No continuous relationship between Veterans Affairs hospital coronary artery bypass grafting surgical volume and operative mortality

Surgeon and Hospital Factors Associated With Outcomes in the New York State Database

INTRODUCTION

We sought to explore the relationship between various surgeon-related and hospital-level characteristics and clinical outcomes among patients requiring cardiac surgery.

METHODS

We searched the New York State Cardiac Data Reporting System for all coronary artery bypass grafting (CABG) and valve cases between 2015 and 2017. The data were analyzed without dichotomization.

RESULTS

Among CABG/valve surgeons, case volume was positively correlated with years in practice (P = 0.002) and negatively correlated with risk-adjusted mortality ratio (P = 0.014). For CABG and CABG/valve surgeons, our results showed a negative association between teaching status and case volume (P = 0.002, P = 0.018). Among CABG surgeons, hospital teaching status and presence of cardiothoracic surgery residency were inversely associated with risk-adjusted mortality ratio (P = 0.006, P = 0.029).

CONCLUSIONS

There is a complex relationship between case volume, teaching status, and surgical outcomes suggesting that balance between academics and volume is needed.

Practice makes perfect? Institutional coronary artery bypass case volumes and outcomes

OBJECTIVES

Older studies of coronary artery bypass grafting (CABG) institutional case volumes and outcomes reported conflicting results. We explored this association in the rapidly changing contemporary practice of American surgeons using the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database.

METHODS

The 2018-2019 isolated primary CABG experience in the STS Adult Cardiac Surgery Database was analysed (241 902 patients; 1014 hospitals; 2718 surgeons). Generalized Estimating Equations were used to estimate coefficients between CABG institutional case volumes and outcomes. The observed-to-expected ratios based on STS risk models were used to assess risk-adjusted operative mortality (OM), mortality/major morbidity (MM) and deep sternal wound infections (DSWI) as a function of institutional case volumes.

RESULTS

The mean (standard deviation) OM, MM and DSWI rates were 2.1% (2.7), 11.1% (9.2) and 0.6% (0.5), respectively. The mean (standard deviation) institutional case volumes per study period was 239 (192); 23% and 9% of institutions performed <100 and >500 cases/study period, respectively. There was a weak negative correlation between expected mortality (R2 -0.0014), OM (R2 -0.0272), MM (R2 -0.1213) and DSWI (R2 -0.003) and institutional case volumes.

CONCLUSIONS

CABG outcomes generally improve with increasing institutional case volumes. Given the large number of CABG cases performed nationally, even the documented weak correlation has the potential to appreciably decrease OM, MM and DSWI if cases are performed at higher volume institutions. Studies focusing on additional hospital and surgeon factors are warranted to further define quality improvement opportunities.

Volume-Outcome Relationship of Resternotomy Coronary Artery Bypass Grafting

BACKGROUND

We assessed volume-outcome relationships of resternotomy coronary artery bypass grafting (CABG).

METHODS

We studied 1,362,218 first-time CABG and 93,985 resternotomy CABG patients reported to The Society of Thoracic Surgeons Adult Cardiac Surgery Database between 2010 and 2019. Primary outcomes were in-hospital mortality and mortality and morbidity (M&M) rates calculated per hospital and per surgeon. Outcomes were compared across 6 total cardiac surgery volume categories. Multivariable generalized linear mixed-effects models were used considering continuous case volume as the main exposure, adjusting for patient characteristics and within-surgeon and hospital variation.

RESULTS

We observed a decline in resternotomy CABG unadjusted mortality and M&M from the lowest to the highest case-volume categories (hospital-level mortality, 3.9% ± 0.6% to 3.3% ± 0.1%; M&M, 18.5% ± 1.1% to 15.7% ± 0.4%, P < .001; surgeon-level mortality, 4.1% ± 0.3% to 4.1% ± 1.3%; M&M, 18.5% ± 0.6% to 14.5% ± 2.2%, P < .001). Looking at outcomes vs continuous volume showed that beyond a minimum annual volume (hospital 200-300 cases; surgeon 100-150 cases, approximately), mortality and M&M rates did not further improve. Using individual-level data and adjusting for patient characteristics and clustering within surgeon and hospital, we found higher procedural volume was associated with improved surgeon-level outcomes (mortality adjusted odds ratio, 0.39/100 procedures; 95% CI, 0.24-0.61; M&M adjusted odds ratio, 0.37/100 procedures; 95% CI, 0.28-0.48; P < .001 for both). Hospital-level adjusted volume-outcomes associations were not statistically significant.

CONCLUSIONS

We observed an inverse relationship between total cardiac case volume and resternotomy CABG outcomes at the surgeon level only, indicating that individual surgeon's experience, rather than institutional volume, is the key determinant.

Institutional case volume and mortality after aortic and mitral valve replacement: a nationwide study in two Korean cohorts

Background

There are only a handful of published studies regarding the volume-outcome relationship in heart valve surgery. We evaluated the association between institutional case volume and mortality after aortic valve replacement (AVR) and mitral valve replacement (MVR).

Methods

Two separate cohorts of all adults who underwent AVR or MVR, respectively, between 2009 and 2016 were analyzed using a Korean healthcare insurance database. Hospitals performing AVRs were divided into three groups according to the average annual case volume: the low- (< 20 cases/year), medium- (20–70 cases/year), and high-volume centers (> 70 cases/year). Hospitals performing MVRs were also grouped as the low- (< 15 cases/year), medium- (15–40 cases/year), or high-volume centers (> 40 cases/year). In-hospital mortality after AVR or MVR were compared among the groups.

