Development of the new lung allocation system in the United States.

This article reviews the development of the new U.S. lung allocation system that took effect in spring 2005. In 1998, the Health Resources and Services Administration of the U.S. Department of Health and Human Services published the Organ Procurement and Transplantation Network (OPTN) Final Rule. Under the rule, which became effective in 2000, the OPTN had to demonstrate that existing allocation policies met certain conditions or change the policies to meet a range of criteria, including broader geographic sharing of organs, reducing the use of waiting time as an allocation criterion and creating equitable organ allocation systems using objective medical criteria and medical urgency to allocate donor organs for transplant. This mandate resulted in reviews of all organ allocation policies, and led to the creation of the Lung Allocation Subcommittee of the OPTN Thoracic Organ Transplantation Committee. This paper reviews the deliberations of the Subcommittee in identifying priorities for a new lung allocation system, the analyses undertaken by the OPTN and the Scientific Registry for Transplant Recipients and the evolution of a new lung allocation system that ranks candidates for lungs based on a Lung Allocation Score, incorporating waiting list and posttransplant survival probabilities.

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.

Off-pump coronary artery bypass grafting decreases risk-adjusted mortality and morbidity.

BACKGROUND: The purpose of this study was to determine whether coronary artery bypass grafting without cardiopulmonary bypass (off-pump CABG) decreases risk-adjusted operative death and major complications after coronary artery bypass grafting in selected patients. METHODS: Using The Society of Thoracic Surgeons (STS) National Adult Cardiac Surgery Database, procedural outcomes were compared for conventional and off-pump CABG procedures from January 1, 1998, through December 31, 1999. Mortality and major complications were examined, both as unadjusted rates and after adjusting for known base line patient risk factors. RESULTS: A total of 126 experienced centers performed 118,140 total CABG procedures. The number of off-pump CABG cases was 11,717 cases (9.9% of total cases). The use of an off-pump procedure was associated with a decrease in risk-adjusted operative mortality from 2.9% with conventional CABG to 2.3% in the off-pump group (p < 0.001). The use of an off-pump procedure decreased the risk-adjusted major complication rate from 14.15% with conventional CABG to 10.62% in the off-pump group (p < 0.0001). Patients receiving off-pump procedures were less likely to die (adjusted odds ratio 0.81, 95% CI 0.70 to 0.91) and less likely to have major complications (adjusted odds ratio 0.77, 95% CI 0.72 to 0.82). CONCLUSIONS: Off-pump CABG is associated with decreased mortality and morbidity after coronary artery bypass grafting. Off-pump CABG may prove superior to conventional CABG in appropriately selected patients.

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.

Off-pump coronary artery bypass is associated with improved risk-adjusted outcomes.

BACKGROUND: The impact of off-pump median sternotomy coronary artery bypass grafting procedures on risk-adjusted mortality and morbidity was evaluated versus on-pump procedures. METHODS: Using the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Program records from October 1997 through March 1999, nine centers were designated as having experience (with at least 8% coronary artery bypass grafting procedures performed off-pump). Using all other 34 Veterans Affairs cardiac surgery programs, baseline logistic regression models were built to predict risk of 30-day operative mortality and morbidity. These models were then used to predict outcomes for patients at the nine study centers. A final model evaluated the impact of the off-pump approach within these nine centers adjusting for preoperative risk. RESULTS: Patients treated off-pump (n = 680) versus on-pump (n = 1,733) had lower complication rates (8.8% versus 14.0%) and lower mortality (2.7% versus 4.0%). Risk-adjusted morbidity and mortality were also improved for these patients (0.52 and 0.56 multivariable odds ratios for off-pump versus on-pump, respectively, p < 0.05). CONCLUSIONS: An off-pump approach for coronary artery bypass grafting procedures is associated with lower risk-adjusted morbidity and mortality.

Reoperative homograft right ventricular outflow tract reconstruction.

