The Department of Veterans Affairs' NSQIP: the first national, validated, outcome-based, risk-adjusted, and peer-controlled program for the measurement and enhancement of the quality of surgical care. National VA Surgical Quality Improvement Program

OBJECTIVE

To provide reliable risk-adjusted morbidity and mortality rates after major surgery to the 123 Veterans Affairs Medical Centers (VAMCs) performing major surgery, and to use risk-adjusted outcomes in the monitoring and improvement of the quality of surgical care to all veterans.

SUMMARY BACKGROUND DATA

Outcome-based comparative measures of the quality of surgical care among surgical services and surgical subspecialties have been elusive.

METHODS

This study included prospective assessment of presurgical risk factors, process of care during surgery, and outcomes 30 days after surgery on veterans undergoing major surgery in 123 medical centers; development of multivariable risk-adjustment models; identification of high and low outlier facilities by observed-to-expected outcome ratios; and generation of annual reports of comparative outcomes to all surgical services in the Veterans Health Administration (VHA).

RESULTS

The National VA Surgical Quality Improvement Program (NSQIP) data base includes 417,944 major surgical procedures performed between October 1, 1991, and September 30, 1997. In FY97, 11 VAMCs were low outliers for risk-adjusted observed-to-expected mortality ratios; 13 VAMCs were high outliers for risk-adjusted observed-to-expected mortality ratios. Identification of high and low outliers by unadjusted mortality rates would have ascribed an outlier status incorrectly to 25 of 39 hospitals, an error rate of 64%. Since 1994, the 30-day mortality and morbidity rates for major surgery have fallen 9% and 30%, respectively.

CONCLUSIONS

Reliable, valid information on patient presurgical risk factors, process of care during surgery, and 30-day morbidity and mortality rates is available for all major surgical procedures in the 123 VAMCs performing surgery in the VHA. With this information, the VHA has established the first prospective outcome-based program for comparative assessment and enhancement of the quality of surgical care among multiple institutions for several surgical subspecialties. Key features to the success of the NSQIP are the support of the surgeons who practice in the VHA, consistent clinical definitions and data collection by dedicated nurses, a uniform nationwide informatics system, and the support of VHA administration and managerial staff.

Independent association between acute renal failure and mortality following cardiac surgery

PURPOSE

To determine whether there is an independent association of acute renal failure requiring dialysis with operative mortality after cardiac surgery.

PATIENTS AND METHODS

The 42,773 patients who underwent coronary artery bypass or valvular heart surgery at 43 Department of Veterans Affairs Medical Centers between 1987 and 1994 were evaluated to determine the association between acute renal failure sufficient to require dialysis and operative mortality, with and without adjustment for comorbidity and postoperative complications. Crude and adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were derived from logistic regression analysis.

RESULTS

Acute renal failure occurred in 460 (1.1%) patients. Overall operative mortality was 63.7% in these patients, compared with 4.3% in patients without this complication. The unadjusted OR for death was 39 (95% CI 32 to 48). After adjustment for comorbid factors related to the development of acute renal failure (surgery type, baseline renal function, preoperative intraaortic balloon pump, prior heart surgery, NYHA class IV status, peripheral vascular disease, pulmonary rales, left ventricular ejection fraction below 35%, chronic obstructive pulmonary disease, systolic blood pressure, and the cross-product of systolic blood pressure and surgery type), the OR was 27 (95% CI 22 to 34). Further adjustment was made for seven postoperative complications (low cardiac output, cardiac arrest, perioperative myocardial infarction, prolonged mechanical ventilation, reoperation for bleeding or repeat cardiopulmonary bypass, stroke or coma, and mediastinitis), that were independently associated with operative mortality. The OR adjusted for comorbidity and postoperative complications associated with acute renal failure was 7.9 (95% CI 6 to 10).

CONCLUSIONS

Acute renal failure was independently associated with early mortality following cardiac surgery, even after adjustment for comorbidity and postoperative complications. Interventions to prevent or improve treatment of this condition are urgently needed.

Outcomes 15 years after valve replacement with a mechanical versus a bioprosthetic valve: final report of the Veterans Affairs randomized trial

OBJECTIVES

The goal of this study was to compare long-term survival and valve-related complications between bioprosthetic and mechanical heart valves.

BACKGROUND

Different heart valves may have different patient outcomes.

METHODS

Five hundred seventy-five patients undergoing single aortic valve replacement (AVR) or mitral valve replacement (MVR) at 13 VA medical centers were randomized to receive a bioprosthetic or mechanical valve.

RESULTS

By survival analysis at 15 years, all-cause mortality after AVR was lower with the mechanical valve versus bioprosthesis (66% vs. 79%, p = 0.02) but not after MVR. Primary valve failure occurred mainly in patients <65 years of age (bioprosthesis vs. mechanical, 26% vs. 0%, p < 0.001 for AVR and 44% vs. 4%, p = 0.0001 for MVR), and in patients > or =65 years after AVR, primary valve failure in bioprosthesis versus mechanical valve was 9 +/- 6% versus 0%, p = 0.16. Reoperation was significantly higher for bioprosthetic AVR (p = 0.004). Bleeding occurred more frequently in patients with mechanical valve. There were no statistically significant differences for other complications, including thromboembolism and all valve-related complications between the two randomized groups.