Results

In total, 7875 AVR and 5084 MVR cases were analyzed. In-hospital mortality after AVR was 8.3% (192/2318), 4.0% (84/2102), and 2.6% (90/3455) in the low-, medium-, and high-volume centers, respectively. The adjusted risk was higher in the low- (OR 2.31, 95% CI 1.73–3.09) and medium-volume centers (OR 1.53, 95% CI 1.09–2.15) compared to the high-volume centers. In-hospital mortality after MVR was 9.3% (155/1663), 6.3% (94/1501), and 2.9% (56/1920) in the low-, medium-, and high-volume centers, respectively. Compared to the high-volume centers, the medium- (OR 1.97, 95% CI 1.35–2.88) and low-volume centers (OR 2.29, 95% CI 1.60–3.27) showed higher adjusted risk of in-hospital mortality.

Conclusions

Lower case volume is associated with increased in-hospital mortality after AVR and MVR. The results warrant a comprehensive discussion regarding regionalization/centralization of cardiac valve replacements to optimize patient outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-022-01945-0.

Impact of Mitral Valve Repair Case Volume on Postoperative Mortality - A Nationwide Korean Cohort Study

BACKGROUND

Although mitral valve repair is recommended over replacement due to better outcomes, repair rates vary significantly among centers. This study examined the effect of institutional mitral valve repair volume on postoperative mortality.Methods and Results:All cases of adult mitral valve repair performed in Korea between 2009 and 2016 were analyzed. The association between case volume and 1-year mortality was analyzed after categorizing centers according to the number of mitral valve repairs performed as low-, medium-, or high-volume centers (<20, 20-40, and >40 cases/year, respectively). The effect of case volume on cumulative all-cause mortality was also assessed. In all, 6,041 mitral valve repairs were performed in 86 centers. The 1-year mortality in low-, medium-, and high-volume centers was 10.1%, 8.7%, and 4.7%, respectively. Low- and medium-volume centers had increased risk of 1-year mortality compared with high-volume centers, with odds ratios of 2.80 (95% confidence interval [CI] 2.15-3.64; P<0.001) and 2.66 (95% CI 1.94-3.64; P<0.001), respectively. The risk of cumulative all-cause mortality was also worse in low- and medium-volume centers, with hazard ratios of 1.96 (95% CI 1.68-2.29; P<0.001) and 1.77 (95% CI 1.47-2.12; P<0.001), respectively.

CONCLUSIONS

Lower institutional case volume was associated with higher mortality after mitral valve repair. A minimum volume standard may be required for hospitals performing mitral valve repair to guarantee adequate outcome.

A Nationwide Study Assessing Preventable Hospitalization Rate on Mortality After Major Cardiovascular Surgery

Despite the use of various factors to measure hospital quality, most measures have not resulted in long-term improvements in patient outcomes. This study's purpose is to determine the effect of a previously unassessed measure of quality of care-a hospital's preventable hospitalization rate-on 30-day mortality at both the hospital and individual levels after three major cardiovascular surgery procedures. This is a population-based study using Taiwan's National Health Insurance database. We retrieved data from 2001 to 2014 for patients who had undergone abdominal aortic aneurysm (AAA) repair, coronary artery bypass graft, or aortic valve replacement (AVR). Preventable hospitalizations are hospitalizations for 11 chronic conditions that are considered preventable with effective primary care. The outcome was 30-day surgical mortality. Our dataset contained 65,863 patients who had undergone surgery for one of the three cardiovascular procedures. Preventable hospitalization rate was significantly associated with higher hospital mortality rates for all procedures. At the patient level, the adjusted odds of mortality after AAA repair were increased 55% (P < 0.01) for every 2% increase in the preventable hospitalization rate. For coronary artery bypass graft, preventable hospitalization was not a significant predictor of mortality, but rather patient factors and surgeon factors were significant. For AVR, the adjusted odds of mortality were increased 7% (P < 0.01) for every 1% increase in preventable hospitalization rate. High preventable hospitalization rate may serve as a hospital quality measure that could signal increased odds of mortality for selected cardiovascular procedures, especially for higher risk-lower volume procedures such as AAA repair and AVR.

Quality metrics in coronary artery bypass grafting

Studies on the association between care quality, case volume, and outcomes in coronary artery bypass grafting (CABG) have concluded that consistent adherence to quality measures improves mortality rates and outcomes. However, the quality metrics are not well-defined, and their significance to surgeons and healthcare providers remains uncertain. We review the concept of "quality and quality metrics" and discuss their importance in the context of CABG.

Beyond volume: hospital-based healthcare technology as a predictor of mortality for cardiovascular patients in Korea

To examine whether hospital-based healthcare technology is related to 30-day postoperative mortality rates after adjusting for hospital volume of cardiovascular surgical procedures.This study used the National Health Insurance Service-Cohort Sample Database from 2002 to 2013, which was released by the Korean National Health Insurance Service. A total of 11,109 cardiovascular surgical procedure patients were analyzed. The primary analysis was based on logistic regression models to examine our hypothesis.After adjusting for hospital volume of cardiovascular surgical procedures as well as for all other confounders, the odds ratio (OR) of 30-day mortality in low healthcare technology hospitals was 1.567-times higher (95% confidence interval [CI] = 1.069-2.297) than in those with high healthcare technology. We also found that, overall, cardiovascular surgical patients treated in low healthcare technology hospitals, regardless of the extent of cardiovascular surgical procedures, had the highest 30-day mortality rate.Although the results of our study provide scientific evidence for a hospital volume-mortality relationship in cardiovascular surgical patients, the independent effect of hospital-based healthcare technology is strong, resulting in a lower mortality rate. As hospital characteristics such as clinical pathways and protocols are likely to also play an important role in mortality, further research is required to explore their respective contributions.

