Meta-Analysis and Systematic Review of the Relationship between Hospital Volume and Outcome Following Carotid Endarterectomy

Unchanged safety outcomes in deep brain stimulation surgery for Parkinson disease despite a decentralization of care

OBJECT

Early work on deep brain stimulation (DBS) surgery, when procedures were mostly carried out in a small number of high-volume centers, demonstrated a relationship between surgical volume and procedural safety. However, over the past decade, DBS has become more widely available in the community rather than solely at academic medical centers. The authors examined the Nationwide Inpatient Sample (NIS) to study the safety of DBS surgery for Parkinson disease (PD) in association with this change in practice patterns.

METHODS

The NIS is a stratified sample of 20% of all patient discharges from nonfederal hospitals in the United States. The authors identified patients with a primary diagnosis of PD (332.0) and a primary procedure code for implantation/replacement of intracranial neurostimulator leads (02.93) who underwent surgery between 2002 and 2009. They analyzed outcomes using univariate and hierarchical, logistic regression analyses.

RESULTS

The total number of DBS cases remained stable from 2002 through 2009. Despite older and sicker patients undergoing DBS, procedural safety (rates of non-home discharges, complications) remained stable. Patients at low-volume hospitals were virtually indistinguishable from those at high-volume hospitals, except that patients at low-volume hospitals had slightly higher comorbidity scores (0.90 vs 0.75, p < 0.01). Complications, non-home discharges, length of hospital stay, and mortality rates did not significantly differ between low- and high-volume hospitals when accounting for hospital-related variables (caseload, teaching status, location).

CONCLUSIONS

Prior investigations have demonstrated a robust volume-outcome relationship for a variety of surgical procedures. However, the present study supports safety of DBS at smaller-volume centers. Prospective studies are required to determine whether low-volume centers and higher-volume centers have similar DBS efficacy, a critical factor in determining whether DBS is comparable between centers.

Regionalization of services improves access to emergency vascular surgical care

Management of vascular surgical emergencies requires rapid access to a vascular surgeon and hospital with the infrastructure necessary to manage vascular emergencies. The purpose of this study was to assess the impact of regionalization of vascular surgery services in Toronto to University Health Network (UHN) and St Michael's Hospital (SMH) on the ability of CritiCall Ontario to transfer patients with life- and limb-threatening vascular emergencies for definitive care. A retrospective review of the CritiCall Ontario database was used to assess the outcome of all calls to CritiCall regarding patients with vascular disease from April 2003 to March 2010. The number of patients with vascular emergencies referred via CritiCall and accepted in transfer by the vascular centers at UHN or SMH increased 500% between 1 April 2003-31 December 2005 and 1 January 2006-31 March 2010. Together, the vascular centers at UHN and SMH accepted 94.8% of the 1002 vascular surgery patients referred via CritiCall from other hospitals between 1 January 2006 and 31 March 2010, and 72% of these patients originated in hospitals outside of the Toronto Central Local Health Integration Network. Across Ontario, the number of physicians contacted before a patient was accepted in transfer fell from 2.9 ± 0.4 before to 1.7 ± 0.3 after the vascular centers opened. In conclusion, the vascular surgery centers at UHN and SMH have become provincial resources that enable the efficient transfer of patients with vascular surgical emergencies from across Ontario. Regionalization of services is a viable model to increase access to emergent care.

Regional anesthesia for vascular surgery

Vascular surgical patients are a diverse group of patients who tend to be elderly, with multiple comorbidities, while vascular procedures may involve significant blood loss and ischemia of tissues beyond the arterial obstruction. Regional anesthesia techniques may offer benefits to patients undergoing vascular surgery because of their cardiorespiratory comorbidities. However, this group of patients is commonly receiving multiple medications, including anticoagulants, so regional techniques are not without risks. This review will discuss this topic based around 3 fundamental revascularization procedures, carotid, abdominal aortic aneurysm repair, and infrainguinal surgery, discussing the clinical applications of regional techniques relevant to each key area.

Simulator training on pulsatile vascular models significantly improves surgical skills and the quality of carotid patch plasty

OBJECTIVE

Vascular surgeons perform numerous highly sophisticated and delicate procedures. Due to restrictions in training time and the advent of endovascular techniques, new concepts including alternative environments for training and assessment of surgical skills are required. Over the past decade, training on simulators and synthetic models has become more sophisticated and lifelike. This study was designed to evaluate the impact of a 3-day intense training course in open vascular surgery on both specific and global vascular surgical skills.

