Laura P. Coombs

The society of thoracic surgeons: 30-day operative mortality and morbidity risk models

BACKGROUND Although 30 day risk-adjusted operative mortality (ROM) has been used for quality assessment, it is not sufficient to describe the outcomes after coronary artery bypass grafting (CABG) surgery. Risk-adjusted major morbidity may differentially impact quality of care (as complications occur more frequently than death) and enhance a surgical teams ability to assess their quality. This study identified the preoperative risk factors associated with several complications and a composite outcome (the presence of any major morbidity or 30-day operative mortality or both). METHODS For CABG procedures, the 1997 to 1999 Society of Thoracic Surgeons (STS) National Adult Cardiac Surgery Database was used to develop ROM and risk-adjusted morbidity (ROMB) models. Risk factors were selected using standard STS univariate screening and multivariate logistic regression approaches. Risk model performance was assessed. Across STS participating sites, the association of observed-to-expected (O/E) ratios for ROM and ROMB was evaluated. RESULTS The 30-day operative death and major complication rates for STS CABG procedures were 3.05% and 13.40%, respectively (503,478 CABG procedures), including stroke (1.63%), renal failure (3.53%), reoperation (5.17%), prolonged ventilation (5.96%), and sternal infection (0.63%). Risk models were developed (c-indexes for stroke [0.72], renal failure [0.76], reoperation [0.64], prolonged ventilation [0.75], sternal infection [0.66], and the composite endpoint [0.71]). Only a slight correlation was found, however, between ROMB and ROM indicators. CONCLUSIONS Used in combination, ROMB and ROM may provide the surgical team with additional information to evaluate the quality of their care as well as valuable insights to allow them to focus on areas for improvement.

Prediction of operative mortality after valve replacement surgery

OBJECTIVES We sought to develop national benchmarks for valve replacement surgery by developing statistical risk models of operative mortality. BACKGROUND National risk models for coronary artery bypass graft surgery (CABG) have gained widespread acceptance, but there are no similar models for valve replacement surgery. METHODS The Society of Thoracic Surgeons National Cardiac Surgery Database was used to identify risk factors associated with valve surgery from 1994 through 1997. The population was drawn from 49,073 patients undergoing isolated aortic valve replacement (AVR) or mitral valve replacement (MVR) and from 43,463 patients undergoing CABG combined with AVR or MVR. Two multivariable risk models were developed: one for isolated AVR or MVR and one for CABG plus AVR or CABG plus MVR. RESULTS Operative mortality rates for AVR, MVR, combined CABG/AVR and combined CABG/ MVR were 4.00%, 6.04%, 6.80% and 13.29%, respectively. The strongest independent risk factors were emergency/salvage procedures, recent infarction, reoperations and renal failure. The c-indexes were 0.77 and 0.74 for the isolated valve replacement and combined CABG/valve replacement models, respectively. These models retained their predictive accuracy when applied to a prospective patient population undergoing operation from 1998 to 1999. The Hosmer-Lemeshow goodness-of-fit statistic was 10.6 (p = 0.225) for the isolated valve replacement model and 12.2 (p = 0.141) for the CABG/valve replacement model. CONCLUSIONS Statistical models have been developed to accurately predict operative mortality after valve replacement surgery. These models can be used to enhance quality by providing a national benchmark for valve replacement surgery.

Sex differences in neurological outcomes and mortality after Cardiac Surgery : A Society of Thoracic Surgery National Database report