Beyond Volume: Hospital-Based Healthcare Technology for Better Outcomes in Cerebrovascular Surgical Patients Diagnosed With Ischemic Stroke: A Population-Based Nationwide Cohort Study From 2002 to 2013

We examined whether the level of hospital-based healthcare technology was related to the 30-day postoperative mortality rates, after adjusting for hospital volume, of ischemic stroke patients who underwent a cerebrovascular surgical procedure. Using the National Health Insurance Service-Cohort Sample Database, we reviewed records from 2002 to 2013 for data on patients with ischemic stroke who underwent cerebrovascular surgical procedures. Statistical analysis was performed using Cox proportional hazard models to test our hypothesis. A total of 798 subjects were included in our study. After adjusting for hospital volume of cerebrovascular surgical procedures as well as all for other potential confounders, the hazard ratio (HR) of 30-day mortality in low healthcare technology hospitals as compared to high healthcare technology hospitals was 2.583 (P < 0.001). We also found that, although the HR of 30-day mortality in low healthcare technology hospitals with high volume as compared to high healthcare technology hospitals with high volume was the highest (10.014, P < 0.0001), cerebrovascular surgical procedure patients treated in low healthcare technology hospitals had the highest 30-day mortality rate, irrespective of hospital volume. Although results of our study provide scientific evidence for a hospital volume/30-day mortality rate relationship in ischemic stroke patients who underwent cerebrovascular surgical procedures, our results also suggest that the level of hospital-based healthcare technology is associated with mortality rates independent of hospital volume. Given these results, further research into what components of hospital-based healthcare technology significantly impact mortality is warranted.

Quality Markers in Cardiology. Main Markers to Measure Quality of Results (Outcomes) and Quality Measures Related to Better Results in Clinical Practice (Performance Metrics). INCARDIO (Indicadores de Calidad en Unidades Asistenciales del Área del Corazón): A SEC/SECTCV Consensus Position Paper

Cardiology practice requires complex organization that impacts overall outcomes and may differ substantially among hospitals and communities. The aim of this consensus document is to define quality markers in cardiology, including markers to measure the quality of results (outcomes metrics) and quality measures related to better results in clinical practice (performance metrics). The document is mainly intended for the Spanish health care system and may serve as a basis for similar documents in other countries.

Forgetting the learning curve for a moment: how much performance is unrelated to own experience?

Volume-outcome relationships are of clear importance for most participants in the health-care industry; research and appropriate policy implications are of critical importance. In this letter we critique the prevailing 'learning-by-doing' view in cardiac surgery. We illustrate the very wide disparity in empirical findings on volume-outcome relationships there, in the context of broader open issues in 'learning curves' in general. Potential complementary mechanisms, e.g. 'social learning by knowledge spillovers' are introduced; these cast into doubt the prevailing policy recommendations of simple regionalization and volume smoothing.

Opportunities for improved performance in surgical specialty practice

OBJECTIVE

To identify opportunities for improvement in quality performance profile while maintaining better clinical outcomes.

METHODS

A prospective study of 5285 surgical specialty procedures including hip and knee replacement, cholecystectomy, hysterectomy, nonaccess vascular and cardiac procedures, and colorectal resections in 16 Kentucky hospitals was undertaken. The following observations were made after univariate and stepwise logistic regression analysis, from the Surgical Care Improvement Project.

RESULTS

(1) Impaired functional status, age > or =65, and ASA class 4 or 5 status were significant predictors for both morbidity and mortality. (2) beta blockade medication was maintained in only 70% of patients already receiving such medications; interestingly, vascular surgery and patients with known cardiac history did not have beta blockade initiated 52% of the time. (3) Appropriate blood glucose control was not achieved in 31% of patients with diabetes and in 20% of nondiabetics. (4) deep vein thrombosis (DVT) prophylaxis was independent of high-risk status, with wide variation in practice. Patients undergoing total hip or knee replacement or colorectal resections had highest rates (0.7%) of pulmonary emboli. (5) A poor choice of antibiotic prophylaxis agent occurred in 8% of patients and was associated with a 3-fold increase in mortality (P < 0.01). (6) Hypothermia on arrival in PACU was present in 7% of patients after major colorectal resections and was ominously associated with an over 4-fold increase in mortality (P < 0.01). (7) Preoperative WBC >11,000/mm in elective operations was associated with nearly 3-fold increase in mortality (P < 0.05).

CONCLUSION

Now more than ever, surgeons must verify performance measures and outcomes. This study of clinical outcomes permits identification of underappreciated contemporary risk factors and some obvious measures by which surgical practices can more objectively be evaluated.

A systematic review of the impact of volume of surgery and specialization on patient outcome

BACKGROUND AND METHODS

Volume of surgery and specialization may affect patient outcome. Articles examining the effects of one or more of three variables (hospital volume of surgery, surgeon volume and specialization) on outcome (measured by length of hospital stay, mortality and complication rate) were analysed. Reviews, opinion articles and observational studies were excluded. The methodological quality of each study was assessed, a correlation between the variables analysed and the outcome accepted if it was significant.