CONCLUSIONS

At 15 years, patients undergoing AVR had a better survival with a mechanical valve than with a bioprosthetic valve, largely because primary valve failure was virtually absent with mechanical valve. Primary valve failure was greater with bioprosthesis, both for AVR and MVR, and occurred at a much higher rate in those aged <65 years; in those aged > or =65 years, primary valve failure after AVR was not significantly different between bioprosthesis and mechanical valve. Reoperation was more common for AVR with bioprosthesis. Thromboembolism rates were similar in the two valve prostheses, but bleeding was more common with a mechanical valve.

Variables predictive of survival in patients with coronary disease. Selection by univariate and multivariate analyses from the clinical, electrocardiographic, exercise, arteriographic, and quantitative angiographic evaluations

A progression of univariate followed by multivariate analyses was applied to 46 variables selected from the clinical examination, exercise test, coronary arteriography, and quantitative angiographic assessment of left ventricular function in patients with coronary disease to determine those variables most predictive of survival. For the 733 medically treated patients, the final Cox's regression analysis showed that the left ventricular ejection fraction was most predictive of survival, followed by age, number of vessels with stenosis(es) greater than or equal to 70%, and ventricular arrhythmia on the resting electrocardiogram. For the 1870 surgically treated patients, ventricular arrhythmia on the resting electrocardiogram was most predictive of survival followed by ejection fraction, heart murmur, left main coronary artery stenosis greater than or equal to 50%, and use of diuretic agents.

Atrial fibrillation after cardiac surgery: a major morbid event?

OBJECTIVE

The purpose of the study was to investigate the incidence, predictors, morbidity, and mortality associated with postoperative atrial fibrillation (AF) and its impact on intensive care unit (ICU) and postoperative hospital stay in patients undergoing cardiac surgery in the Department of Veterans Affairs (VA).

SUMMARY BACKGROUND DATA

Postoperative AF after open cardiac surgery is rather common. The etiology of this arrhythmia and factors responsible for its genesis are unclear, and its impact on postoperative surgical outcomes remains controversial. The purpose of this special substudy was to elucidate the incidence of postoperative AF and the factors associated with its development, as well as the impact of AF on surgical outcome.

METHODS

The study population consisted of 3855 patients who underwent open cardiac surgery between September 1993 and December 1996 at 14 VA Medical Centers. Three hundred twenty-nine additional patients were excluded because of lack of complete data or presence of AF before surgery, and 3794 (98.4%) were male with a mean age of 63.7+/-9.6 years. Operations included coronary artery bypass grafting (CABG) (3126, 81%), CABG + AVR (aortic valve replacement) (228, 5.9%), CABG + MVR (mitral valve replacement) (35, 0.9%), AVR (231, 6%), MVR (41, 1.06%), CABG + others (95, 2.46%), and others (99, 2.5%). The incidence of postoperative AF was 29.6%. Multivariate logistic regression analysis of factors found significant on univariate analysis showed the following predictors of postoperative AF: preoperative patient risk predictors: advancing age (odds ratio [OR] 1.61, 95% confidence interval [CI] 1.48-1.75, p < 0.001), chronic obstructive pulmonary disease (OR 1.37, 95% CI 1.12-1.66, p < 0.001), use of digoxin within 2 weeks before surgery (OR 1.37, 95% CI 1.10-1.70, p < 0.003), low resting pulse rate <80 (OR 1.26, 95% CI 1.06-1.51, p < 0.009), high resting systolic blood pressure >120 (OR 1.19, 95% CI 1.02-1.40, p < 0.026), intraoperative process of care predictors: cardiac venting via right superior pulmonary vein (OR 1.42, 95% CI 1.21-1.67, p < 0.0001), mitral valve repair (OR 2.86, 95% CI 1.72-4.73, p < 0.0001) and replacement (OR 2.33, 95% CI 1.55-3.55, p < 0.0001), no use of topical ice slush (OR 1.29, 95% CI 1.10-1.49, p < 0.0009), and use of inotropic agents for greater than 30 minutes after termination of cardiopulmonary bypass (OR 1.36, 95% CI 1.16-1.59, p < 0.0001). Postoperative median ICU stay (3.6 days AF vs. 2 days no AF, p < 0.001) and hospital stay (10 days AF vs. 7 days no AF, p < 0.001) were higher in AF. Morbid events, hospital mortality, and 6-month mortality were significantly higher in AF (p < 0.001): ICU readmission 13% AF vs. 3.9% no AF, perioperative myocardial infarction 7.41 % AF vs. 3.36% no AF, persistent congestive heart failure 4.57% AF vs. 1.4% no AF, reintubation 10.59% AF vs. 2.47% no AF, stroke 5.26% AF vs. 2.44% no AF, hospital mortality 5.95% AF vs. 2.95% no AF, 6-month mortality 9.36% AF vs. 4.17% no AF.

CONCLUSIONS

Atrial fibrillation after cardiac surgery occurs in approximately one third of patients and is associated with an increase in adverse events in all measurable outcomes of care and increases the use of hospital resources and, therefore, the cost of care. Strategies to reduce the incidence of AF after cardiac surgery should favorably affect surgical outcomes and reduce utilization of resources and thus lower cost of care.

