Multifactorial comparison of modified and conventional perfusion strategies in a porcine model of cardiopulmonary bypass.

BACKGROUND: Utilization of thromboresistant circuits in cardiopulmonary bypass (CPB) surgery has been controversial. However, due to the advantages associated with these types of circuits, we sought to evaluate the efficacy of use of low-dose heparin in conjunction with thromboresistant surfaces, closed perfusion system, elimination of blood-gas interface, maintenance of hematocrit to >25%, and systemic normothermia, with respect to the conventional strategy of non-thromboresistant open circuits with high-dose heparin, during 3 h of CPB in an animal model. METHODS: Using an open-chest swine model, animals were placed on CPB for 3 h with additional monitoring for 1 h post-CPB. Pigs were randomized into either a heparin-bonded circuit (HBC) group (n = 10) or a non-HBC (NHB) group (n = 10). Hemodynamic, hematologic, and biochemical parameters and multiphoton microscopy were used to compare the two groups. RESULTS: Pigs in the HBC group showed a 38.4% reduction in post-CPB blood loss in comparison with the NHB group (P = 0.0007). Additionally, compared with the HBC group, the NHB group exhibited a 32.7% post-CPB reduction in platelets (P < 0.001) and significant increases in alkaline phosphatase, aspartate aminotransferase, and creatine phosphokinase enzymes (P < 0.0202, P = 0.0015, P < 0.0001; respectively). Multiphoton imaging of the arterial filters revealed no entrapment of RBC, WBC, and platelets in the HBC group, while the filters in the NHB group were clogged by these cells. CONCLUSION: Utilization of modified perfusion strategy employing low-dose heparin and closed thromboresistant circuits is successful in ameliorating the potential adverse hematologic and pro-inflammatory elements induced with open perfusion system of non-thromboresistant circuits most commonly used in cardiac surgery.

Development and evaluation of a novel solution, Somah, for the procurement and preservation of beating and nonbeating donor hearts for transplantation.

BACKGROUND: Injury to myocytes, endocardium, and the coronary endothelium during harvesting and storage can compromise outcomes after heart transplantation. Safeguarding of structure and function of cardiomyocytes and endothelium in donor hearts may lead to improved patient survival after transplantation. Information gained from porcine hearts stored in standard transplant solution was used to design a superior preservation solution that would optimally protect and maintain organs from beating heart and/or nonbeating heart donors during long-term storage. METHODS AND RESULTS: Multiphoton microscopy was used to image deep within cardiac biopsies and coronary artery tissue harvested from porcine hearts obtained from beating heart and nonbeating heart donors for analysis of myocyte and endothelial cell structure and function. Cell structural integrity and viability, calcium mobilization, and nitric oxide generation were determined with fluorescence viability markers, immunofluorescence, and Western blots. During hypothermic storage in standard preservation solution, Celsior, myocyte, and endothelial viability was markedly attenuated in hearts obtained from beating heart donors. In contrast, hearts from beating and nonbeating heart donors stored in the newly formulated Somah solution demonstrated an increase in high-energy phosphate levels, protection of cardiac myocyte viability, mitochondrial membrane polarization, and structural proteins. Similarly, coronary artery endothelial organization and function, calcium mobilization, and nitric oxide generation were well maintained during temporal storage in Somah. CONCLUSIONS: The Celsior preservation solution in clinical use today has led to a profound decline in cardiomyocyte and endothelial cell viability, whereas the newly designed Somah solution has safeguarded myocyte and endothelial integrity and function during organ storage. Use of Somah as a storage medium may lead to optimized graft function and long-term patient survival after transplantation.

Derivation and validation of a preoperative prediction rule for delirium after cardiac surgery.