RESULTS

The search identified 55,391 articles published between 1957 and 2002; 1075 were relevant to the study, of which 163 (9,904,850 patients) fulfilled the entry criteria. These 163 examined 42 different surgical procedures, spanning 13 surgical specialities. None were randomized and 40 investigated more than one variable. Hospital volume was reported in 127 studies; high-volume hospitals had significantly better outcomes in 74.2 per cent of studies, but this effect was limited in prospective studies (40 per cent). Surgeon volume was reported in 58 studies; high-volume surgeons had significantly better outcomes in 74 per cent of studies. Specialization was reported in 22 studies; specialist surgeons had significantly better outcomes than general surgeons in 91 per cent of studies. The benefit of high surgeon volume and specialization varied in magnitude between specialities.

CONCLUSION

High surgeon volume and specialization are associated with improved patient outcome, while high hospital volume is of limited benefit.

Veterans Health Administration patients' use of the private sector for coronary revascularization in New York: opportunities to improve outcomes by directing care to high-performance hospitals

OBJECTIVE

We sought to quantify Veterans Health Administration (VA) patients' utilization of coronary revascularization in the private sector and to assess the potential impact of directing this care to high-performance hospitals.

METHODS

Using VA and New York State administrative and clinical databases, we conducted a retrospective cohort study examining residents of New York State who were enrolled in the VA and underwent either coronary artery bypass graft (CABG) surgery or percutaneous coronary intervention (PCI) in 1999 or 2000 (n=6562) in either the VA or the private sector. We first calculated the proportion of revascularizations obtained in the VA and the private sector. We then identified the private sector hospitals in which these men obtained revascularizations and determined potential changes in mortality and travel burden associated with directing private sector care to high performance hospitals.

RESULTS

VA patients in New York were much more likely to undergo revascularization in the private sector than in VA hospitals: 83% of CABGs (2341/2829) and 87% of PCIs (4054/4665) were obtained in the private sector. Private sector utilization was distributed evenly across high- and low-mortality hospitals. Directing private-sector CABG surgery to high-performance hospitals could have reduced expected mortality by 24% (from 2.3% to 1.7%) and would only increase median travel time from 21 to 30 minutes. The benefit of redirecting PCI care is minimal.

CONCLUSIONS

For high-mortality procedures that veterans frequently obtain in the private sector, like CABG, directing care to high-performance hospitals may be an effective way to improve outcomes for veterans.

Association Between Surgeon and Hospital Volume in Coronary Artery Bypass Graft Surgery Outcomes: A Population-Based Study

BACKGROUND

We have found no study conducted outside of the United States on the association between physician volume and patient outcomes after coronary artery bypass graft surgery. The aim of this study is to examine the association between surgeon-hospital coronary artery bypass graft volume and patient outcomes using three-year population-based data on Taiwan.

METHODS

This study uses the Taiwan National Health Insurance Research Database covering the period 2000 to 2002, with the study sample comprising 9,895 first-time coronary artery bypass graft admissions, treated by 316 surgeons in 46 hospitals.

RESULTS

Of the sampled patients, 356 (3.6%) were discharged after death. Those patients treated by low-volume (1-50 cases) surgeons had significantly higher mortality rates than those treated by medium-volume (51-100 cases) surgeons (7.0% vs 3.8%), high-volume (101-150 cases) surgeons (7.0% vs 2.7%), or very-high-volume (> or = 151 cases) surgeons (7.0% vs 3.2%). However, hospital coronary artery bypass graft volume alone is an insufficient predictor of hospital in-patient deaths (p = 0.078). The adjusted odds ratio of hospital in-patient deaths declined with increasing surgeon volume, with the odds of in-patient death for those patients treated by low-volume surgeons being 1.52 times those of medium-volume surgeons, 1.89 times those of high-volume surgeons, and 2.04 times those of very-high-volume surgeons.

CONCLUSIONS

We conclude that for all coronary artery bypass graft surgeries taking place in Taiwan, the skill and experience of individual surgeons is a more critical factor for patient outcome than either hospital equipment or surgical teams.

Exploring the Volume-Outcome Relationship for Off-Pump Coronary Artery Bypass Graft Procedures

BACKGROUND

The relationship between the surgical case volume and risk-adjusted clinical outcomes has been examined for different surgical specialties. The purpose of this study was to explore the relationship between the off-pump coronary artery bypass graft procedure volumes (OPCABG) with risk-adjusted outcomes within the Department of Veterans Affairs (VA) 44 cardiac surgery programs.

METHODS

Based on VA Continuous Improvement in Cardiac Surgery Program data, the results of 5,076 OPCABG surgical procedures performed between October 1998 and September 2003 were analyzed. Hierarchical logistic regression models evaluated the relationship between OPCABG procedure volume with risk-adjusted 30-day operative mortality, perioperative morbidity, and 180-day mortality. Both a hospital's average OPCABG volume per 6-month period and the hospital's most recent 6-month OPCABG volume were examined.

RESULTS

Hospital OPCABG average volume in a 6-month period ranged from 0.2 to 47.4 procedures; whereas the most recent 6-month OPCABG hospital volume ranged from 0 to 76 OPCABG per site. No relationship between the volume measures and the outcome variables was found.

CONCLUSIONS

We did not find an association between OPCABG volume with short-term mortality, perioperative morbidity, or intermediate-term (180-day) mortality.