Preoperative renal risk stratification

BACKGROUND

After cardiac surgery, acute renal failure (ARF) requiring dialysis develops in 1% to 5% of patients and is strongly associated with perioperative morbidity and mortality. Prior studies have attempted to identify predictors of ARF but have had insufficient power to perform multivariable analyses or to develop risk stratification algorithms.

METHODS AND RESULTS

We conducted a prospective cohort study of 43 642 patients who underwent coronary artery bypass or valvular heart surgery in 43 Department of Veterans Affairs medical centers between April 1987 and March 1994. Logistic regression analysis was used to identify independent predictors of ARF requiring dialysis. A risk stratification algorithm derived from recursive partitioning was constructed and was validated on an independent sample of 3795 patients operated on between April and December 1994. The overall risk of ARF requiring dialysis was 1.1%. Thirty-day mortality in patients with ARF was 63.7%, compared with 4.3% in patients without ARF. Ten clinical variables related to baseline cardiovascular disease and renal function were independently associated with the risk of ARF. A risk stratification algorithm partitioned patients into low-risk (0.4%), medium-risk (0.9% to 2.8%), and high-risk (> or = 5.0%) groups on the basis of several of these factors and their interactions.

CONCLUSIONS

The risk of ARF after cardiac surgery can be accurately quantified on the basis of readily available preoperative data. These findings may be used by physicians and surgeons to provide patients with improved risk estimates and to target high-risk subgroups for interventions aimed at reducing the risk and ameliorating the consequences of this serious complication.

Health-related quality of life as a predictor of mortality following coronary artery bypass graft surgery. Participants of the Department of Veterans Affairs Cooperative Study Group on Processes, Structures, and Outcomes of Care in Cardiac Surgery

CONTEXT

Health-related quality of life has not been evaluated as a predictor of mortality following coronary artery bypass graft (CABG) surgery. Evaluation of health status as a mortality predictor may be useful for preoperative risk stratification.

OBJECTIVE

To determine whether the Physical and Mental Component Summary scores from the preoperative Short-Form 36 (SF-36) health status survey predict mortality following CABG surgery after adjustment for known clinical risk variables.

DESIGN

Prospective cohort study conducted between September 1992 and December 1996.

SETTING

Fourteen Veterans Affairs hospitals.

PATIENTS

Of the 3956 patients undergoing CABG surgery only and who were enrolled in the Processes, Structures, and Outcomes of Care in Cardiac Surgery study, the 2480 who completed a preoperative SF-36.

MAIN OUTCOME MEASURE

All-cause mortality within 180 days after surgery.

RESULTS

A total of 117 deaths (4.7%) occurred within 180 days of CABG surgery. The Physical Component Summary of the preoperative SF-36 was a statistically significant risk factor for 6-month mortality after adjustment for known clinical risk factors for mortality following CABG surgery. In multivariate analysis, a 10-point lower SF-36 Physical Component Summary score had an odds ratio (OR) of 1.39 (95% confidence interval [CI], 1.11-1.77; P=.006) for predicting mortality. The SF-36 Mental Component Summary score was not associated with 6-month mortality in multivariate analyses (OR, 1.09; 95% CI, 0.92-1.29; P=.31).

CONCLUSIONS

The Physical Component Summary score from the preoperative SF-36 is an independent risk factor for mortality following CABG surgery. The baseline Mental Component Summary score does not appear to be predictive of mortality. Preoperative patient self-report of the physical component of health status may be helpful for risk stratification and clinical decision making for patients undergoing CABG surgery.

A comparison of outcomes in men 11 years after heart-valve replacement with a mechanical valve or bioprosthesis. Veterans Affairs Cooperative Study on Valvular Heart Disease

BACKGROUND

Mechanical heart valves are durable but thrombogenic, and their use requires that the patient receive anticoagulants. In contrast, bioprosthetic valves are less thrombogenic, but they have limited durability because of tissue deterioration.

METHODS

To compare the outcomes of patients who receive these two types of valves, we randomly assigned 575 men scheduled to undergo aortic-valve or mitral-valve replacement to receive either a mechanical or a bioprosthetic valve. The primary end points were death from any cause and any valve-related complication.

RESULTS

During an average follow-up of 11 years, there was no difference between the two groups in the probability of death from any cause (11-year probability for mechanical valves, 0.57; for bioprostheses, 0.62; P = 0.57) or in the probability of any valve-related complication (0.65 and 0.69, respectively; P = 0.39). There was a much higher rate of structural valve failure among patients who received bioprosthetic valves (11-year probability, 0.15 for the aortic valves and 0.36 for the mitral valves) than among those who received mechanical valves (no valve failures; P < 0.001). However, this difference was offset by a higher rate of bleeding complications among patients with mechanical valves than among those with bioprosthetic valves (11-year probability, 0.42 and 0.26, respectively; P < 0.001) and by a greater frequency of peri-prosthetic valvular regurgitation among patients with mechanical mitral valves than among those with mitral bioprostheses (11-year probability, 0.17 and 0.09, respectively; P = 0.05).