BackgroundThe purpose of this study was to evaluate whether women undergoing cardiac surgery are more likely to suffer neurological complications than men and whether these complications could explain, at least in part, their higher perioperative mortality. Methods and ResultsThe Society of Thoracic Surgery National Cardiac Surgery Database was examined for the years 1996 and 1997 to determine the frequency of new neurological events (stroke, transient ischemic attack, or coma) occurring after cardiac surgery. We reviewed clinical information on 416 347 patients (32% women) for whom complete neurological outcome data were available. New neurological events after surgery were higher for women than for men (3.8% versus 2.4%, P =0.001). For the whole group, the 30-day mortality was higher for women than for men (5.7% versus 3.5%, P =0.001), and among those patients who suffered a perioperative neurological event, mortality was also significantly higher for women than men (32% versus 28%, P =0.001). After adjustment for other risk factors (eg, age, history of hypertension and/or diabetes, duration of cardiopulmonary bypass, and other comorbid conditions) by multivariable logistic regression, female sex was independently associated with significantly higher risk of suffering new neurological events after cardiac surgery (OR 1.21, 95% CI 1.14 to 1.28, P =0.001). ConclusionsWomen undergoing cardiac surgery are more likely than men to suffer new perioperative neurological events, and they have higher 30-day mortality when these complications occur. The higher incidence of perioperative neurological complications in women cannot be explained by currently known risk factors.

Cardiac surgery in nonagenarians and centenarians

BACKGROUND Nonagenarians and centenarians are a rapidly growing segment of the population. No previous study has used a national database to compare outcomes in these patients to those of other groups undergoing cardiac surgical procedures. STUDY DESIGN The Society of Thoracic Surgeons National Database was used to review retrospectively 662,033 patients (5 patients more than 100 years of age; 1,092 patients 90 to 99 years; 59,576 patients 80 to 89 years; and 621,360 patients 50 to 79 years of age) who underwent cardiac surgical procedures from 1997 through 2000. These included 575,389 patients who had undergone coronary artery bypass grafting (CABG) only; 56,915 patients with CABG and concomitant mitral or aortic valve replacement or repair (CABG+VALVE); and 49,729 patients with mitral or aortic valve repair or replacement only (VALVE-only). A multivariate logistic regression model was developed to examine predictors of operative mortality in patients more than 90 years of age. RESULTS For CABG-only patients, operative mortality was 11.8% for patients more than 90 years of age, 7.1% for those 80 to 89 years, and 2.8% for those 50 to 79 years. The incidence of renal failure and prolonged ventilation was highest among patients more than 90 years of age (9.2% and 12.2%), compared with those 80 to 89 years (7.7% and 10.5%) or 50 to 79 years (3.5% and 6.0%). For VALVE-only patients and CABG+VALVE patients operative mortality for those more than 90 years of age was 11.4% and 12.0%, respectively, compared with 8.3% and 11.5% for those 80 to 89 years and 4.3% and 7.6% for those 50 to 79 years. The major preoperative risk factors for operative mortality among patients more than 90 years of age undergoing isolated CABG were as follows (C-index, 0.68): emergent/salvage: odds ratio, 2.26; 95% confidence interval, 1.38-3.69; preoperative intraaortic balloon pump: odds ratio, 2.79; 95% confidence interval, 1.47-5.32; renal failure: odds ratio, 2.08; 95% confidence interval, 1.12-3.86; peripheral vascular disease or cerebrovascular vascular disease: odds ratio, 1.39, 95% confidence interval, 0.96-2.02; mitral insufficiency: odds ratio, 1.50; 95% confidence interval, 0.93-2.41. Approximately 57% of the nonagenarians and centenarians lacked any of the first four risk factors and had an operative mortality of 7.2%. CONCLUSIONS Operative mortality and complication rates associated with cardiac surgical procedures are highest for nonagenarians and centenarians. But with careful patient selection, a majority of these patients have a lower risk of CABG-related mortality approaching that of younger patients.