The Relation Between Surgeon Volume and Outcome Following Off-Pump vs On-Pump Coronary Artery Bypass Graft Surgery

STUDY OBJECTIVE

Off-pump coronary artery bypass graft (CABG) surgery has been recently reintroduced into clinical practice. In light of the relatively low level of experience of most cardiac surgeons with off-pump CABG surgery, and the exceptional technical challenge of working on a "beating heart," off-pump CABG surgery presents a unique opportunity to explore the effect of surgeon case volume on surgical outcome after controlling for the effects of patient case mix and hospital volume.

DESIGN

A retrospective cohort study analyzing the association between surgeon volume and in-hospital mortality rate for off-pump and on-pump CABG surgery using random-effects logistic regression modeling.

SETTING AND PATIENTS

The analyses were based on the New York State clinical CABG surgery registry. The study sample consisted of 36,930 patients undergoing isolated CABG surgery between 1998 and 1999 that was performed by 181 surgeons at 33 hospitals.

INTERVENTIONS

None.

RESULTS

There is no association between the number of CABG procedures performed off-pump by an individual surgeon and in-hospital mortality rates (p = 0.93) after controlling for hospital CABG surgery volume and patient-level risk factors. There is also no association between the off-pump CABG surgery mortality rate and the total number of both off-pump and on-pump CABG surgery cases (p = 0.78). In the on-pump CABG surgery cohort, surgeons performing a high volume of CABG procedures had significantly lower risk-adjusted mortality rates among their patients compared to those performing a very low volume, a low-volume, and a medium volume of CABG procedures (p < 0.006).

CONCLUSION

For off-pump CABG surgery, surgeons performing a high volume of procedures do not have better mortality outcomes than those performing a low volume of procedures. However, higher surgeon case volumes are associated with lower mortality rates for on-pump CABG surgery. The absence of a volume-outcome association for off-pump CABG surgery is especially surprising in light of the more technically demanding nature of off-pump CABG surgery compared to on-pump CABG surgery.

Is Hospital Procedure Volume a Reliable Marker of Quality for Coronary Artery Bypass Surgery? A Comparison of Risk and Propensity Adjusted Operative and Midterm Outcomes

BACKGROUND

Worse operative mortality has been reported for hospitals with low versus high coronary artery bypass grafting surgery volumes. Despite a lack of comparisons beyond the early postoperative period and evidence of surgeon-volume confounding, some have suggested that regionalization of coronary artery bypass grafting in favor of high volume institutions is warranted.

METHODS

We retrospectively compared operative mortality and 3-year survival in coronary artery bypass grafting patients (2001 to 2003) at a low-volume hospital (n = 504; 160 per year [median]) versus a high-volume hospital (n = 1,410; 487 per year) served by the same high-volume surgeon team. Covariate risk adjustment was done via multivariate and propensity modeling.

RESULTS

The two hospital cohorts exhibited multiple demographic and risk factor differences. Unadjusted low-volume hospital vs high-volume hospital operative mortality was similar overall (2.38% vs 2.98%; p = 0.59) with nearly identical Society of Thoracic Surgeons observed-to-expected ratios (0.83 vs 0.82), irrespective of preoperative risk category. Hospital volume did not predict operative mortality (odds ratio, 95% confidence interval = 0.82; p = 0.602). At follow-up, a total of 28 low-volume hospital deaths (5.6%) and 135 high-volume hospital deaths (9.6%) occurred at similar surgery-to-death intervals (p = 0.7). Unadjusted 0 to 3-year survival was significantly worse for high-volume hospitals (risk ratio = 1.59; 1.06 to 2.39; p = 0.026). Yet procedure volume was not independently associated with worse midterm survival after covariate (risk ratio = 1.28; 0.84 to 1.96; p = 0.247) or propensity score (risk ratio = 1.11; 0.72 to 1.71; p = 0.648) adjustment.

CONCLUSIONS

Hospital and surgeon volume effects on coronary artery bypass grafting outcomes are interdependent, and therefore hospital coronary artery bypass grafting volume per se is not a reliable marker of quality. Instead, outcome quality markers should rely on thorough risk-adjustment based on detailed clinical databases, possibly including annual and cumulative surgeon volume.

Early efficacy of CABG care delivery in a low procedure-volume community hospital: operative and midterm results

Background

The Leapfrog Group recommended that coronary artery bypass grafting (CABG) surgery should be done at high volume hospitals (>450 per year) without corresponding surgeon-volume criteria. The latter confounds procedure-volume effects substantially, and it is suggested that high surgeon-volume (>125 per year) rather than hospital-volume may be a more appropriate indicator of CABG quality.

Methods

We assessed 3-year isolated CABG morbidity and mortality outcomes at a low-volume hospital (LVH: 504 cases) and compared them to the corresponding Society of Thoracic Surgeons (STS) national data over the same period (2001–2003). All CABGs were performed by 5 high-volume surgeons (161–285 per year). "Best practice" care at LVH – including effective practice guidelines, protocols, data acquisition capabilities, case review process, dedicated facilities and support personnel – were closely modeled after a high-volume hospital served by the same surgeon-team.

Results

Operative mortality was similar for LVH and STS (OM: 2.38% vs. 2.53%), and the corresponding LVH observed-to-expected mortality (O/E = 0.81) indicated good quality relative to the STS risk model (O/E<1). Also, these results were consistent irrespective of risk category: O/E was 0, 0.9 and 1.03 for very-low risk (<1%), low risk (1–3%) and moderate-to-high risk category (>3%), respectively. Postoperative leg wound infections, ventilator hours, renal dysfunction (no dialysis), and atrial fibrillation were higher for LVH, but hospital stay was not. The unadjusted Kaplan-Meier survival for the LVH cohort was 96%, 94%, and 92% at one, two, and three years, respectively.