METHODS

Prospective observational cohort analysis with various parameter measurements of both surgical skills and the technical quality of the finished product, performed before and after 3 days of simulator training of 10 participants (seven male and three female) in a vascular surgery training course. The simulator model used was a conventional carotid endarterectomy with a Dacron patch plasty on a lifelike carotid bench model under pulsatile pressure. The primary end points were assessment of any changes in the participants' surgical skills and in the technical quality of their completed carotid patches documented by procedure-based assessment forms. Scores ranging from 1 (inadequate) to 5 (excellent) were compared by a related-sample Wilcoxon signed test. Interobserver reliability was estimated by Cronbach's alpha (CA).

RESULTS

A significant improvement in surgical skills tasks was observed (P < .001). The mean score increased significantly by 21.5% from fair (3.43 ± 0.93) to satisfactory (4.17 ± 0.69; P < .001). The mean score for the quality of the carotid patch increased significantly by 0.96 (27%) from fair (3.55 ± 0.87) to satisfactory (4.51 ± 0.76; P < .01). The median interassessor reliability for the quality of the carotid patch was acceptable (CA = 0.713) and for surgical skills was low (CA = 0.424).

CONCLUSIONS

This study shows that lifelike simulation featuring pulsatile flow can increase surgical skills and technical quality in a highly sophisticated multistep vascular intervention. This training provides comparatively inexpensive and lifelike training possibilities for the adoption and assessment of surgical skills required to perform delicate vascular surgical procedures.

Using risk models to improve patient selection for high-risk vascular surgery

Vascular surgeons frequently perform procedures aimed at limiting death, stroke, or amputation on patients who present with diseases such as aortic aneurysms, carotid atherosclerosis, and peripheral arterial occlusive disease. However, now more than ever surgeons must balance the potential benefits associated with these interventions with the risks of physiologic insult for these elderly patients, who often have significant comorbidity burdens and the potential for costly complications. In this paper, we highlight how regional and national datasets can help surgeons identify which patients are most likely to benefit from vascular operations and which patients are most likely to suffer complications in the postoperative period. By using these guidelines to improve patient selection, our risk models can help patients, physicians, and policymakers improve the clinical effectiveness of surgical and endovascular treatments for vascular disease.

Towards national surgical surveillance in the UK--a pilot study

OBJECTIVE

The Bristol heart inquiry in the United Kingdom (UK) highlighted the lack of standards for evaluating surgical performance and quality. In 2009, the World Health Organisation (WHO) proposed six standardised metrics for surgical surveillance. This is the first study to collect and analyse such metrics from a cohort of National Health Service (NHS) Trusts in England, helping to determine their feasibility and utility in measuring surgical performance, its impact on public health and mortality, and for tracking surgical trends over time.

METHODS

Freedom of Information Act 2000 (FOI) requests for WHO standardised surgical metrics were made to 36 NHS Trusts in England during July to November 2010. Additional data on Hospital Standardised Mortality Ratio (HSMR), Patient Safety Score and Abdominal Aortic Aneurysm (AAA) volume and mortality was obtained from Dr Foster Health and The Guardian Newspaper. Analysis was performed using mixed-effect logistic regression.

RESULTS

30/36 trusts responded (83%). During 2005-9, 5.4 million operations were performed with a 24.2% increase in annual number of operations. This rising volume within hospitals was associated with lower mortality ratios. A 10% increase in operative volume was associated with a lower day of surgery death rate (DDR OR = 0.94, p = 0.056) and post-operative inpatient 30-day mortality (PDR30 OR = 0.93, p = 0.001). For every 10,000 more operations that an NHS Trust does, a 4% drop in PDR30 mortality was achieved. A 10% increase in the volume of elective AAAs was associated with lower elective AAA (OR = 0.96, p = 0.032) and emergency AAA (OR = 0.95, p = 0.009) PDR30 mortality. Lower DDR mortality was noted for emergency AAA mortality (OR = 0.95, p = 0.025) but not elective AAAs (OR = 0.97, p = 0.116).

CONCLUSION

Standarised surgical metrics can provide policy makers and commissioners with valuable summary data on surgical performance allowing for statistical process control of a complex intervention. This study has shown their collection is feasible albeit using FOI and the first to show a statistically significant volume-outcome relationship for surgery as a whole within hospitals. It adds weight to the argument that patients are safer in larger hospitals or those that become larger by growing their patient base. Together with other measures, such metrics can help build a picture of surgical surveillance in the UK and potentially lead us to safer surgery.