BACKGROUND: Delirium is a common outcome after cardiac surgery. Delirium prediction rules identify patients at risk for delirium who may benefit from targeted prevention strategies, early identification, and treatment of underlying causes. The purpose of the present prospective study was to develop a prediction rule for delirium in a cardiac surgery cohort and to validate it in an independent cohort. METHODS AND RESULTS: Prospectively, cardiac surgery patients > or =60 years of age were enrolled in a derivation sample (n=122) and then a validation sample (n=109). Beginning on the second postoperative day, patients underwent a standardized daily delirium assessment, and delirium was diagnosed according to the confusion assessment method. Delirium occurred in 63 (52%) of the derivation cohort patients. Multivariable analysis identified 4 variables independently associated with delirium: prior stroke or transient ischemic attack, Mini Mental State Examination score, abnormal serum albumin, and the Geriatric Depression Scale. Points were assigned to each variable: Mini Mental State Examination < or =23 received 2 points, and Mini Mental State Examination score of 24 to 27 received 1 point; Geriatric Depression Scale >4, prior stroke/transient ischemic attack, and abnormal albumin received 1 point each. In the derivation sample, the cumulative incidence of delirium for point levels of 0, 1, 2, and > or =3 was 19%, 47%, 63%, and 86%, respectively (C statistic, 0.74). The corresponding incidence of delirium in the validation sample was 18%, 43%, 60%, and 87%, respectively (C statistic, 0.75). CONCLUSIONS: Delirium occurs frequently after cardiac surgery. Using 4 preoperative characteristics, clinicians can determine cardiac surgery patients' risk for delirium. Patients at higher delirium risk could be candidates for close postoperative monitoring and interventions to prevent delirium.

Operative blood loss, blood transfusion, and 30-day mortality in older patients after major noncardiac surgery.

OBJECTIVE: Anemia and operative blood loss are common in the elderly, but evidence is lacking on whether intraoperative blood transfusions can reduce the risk of postoperative death. METHODS: We analyzed retrospective data from 239,286 patients 65 years of older who underwent major noncardiac surgery in 1997 to 2004 at veteran hospitals nationwide. Propensity-score matching was used to adjust for differences between patients who received intraoperative blood transfusions (9.4%) and those who did not, and data were used to determine the association between intraoperative blood transfusion and 30-day postoperative mortality. RESULTS: After propensity-score matching, intraoperative blood transfusion was associated with mortality risk reductions in patients with preoperative hematocrit levels of <24% (odds ratio: 0.60, 95% CI: 0.41-0.87), and in patients with hematocrit of 30% or greater when there is substantial (500-999 mL) blood loss (odds ratio: 0.35, 95% CI: 0.22-0.56 for hematocrit levels between 30%-35.9% and 0.78, 95% CI: 0.62-0.97 for hematocrit levels of 36% or greater). When operative blood loss was <500 mL, transfusion was not associated with mortality reductions for patients with hematocrit levels of 24% or greater, and conferred increased mortality risks in patients with preoperative hematocrit levels between 30% to 35.9% (odds ratio 1.29, 95% CI: 1.04-1.60). CONCLUSIONS: Intraoperative blood transfusion is associated with a lower 30-day postoperative mortality among elderly patients undergoing major noncardiac surgery if there is substantial operative blood loss or low preoperative hematocrit levels (<24%). Transfusion is associated with increased mortality risks for those with preoperative hematocrit levels between 30% and 35.9% and <500 mL of blood loss.

Evaluation of blood components exposed to coated arterial filters in extracorporeal circuits.

BACKGROUND: Biocompatible surfaces play an important role in the inflammatory response during cardiopulmonary bypass (CBP), with the arterial filter contributing a large surface area of the circuit. Different filter-coating materials designed to improve blood-filter biocompatibility are currently used in CPB circuits. This study evaluates eight biocompatible coatings used for arterial filters and their effects on blood components during circulation. METHODS: Arterial filters were randomly assigned in eight independent heparin-bonded tubing loops and perfused by a single swine (n=8). Arterial blood was routed simultaneously, but separately, into each circuit and circulated for 30 minutes at 37 degrees C. Blood samples were drawn for CBC, ACT, and TAT III measurements at baseline, post-heparinization and post-circulation. At study completion, filters were imaged using multiphoton microscopy. RESULTS: RBC, platelet, and WBC counts, and TAT III complex were all decreased after 30 minutes of circulation; however, WBC count was the only parameter that showed statistically significant differences between the filters. Circulating WBC reduction ranged from 6% (Carmeda and Trillium) to 41% (Terumo-X-coating) with corresponding microscopic confirmation of increased WBC entrapment. CONCLUSION: All eight filter coatings altered the blood components to varying degrees. Selection of the most effective filter, in conjunction with a heparin-bonded circuit for CPB, may decrease the intraoperative foreign-surface activation of blood cells.

