% CI, 0.83-1.01). After both BMS and DES placement, the risk of MACE was stable at 6 months. A case-control analysis of 284 matched pairs found no association between antiplatelet cessation and MACE (OR, 0.86; 95% CI, 0.57-1.29).nnnCONCLUSIONS AND RELEVANCEnAmong patients undergoing noncardiac surgery within 2 years of coronary stent placement, MACE were associated with emergency surgery and advanced cardiac disease but not stent type or timing of surgery beyond 6 months after stent implantation. Guideline emphasis on stent type and surgical timing for both DES and BMS should be reevaluated.

Design and statistical methodology of the National Surgical Quality Improvement Program: why is it what it is?

This article reviews the philosophy and principles of the National Surgical Quality Improvement Program (NSQIP) that the founders of the program had in mind when they developed the program; explains how the philosophy and principles led to the design and statistical methods that were chosen for the program; and reviews recently proposed changes to the program and potential problems that these changes may create.

The influence of body mass index obesity status on vascular surgery 30-day morbidity and mortality

OBJECTIVEnMild obesity may have a protective effect against some diseases, termed an obesity paradox. This study examined the effect of body mass index (Kg/m(2) BMI) on surgical 30-day morbidity and mortality in patients undergoing vascular surgical procedures.nnnMETHODSnAs part of the National Surgical Quality Improvement Program (NSQIP), demographic and clinical risk variables, mortality, and 22 defined complications (morbidity) were obtained over three years from vascular services at 14 medical centers. At each medical center, patients from the operative schedule were prospectively and systematically enrolled according to NSQIP protocols. Outcomes and risk variables were compared across NIH-defined obesity classes (underweight [BMI<or=18.5], normal [18.540]) using analysis of variance and means comparisons. Logistic regression was used to control for other risk factors.nnnRESULTSnVascular procedures in 7,543 patients included lower extremity revascularization (24.6%), aneurysm repair (17.4%), cerebrovascular procedures (17.3%), amputations (9.4%), and other procedures (31.3%). In the entire cohort, there were 1,659 (22.0%) patients with complications and 295 (3.9%) deaths. Risk factors of hypertension and diabetes increased with BMI (analysis of variance [ANOVA] P < .05) as expected; smoking, disseminated cancer, and stroke decreased (ANOVA P < .01). Twenty other risk factors, as well as mortality and morbidity, had U or J-shaped distributions with the highest incidence in underweight and/or obese class III extremes but reduced minimums in overweight or obese I classes (ANOVA P < .05). After controlling for age, gender, and operation type, mortality risk remained lowest in obese class I patients (Odds ratio [OR] 0.63, P = .023) while morbidity risk was highest in obese class III patients (OR 1.70, P = .0003), due to wound infection, thromboembolism, and renal complications.nnnCONCLUSIONnUnderweight patients have poorer outcomes and class III obesity is associated with increased morbidity. Mildly obese patients have reduced co-morbid illness, surprisingly even less than normal-class patients, with correspondingly reduced mortality. Mild obesity is not a risk factor for 30-day outcomes after vascular surgery and confers an advantage.

The Case Against Volume as a Measure of Quality of Surgical Care

Healthcare purchasers, represented by the Leapfrog Group, have attempted to set standards for “quality” of surgical care that include a minimum volume for each of five major surgical procedures, with the assumption that higher volumes in surgery bring better outcomes. The VA National Surgical Quality Improvement Program (NSQIP) is a validated, outcome-based program that prospectively collects clinical data on all major surgical operations in the VA, and builds validated risk-adjustment models that generate, for each hospital and each surgical specialty within a hospital, risk-adjusted outcomes expressed as O/E (observed to expected) ratios for 30-day mortality and morbidity. The O/E ratio has been validated as a reliable comparative measure of the quality of surgical care. Unlike retrospective studies that are based on administrative databases, NSQIP studies have failed to demonstrate a direct relationship between volume and risk-adjusted outcomes of surgery across various specialties. These studies have emphasized that the quality of systems of care was more important than volume in determining the overall quality of surgical care at an institution. High-volume hospitals could still deliver poor care in as much as low-volume hospitals could deliver good care. NSQIP studies have also underscored the major limitations of claims data and administrative databases in the provision of adequate risk-adjustment models that are crucial for volume–outcome studies. Therefore, volume should not be substituted for prospectively monitored and properly risk-adjusted outcomes as a comparative measure of the quality of surgical care.