Conclusion

Our results demonstrated that high quality CABG care can be achieved at LVH programs if 1) served by high volume surgeons and 2) patient care procedures similar to those of large programs are implemented. This approach may prove a useful paradigm to ensure high quality CABG care and early efficacy at low volume institutions that wish to comply with the Leapfrog standards.

Hospital coronary artery bypass graft surgery volume and patient mortality, 1998-2000

OBJECTIVE

To evaluate the association between annual hospital coronary artery bypass graft (CABG) surgery volume and in-hospital mortality.

SUMMARY BACKGROUND DATA

The Leapfrog Group recommends health care purchasers contract for CABG services only with hospitals that perform >or=500 CABGs annually to reduce mortality; it is unclear whether this standard applies to current practice.

METHODS

We conducted a retrospective analysis of the National Inpatient Sample database for patients who underwent CABG in 1998-2000 (n = 228738) at low (12-249 cases/year), medium (250-499 cases/year), and high (>or=500 cases/year) CABG volume hospitals. Crude in-hospital mortality rates were 4.21% in low-volume hospitals, 3.74% in medium-volume hospitals, and 3.54% in high-volume hospitals (trend P < 0.001). Compared with patients at high-volume hospitals (odds ratio 1.00, referent), patients at low-volume hospitals remained at increased risk of mortality after multivariable adjustment (odds ratio 1.26, 95% confidence interval = 1.15-1.39). The mortality risk for patients at medium-volume hospitals was of borderline significance (odds ratio 1.11, 95% confidence interval = 1.01-1.21). However, 207 of 243 (85%) of low-volume and 151 of 169 (89%) of medium-volume hospital-years had risk-standardized mortality rates that were statistically lower or comparable to those expected. In contrast, only 11 of 169 (6%) of high-volume hospital-years had outcomes that were statistically better than expected.

CONCLUSIONS

Patients at high-volume CABG hospitals were, on average, at a lower mortality risk than patients at lower-volume hospitals. However, the small size of the volume-associated mortality difference and the heterogeneity in outcomes within all CABG volume groups suggest individual hospital CABG volume is not a reliable marker of hospital CABG quality.

Avaliação da relação entre volume de procedimentos e a qualidade do cuidado: o caso de cirurgia coronariana no Brasil

O volume de procedimentos médicos geralmente apresenta-se negativamente associado com a taxa de mortalidade hospitalar. O objetivo deste trabalho é verificar nos hospitais brasileiros a existência ou não dessa associação no caso das cirurgias de revascularização do miocárdio (CRVM), financiadas pelo Ministério da Saúde (MS). Analisaram-se as CRVM realizadas de 1996 a 1998. Os dados foram obtidos por intermédio do Sistema de Informações Hospitalares do SUS. O procedimento estatístico utilizado foi análise de sobrevida (modelo de Cox). Os hospitais foram agrupados em classes de volume de CRVM. O modelo foi ajustado pelo perfil de gravidade (risco de morrer) dos pacientes. Foram pagas 41.989 CRVM pelo MS entre janeiro de 1996 e dezembro de 1998, realizadas em 131 hospitais. A taxa de mortalidade foi de 7,2%. Observou-se um gradiente crescente nas taxas à medida que diminuiu o volume. No grupo de hospitais do SUS com maior volume de CRVM os pacientes operados apresentaram menor risco de morrer do que no de hospitais com menor volume de cirurgias. Recomenda-se que o SUS deva estimular a concentração regionalizada dos serviços para a realização de CRVM.

Threshold volumes associated with higher survival in health care: a systematic review

BACKGROUND

To date, systematic reviews on the relationship between the volume of specific diagnoses and procedures and patient outcomes have several limitations, including the omission of the most recent publications.

OBJECTIVE

To investigate the relationship between hospital and physician volume and patient mortality rate for all diagnoses and interventions in health care.

RESEARCH DESIGN

Medline and the Cochrane Library were searched from January 1990 to December 2000 for all studies published in Dutch, English, French, German, and Italian. The following Boolean search statement was used: hospitals AND volume AND (outcome OR mortality OR quality). Studies were included in which patient enrollment ended within 10 years of the current study and that were adjusted for case-mix. For each diagnosis and intervention, the study most likely to provide an unbiased estimate of the effect of volume on mortality rate was identified using a specific algorithm (best study).

RESULTS

A total of 34 diagnoses and interventions with at least one qualifying study on the volume-outcome relationship were identified. The summary odds ratio/relative risk for the best studies on hospital and physician volume were 0.87 (95% confidence interval [CI], 0.85-0.89) and 0.87 (95% CI, 0.81-0.94), respectively. From the best studies on hospital volume, 48.5% (16 of 33) were published either in 1999 or 2000.

CONCLUSIONS

There is evidence for a volume-mortality relationship for hospitals and physicians. The use of appropriate methods for analyzing additional diagnoses and interventions as well as a continuous systematic evaluation of the evidence is recommended.

Is the hospital volume-mortality relationship in coronary artery bypass surgery the same for low-risk versus high-risk patients?

BACKGROUND

There is evidence to support the existence of an inverse relation between mortality after coronary artery bypass graft (CABG) surgery and procedure volume. It is unclear whether all patients benefit equally from having CABG surgery performed at high-volume centers. The objective of this study was to determine whether the volume-outcome association for CABG surgery is modified by patient risk.