Race and surgical outcomes: it is not all black and white.

BACKGROUND: Studies using Medicare data have suggested that African American race is an independent predictor of death after major surgery. We hypothesized that the apparent adverse effect of race on surgical outcomes is due to confounding by comorbidity, not race itself. METHODS: We identified all non-Hispanic white and African American general surgery, private sector patients included in the National Surgery Quality Improvement Program (NSQIP) Patient Safety in Surgery Study (2001-2004). Patient characteristics, comorbidities, and postoperative outcomes were collected/analyzed using NSQIP methodology. Characteristics between races were compared using Student t and chi(2) tests. Odds ratios (OR) for 30-day morbidity and mortality were calculated using multivariable logistic regression. RESULTS: We identified 34,141 white and 5068 African American patients. African Americans were younger but more likely to undergo emergency surgery and present with hypertension, dyspnea, diabetes, renal failure, open wounds/infection, or advanced American Society of Anesthesiology class (all P < 0.001). African Americans underwent less complex procedures but had higher unadjusted 30-day morbidity (14.33% vs. 12.35%; P < 0.001) and mortality (2.09% vs. 1.65%; P = 0.02). After controlling for comorbidity, African American race had no independent effect on mortality (OR 0.95, (0.74-1.23)) but was associated with a higher risk of postoperative cardiac arrest (OR 2.49, (1.80-3.45)) and renal insufficiency/failure (OR 1.70 (1.32-2.18)). CONCLUSION: African American race is associated with greater comorbidity and cardiac/renal complications but is not an independent predictor of perioperative mortality after general surgery. Efforts to improve postoperative outcomes in African Americans should focus on reducing the need for emergency surgery and improving perioperative management of comorbid conditions.

Successful implementation of the Department of Veterans Affairs' National Surgical Quality Improvement Program in the private sector: the Patient Safety in Surgery study.

BACKGROUND: The Veterans Affairs' (VA) National Surgical Quality Improvement Program (NSQIP) has been associated with significant reductions in postoperative morbidity and mortality. We sought to determine if NSQIP methods and risk models were applicable to private sector (PS) hospitals and if implementation of the NSQIP in the PS would be associated with reductions in adverse postoperative outcomes. METHODS: Data from patients (n = 184,843) undergoing major general or vascular surgery between October 1, 2001, and September 30, 2004, in 128 VA hospitals and 14 academic PS hospitals were used to develop prediction models based on VA patients only, PS patients only, and VA plus PS patients using logistic regression modeling, with measures of patient-related risk as the independent variables and 30-day postoperative morbidity or mortality as the dependent variable. RESULTS: Nine of the top 10 predictors of postoperative mortality and 7 of the top 10 for postoperative morbidity were the same in the VA and PS models. The ratios of observed to expected mortality and morbidity in the PS hospitals based on a model using PS data only versus VA + PS data were nearly identical (correlation coefficient = 0.98). Outlier status of PS hospitals was concordant in 26 of 28 comparisons. Implementation of the NSQIP in PS hospitals was associated with statistically significant reductions in overall postoperative morbidity (8.7%, P = 0.002), surgical site infections (9.1%, P = 0.02), and renal complications (23.7%, P = 0.004). CONCLUSIONS: The VA NSQIP methods and risk models in general and vascular surgery were fully applicable to PS hospitals. Thirty-day postoperative morbidity in PS hospitals was reduced with the implementation of the NSQIP.

Impact of body mass index on perioperative outcomes in patients undergoing major intra-abdominal cancer surgery.

BACKGROUND: Obesity 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. METHODS: A 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. RESULTS: We identified 2258 patients who underwent esophagectomy (n = 29), gastrectomy (n = 223), hepatectomy (n = 554), pancreatectomy (n = 699), or low anterior resection/proctectomy (n = 753). Patients were stratified by National Institutes of Health (NIH)-defined BMI obesity class, with 573 (25.4%) patients classified as obese (BMI > 30 kg/m(2)). 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). CONCLUSION: In 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.