Predictors of wound complications after laryngectomy: A study of over 2000 patients

OBJECTIVES: To identify risk factors for and the rate of wound complications after laryngectomy in a large, prospectively collected national dataset, and to generate a predictive model. STUDY DESIGN: We used the National Surgical Quality Improvement Program (NSQIP) registry created by the Department of Veterans Affairs (VA) to identify patients undergoing total laryngectomy from 1989 to 1999 (n = 2063). We linked these data to inpatient and outpatient VA administrative records to capture data for prior radiation. Over 20 preoperative and intraoperative risk factors were analyzed using bivariate techniques. Those significant at the P < 0.01 level were analyzed with logistic regression and conjunctive consolidation to identify independent predictors of wound complications. RESULTS: The overall wound complication rate was 10.0%. In adjusted analyses, prolonged operative time (> 10 hours, odds ratio = 2.10, 95% confidence interval: 1.32-3.36), exposure to prior radiation therapy (OR =1.63, 1.07-2.46), presence of diabetes (OR = 1.78, 1.04-3.04), preoperative hypoalbumine-mia (OR =1.90, 1.32-2.74), anemia (OR =1.59, 1.07-2.36), and thrombocytosis (OR =1.48, 1.04-2.10) were independently associated with postoperative wound complications. A prognostic model using three variables—prior radiation therapy, diabetes, and hypoalbuminemia—provided excellent risk stratification into three tiers (6.3%, 13.7%, 21.7%). CONCLUSIONS: Preoperative radiation, prolonged operative time, low albumin, and diabetes were independently associated with postoperative wound infections. These results will help to identify patients at risk for wound complications, thus allowing for heightened surveillance and preventive measures where possible.

Preoperative risks and outcomes of hip and knee arthroplasty in the veterans health administration

The relationship between patient characteristics and outcomes of total joint arthroplasty (TJA) was examined in a population of veterans treated in VA hospitals. Outcomes included 30-day mortality and morbidity, postoperative length of stay, and readmission caused by surgical complications. A larger proportion of women then men were functionally impaired before surgery in both the hip (22% vs. 14%) and knee samples (14% vs. 7%; all P<.01). Rates of adverse outcomes in this population were very low. Preoperative comorbid conditions, abnormal laboratory values, and being nonwhite were related to poor outcomes of TJA. Gender was a significant independent predictor of morbidity and length of stay for total knee arthroplasty.

Open and Laparoscopic Adrenalectomy: Analysis of the National Surgical Quality Improvement Program

BACKGROUNDnNumerous series demonstrate the benefits of laparoscopic versus open adrenalectomy, but fail to adjust for confounding factors. This study uses the Veterans Affairs National Surgical Quality Improvement Program database to compare these two approaches, adjusting for baseline differences.nnnSTUDY DESIGNnLaparoscopic (n=358) and open (n=311) adrenalectomy data were collected at 123 Department of Veterans Affairs and 14 university hospitals from October 1, 2001 to September 30, 2004. Preoperative characteristics, operative data, and 30-day outcomes were compared using the chi-square or Fishers exact test for categorical variables and the t-test for continuous variables. Unadjusted odds ratio (OR) and 95% confidence interval (CI) were computed for the effect of operative approach on postoperative morbidity. Adjusted odds ratios and 95% CI were computed for this same effect, adjusting for variables that were predictive of outcomes or imbalanced at baseline. Data are reported as means +/-SD, unless otherwise indicated.nnnRESULTSnPatients undergoing open adrenalectomy were more likely to be older (57.8+/-11.9 years versus 53.5+/-13.2 years, p < 0.0001), harbor malignancy (44.5% versus 13.5%, p < 0.0001), have higher American Society of Anesthesiologists classifications (p=0.0037), smoke (35.4% versus 22.6%, p=0.0003), and have lower serum albumin levels (3.9+/-0.5 g/dL versus 4.0+/-0.5 g/dL, p=0.0241). Open procedures had increased operative times (3.9+/-1.8 hours versus 2.9+/-1.3 hours, p < 0.0001), transfusion requirements (0.7+/-1.8 U versus 0.1+/-0.5 U, p<0.0001), reoperations (4.8% versus 1.4%, p=0.0094), length of stay (9.4+/-11.0 days versus 4.1+/-4.7 days, p < 0.0001) and 30-day morbidity rates (17.4% versus 3.6%, p < 0.0001) with unadjusted and adjusted odds ratio (95% CI) of 5.52 (2.94, 10.33), and 3.97 (1.92, 8.22), respectively. Open procedures resulted in more pneumonia, unplanned intubation, unsuccessful ventilator wean, systemic sepsis, cardiac arrest, renal insufficiency, and wound infections.nnnCONCLUSIONSnEven after adjustment for confounding factors, 30-day morbidity was much higher for patients having open adrenalectomy.