Use of continuous quality improvement to increase use of process measures in patients undergoing coronary artery bypass graft surgery: a randomized controlled trial ☆

CONTEXT A rigorous evaluation of continuous quality improvement (CQI) in medical practice has not been carried out on a national scale. OBJECTIVE To test whether low-intensity CQI interventions can be used to speed the national adoption of 2 coronary artery bypass graft (CABG) surgery process-of-care measures: preoperative beta-blockade therapy and internal mammary artery (IMA) grafting in patients 75 years or older. DESIGN, SETTING, AND PARTICIPANTS Three hundred fifty-nine academic and nonacademic hospitals (treating 267 917 patients using CABG surgery) participating in the Society of Thoracic Surgeons National Cardiac Database between January 2000 and July 2002 were randomized to a control arm or to 1 of 2 groups that used CQI interventions designed to increase use of the process-of-care measures. INTERVENTION Each intervention group received measure-specific information, including a call to action to a physician leader; educational products; and periodic longitudinal, nationally benchmarked, site-specific feedback. MAIN OUTCOME MEASURE Differential incorporation of the targeted care processes into practice at the intervention sites vs the control sites, assessed by measuring preintervention (January-December 2000)/postintervention (January 2001-July 2002) site differences and by using a hierarchical patient-level analysis. RESULTS From January 2000 to July 2002, use of both process measures increased nationally (beta-blockade, 60.0%-65.6%; IMA grafting, 76.2%-82.8%). Use of beta-blockade increased significantly more at beta-blockade intervention sites (7.3% [SD, 12.8%]) vs control sites (3.6% [SD, 11.5%]) in the preintervention/postintervention (P =.04) and hierarchical analyses (P<.001). Use of IMA grafting also tended to increase at IMA intervention sites (8.7% [SD, 17.5%]) vs control sites (5.4% [SD,15.8%]) (P =.20 and P =.11 for preintervention/postintervention and hierarchical analyses, respectively). Both interventions tended to have more impact at lower-volume CABG sites (for interaction: P =.04 for beta-blockade; P =.02 for IMA grafting). CONCLUSIONS A multifaceted, physician-led, low-intensity CQI effort can improve the adoption of care processes into national practice within the context of a medical specialty society infrastructure.

Patient Selection and Current Practice Strategy for Off-pump Coronary Artery Bypass Surgery

Objective—Previous studies comparing off-pump coronary artery bypass surgery (OPCABG) to conventional techniques utilizing cardiopulmonary bypass (CABG-CPB) have failed to provide patient selection guidelines. We sought to determine guidelines, attempting to rectify the limitations of previous studies. Methods and Results—A retrospective analysis of prospectively collected data from the Society of Thoracic Surgeons National Database, from January 1999 through December 2000, identified 204 602 multivessel coronary artery bypass (CABG) patients. Unadjusted and risk-adjusted odds ratios (OR) were calculated to compare OPCABG and CABG-CPB morbidity and mortality. A propensity model was developed to identify factors associated with selection for OPCABG. All off-pump patients were pair-matched with on-pump patients based on their propensity to receive an off-pump procedure. Off-pump patients, 8.8% of the total, had significantly different patient characteristics than the on-pump group. Characteristics associated with OPCABG selection included fewer diseased vessels, absence of left main disease, fewer bypass grafts, no previous CABG, older age, chronic lung disease, and renal failure. Unadjusted and risk-adjusted odds ratios indicate a significant off-pump survival benefit and decreased morbidity including stroke and renal failure in the overall group. Propensity matching also showed a significant OPCABG survival benefit [OR (95% CI) 0.83 (0.72, 0.96)]. Subgroup analysis of propensity-matched groups identified off-pump survival benefits in patients with previous CABG (OR=0.53), diabetics (OR=0.66), LVEF between 30% to 50% (OR=0.75), females (OR=0.79), and age 66 to 75 years (OR=0.80). Conclusion—OPCABG imparts some survival benefit to most patient subgroups. Higher risk patients including those undergoing reoperative CABG, diabetics, and the elderly may gain the most benefit.