Detecting the blind spot: complications in the trauma registry and trauma quality improvement.

BACKGROUND: The National Surgical Quality Improvement Program (NSQIP) has reduced complications for surgery patients in the Department of Veterans Affairs Healthcare System. The American College of Surgeons Committee on Trauma maintains the National Trauma Data Bank (NTDB) to track injured patient comorbidities, complications, and mortality. We sought to apply the NSQIP methodology to collect comorbidity and outcome data for trauma patients. Data were compared to the NTDB to determine the benefit and validity of using the NSQIP methodology for trauma. STUDY DESIGN: Utilizing the NSQIP methodology, data were collected from August 1, 2004 to July 31, 2005 on all adult patients admitted to the trauma service at a level 1 trauma center. NSQIP data were collected for general surgery patients during the same time period from the same institution. Data were also extracted from v5.0 of the NTDB for patients >or=18 years old admitted to level 1 trauma centers. Comparisons between University of Michigan (UM) NSQIP Trauma and UM NSQIP General Surgery patients and between UM NSQIP Trauma and NTDB (2004) patients were performed using univariate and multivariate analysis. RESULTS: Before risk adjustment, there was a difference in mortality between the UM NSQIP Trauma and NTDB (2004) groups with univariate analysis (8.4% vs 5.7%; odds ratio [OR], 0.7; 95% confidence interval [CI] 0.5-0.9; P = .01). This survival advantage reversed to favor the UM NSQIP Trauma patient group when risk adjustment was performed (OR, 2.3; 95% CI, 1.6-3.4; P < .001). The UM NSQIP Trauma group had more complications than the UM NSQIP general surgery patients. Despite having a lower risk-adjusted rate of mortality, the UM NSQIP Trauma patients had significantly higher rates of complications (wound infection, wound disruption, pneumonia, urinary tract infection, deep vein thrombosis, and sepsis) than the NTDB (2004) patients in both univariate and multivariate analyses. CONCLUSION: Complications occurred more frequently in trauma patients than general surgery patients. The UM NSQIP Trauma patients had higher rates of complications than reported in the NTDB. The NTDB data potentially underreport important comorbidity and outcome data. Application of the NSQIP methodology to trauma may present an improved means of effectively tracking and reducing adverse outcomes in a risk-adjusted manner.

Comparison of risk-adjusted 30-day postoperative mortality and morbidity in Department of Veterans Affairs hospitals and selected university medical centers: general surgical operations in men.

BACKGROUND: We used data from the Patient Safety in Surgery Study to compare patient populations, operative characteristics, and unadjusted and risk-adjusted 30-day postoperative mortality and morbidity between the Veterans Affairs (VA) (n = 94,098) and private (n = 18,399) sectors for general surgery operations in men. STUDY DESIGN: This is a prospective cohort study. Trained nurses collected preoperative risk factors, operative variables, and 30-day postoperative mortality and morbidity outcomes in male patients undergoing major general surgery operations at 128 VA medical centers and 14 university medical centers from October 1, 2001, to September 30, 2004. Multiple logistic regression analysis was used to identify preoperative predictors of postoperative mortality and morbidity. An indicator variable for VA versus private-sector medical center was added to the model to determine if risk-adjusted outcomes were significantly different in the two systems. RESULTS: The unadjusted 30-day mortality rate was higher in the VA compared with the private sector (2.62% versus 2.03%, p = 0.0002); unadjusted morbidity rate was lower in the VA compared with the private sector (12.24% versus 13.99%, p < 0.0001). After risk adjustment, odds ratio for mortality for the VA versus private sector was 1.23 (95% CI, 1.08-1.41). For morbidity after risk adjustment, the indicator variable for health-care system just missed statistical significance (p = 0.0585). Thirty-day postoperative mortality was comparable in the VA and private sector for very common operations but was higher in the VA for less common, more complex operations. CONCLUSIONS: In general surgery operations in men, the VA appeared to have a higher risk-adjusted mortality rate compared with the private sector, but differences in mortality ascertainment in the two sectors might account for some of this effect. The higher mortality in the VA could be the result of higher mortality in the less common, more complex operations. There is a trend toward lower risk-adjusted morbidity in the VA compared with the private sector.