CONCLUSIONS

After 11 years, the rates of survival and freedom from all valve-related complications were similar for patients who received mechanical heart valves and those who received bioprosthetic heart valves. However, structural failure was observed only with the bioprosthetic valves, whereas bleeding complications were more frequent among patients who received mechanical valves.

Relation of surgical volume to outcome in eight common operations: results from the VA National Surgical Quality Improvement Program

OBJECTIVE

To examine, in the Veterans Health Administration (VHA), the relation between surgical volume and outcome in eight commonly performed operations of intermediate complexity.

SUMMARY BACKGROUND DATA

In multihospital health care systems such as VHA, consideration is often given to closing low-volume surgical services, with the assumption that better surgical outcomes are achieved in hospitals with larger surgical volumes. Literature data to support this assumption in intermediate-complexity operations are either limited or controversial.

METHODS

The VHA National Surgical Quality Improvement Program data on nonruptured abdominal aortic aneurysmectomy, vascular infrainguinal reconstruction, carotid endarterectomy (CEA), lung lobectomy/pneumonectomy, open and laparoscopic cholecystectomy, partial colectomy, and total hip arthroplasty were used. Pearson correlation, analysis of variance, mixed effects hierarchical logistic regression, and automatic interaction detection analysis were used to assess the association of annual procedure/specialty volume with risk-adjusted 30-day death (and stroke in CEA).

RESULTS

Eight major surgical procedures (68,631 operations) were analyzed. No statistically significant associations between procedure or specialty volume and 30-day mortality rate (or 30-day stroke rate in CEA) were found.

CONCLUSIONS

In VHA hospitals, the procedure and surgical specialty volume in eight prevalent operations of intermediate complexity are not associated with risk-adjusted 30-day mortality rate from these operations, or with the risk-adjusted 30-day stroke rate from CEA. Volume of surgery in these operations should not be used as a surrogate for quality of surgical care.

Identification of preoperative variables needed for risk adjustment of short-term mortality after coronary artery bypass graft surgery. The Working Group Panel on the Cooperative CABG Database Project

OBJECTIVES

The purpose of this consensus effort was to define and prioritize the importance of a set of clinical variables useful for monitoring and improving the short-term mortality of patients undergoing coronary artery bypass graft surgery (CABG).

BACKGROUND

Despite widespread use of data bases to monitor the outcome of patients undergoing CABG, no consistent set of clinical variables has been defined for risk adjustment of observed outcomes for baseline differences in disease severity among patients.

METHODS

Experts with a background in epidemiology, biostatistics and clinical care with an interest in assessing outcomes of CABG derived from previous work with professional societies, government or academic institutions volunteered to participate in this unsponsored consensus process. Two meetings of this ad hoc working group were required to define and prioritize clinical variables into core, level 1 or level 2 groupings to reflect their importance for relating to short-term mortality after CABG. Definitions of these 44 variables were simple and specific to enhance objectivity of the 7 core, 13 level 1 and 24 level 2 variables. Core and level 1 variables were evaluated using data from five existing data bases, and core variables only were examined in an additional two data bases to confirm the consensus opinion of the relative prognostic power of each variable.

RESULTS

Multivariable logistic regression models of the seven core variables showed all to be predictive of bypass surgery mortality in some of the seven existing data sets. Variables relating to acuteness, age and previous operation proved to be the most important in all data sets tested. Variables describing coronary anatomy appeared to be least significant. Models including both the 7 core and 13 level 1 variables in five of the seven data sets showed the core variables to reflect 45% to 83% of the predictive information. However, some level 1 variables were stronger than some core variables in some data sets.

CONCLUSIONS

A relatively small number of clinical variables provide a large amount of prognostic information in patients undergoing CABG.

The rate of change of left ventricular volume in man. II. Diastolic events in health and disease

Because there is little quantitative information about the hemodynamics of left ventricular diastolic events in man, single-plane cineangiographic left ventricular volume curves were quantitatively analyzed at 16.6 msec intervals to evaluate the rate and amount of left ventricular filling during the early passive stage of filling and during the time of atrial contraction. The peak rate of passive diastolic filling of the left ventricle (D dV/dt), the peak rate of filling during atrial contraction (dV/dt c 'a'), and the increment in diastolic left ventricular volume due to atrial contraction (ΔV c 'a') were analyzed for a group of 110 adult patients with a variety of cardiac lesions. Normal D dV/dt, 503 ± 171 cc/sec, was significantly depressed in patients with mitral stenosis (393 ± 109 cc/sec) and coronary artery disease (394 ± 150 cc/sec). When corrected for end-diastolic volume (EDV), the resultant D dV/dt/EDV was significantly depressed in all disease states studied. D dV/dt corrected similarly for total left ventricular stroke volume (SV) was depressed from normal in patients with coronary disease, mitral stenosis, and valvular regurgitation. These data indicate that patients with coronary disease and chronic valvular disease have an abnormality in early diastolic filling of the left ventricle and that this may have a more profound effect on ventricular performance than changes in late diastolic compliance. D dV/dt has a high correlation with peak systolic ejection rate ( r = 0.71), SV ( r = 0.82), and EDV ( r = 0.51).