Hospital volume of percutaneous radiofrequency ablation is closely associated with treatment outcomes for patients with hepatocellular carcinoma

BACKGROUND

Hospital volume for several major operations is associated with treatment outcomes. In this study, the authors explored the influence of hospital radiofrequency ablation (RFA) volume on the prognosis of patients who received RFA for hepatocellular carcinoma (HCC).

METHODS

The authors searched for all patients who were diagnosed with stage I or stage II HCC from 2004 to 2006 and who received RFA as first-line therapy in a population-based cohort. Overall survival (OS) and liver cancer-specific survival (CSS) were compared according to hospital volume. A Cox proportional hazards model was used for multivariate analysis.

RESULTS

In total, 661 patients received first-line RFA for stage I and II HCC in 28 hospitals. Among these, there were 480 patients (72.6%) in the high-volume group (those who received RFA at hospitals that treated >10 first-line patients per year), and there were 181 patients (27.4%) in the low-volume group (those who received RFA at hospitals that treated ≤ 10 first-line patients per year). The sex, age, stage, tumor size, and year of diagnosis for patients in the 2 groups did not differ significantly. Patients in the high-volume group demonstrated significantly longer OS and CSS than those in the low-volume group (5-year OS rate, 58.7% vs 47.2%; P = .001; 5-year CSS rate, 67.1% vs 57.1%; P = .009). After adjusting for covariates, high-volume hospitals remained an independent predictor of longer OS (hazard ratio, 0.57; P < .001) and CSS (hazard ratio, 0.57; P = .003).

CONCLUSIONS

Patients who received first-line RFA for HCC in high-volume hospitals demonstrated better survival outcomes.

Re-examining the significance of surgical volume to breast cancer survival and recurrence versus process quality of care in Taiwan

OBJECTIVE

This study explored the association of surgical volume versus process quality with breast cancer survival and recurrence.

DATA SOURCES/STUDY SETTING

Population-based cancer registration data and National Health Insurance claim data.

STUDY DESIGN

This population-based study linked Taiwan's Cancer Database with Taiwan's National Health Insurance Database to collect data on all patients diagnosed with breast cancer in 2003-2004 who received surgical treatment.

PRINCIPAL FINDINGS

This study included 6,396 female breast cancer patients, reported by 26 hospitals. After controlling for patient and provider characteristics, Cox's regression models did not reveal any association between a physician's surgical volume and breast cancer recurrence or survival, although hospital volume was marginally associated with positive 5-year recurrence (HR: 1.001, 95%CI: 1.000, 1.001). After controlling for hospital or physician volume of surgery, we found a significant association between quality of care and both 5-year survival and recurrence. Random effects were also identified between patients and providers based on 5-year survival and 5-year recurrence.

CONCLUSIONS

Process quality of care was significantly more related to survival or recurrence than to surgical volume. The random effects found within hospital-patient clustered data indicated that the effect of the clustered feature of this data should be considered when performing volume-outcome related studies.

Regional use of combined carotid endarterectomy/coronary artery bypass graft and the effect of patient risk

INTRODUCTION

Although carotid artery stenosis and coronary artery disease often coexist, many debate which patients are best served by combined concurrent revascularization (carotid endarterectomy [CEA]/coronary artery bypass graft [CABG]). We studied the use of CEA/CABG in New England and compared indications and outcomes, including stratification by risk, symptoms, and performing center.

METHODS

Using data from the Vascular Study Group of New England from 2003 to 2009, we studied all patients who underwent combined CEA/CABG across six centers in New England. Our main outcome measure was in-hospital stroke or death. We compared outcomes between all patients undergoing combined CEA/CABG to a baseline CEA risk group comprised of patients undergoing isolated CEA at non-CEA/CABG centers. Further, we compared in-hospital stroke and death rates between high and low neurologic risk patients, defining high neurologic risk patients as those who had at least one of the following clinical or anatomic features: (1) symptomatic carotid disease, (2) bilateral carotid stenosis >70%, (3) ipsilateral stenosis >70% and contralateral occlusion, or (4) ipsilateral or bilateral occlusion.