Comparison of risk-adjusted 30-day postoperative mortality and morbidity in Department of Veterans Affairs hospitals and selected university medical centers: general surgical operations in women.

BACKGROUND: In 1985, Congress mandated that the Department of Veterans Affairs (VA) compare its risk-adjusted surgical results with those in the private sector. The National Surgical Quality Improvement Program was developed as a result, in the VA system, and subsequently trialed in 14 university medical centers in the private sector. This report examines the results of the comparison between patient characteristics and outcomes of female general surgical patients in the two health care environments. STUDY DESIGN: Preoperative patient characteristics and laboratory variables, operative variables, and unadjusted postoperative outcomes were compared between VA and the private sector populations. In addition, stepwise logistic regression models were developed for 30-day postoperative mortality and morbidity. Finally, the effect of being treated in a VA or private sector hospital was assessed by adding an indicator variable to the models and testing it for statistical significance. RESULTS: Data from 5,157 female general surgical VA patients who underwent eligible procedures were compared with those from 27,467 patients in the private sector. Unadjusted 30-day mortality was virtually identical in the two groups (1.3%). The unadjusted morbidity rate was slightly, but notably, higher in the private sector (10.9%) as compared with that observed in the VA (8.5%, p < 0.0001). Predictive models were generated for mortality and morbidity combining both groups; top variables in these models were similar to those described previously in the National Surgical Quality Improvement Program. The indicator variable for system of care (VA versus private sector) was not statistically significant in the mortality model, but substantially favored the VA in the morbidity model (odds ratio=0.80, 95% CI=0.71, 0.90). CONCLUSIONS: The data demonstrate that in female general surgical patients, risk-adjusted mortality rates are comparable in the VA and the private sector, but risk-adjusted morbidity is higher in the private sector. Rates of urinary tract infections in the two populations may account for much of the latter difference.

Comparison of risk-adjusted 30-day postoperative mortality and morbidity in Department of Veterans Affairs hospitals and selected university medical centers: vascular surgical operations in women.

BACKGROUND: Women with peripheral vascular disease requiring vascular operations are less well studied than their male counterparts. The surgical outcomes of female vascular patients in the Department of Veterans Affairs (VA) and private sector hospitals have not previously been compared, and their preoperative risk profile, postoperative morbidity, and mortality need to be better elucidated. STUDY DESIGN: Patients undergoing vascular operations at 14 private sector and 128 VA hospitals, from October 2001 through September 2004, had their preoperative characteristics, operative data, and 30-day postoperative morbidity and mortality compared, as part of the Patient Safety in Surgery (PSS) Study. Logistic regression analysis was performed to develop predictive models for morbidity and mortality, which allowed for a comparison of risk-adjusted outcomes between the two hospital groups. RESULTS: There were 458 vascular surgical operations performed in women in the VA, and 3,535 vascular operations were performed in women in the private sector. Eighteen of 45 preoperative comorbidities and laboratory variables differed considerably between the institutions, and 16 of 18 were adverse among the private sector patients. The unadjusted 30-day mortality rate was higher in the private sector compared with the VA (5.2% versus 2.4%, p=0.008); the unadjusted morbidity rate was higher in the private sector compared with the VA sector (23.4% versus 13.3%, p < 0.0001). After risk adjustment, there was no marked difference between the VA and the private sector in mortality (p=0.12), but the difference in morbidity rates remained pronounced, with an odds ratio of 0.60 for VA versus private sector (95% CI=0.44, 0.81). CONCLUSIONS: Compared with their VA counterparts, women undergoing vascular operations at private sector hospitals had a higher incidence of preoperative comorbidities; after risk adjustment, mortality did not differ substantially. Despite risk adjustment, the incidence of postoperative morbidity in the VA patients was considerably lower, suggesting unidentified differences in the hospital populations, their processes of care, or both.