The normal ΔV c 'a' represents 21% of the stroke volume (16% of the stroke volume if corrected for passive filling during this time period). Patients with coronary artery disease, valvular regurgitation, and aortic stenosis have an increased ΔV c'a'. Atrial contraction results in a second peak in mitral valve flow in late diastole (dV/dt c 'a'). In normal patients dV/dt c 'a' is 38% of D dV/dt, but in disease states this ratio is substantially increased. In the diseased heart atrial contraction makes a greater contribution to cardiac output than in the normal heart.

A decade's experience with quality improvement in cardiac surgery using the Veterans Affairs and Society of Thoracic Surgeons national databases

OBJECTIVE

To review the Department of Veteran Affairs (VA) and the Society of Thoracic Surgeons (STS) national databases over the past 10 years to evaluate their relative similarities and differences, to appraise their use as quality improvement tools, and to assess their potential to facilitate improvements in quality of cardiac surgical care.

SUMMARY BACKGROUND DATA

The VA developed a mandatory risk-adjusted database in 1987 to monitor outcomes of cardiac surgery at all VA medical centers. In 1989 the STS developed a voluntary risk-adjusted database to help members assess quality and outcomes in their individual programs and to facilitate improvements in quality of care.

METHODS

A short data form on every veteran operated on at each VA medical center is completed and transmitted electronically for analysis of unadjusted and risk-adjusted death and complications, as well as length of stay. Masked, confidential semiannual reports are then distributed to each program's clinical team and the associated administrator. These reports are also reviewed by a national quality oversight committee. Thus, VA data are used both locally for quality improvement and at the national level with quality surveillance. The STS dataset (217 core fields and 255 extended fields) is transmitted for each patient semiannually to the Duke Clinical Research Institute (DCRI) for warehousing, analysis, and distribution. Site-specific reports are produced with regional and national aggregate comparisons for unadjusted and adjusted surgical deaths and complications, as well as length of stay for coronary artery bypass grafting (CABG), valvular procedures, and valvular/CABG procedures. Both databases use the logistic regression modeling approach. Data for key processes of care are also captured in both databases. Research projects are frequently carried out using each database.

RESULTS

More than 74,000 and 1.6 million cardiac surgical patients have been entered into the VA and STS databases, respectively. Risk factors that predict surgical death for CABG are very similar in the two databases, as are the odds ratios for most of the risk factors. One major difference is that the VA is 99% male, the STS 71% male. Both databases have shown a significant reduction in the risk-adjusted surgical death rate during the past decade despite the fact that patients have presented with an increased risk factor profile. The ratio of observed to expected deaths decreased from 1.05 to 0.9 for the VA and from 1.5 to 0.9 for the STS.

CONCLUSION

It appears that the routine feedback of risk-adjusted data on local performance provided by these programs heightens awareness and leads to self-examination and self-assessment, which in turn improves quality and outcomes. This general quality improvement template should be considered for application in other settings beyond cardiac surgery.

Initial report of the Veterans Administration Preoperative Risk Assessment Study for Cardiac Surgery

This study was authorized by the Department of Veterans Affairs to improve the quality assurance of cardiac surgery by assessing preoperative risk factors and relating them to operative mortality. Data were received on 10,480 patients over a 2-year period. Preoperative risk variables were subjected to univariate and multivariate logistic regression analyses. Significant variables for coronary artery bypass grafting after logistic regression analysis in order of importance are previous cardiac operation, priority of operation, New York Heart Association functional class, peripheral vascular disease, age, pulmonary rales, current diuretic use, and chronic obstructive pulmonary disease. For patients undergoing valve or other cardiac operations with or without coronary artery bypass grafting, those variables found to be significant after multivariate logistic regression analysis are priority of operation; age; peripheral vascular disease; great vessel repair; all other except aortic valve replacement, mitral valve replacement, and great vessel repair; mitral valve replacement; and cardiomegaly. By identifying these current risk factors and the coefficients from the multivariate stepwise logistic regression analysis, expected mortality can be calculated. We propose that the ratio of observed to expected mortality is a better measure of quality of care than unadjusted mortality.

Determinants of survival and left ventricular performance after mitral valve replacement. Department of Veterans Affairs Cooperative Study on Valvular Heart Disease

To determine how survival and clinical status were related to left ventricular (LV) size and systolic function after mitral valve replacement, 104 patients (48 mitral regurgitation [MR], 33 mitral stenosis [MS], and 23 MS/MR) with isolated mitral valve replacement were evaluated before and after surgery. Preoperative hemodynamic abnormalities by cardiac catheterization were improved 6 months after surgery in all three patient groups. The patients with MR exhibited reductions in LV end-diastolic volume index (EDVI) (117 +/- 51 to 89 +/- 27 ml/m2, p less than 0.001) and ejection fraction (EF) (0.56 +/- 0.15 to 0.45 +/- 0.13, p less than 0.001); however, the ratio of forward stroke volume to end-diastolic volume increased (0.32 +/- 0.21 to 0.45 +/- 0.17, p less than 0.001) because of the elimination of regurgitant volume. Survival analysis revealed that mortality was significantly higher in MS or MS/MR patients with postoperative EDVI more than 101 ml/m2 (p less than 0.001 and p less than 0.042, respectively) and in MR patients with postoperative EF less than or equal to 0.50 (p less than 0.031). Also, the majority of patients with MR or MS/MR and postoperative EDVI more than 101 ml/m2 and EF less than or equal to 0.50 were in New York Heart Association class III or IV. Multivariate logistic regression analysis in the patients with MR revealed that the strongest predictor of postoperative EF was preoperative EF (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of surgical outcomes between teaching and nonteaching hospitals in the Department of Veterans Affairs

OBJECTIVE

To determine whether the investment in postgraduate education and training places patients at risk for worse outcomes and higher costs than if medical and surgical care was delivered in nonteaching settings.