METHODS

This retrospective cohort analysis was conducted using data from the Cardiac Surgery Reporting System database on all patients (20,078) undergoing CABG surgery in New York State who were discharged in 1996. The main outcome measure was in-hospital mortality as a function of procedure volume after adjusting for severity of disease. Logistic regression modeling was used to explore the interaction between patient risk and procedure volume.

RESULTS

There is a significant interaction between procedure volume and patient risk (p = 0.01). The final model exhibits excellent discrimination (C statistic = 0.818) and goodness-of-fit (Hosmer-Lemeshow statistic = 6.02; p = 0.645). Very low (<0.5%) and low-risk (0.5%-2.0%) patients exhibit a greater reduction in CABG mortality than high (5.0%-10.0%) and very high risk (>10%) patients at high-volume centers relative to low-volume centers. Among the highest risk patients (>25% risk of mortality), higher risk patients have better outcomes at higher volume centers.

CONCLUSIONS

For the vast majority of patients, low-risk patients benefit significantly more than high-risk patients from undergoing CABG surgery at high-volume centers instead of at low-volume centers. Low-risk patients benefit significantly more than high-risk patients from undergoing CABG surgery at high-volume centers instead of at low-volume centers. However, before generalizing these findings to other states, this study should be repeated using other regional population-based clinical databases.

Do hospitals and surgeons with higher coronary artery bypass graft surgery volumes still have lower risk-adjusted mortality rates?

BACKGROUND

Studies that are the basis of recommended volume thresholds for CABG surgery are outdated and not reflective of recent advances in the field. This study examines both hospital and surgeon volume-mortality relations for CABG surgery through the use of a population-based clinical data set.

METHODS AND RESULTS

Data from New York's clinical CABG surgery registry from 1997 to 1999 (total number of procedures, 57 150) were used to examine the individual and combined impact of annual hospital volume and annual surgeon volume on in-hospital mortality rates after adjusting for differences in severity of illness. Significantly lower risk-adjusted mortality rates occurred above all annual hospital volume thresholds between 200 and 800 and above all surgeon volume thresholds between 50 and 200. The number needed to treat (NNT) at higher-volume providers to avoid a death was minimized for a hospital threshold volume of 100 (NNT=50) and a surgeon threshold volume of 50 (NNT=118). The risk-adjusted mortality rate (RAMR) for patients undergoing surgery performed by surgeons with volumes of > or =125 in hospitals with volumes of > or =600 was 1.89%. The RAMR was significantly higher (2.67%) for patients undergoing surgery performed by surgeons with volumes of <125 in hospitals with volumes of <600.

CONCLUSIONS

Higher-volume surgeons and hospitals continue to have lower risk-adjusted mortality rates, and patients undergoing surgery performed by higher-volume surgeons in higher-volume hospitals have the lowest mortality rates.

In-hospital mortality following coronary artery bypass graft surgery in Veterans Health Administration and private sector hospitals

OBJECTIVES

Compare severity-adjusted in-hospital mortality in patients undergoing coronary artery bypass graft surgery (CABG) in VA and private sector hospitals in two geographic regions.

RESEARCH DESIGN

Retrospective Cohort Study.

SUBJECTS

Consecutive male patients undergoing CABG from October 1993 to December 1996 in: 43 VA hospitals with cardiac surgery programs (n = 19,266); 32 hospitals in New York (NY) State (n = 44,247); and 10 hospitals in Northeast (NE) Ohio (n = 9696).

METHODS

Demographic and clinical data were abstracted from medical records. Logistic regression analysis identified 10 independent patient-level predictors (P <0.01) of in-hospital mortality: age, prior CABG, angioplasty before CABG, ejection fraction, diabetes, peripheral vascular disease, congestive heart failure (CHF), cerebrovascular disease, renal insufficiency, and chronic obstructive pulmonary disease (COPD).

RESULTS

Unadjusted mortality was higher in VA patients than in NY or NE Ohio patients (3.5% vs. 2.0%, and 2.2%, respectively). Mortality decreased (P <0.001) with increasing volume (3.6% in low [<500 cases], 3.0% in moderate [500-1000 cases], and 2.0% in high [>1000 cases] volume hospitals). Median volume was lower in VA than private sector hospitals (410 vs. 1520), and no VA hospitals were classified as high volume. Adjusting for patient-level predictors and volume, the odds of death was higher in VA patients, relative to private sector patients (OR, 1.34; 95% CI, 1.11-1.63; P <0.001). In stratified analyses, the odds of death in VA patients was similar in low volume hospitals (OR, 0.86; P = 0.39), but higher in moderate volume hospitals (OR, 1.50; P = 0.01).

CONCLUSIONS

VA hospitals had lower CABG volume than private sector hospitals in NY and NE Ohio, and higher in-hospital mortality. However, the difference in mortality was limited to moderate-volume hospitals. These findings suggest that hospital volume is an important modifier in comparisons of CABG mortality in VA and private sector hospitals. The higher mortality in VA hospitals may, in part, be caused by differences in surgical capacity and patient demand that lead to lower volume cardiac surgery programs.