BACKGROUND: Homografts are implanted in the right ventricular outflow tract (RVOT) of children, with the knowledge that reoperation might be required. We reviewed 14 years of homograft RVOT reconstruction to assess the feasibility of homograft replacement and to determine risk factors for homograft survival. METHODS: From February 1985 through March 1999, 223 children (age 5 days to 16.9 years) underwent primary RVOT reconstruction with an aortic or pulmonary homograft. Of these, 35 patients underwent homograft explant at the implanting hospital with insertion of a second homograft from 2 months to 13.3 years after the first implantation. The primary operation and reoperation patient groups were compared with regard to incidence of early death, late death, homograft-related intervention without explant, and homograft explant. RESULTS: Actuarial survival and event-free curves for initial and replacement homografts were not significantly different. Univariable analysis was performed for the following risk factors: weight (p < 0.0001), age (p < 0.003), homograft diameter (p < 0.0001), homograft type (p < 0.01), surgery date (not significant [NS]), gender (NS), Blood Group match (NS), and type of distal anastomosis (NS). Multivariable analysis of significant univariable risks revealed small homograft diameter to be a significant risk factor (p < 0.001) for replacement. CONCLUSIONS: The RVOT homografts eventually require replacement. Patient and homograft survival for replacement homografts is similar to primary homografts. Reoperative homograft RVOT reconstruction is possible, with reasonably low morbidity and mortality.

Effects of race, with or without gender, on operative mortality after coronary artery bypass grafting: a study using The Society of Thoracic Surgeons National Database.

BACKGROUND: Although gender is known to be an independent predictor of 30-day operative mortality (OM) after coronary artery bypass grafting, the purpose of this study was to determine whether race-alone or in combination with gender-affects OM. METHODS: For 1994 to 1996, The Society of Thoracic Surgeons database records for 441,542 coronary artery bypass grafting-only procedures were analyzed. Baseline annual multivariate models were built. Gender and race were added to each model. Risk-adjusted OM rates were then calculated for race, gender, and their combination. Patients were also stratified into groups of comparable predicted OM to allow for a direct comparison of risk-matched Caucasians and non-Caucasians. RESULTS: Of the procedures, 28.2% were on women and 8.5% on non-Caucasians. Overall, OM was 3.29%. Multivariate risk-adjusted OM varied by gender and race (p < 0.10). Risk-adjusted OM rates (with 95% confidence intervals) were 4.0% (3.9% to 4.1%) for females and 3.2% (3.2% to 3.3%) for males. Risk-adjusted OM rates were 3.9% (3.7% to 4.1%) for non-Caucasians and 3.3% (3.2% to 3.3%) for Caucasians. Among equally risk-matched Caucasians and non-Caucasians, non-Caucasians had significantly higher (p < 0.005) mortality among the lower risk subgroups (up to 10% predicted OM) but not among the higher risk subgroups. CONCLUSIONS: Race and gender are independent predictors of adverse outcome following coronary artery bypass grafting, holding all other risk factors constant.

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.

Identification of risk factors for increased cost, charges, and length of stay for cardiac patients.

BACKGROUND: In this study we explored different risk model options to provide clinicians with predictions for resource utilization. The hypotheses were that predictors of mortality are not predictive of resource consumption, and that there is a correlation between cost estimates derived using a cost-to-charge ratio or a product-line costing approach. METHODS: From March 1992 to June 1995, 2,481 University of Colorado Hospital patients admitted for ischemic heart disease were classified by diagnosis-related group code as having undergone or experienced coronary bypass procedures (CBP), percutaneous cardiovascular procedures (PCVP), acute myocardial infarction (AMI), and other cardiac-related discharges (Other). For each diagnosis-related group, Cox proportional hazards models were developed to determine predictors of cost, charges, and length of stay. RESULTS: The diagnosis groups differed in the clinical factors that predicted resource use. As the two costing methods were highly correlated, either approach may be used to assess relative resource consumption provided costs are reconciled to audited financial statements. CONCLUSIONS: To develop valid prediction models for costs of care, the clinical risk factors that are traditionally used to predict risk-adjusted mortality may need to be expanded.