SUMMARY BACKGROUND DATA

The Veterans Health Administration (VA) plays a major role in the training of medical students, residents, and fellows.

METHODS

The database of the VA National Surgical Quality Improvement Program was analyzed for all major noncardiac operations performed during fiscal years 1997, 1998, and 1999. Teaching status of a hospital was determined on the basis of a background and structure questionnaire that was independently verified by a research fellow. Stepwise logistic regression was used to construct separate models predictive of 30-day mortality and morbidity for each of seven surgical specialties and eight operations. Based on these models, a severity index for each patient was calculated. Hierarchical logistic regression models were then created to examine the relationship between teaching versus nonteaching hospitals and 30-day postoperative mortality and morbidity, after adjusting for patient severity.

RESULTS

Teaching hospitals performed 81% of the total surgical workload and 90% of the major surgery workload. In most specialties in teaching hospitals, the residents were the primary surgeons in more than 90% of the operations. Compared with nonteaching hospitals, the patient populations in teaching hospitals had a higher prevalence of risk factors, underwent more complex operations, and had longer operation times. Risk-adjusted mortality rates were not different between the teaching and nonteaching hospitals in the specialties and operations studied. The unadjusted complication rate was higher in teaching hospitals in six of seven specialties and four of eight operations. Risk adjustment did not eliminate completely these differences, probably reflecting the relatively poor predictive validity of some of the risk adjustment models for morbidity. Length of stay after major operations was not consistently different between teaching and nonteaching hospitals.

CONCLUSION

Compared with nonteaching hospitals, teaching hospitals in the VA perform the majority of complex and high-risk major procedures, with comparable risk-adjusted 30-day mortality rates. Risk-adjusted 30-day morbidity rates in teaching hospitals are higher in some specialties and operations than in nonteaching hospitals. Although this may reflect the weak predictive validity of some of the risk adjustment models for morbidity, it may also represent suboptimal processes and structures of care that are unique to teaching hospitals. Despite good quality of care in teaching hospitals, as evidenced by the 30-day mortality data, efforts should be made to examine further the structures and processes of surgical care prevailing in these hospitals.

Renal failure predisposes patients to adverse outcome after coronary artery bypass surgery. VA Cooperative Study #5

BACKGROUND

More than 600,000 coronary artery bypass graft (CABG) procedures are done annually in the United States. Some data indicate that 10 to 20% of patients who are undergoing a CABG procedure have a serum creatinine of more than 1.5 mg/dl. There are few data on the impact of a mild increase in serum creatinine concentration on CABG outcome.

METHODS

We analyzed a Veterans Affairs database obtained prospectively from 1992 through 1996 at 14 of 43 centers performing heart surgery. We compared the outcome after CABG in patients with a baseline serum creatinine of less than 1.5 mg/dl (median 1.1 mg/dl, N = 3271) to patients with a baseline serum creatinine of 1.5 to 3.0 mg/dl (median 1.7, N = 631).

RESULTS

Univariate analysis revealed that patients with a serum creatinine of 1.5 to 3.0 mg/dl had a higher 30-day mortality (7% vs. 3%, P < 0.001) requirement for prolonged mechanical ventilation (15% vs. 8%, P = 0.001), stroke (7% vs. 2%, P < 0.001), renal failure requiring dialysis at discharge (3% vs. 1%, P < 0.001), and bleeding complications (8% vs. 3%, P < 0.001) than patients with a baseline serum creatinine of less than 1.5 mg/dl. Multiple logistic regression analyses found that patients with a baseline serum creatinine of less than 1.5 mg/dl had significantly lower (P < 0.02) 30-day mortality and postoperative bleeding and ventilatory complications than patients with a serum creatinine of 1.5 to 3.0 mg/dl when controlling for all other variables.

CONCLUSION

These results demonstrate that mild renal failure is an independent risk factor for adverse outcome after CABG.

The Veterans Affairs Continuous Improvement in Cardiac Surgery Study

The Department of Veterans Affairs Cardiac Surgery Consultants Committee is responsible for reviewing the quality of cardiac surgical treatment at the 43 Veterans Affairs cardiac surgical centers where these procedures are performed. It does so by reviewing both the unadjusted and risk-adjusted operative mortality data and the incidence of perioperative complications. These data are reviewed by the committee semiannually, and the overall summary and hospital-specific data are shared with the individual cardiac surgical program directors. Paper audits and site visits are performed when indicated by increased unadjusted and risk-adjusted operative mortality. Constructive criticism is shared with the program director and medical center administration. The relative risk of death for numerous patient risk factors has been estimated, and is now used in prospective clinical decision making. During the 7-year period that risk-adjusted outcomes have been utilized, there has been an overall significant reduction in the observed-to-expected operative mortality ratio. Although many factors could have contributed to this, including continually improving surgical techniques, it is also likely that part of this improvement has occurred because of the continuous feedback of these quality improvement data to our cardiothoracic surgeons and cardiologists.