The effect of race on coronary bypass operative mortality

OBJECTIVES The study was done to determine whether race is an independent predictor of operative mortality after coronary artery bypass graft (CABG) surgery. BACKGROUND Blacks are less frequently referred for cardiac catheterization and CABG than are whites. Few reports have investigated the relative fate of patients who undergo CABG as a function of race. METHODS The Society of Thoracic Surgeons National Database was used to retrospectively review 25,850 black and 555,939 white patients who underwent CABG-alone from 1994 through 1997. A multivariate logistic regression model was developed to determine whether race affected risk-adjusted operative mortality. RESULTS Operative mortality was 3.83% for blacks versus 3.14% for whites (unadjusted black/white odds ratio [OR] 1.23 [1.15-1.31]). Blacks were younger, more likely female, hypertensive, diabetic and in heart failure. Nonetheless, the influence of these and other preoperative risk factors on procedural mortality was quite similar in black and white patients. After controlling for all risk factors, race remained a significant independent predictor of mortality in the multivariate logistic model (adjusted black/white OR 1.29 [1.21, 1.38]). Proportionately, these differences were greatest among lower-risk patients. The race-by-gender interaction was significant (p<0.05). The unadjusted mortality for black men, 3.30% and white men, 2.64% differed significantly (p<0.05), whereas for women there was no difference (black, 4.49%; white 4.41%). CONCLUSIONS Black race is an independent predictor of operative mortality after CABG except for very high-risk patients. The difference in mortality is greatest for male patients and, though statistically significant, is small in absolute terms. Therefore, patients should be referred for CABG based on clinical characteristics irrespective of race.

Testing an intervention to increase cardiac rehabilitation enrollment after coronary artery bypass grafting

C rehabilitation has been shown to improve functional status, cardiac risk factor profiles, and psychosocial well-being after coronary artery bypass graft surgery to a similar extent in young and old patients. Despite these benefits, prior studies have consistently documented that only a quarter of eligible revascularization patients actually enroll in such a program. Participation among the elderly population has been particularly low, with rates often half that seen in younger patients. Although the reasons for this poor utilization of cardiac rehabilitation programs are multiple, physician recommendation and referral is considered to be the most important factor. This study examines whether a simple postdischarge patient education and referral intervention could improve cardiac rehabilitation participation rates after bypass. • • • We identified 100 consecutive patients who underwent bypass surgery at Duke University Medical Center between September and December 2000 who lived within 30 miles of 1 of the 75 cardiac rehabilitation centers in North Carolina or Southeastern Virginia. Patients were excluded if they had significant ambulatory impairment (e.g., wheelchair bound or otherwise nonambulatory), dementia, blindness, or had been rehospitalized before our intervention. With the approval of the cardiac surgery service, a medical student (SKP) contacted patients by phone 6 to 12 weeks (mean 9.7 2.0) after bypass. Patients were provided with information regarding the potential health benefits of cardiac rehabilitation. If interested, they were assisted in the referral process by our contacting their local cardiac rehabilitation center and/or their primary care physician. Phone calls were made 3 to 7 weeks (mean 4.0 0.79) after initial contact to determine subsequent enrollment in a cardiac rehabilitation program. Reasons for nonparticipation were also assessed through a standardized questionnaire. Follow-up was 100% complete. Descriptive statistics summarizing baseline characteristics and participation rates are presented as percentages for discrete variables, and mean SDs for continuous variables. Differences in participation rates in patients aged 70 years versus 70 years were assessed by the chi-square test, and differences in participation rates before and after intervention were assessed by the McNemar test. A p value of 0.05 was considered significant. Of 107 patients initially identified, 7 were excluded (5 because of rehospitalization before initial contact, 1 because of a severe ambulatory limitation, and 1 because of blindness), leaving 100 patients for our analysis. Patients’ mean age was 65 years and 62% were men (Table 1). Most had several cardiac risk factors, and 34% had a myocardial infarction before bypass surgery. Overall, enrollment in a cardiac rehabilitation program nearly doubled after intervention (31% vs 56%, p 0.0001, Figure 1). Before intervention, patients aged 70 years tended to be less likely than those 70 years to enroll in a cardiac rehabilitation program (25% vs 34%). After intervention, enrollment more than doubled (2.2 times) to 56% (p 0.001) in those aged 70 years and increased by 1.6 times, and also to 56% (p 0.001) in those aged 70 years (Figure 1). Before intervention, the most common reason cited for nonparticipation was lack of physician referral (54 of 69 patients [78%], Table 2). This was consistent across age subgroups. Other common reasons included transportation problems, not feeling well, lack of interest, and already exercising on their own. Financial or safety concerns and being too busy were cited by only a few patients. After intervention, the most common reason for nonparticipation cited was “lack of interest.” The number of patients reporting transportation problems decreased from 9 to 4, whereas the number of patients citing financial concerns, not feeling well, being too busy, and safety concerns remained constant. The total time commitment for intervention and follow-up was estimated to be approximately 30 minutes/patient (total 50 hours). Most patients were at home during business hours and could be easily contacted during the postoperative recovery period. In general, patients reported feeling overwhelmed with the variety of instructions concerning new medications, follow-up appointments, and so forth, at the time of discharge, and appreciated the additional information regarding cardiac rehabilitation being provided at a later date. Many were surprised to learn there was a rehabilitation center in their hometown. • • • Although cardiac rehabilitation after bypass surgery has been shown to improve functional capacity, cardiac risk factors, and psychosocial well-being regardless of age, enrollment is low, particularly among the elderly population. We show that a simple postFrom The Outcomes Research and Assessment Group, The Duke Clinical Research Institute, Durham, North Carolina. Dr. Peterson’s address is: Duke Clinical Research Institute, PO Box 107969, Durham, North Carolina 27715. E-mail: peter016@mc.duke.edu. Manuscript received June 13, 2001; revised manuscript received and accepted August 21, 2001.