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.

Mild renal failure is associated with adverse outcome after cardiac valve surgery.

The present study was performed to ascertain whether the presence of mild renal failure (defined as a serum creatinine concentration of 1. 5 to 3.0 mg/dL) is an independent risk factor for adverse outcome after cardiac valve surgery. An extensive set of preoperative and postoperative data was collected in 834 prospectively evaluated patients undergoing cardiac valve surgery at 14 Veterans Affairs Medical Centers. Univariate and multivariable analyses were performed to determine whether an independent association of mild renal dysfunction with adverse outcomes was present. Patients with mild renal failure had significantly greater 30-day mortality rates (P = 0.001; 16% versus 6%) and frequency of postoperative bleeding (P = 0.023; 16% versus 8%), respiratory complications (P = 0.02, 29% versus 16%), and cardiac complications (P = 0.002; 18% versus 7%) than patients with normal renal function (serum creatinine <1.5 mg/dL) when controlling for multiple other variables. The presence of a serum creatinine concentration of 1.5 to 3.0 mg/dL is significantly and independently associated with adverse outcomes after cardiac valve surgery.

The STS National Database: current changes and challenges for the new millennium. Committee to Establish a National Database in Cardiothoracic Surgery, The Society of Thoracic Surgeons.

BACKGROUND: The Society of Thoracic Surgeons (STS) established the National Database (NDB) for Cardiac Surgery in 1989. Since then it has grown to be the largest database of its kind in medicine. The NDB has been one of the pioneers in the analysis and reporting of risk-adjusted outcomes in cardiothoracic surgery. METHODS AND RESULTS: This report explains the numerous changes in the NDB and its structure that have occurred over the past 2 years. It highlights the benefits of these changes, both to the individual member participants and to the STS overall. Additionally, the vision changes to the NDB and reporting structure are identified. The individuals who have participated in this effort since 1989 are acknowledged, and the STS owes an enormous debt of gratitude to each of them. CONCLUSIONS: Because of their collective efforts, the goal to establish the STS NDB as a "gold standard" worldwide for process and outcomes analysis related to cardiothoracic surgery is becoming a reality.

Secondary pulmonary hypertension does not adversely affect outcome after single lung transplantation.

OBJECTIVE: Primary and secondary pulmonary hypertension have been associated with poor outcomes after single lung transplantation. Some groups advocate double lung transplantation and the routine use of cardiopulmonary bypass during transplantation in this population. However, the optimal procedure for these patients remains controversial. The goal of our study was to determine the safety of single lung transplantation without cardiopulmonary bypass in patients with secondary pulmonary hypertension. METHODS: We retrospectively reviewed 76 consecutive patients with pulmonary parenchymal disease who underwent single lung transplantation from 1992 to 1998. Recipients were stratified according to preoperative mean pulmonary artery pressure. Secondary pulmonary hypertension was defined as parenchymal lung disease with a preoperative mean pulmonary artery pressure of 30 mm Hg or more. Patients with primary pulmonary hypertension or Eisenmenger's syndrome were excluded from analysis. RESULTS: Eighteen of 76 patients had secondary pulmonary hypertension. No patient with secondary pulmonary hypertension required cardiopulmonary bypass, whereas 1 patient without pulmonary hypertension required bypass. After the operation, no significant differences were seen in lung injury as measured by chest radiograph score and PaO(2)/FIO(2) ratio, the requirement for inhaled nitric oxide, the length of mechanical ventilation, the intensive care unit or hospital length of stay, and 30-day survival. There were no differences in the forced expiratory volume in 1 second or 6-minute walk at 1 year, or the incidence of rejection, infection, or bronchiolitis obliterans syndrome greater than grade 2. Survival at 1, 2, and 4 years after transplantation was 86%, 79%, and 65%, respectively, in the low pulmonary artery pressure group and 81%, 81%, and 61%, respectively, in the group with secondary pulmonary hypertension (P >.2). CONCLUSION: We found that patients with pulmonary parenchymal disease and concomitant secondary pulmonary hypertension had successful outcomes as measured by early and late allograft function and appear to have acceptable long-term survival after single lung transplantation. Our results do not support the routine use of cardiopulmonary bypass or double lung transplantation for patients with this disorder.