Relationship of processes and structures of care in general surgery to postoperative outcomes: a qualitative analysis.

BACKGROUND: With increased focus on improving surgical care quality, understanding structures and processes that influence surgical care is timely and important, as is more precise specification of these through improved measurement. STUDY DESIGN: We conducted a qualitative study to help design a quantitative survey of structures and processes of surgical care. We audiotaped 44 face-to-face interviews with surgical care leaders and other diverse members of the surgical care team from 6 hospitals (two Veterans Affairs, four private sector). Qualitative interviews were transcribed and analyzed to identify common structures and processes mentioned by interviewees to include on a quantitative survey and to develop a rich description of salient themes on indicators of effective surgical care services and surgical care teams. RESULTS: Qualitative analyses of transcripts resulted in detailed descriptions of structures and processes of surgical care services that affected surgical care team performance--and how particular structures led to effective and ineffective processes that impacted quality and outcomes of surgical care. Communication and care coordination were most frequently mentioned as essential to effective surgical care services and teams. Informants also described other influences on surgical quality and outcomes, such as staffing, the role of residents, and team composition and continuity. CONCLUSIONS: Surgical care team members reinforced the importance of understanding surgical care processes and structures to improve both quality and outcomes of surgical care. The analysis of interviews helped the study team identify potential measures of structures and processes to include in our quantitative survey.

Relationship of processes and structures of care in general surgery to postoperative outcomes: a hierarchical analysis.

BACKGROUND: The majority of studies relating processes and structures of surgical care to outcomes focus on mortality alone, even though morbidity outcomes are frequent, costly, and can have an adverse effect on a patient's short- and longterm survival and quality of life. The purpose of this study was to identify the important processes and structures of surgical care that relate to 30-day, risk-adjusted postoperative morbidity in general surgery. STUDY DESIGN: Department of Veterans Affairs general surgery patients operated on in the period October 1, 2003 to September 30, 2004 at medical centers that participated in the Patient Safety in Surgery (PSS) Study and responded to a process and structure of care survey were included in this study. The patient's risk information was combined with key process and structure variables in a hierarchical maximum likelihood analysis to predict 30-day postoperative morbidity. RESULTS: A number of hospital-level processes and structures of care were identified that predicted 30-day postoperative morbidity. The dominant factor was university affiliation. Affiliated hospitals showed an increase in risk of morbidity even after adjustment for patient risk. CONCLUSIONS: Risk-adjusted morbidity is higher in Veterans Affairs hospitals that are affiliated with university medical centers. These findings mandate additional study to identify the exact factors responsible for this increased morbidity.

Multivariable predictors of postoperative respiratory failure after general and vascular surgery: results from the patient safety in surgery study.

BACKGROUND: Postoperative respiratory failure (RF) is associated with an increase in hospital morbidity, mortality, cost, and late mortality. We developed and tested a model to predict the risk of postoperative RF in patients undergoing major vascular and general surgical operations. This model is an extension of an earlier model that was derived and tested exclusively from a population of male patients from the Veterans Affairs National Surgical Quality Improvement Program. METHODS: Patients undergoing vascular and general surgical procedures at 14 academic and 128 Veterans Affairs Medical Centers from October 2001 through September 2004 were used to develop and test a predictive model of postoperative RF using logistic regression analyses. RF was defined as postoperative mechanical ventilation for longer than 48 hours or unanticipated reintubation. RESULTS: Of 180,359 patients, 5,389 (3.0%) experienced postoperative RF. Twenty-eight variables were found to be independently associated with RF. Current procedural terminology group, patients with a higher American Society of Anesthesiologists classification, emergency operations, more complex operation (work relative value units), preoperative sepsis, and elevated creatinine were more likely to experience RF. Older patients, male patients, smokers, and those with a history of congestive heart failure or COPD, or both, were also predisposed. The model's discrimination (c-statistic) was excellent, with no decrement from development (0.856) to validation (0.863) samples. CONCLUSIONS: This model updates a previously validated one and is more broadly applicable. Its use to predict postoperative RF risk enables the study of preventative measures or preoperative risk adjustment and intervention to improve outcomes.