RESULTS

Overall, compared to patients undergoing isolated CEA at non-CEA/CABG centers (n = 1563), patients undergoing CEA/CABG (n = 109) were more likely to have diabetes (44% vs 29%; P = .001), creatinine >1.8 mg/dL (11% vs 5%; P = .007), and congestive heart failure (23% vs 10%; P < .001). Patients undergoing CEA/CABG were also more likely to take preoperative beta-blockers (94% vs 75%; P < .001) and less likely to take preoperative clopidogrel (7% vs 25%; P < .001). Patients undergoing CEA/CABG had higher rates of contralateral carotid occlusion (13% vs 5%; P = .001) and were more likely to undergo an urgent/emergent procedure (30% vs 15%; P < .001). The risk of complications was higher in CEA/CABG compared to isolated CEA, including increased risk of stroke (5.5% vs 1.2%; P < .001), death (5.5% vs 0.3%; P < .001), and return to the operating room for any reason (7.6% vs 1.2%; P < .001). Of 109 patients undergoing CEA/CABG, 61 (56%) were low neurologic risk and 48 (44%) were high neurologic risk but showed no demonstrable difference in stroke (4.9% vs 6.3%; P = .76), death, (4.9 vs 6.3%; P = .76), or return to the operating room (10.2% vs 4.3%; P = .25).

CONCLUSIONS

Although practice patterns in the use of CEA/CABG vary across our region, the risk of complications with CEA/CABG remains significantly higher than in isolated CEA. Future work to improve patient selection in CEA/CABG is needed to improve perioperative results with combined coronary and carotid revascularization.

Socioeconomic and hospital-related predictors of amputation for critical limb ischemia

OBJECTIVE

Disparities in limb salvage procedures may be driven by socioeconomic status (SES) and access to high-volume hospitals. We sought to identify SES factors associated with major amputation in the setting of critical limb ischemia (CLI).

METHODS

The 2003-2007 Nationwide Inpatient Sample was queried for discharges containing lower extremity revascularization (LER) or major amputation and chronic CLI (N = 958,120). The Elixhauser method was used to adjust for comorbidities. Significant predictors in bivariate logistic regression were entered into a multivariate logistic regression for the dependent variable of amputation vs LER.

RESULTS

Overall, 24.2% of CLI patients underwent amputation. Significant differences were seen between both groups in bivariate and multivariate analysis of SES factors, including race, income, and insurance status. Lower-income patients were more likely to be treated at low-LER-volume institutions (odds ratio [OR], 1.74; P < .001). Patients at higher-LER-volume centers (OR, 15.16; P <.001) admitted electively (OR, 2.19; P < .001) and evaluated with diagnostic imaging (OR, 10.63; P < .001) were more likely to receive LER.

CONCLUSIONS

After controlling for comorbidities, minority patients, those with lower SES, and patients with Medicaid were more likely receive amputation for CLI in low-volume hospitals. Addressing SES and hospital factors may reduce amputation rates for CLI.

Volume-outcome relationships in vascular surgery: the current status

Vascular surgery has been widely practiced in hospitals within a general surgical service, although the consequent workload of individual vascular units has been small. There is an increasing body of evidence in favor of a positive relationship between hospital and surgeon volumes and the outcome of arterial surgery. These relationships suggest that vascular surgical procedures might be best placed within a centralized model of care to increase volume and thereby attain best outcomes. This systematic review appraises the current evidence for volume-outcome relationships in vascular surgery from a number of healthcare systems to examine the basis for centralization of vascular surgical services. The index procedures addressed in this review are open or endovascular repair of abdominal aortic aneurysm (AAA), ruptured AAA, descending thoracic aortic aneurysm, and thoracoabdominal aortic aneurysm, along with carotid endarterectomy and lower extremity arterial bypass.

Systematic review and meta-analysis of the relationship between hospital volume and outcome for lower limb arterial surgery

Background

The aim was to investigate whether a relationship existed between case volume and outcome for lower limb vascular surgical procedures.

Methods

PubMed, Embase, the Cochrane Library and Google Scholar were searched for all articles on population-based studies on the volume–outcome relationship for lower limb vascular surgery at hospital level. Outcomes were mortality and subsequent amputation after lower limb vascular surgery. The data were subjected to meta-analysis by outcome.

Results

Some 452 093 patients from ten studies were included in the systematic review and five studies were included in meta-analyses. Seven of these articles found a significant positive hospital–volume outcome relationship. The pooled effect estimate for mortality was odds ratio (OR) 0·81 (95 per cent confidence interval 0·71 to 0·91) and that for amputation was OR 0·88 (0·79 to 0·98), with better results being found after surgery at higher-volume hospitals. Significant heterogeneity was seen in the data.