Changes in health-related quality of life following coronary artery bypass graft surgery

BACKGROUND

There are limited data to help clinicians identify patients likely to have an improvement in quality of life following CABG surgery. We evaluated the relationship between preoperative health status and changes in quality of life following CABG surgery.

METHODS

We evaluated 1,744 patients enrolled in the VA Cooperative Processes, Structures, and Outcomes in Cardiac Surgery study who completed preoperative and 6-month postoperative Short Form-36 (SF-36) surveys. The primary outcome was change in the Mental Component Summary (MCS) and Physical Component Summary (PCS) scores from the SF-36.

RESULTS

On average, physical and mental health status improved following the operation. Preoperative health status was the major determinant of change in quality of life following surgery, independent of anginal burden and other clinical characteristics. Patients with MCS scores less than 44 or PCS scores less than 38 were most likely to have an improvement in quality of life. Patients with higher preoperative scores were unlikely to have an improvement in quality of life.

CONCLUSIONS

Patients with preoperative health status deficits are likely to have an improvement in their quality of life following CABG surgery. Alternatively, patients with relatively good preoperative health status are unlikely to have a quality of life benefit from surgery and the operation should primarily be performed to improve survival.

Stroke in cardiac surgical patients: determinants and outcome

BACKGROUND

Despite improving outcomes in cardiac surgical patients, stroke continues to remain a major complication. Few prospective studies are available on postoperative stroke. The present study was conducted to elucidate the incidence and predictors of stroke in a large group of cardiac surgical patients.

METHODS AND RESULTS

Prospective data collected on 4,941 patients undergoing cardiac surgery were subjected to univariate and logistic regression analyses (98.4% men; 72% older than 60 years; 9.1% with history of prior stroke; 80.4% underwent isolated coronary artery bypass grafting). Stroke predictors include history of stroke and hypertension, older age, systolic hypertension, bronchodilator and diuretic use, high serum creatinine, surgical priority, great vessel repair, use of inotropic agents after cardiopulmonary bypass, and total cardiopulmonary bypass time (p < 0.05 for all comparisons). Median intensive care unit and hospital stays were longer, and hospital mortality and 6-month mortality were higher for patients with stroke (p < 0.001).

CONCLUSIONS

Stroke after cardiac surgical procedures is a morbid event. Identification of predictors and development of strategies to modify these factors should lead to a lower incidence of stroke.

Continuous assessment and improvement in quality of care. A model from the Department of Veterans Affairs Cardiac Surgery

OBJECTIVE

The authors organized the Department of Veterans Affairs (VA) Continuous Improvement in Cardiac Surgery Study (CICSS) to provide risk-adjusted outcome data for the continuous assessment and improvement of quality of care for all patients undergoing cardiac surgery in the VA.

BACKGROUND

The use of risk-adjusted outcomes to monitor quality of health care has the potential advantage over consensus-derived standards of being free of preconceived biases about how health care should be provided. Monitoring outcomes of all health care episodes, as opposed to review of selected cases (e.g., adverse outcomes), has the advantages of greater statistical power, the opportunity to compare processes of care between good and bad outcomes, and the positive psychology of treating all providers equally. These two concepts, together with a pre-existing peer committee (the VA Cardiac Surgery Consultants Committee) to review, interpret, and act on the risk-adjusted outcome data, form the primary design considerations for CICSS.

METHODS

Patient-level risk and outcome (operative mortality and morbidity) data are collected prospectively on each of the approximately 7000 patients undergoing cardiac surgery in the VA each year. These outcomes, adjusted for patient risk using logistic regression, are provided every 6 months to each cardiac surgery program and to a national peer review committee for internal and external quality assessment and improvement.

RESULTS

For the most recent 12-month period with complete data collection, observed-to-expected (O/E) ratios ranged from 0.2 to 2.2, with eight centers falling outside of the 90% confidence limits for an O/E ratio equaling 1.0. The O/E ratio for all centers has fallen by 14% over the 4.5-year period of this program (p = 0.06).

CONCLUSIONS

A large-scale, low-cost program of continuous quality improvement using risk-adjusted outcome is feasible. This program has been associated with a decrease in risk-adjusted operative mortality.

Effect of aortocoronary saphenous vein bypass grafting on death and sudden death. Comparison of nonrandomized medically and surgically treated cohorts with comparable coronary disease and left ventricular function

The effect of saphenous vein bypass grafting on the incidence of sudden cardiac death and total cardiovascular death was studied by comparing the survival of subsets of surgically and medically treated patients with coronary disease who were similar in two major prognostic variables: extent of coronary disease and ejection fraction. Significant differences in some baseline variables existed between medical and surgical subgroups with similar ejection fraction and extent of coronary disease. Medically treated patients tended to be in a lower functional class, to have more extensive ventricular contraction abnormalities, to have a larger end-diastolic volume, and to have fewer distal vessels feasible for grafting. Surgically treated patients with two vessel disease and normal or moderately reduced election fraction had improved survival when compared with medically treated patients with two vessel disease and similar ejection fraction. Improved survival of borderline statistical significance was also seen in surgically treated patients with three vessel disease and moderately reduced ejection fraction. When categorized according to end-diastolic volume, surgically treated patients with two vessel disease and normal or moderately increased end-diastolic volume also had improved survival over similarly defined medically treated patients. The sudden death rates for subgroups of mecically treated patients were 1.8 to 10.9 times higher than the rates in subgroups of surgically treated patients with a comparable extent of coronary disease and ejection fraction.