Multivariable predictors of postoperative cardiac adverse events after general and vascular surgery: results from the patient safety in surgery study.

BACKGROUND: Cardiac adverse events (CAEs) are relatively infrequent, but highly lethal, after noncardiac operations. The value of available risk scoring systems is uncertain and these systems can be outdated. We used the Patient Safety in Surgery Study database to develop and test a model to predict patient risk for CAEs after general and vascular surgical operations. STUDY DESIGN: As part of the Patient Safety in Surgery Study, following the National Surgical Quality Improvement Program's protocol, multiple demographic, preoperative, perioperative, and outcomes variables were measured during a 3-year period. Data from 128 Veterans Affairs medical center hospitals and from 14 academic medical centers on 183,069 patients were used in a logistic regression analysis to model multivariable predictors of serious CAEs (cardiac arrest or acute myocardial infarction within 30 days of operation). RESULTS: CAEs occurred in 2,362 patients (1.29%) and of these, 59.44% expired. Multivariable stepwise logistic regression identified 20 independent predictors of CAEs, which excluded most cardiac-specific risk factors. The most important multivariable predictors of CAE were American Society of Anesthesiologists physical status classification, work relative value units of the most complex procedure, age, and type of operation. A risk prediction scoring system using the logistic regression odds ratios proved to be a useful prediction tool when tested using a random sample from the database. CONCLUSIONS: CAEs after noncardiac operations are relatively infrequent but highly lethal. Operation type and urgency and American Society of Anesthesiologists physical status assessment are important independent predictors of cardiac morbidity, but angina, recent MI, and earlier cardiac operation are not. A prediction scoring system based on the Patient Safety in Surgery Study multivariable odds ratios is likely to be predictive of future events in a similar population requiring noncardiac procedures. This risk model can also serve as a tool to measure quality and effectiveness of care by providers who perform noncardiac operations.

Multivariable predictors of postoperative surgical site infection after general and vascular surgery: results from the patient safety in surgery study.

BACKGROUND: Surgical site infection (SSI) is a potentially preventable complication. We developed and tested a model to predict patients at high risk for surgical site infection. STUDY DESIGN: Data from the Patient Safety in Surgery Study/National Surgical Quality Improvement Program from a 3-year period were used to develop and test a predictive model of SSI using logistic regression analyses. RESULTS: From October 2001 through September 2004, 7,035 of 163,624 (4.30%) patients undergoing vascular and general surgical procedures at 14 academic and 128 Department of Veterans Affairs (VA) medical centers experienced SSI. Fourteen variables independently associated with increased risk of SSI included patient factors (age greater than 40 years, diabetes, dyspnea, use of steroids, alcoholism, smoking, recent radiotherapy, and American Society of Anesthesiologists class 2 or higher), preoperative laboratory values (albumin<3.5 mg/dL, total bilirubin>1.0 mg/dL), and operative characteristics (emergency, complexity [work relative value units>/=10], type of procedure, and wound classification). The SSI risk score is more accurate than the National Nosocomial Infection Surveillance score in predicting SSI (c-indices 0.70, 0.62, respectively). CONCLUSIONS: We developed and tested an accurate prediction score for SSI. Clinicians can use this score to predict their patient's risk of an SSI and implement appropriate prevention strategies.

Multivariable predictors of postoperative venous thromboembolic events after general and vascular surgery: results from the patient safety in surgery study.