The volume-outcome relationship: from Luft to Leapfrog

Numerous reports have documented a volume-outcome relationship for complex medical and surgical care, although many such studies are compromised by the use of discharge abstract data, inadequate risk adjustment, and problematic statistical methodology. Because of the volume-outcome association, and because valid outcome measurements are unavailable for many procedures, volume-based referral strategies have been advocated as an alternative approach to health-care quality improvement. This is most appropriate for procedures with the greatest outcome variability between low-volume and high-volume providers, such as esophagectomy and pancreatectomy, and for particularly high-risk subgroups of patients. Whenever possible, risk-adjusted outcome data should supplement or supplant volume standards, and continuous quality improvement programs should seek to emulate the processes of high-volume, high-quality providers. The Leapfrog Group has established a minimum volume requirement of 500 procedures for coronary artery bypass grafting. In view of the questionable basis for this recommendation, we suggest that it be reevaluated.

Morbidity and mortality of gastrectomy for cancer in Department of Veterans Affairs Medical Centers

BACKGROUND

The purpose of this study was to define risk factors that predict 30-day morbidity and mortality after gastrectomy for cancer in Veterans Affairs (VA) Medical Centers.

METHODS

The VA National Surgical Quality Improvement Program prospectively collected data on 708 patients undergoing gastrectomy for cancer in 123 participating VA medical centers from 1991 to 1998. Independent variables included 68 preoperative patient characteristics and 12 intraoperative variables; the dependent variables were 21 defined adverse outcomes and death. Predictive models for 30-day morbidity and mortality were constructed by using stepwise logistic regression analysis.

RESULTS

The 30-day morbidity rate was 33.3% (236 of 708). The overall 30-day mortality rate was 7.6% (54 of 708). Significant positive predictors of morbidity (P <.05) included current pneumonia, American Society of Anesthesiologists class IV (threat to life), partially dependent functional status, dyspnea on minimal exertion, preoperative transfusion, extended operative time, and increasing age. Significant positive predictors of mortality (P <.05) included do not resuscitate status, prior stroke, intraoperative transfusion, preoperative weight loss, preoperative transfusion, and elevated preoperative alkaline phosphatase level.

CONCLUSIONS

Risk factors predicting morbidity and mortality rates at VA hospitals after gastrectomy for gastric cancer are reported by using a prospectively collected, multi-institutional database. Assigning relative weights to factors associated with adverse outcomes may help improve patient care.

The role of hospital volume in coronary artery bypass grafting: is more always better?

OBJECTIVES

The goal of this study was to determine whether outcomes of nonemergent coronary artery bypass grafting (CABG) differed between low- and high-volume hospitals in patients at different levels of surgical risk.

BACKGROUND

Regionalizing all CABG surgeries from low- to high-volume hospitals could improve surgical outcomes but reduce patient access and choice. "Targeted" regionalization could be a reasonable alternative, however, if subgroups of patients that would clearly benefit from care at high-volume hospitals could be identified.

METHODS

We assessed outcomes of CABG at 56 U.S. hospitals using 1997 administrative and clinical data from Solucient EXPLORE, a national outcomes benchmarking database. Predicted in-hospital mortality rates for subjects were calculated using a logistic regression model, and subjects were classified into five groups based on surgical risk: minimal (< 0.5%), low (0.5% to 2%), moderate (2% to 5%), high (5% to 20%), and severe (> or =20%). We assessed differences in in-hospital mortality, hospital costs and length of stay between low- and high-volume facilities (defined as > or =200 annual cases) in each of the five risk groups.

RESULTS

A total of 2,029 subjects who underwent CABG at 25 low-volume hospitals and 11,615 subjects who underwent CABG at 31 high-volume hospitals were identified. Significant differences in in-hospital mortality were seen between low- and high-volume facilities in subjects at moderate (5.3% vs. 2.2%; p = 0.007) and high risk (22.6% vs. 11.9%; p = 0.0026) but not in those at minimal, low or severe risk. Hospital costs and lengths of stay were similar across each of the five risk groups. Based on these results, targeted regionalization of subjects at moderate risk or higher to high-volume hospitals would have resulted in an estimated 370 transfers and avoided 16 deaths; in contrast, full regionalization would have led to 2,029 transfers and avoided 20 deaths.

CONCLUSIONS

Targeted regionalization might be a feasible strategy for balancing the clinical benefits of regionalization with patients' desires for choice and access.

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.

Volume standards for high-risk surgical procedures: potential benefits of the Leapfrog initiative

BACKGROUND

As part of a broader effort aimed at improving hospital safety, a large coalition of employers, the Leapfrog Group, will soon require hospitals caring for their employees to meet volume standards for 5 high-risk surgical procedures. We estimated the potential benefits of full nationwide implementation of these volume standards. METHODS. Using data from Nationwide Inpatient Sample and other sources, we first estimated the total number of each of the 5 procedures-coronary-artery bypass graft, abdominal aortic aneurysm repair, coronary angioplasty, esophagectomy, and carotid endarterectomy-performed each year in hospitals in US metropolitan areas. (Leapfrog exempts hospitals in rural areas to avoid access issues.) We then projected the effectiveness of volume standards (in terms of relative risks of mortality) for each procedure using data from a published structured literature review.

RESULTS

With full implementation nationwide, the Leapfrog volume standards would save 2581 lives. Of the procedures, volume standards would save the most lives with coronary-artery bypass graft (1486), followed by abdominal aortic-aneurysm repair (464), coronary angioplasty (345), esophagectomy (168), and carotid endarterectomy (118). In our estimates of the number of lives saved, we considered assumptions about how many patients would be affected and the effectiveness of volume standards (ie, strength of underlying volume-outcome relationships with each procedure).

CONCLUSIONS

If the Leapfrog volume standards are successfully implemented, employers and health-care purchasers could prevent many surgical deaths by requiring hospital volume standards for high-risk procedures.