Conclusion

Higher-volume hospitals were associated with reduced amputation and mortality rates after lower limb vascular surgery. These data were not as conclusive as those for other vascular surgical procedures owing to significant heterogeneity.

Management of anterior triangle swellings in a tertiary vascular centre with emphasis on the roles of duplex ultrasound, computed tomography angiogram and magnetic resonance angiogram: a case series

Background

Anterior triangle masses pose an important clinical dilemma. It is very difficult to distinguish the potential pathologies pre operatively by clinical and radiological assessment.

Case report

The first case highlights the management of a bilateral chemodectoma, the second case is a presentation of castleman's disease and the third is that of metastatic tonsillar adenocarcinoma. All three cases had a similar presentation and radiological appearance pre-operatively.

Conclusion

Anterior triangle masses span the clinical spectrum of pathologies from chemodectoma to castleman's disease to carcinoma. Expert vascular and radiological management is required for optimum patient care and should take place in a tertiary referral centre. Duplex US, CTA and MRA are important pre operative assessment tools to ensure that adequate information regarding the relationship of the lesion to the carotid artery is available to the operating surgeon who should have vascular expertise as deliberate practice volume has been repeatedly shown to result in improved patient outcome.

The relationship between hospital volume and post-operative mortality rates for upper gastrointestinal cancer resections: Scotland 1982-2003

BACKGROUND

Centralisation of surgical treatment of cancer has resulted in improved outcomes. We aimed to determine evidence of benefit for specialised management of upper gastrointestinal cancer in high-volume centres in Scotland.

METHODS

Discharge records of patients undergoing oesophagectomy, gastrectomy, hepatectomy or pancreatectomy between 1982 and 2003 were identified. Hospital data were analysed on a year-by-year basis to derive 'hospital-years'. Hospital-years were divided into quartiles by volume, and were analysed with regard to in-hospital mortality during the operative admission [Chi-square test (chi(2)) and Chi-square test for trend (chi(2)(trend))].

RESULTS

10,625 patients and 982 in-hospital deaths were included. In-hospital mortality rates declined during the study period: oesophagectomy 11.7-7.9%; gastrectomy 11.2-7.2%; hepatectomy 11.1-3.0%; and pancreatectomy 8.3-4.9%. For all resections except gastrectomy, mortality decreased as quartile of hospital-year volume increased (oesophagectomy: chi(2)p=0.006, chi(2)(trend)p=0.001; hepatectomy: chi(2)p=0.004, chi(2)(trend)p=0.003; pancreatectomy: chi(2)p=0.002, chi(2)(trend)p=0.001). ORs of death were lower for oesophagectomy (OR=0.58; 95%CI=0.39, 0.88; p=0.009) and pancreatectomy (OR=0.35; 95%CI=0.19, 0.64; p<0.001) in hospital-years within highest-volume quartiles compared with lowest. Scattergraphs of all resection types demonstrated inverse power relationships between number of resections per hospital-year and mortality.

CONCLUSION

Concentration of cancer care has had major effects on health service delivery in Scotland. Centralisation should be supported in surgical management of upper gastrointestinal cancer.

Model for the reconfiguration of specialized vascular services

Background

This article built on previous work to develop an algorithm for elective abdominal aortic aneurysm (AAA) repair and carotid endarterectomy (CEA), with the aim of improving patient survival by regionalization of services. Vascular procedures were used as an example of specialized surgical services.

Methods

A model was generated based on a national data set that incorporated the statistical demonstration of procedural safety, hospital annual surgical case volume, and travel distance and time. Elective AAA repair was used to construct a hub-and-spoke model that was tested against CEA. The impact of the model was quantified in terms of mortality rates, and travel distance and time.

Results

Only 48 vascular hubs were required to provide adequate coverage in England, with the majority of patients travelling for less than 1 h to access inpatient vascular surgery. The model predicted a reduction in the number of deaths from elective surgery for AAA (P &lt; 0·001) and CEA (P = 0·016).

Conclusion

Adoption of this strategic model may lead to improved outcome after AAA and CEA. It could be used as a model for the regionalization of specialized surgery. The model does not take into account the complexity of providing a comprehensive vascular service in every locality.

Surgeon knowledge, behavior, and opinions regarding intraoperative cholangiography

BACKGROUND

The risk of common bile duct injury during laparoscopic cholecystectomy (LC) is 50% to 70% lower when an intraoperative cholangiogram (IOC) is used, and this effect is exaggerated among less experienced surgeons. Routine IOC is not universal, and barriers to its use, including surgeon knowledge, behavior, and attitudes, should be understood in developing quality-improvement interventions aimed at increasing IOC use.