BACKGROUND: Venous thromboembolism (VTE) is a potentially preventable postoperative complication. Accurate risk prediction is an essential first step toward limiting serious, and sometimes fatal, postoperative VTE. We sought to develop and test a model to predict patients at high risk for postoperative VTE. STUDY DESIGN: Data from the Patient Safety in Surgery (PSS) Study were used to develop and test a predictive model of VTE using multiple logistic regression analyses. RESULTS: VTE occurred in 1,162 of 183,069 (0.63%) patients undergoing vascular and general surgical procedures. The 30-day mortality in patients who suffered a VTE was 11.19%. Fifteen variables independently associated with increased risk of VTE included patient factors (female gender, higher American Society of Anesthesiologists class, ventilator dependence, preoperative dyspnea, disseminated cancer, chemotherapy within 30 days, and > 4 U packed red blood cell transfusion in the 72 hours before operation), preoperative laboratory values (albumin < 3.5 mg/dL, bilirubin > 1.0 mg/dL, sodium > 145 mmol/L, and hematocrit < 38%), and operative characteristics (type of surgical procedure, emergency operation, work relative value units, and infected/contaminated wounds). These variables were used to develop a predictive model for postoperative VTE (c-index = 0.7647) and a risk score that can be used in the preoperative assessment of patients undergoing major operations. CONCLUSIONS: Venous thromboembolic events after noncardiac operations are relatively infrequent but highly lethal. Important multivariable risk factors for VTE in this setting were identified in the large PSS database. The risk-prediction scoring system, developed by using the logistic regression odds ratios, helps to identify patients at risk for postoperative VTE and to institute appropriate perioperative prophylactic measures.

Thyroid and parathyroid operations in veterans affairs and selected university medical centers: results of the patient safety in surgery study.

BACKGROUND: There is increasing interest in surgical outcomes. The Patient Safety in Surgery (PSS) Study database was examined about thyroid and parathyroid procedures to determine risk factors for adverse outcomes and outcomes rates. Relative outcomes performance for the Veterans Affairs (VA) and private-sector populations was compared after risk adjustment. STUDY DESIGN: Preoperative, operative, and postoperative data were analyzed for 7,082 patients: 2,814 VA patients and 4,268 private sector patients. Prevalence of risk or process factors was described. Occurrence rates and unadjusted odds ratios (OR) for adverse outcomes were calculated. Stepwise multiple logistic regressions were performed to model the impact of various factors on outcomes and to calculate the adjusted OR for any adverse event for the VA population compared with the private sector. RESULTS: Overall mortality rate was 0.35% and 0.60% in the VA and 0.19% in the private sector. Overall rate of any adverse outcomes was 2.90% and 4.48% in the VA and 1.97% in the private sector. Adjusted OR for thyroid versus parathyroid operation was 0.94 (95% CI, 0.67-1.31). Adjusted OR for operation in the VA versus private sector was 1.25 (95% CI, 0.87-1.78). CONCLUSIONS: Overall rates of mortality and any morbidity were low and consistent with previous reports. Based on adjusted OR, there was no significant difference in outcomes for thyroid versus parathyroid operation. Similarly, there was no apparent significant difference in surgical outcomes between the VA and private-sector groups after risk adjustment.

Breast cancer surgery in Veterans Affairs and selected university medical centers: results of the patient safety in surgery study.

BACKGROUND: Breast cancer is a common diagnosis. We compare perioperative characteristics and outcomes between male and female patients undergoing treatment for breast cancer and between hospital systems (Department of Veterans Affairs [VA] and private sector [PS]) as part of the Patient Safety in Surgery (PSS) Study. STUDY DESIGN: We performed an analysis of a prospectively collected clinical database. Data collected from 128 VA hospitals and 14 PS academic medical centers as part of the Patient Safety in Surgery Study for fiscal years 2002 through 2004 were used. Analysis included calculation of crude and adjusted odds ratios for morbidity. RESULTS: A total of 3,823 patients were included. Female VA patients at baseline had higher rates of smoking, steroid use, COPD, acute renal failure, dialysis, weight loss > 10%, preoperative chemotherapy, and abnormal laboratory values than female PS patients did. Male patients were older than the female patients in both hospital systems. Mortality rates were very low and similar among groups. All VA patients in this study had substantially longer lengths of stay than the patients in the PS. The unadjusted overall complication rate was 5.21%; the VA female patients experienced an unadjusted complication rate twice that of the PS female patients. When adjusted for confounding variables and differences in preoperative comorbidities, the odds ratio comparing VA with PS females was no longer markedly different (1.404; 95% CI, 0.894, 2.204). CONCLUSIONS: VA patients with breast cancer have higher incidences of most comorbidities than patients in the PS. Differences in complication rates females disappear when adjustment is made for the higher rates of comorbidities in the VA patients.