Association between Intraoperative Hypotension and Hypertension and 30-day Postoperative Mortality in Noncardiac Surgery.

Background:Although deviations in intraoperative blood pressure are assumed to be associated with postoperative mortality, critical blood pressure thresholds remain undefined. Therefore, the authors estimated the intraoperative thresholds of systolic blood pressure (SBP), mean blood pressure (MAP), and diastolic blood pressure (DBP) associated with increased risk-adjusted 30-day mortality. Methods:This retrospective cohort study combined intraoperative blood pressure data from six Veterans Affairs medical centers with 30-day outcomes to determine the risk-adjusted associations between intraoperative blood pressure and 30-day mortality. Deviations in blood pressure were assessed using three methods: (1) population thresholds (individual patient sum of area under threshold [AUT] or area over threshold 2 SDs from the mean of the population intraoperative blood pressure values), (2). absolute thresholds, and (3) percent change from baseline blood pressure. Results:Thirty-day mortality was associated with (1) population threshold: systolic AUT (odds ratio, 3.3; 95% CI, 2.2 to 4.8), mean AUT (2.8; 1.9 to 4.3), and diastolic AUT (2.4; 1.6 to 3.8). Approximate conversions of AUT into its separate components of pressure and time were SBP < 67 mmHg for more than 8.2u2009min, MAP < 49 mmHg for more than 3.9u2009min, DBP < 33 mmHg for more than 4.4u2009min. (2) Absolute threshold: SBP < 70 mmHg for more than or equal to 5u2009min (odds ratio, 2.9; 95% CI, 1.7 to 4.9), MAP < 49 mmHg for more than or equal to 5u2009min (2.4; 1.3 to 4.6), and DBP < 30 mmHg for more than or equal to 5u2009min (3.2; 1.8 to 5.5). (3) Percent change: MAP decreases to more than 50% from baseline for more than or equal to 5u2009min (2.7; 1.5 to 5.0). Intraoperative hypertension was not associated with 30-day mortality with any of these techniques. Conclusion:Intraoperative hypotension, but not hypertension, is associated with increased 30-day operative mortality.

Predictors of cognitive decline following coronary artery bypass graft surgery

BACKGROUNDnA significant number of patients develop cognitive impairment that persists for months following coronary artery bypass grafting (CABG) surgery. Our objectives were to identify patient-related risk factors, processes of care, and the occurrence of any perioperative complications associated with cognitive decline.nnnMETHODSnNine hundred thirty-nine patients enrolled in the Processes, Structures, and Outcomes of Care in Cardiac Surgery study undergoing CABG-only surgery at 14 Veterans Administration medical centers between 1992 and 1996 completed a short battery of cognitive tests at baseline and 6-months post-CABG. The composite cognitive score was based on the sum of errors for each individual item in the battery. Multiple linear regression analyses were used to identify independent predictors of the 6-month composite cognitive score.nnnRESULTSnIn multivariable analyses, patient characteristics associated with cognitive decline included cerebrovascular disease (p = 0.009), peripheral vascular disease (p = 0.007), history of chronic disabling neurologic illness (p = 0.016), and living alone (p = 0.049), while the number of years of education (p = 0.001) was inversely related to cognitive decline. After adjustment for baseline patient risk factors, the presence of any postoperative complication(s) (p = 0.001) was also associated with cognitive decline while cardiopulmonary bypass time (p = 0.008) was inversely related to cognitive decline.nnnCONCLUSIONSnPatients with noncoronary manifestations of atherosclerosis, chronic disabling neurologic illness, or limited social support are at risk for cognitive decline after CABG surgery. In contrast, more years of education were associated with less cognitive decline. Preoperative assessment of risk factors identified in this study may be useful when counseling patients about the risk for cognitive decline following CABG surgery.