Clinical science research.

Clinical science research incorporates the fields of clinical investigation and health services research. With a focus on the use of either human specimens or subjects, clinical investigation research projects translate knowledge gained from basic science research based on animal models for disease. The goal of clinical investigation is to develop new prevention, intervention, and therapeutic approaches to improve patient clinical outcomes. In contrast, health services research focuses on the improvement of the efficacy, cost-effectiveness, and outcomes of care. Health services research projects examine options to improve the health care delivery system, organization, financing, and reimbursement mechanisms in place today. The purpose of this article is to review common terminology and methodologic approaches that are used in clinical science research. The process of designing a research project is reviewed. Beginning with the development of a research question and hypothesis, the steps for successful completion of the project are discussed. Different study design approaches are presented with their respective strengths and weaknesses. The challenges associated with conducting a clinical research study are discussed, including the development of an appropriate sampling strategy, the designing of data collection, instruments, and the assurance of study data integrity. Possible threats to study validity and generalizability are assessed.One the major advantages of clinical research is that it offers an opportunity to study clinical questions in the clinical setting without the expenses of a basic research laboratory and basic science technology. Thus important clinical questions related to patient care, new technology assessment, clinical practice management, health care administration, or health policy may be addressed.

Association of fast-track cardiac management and low-dose to moderate-dose glucocorticoid administration with perioperative hyperglycemia.

OBJECTIVE: To delineate associations between preoperative risk factors and clinical processes of care and perioperative glucose tolerance in patients managed on a fast-track cardiac surgery clinical pathway with prebypass methylprednisolone administration. DESIGN: Retrospective sequential cohort study. SETTING: University-affiliated Department of Veterans Affairs medical center. PARTICIPANTS: Fast-track patients (n = 293; n = 72 low-dose methylprednisolone [100-125 mg]; n = 221 moderate-dose methylprednisolone [500 mg]) plus pre-fast-track patients (n = 258; no methylprednisolone) undergoing cardiac surgery with cardiopulmonary bypass. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Multivariate linear regression was used to model the association of 17 preoperative risk and intraoperative process-of-care variables with serum glucose concentration on arrival in the intensive care unit. Preoperative serum glucose concentrations were not significantly different among the pre-fast-track, fast-track with low-dose methylprednisolone, and fast-track with moderate-dose methylprednisolone cohorts (129 +/- 54, 137 +/- 55, 127 +/- 46 mg/dL [mean +/- SD]). Postoperative serum glucose concentrations were significantly different (171 +/- 58, 223 +/- 56, 250 +/- 75 mg/dL; p < 0.03, for all pairwise comparisons). Using backward elimination from the full 17-variable multivariate model (R-square = 0.63), 4 variables remained significant (all p < 0.0001; R-square = 0.60): (1) Preoperative diabetes status (adjusted mean post-operative glucose level, mg/dL; [95% confidence interval (CI)]): no treatment, 193 (188-199); oral agent, 276 (262-291); insulin requiring, 301 (283-320); (2) steroid group: pre-fast-track, 201 (195-209), fast-track with low-dose methylprednisolone, 271 (256-287); fast-track with moderate-dose methylprednisolone, 295 (284-306); (3) volume of glucose-containing cardioplegia (beta coefficient, 95% CI): 2.22% (1.37-3.10) increase per 100 mL; and (4) intraoperative epinephrine infusion: none, 231 (224-239); yes, 276 (264-288). No significant interactions were identified. No significant effect of opioid dose was observed. CONCLUSION: At this institution, implementation of the fast-track pathway was associated with a deterioration of glucose tolerance. Preoperative diabetes, pre-cardiopulmonary bypass administration of steroids, volume of glucose-containing cardioplegia solution administered, and use of epinephrine infusions were significantly associated multivariate factors.