Preoperative β-blocker use and mortality and morbidity following CABG surgery in North America ☆

CONTEXT beta-Blockade therapy has recently been shown to convey a survival benefit in preoperative noncardiac vascular surgical settings. The effect of preoperative beta-blocker therapy on coronary artery bypass graft surgery (CABG) outcomes has not been assessed. OBJECTIVES To examine patterns of use of preoperative beta-blockers in patients undergoing isolated CABG and to determine whether use of beta-blockers is associated with lower operative mortality and morbidity. DESIGN, SETTING, AND PATIENTS Observational study using the Society of Thoracic Surgeons National Adult Cardiac Surgery Database (NCD) to assess beta-blocker use and outcomes among 629 877 patients undergoing isolated CABG between 1996 and 1999 at 497 US and Canadian sites. MAIN OUTCOME MEASURE Influence of beta-blockers on operative mortality, examined using both direct risk adjustment and a matched-pairs analysis based on propensity for preoperative beta-blocker therapy. RESULTS From 1996 to 1999, overall use of preoperative beta-blockers increased from 50% to 60% in the NCD (P<.001 for time trend). Major predictors of use included recent myocardial infarction; hypertension; worse angina; younger age; better left ventricular systolic function; and absence of congestive heart failure, chronic lung disease, and diabetes. Patients who received beta-blockers had lower mortality than those who did not (unadjusted 30-day mortality, 2.8% vs 3.4%; odds ratio [OR], 0.80; 95% confidence interval [CI], 0.78-0.82). Preoperative beta-blocker use remained associated with slightly lower mortality after adjusting for patient risk and center effects using both risk adjustment (OR, 0.94; 95% CI, 0.91-0.97) and treatment propensity matching (OR, 0.97; 95% CI, 0.93-1.00). Procedural complications also tended to be lower among treated patients. This treatment advantage was seen among the majority of patient subgroups, including women; elderly persons; and those with chronic lung disease, diabetes, or moderately depressed ventricular function. Among patients with a left ventricular ejection fraction of less than 30%, however, preoperative beta-blocker therapy was associated with a trend toward a higher mortality rate (OR, 1.13; 95% CI, 0.96-1.33; P =.23). CONCLUSIONS In this large North American observational analysis, preoperative beta-blocker therapy was associated with a small but consistent survival benefit for patients undergoing CABG, except among patients with a left ventricular ejection fraction of less than 30%. This analysis further suggests that preoperative beta-blocker therapy may be a useful process measure for CABG quality improvement assessment.