Factors predictive of operative mortality among coronary artery bypass subsets

As risk-adjusted outcome is increasingly being used to make clinical decisions and to assess and improve quality of care, it is important to develop simple, stable models for predicting outcome. Here we address the hypothesis that a risk factor for increased operative mortality at coronary artery bypass grafting may have differential effects in subgroups of patients defined by the presence or absence of other risk variables. We used a series of univariate and multivariate analyses to identify a group of ten patient-related preoperative characteristics independently predictive of operative death in the total population of 12,712 patients undergoing coronary artery bypass grafting at 43 Department of Veterans Affairs medical centers participating in the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Study. Separate logistic regression models were then developed for each of 14 clinically important subgroups defined by the presence or absence of seven risk variables. Odds ratios for operative death and estimated operative mortality were calculated from these subgroup regression models. Of 65 comparisons of pairs odds ratios of preoperative risk variables between the subgroups with and without a second risk variable, only five were found to be significant (p < 0.05 without adjustment for multiple comparisons); this is only slightly more than would be expected by chance alone. Risk factors for increased operative death appear to have similar odds ratios for subgroups of patients defined by a second risk variable. This finding greatly simplifies the use of predicted operative mortality in clinical decision making and quality assessment and improvement in coronary artery bypass grafting.

Left ventricular thrombi: in vivo detection by indium-111 platelet imaging and two dimensional echocardiography

Indium-111 platelet imaging, which can identify sites of active intravascular platelet deposition, and two dimensional echocardiography, which can identify intracardiac masses, can both be used to detect left ventricular thrombi noninvasively. We compared these techniques in 44 men at risk for thrombi from remote transmural myocardial infarction (31 patients) or cardiomyopathy (13 patients). All 44 patients underwent platelet imaging; 35 underwent echocardiography. On platelet imaging nine patients had thrombi and one had a possible thrombus. Of these 10 studies, none were positive at 2 hours, 5 were positive at 24 hours and all were positive 48 or 72 hours after platelet labeling. Nine of these patients underwent echocardiography, and all had an intraventricular mass. The findings on platelet scanning were negative in six patients who had positive (four patients) or equivocally positive (two patients) findings on echocardiography. All patients with thrombi detected by either noninvasive method had transmural anterior myocardial infarction with ventricular aneurysm. Of the seven patients who underwent cardiac surgery or autopsy, three had thrombi. Platelet imaging failed to identify one thrombus in a patient in whom imaging was performed only at 24 hours after labeling. There were no false positive platelet images in this group. Five of these seven patients (two with thrombi, three without) underwent echocardiography; in all cases the echocardiographic findings agreed with the pathologic findings. Both platelet imaging and echocardiography detect ventricular thrombi. Platelet imaging may detect only the most hematologically active thrombi. Both techniques may help define patients at risk of embolization and may be useful for in vivo assessment of antithrombotic drugs.

Impact of mammary grafts on coronary bypass operative mortality and morbidity. Department of Veterans Affairs Cardiac Surgeons

The internal mammary artery is frequently used as a coronary artery bypass graft conduit because of superior long-term patency. The purpose of this study was to determine if there was also an advantage to the internal mammary artery in terms of operative mortality and morbidity. The Department of Veterans Affairs Cardiac Surgery Database was reviewed for two separate time periods, April 1987 through March 1989 and October 1990 through September 1991. During these periods, 14,172 patients underwent coronary artery bypass grafting. Univariate and multivariate logistic regression analyses were used to determine preoperative variables predictive of operative mortality and morbidity, with the independent variable of use of the internal mammary artery added to previously determined indicators. The total group was analyzed in risk quartiles according to expected mortality. Univariate analysis revealed an operative mortality of 6.8% in the early period and 6.5% in the latter period for the saphenous vein groups compared with 3.7% and 3.2%, respectively, for the internal mammary artery groups (p = 0.000). Multivariate analysis revealed an odds ratio of operative death with use of the internal mammary artery graft versus use of vein grafts of 0.78 during the first period and 0.72 during the second period, reductions of 22% and 28%, respectively. There were 29% and 37% reductions in the odds of operative mortality in the highest-risk quartile group of patients using the internal mammary artery graft. The odds ratio of developing mediastinitis with one internal mammary artery graft was 1.84 (p < 0.01) in the first time period and 1.11 in the second time period (p = not significant). However, with multiple mammary bypass grafts, the odds ratios were 3.70 (p < 0.01) and 2.96 (p < 0.01) in the respective time periods. On the basis of this study, it is concluded that internal mammary artery grafts in addition to providing superior long-term patency also decreased operative mortality after adjustment for patient risk factors. Use of the mammary artery does not consistently increase operative complications with the exception of mediastinitis when both internal mammary arteries are employed.