STUDY DESIGN

There were 4,100 general surgeons randomly selected from the American College of Surgeons who were mailed a survey about IOC. Surveys with a valid exclusion (retired, no LC experience) were considered responsive but were excluded from data analysis.

RESULTS

Forty-four percent responded, with 1,417 surveys analyzed (mean age 51.8+/-9.6 years; 89.2% men; 55.3% private practice). Twenty-seven percent of respondents defined themselves as routine IOC users and 91.3% of routine users reported IOC use in more than 75% of LCs performed. Academic surgeons were less often routine users compared with nonacademics (15% versus 30%; p < 0.001). Selective users were more often low-volume (less than 20 LC/year) surgeons (8% versus 15%) as compared with routine users, who were more often high-volume (more than 100 LC/year) surgeons (27% versus 20%). Routine users had more favorable and accurate opinions about IOC (less costly and more protective of injury) than did selective users. Thirty-nine percent of routine users thought IOC decreased the risk of common bile duct injury by at least half compared with 10% of selective users.

CONCLUSIONS

Surgeons at greatest risk for causing common bile duct injury (inexperienced, low-volume surgeons) and those who have the greatest opportunity to train others are less likely to use IOC routinely. These represent target groups for quality-improvement interventions aimed at broader IOC use.

Socioeconomic status, hospital volume, and stroke fatality in Canada

BACKGROUND AND PURPOSE

Low socioeconomic status is associated with stroke fatality; however, the mechanism behind this association is uncertain. We sought to determine whether residence in a low-income neighborhood was associated with admission to low-volume facilities and whether this contributed to differences in fatality after stroke.

METHODS

All hospitalizations for ischemic stroke from April 2003 to March 2004 were identified from a national administrative database containing patient-level sociodemographic, diagnostic, procedural, and administrative information. Patients were assigned to income quintiles based on the median income of their primary neighborhood of residence and then categorized as low income (quintiles 1 and 2) or high income (quintiles 3 through 5). Hospitals were categorized as low or high volume on the basis of their annual number of stroke admissions. Multivariable analyses were performed to compare stroke fatality at 7 days and at discharge in patients in low- and high-income groups seen at low- and high-volume facilities.

RESULTS

Overall, 25,228 patients with ischemic stroke were included in the analysis. Those from high-income areas were more likely to be admitted to high-volume hospitals. Fatality at 7 days was 8.4%, 8.2%, 7.7%, 7.1, and 6.6% (chi(2)=0.002) for income quintiles 1 (lowest) to 5 (highest), respectively. Low-income patients admitted to low-volume hospitals had the highest risk-adjusted stroke fatality.

CONCLUSIONS

Patients from low-income areas presenting with acute stroke are more likely to be seen in low-volume facilities. This subgroup of patients had a higher risk-adjusted fatality than those from high-income areas seen at high-volume facilities. Understanding the pathways through which socioeconomic status affects health care may lead to strategies for quality improvement.

How to improve surgical outcomes

Data should be monitored and acted on at local and national levels

Demonstrating safety through in-hospital mortality analysis following elective abdominal aortic aneurysm repair in England

Background

The aims were to assess the evidence that individual hospitals had mortality rates in excess of the national average after abdominal aortic aneurysm (AAA) repair and to develop an effective method for monitoring mortality using local data.

Methods

Hospital Episode Statistics identified patients undergoing elective infrarenal AAA repair. A technique was developed that compared individual hospital mortality rates with the mortality rate in the remainder of England. The strength of evidence that the death rate was less than elsewhere, and less than twice elsewhere, was quantified using a test of statistical significance. A moving average chart technique was devised using local data for mortality monitoring and comparison to the national average.

Results

For 30 hospitals, the mortality rate was significantly greater than elsewhere, and in three hospitals it was demonstrably greater than twice that in the remainder of England. The moving average chart appeared to provide a useful technique for local mortality monitoring.

Conclusion

Different mortality rates exist for AAA repair within England. Mortality can be monitored locally and compared with the national average.

The Relationship between Hospital Case Volume and Outcome from Carotid Endartectomy in England from 2000 to 2005

OBJECTIVES

To assess the outcome of carotid endarterectomy in England with respect to the hospital case-volume.

METHODS

Data were from English Hospital Episode Statistics (2000-2005). Admissions were classified as elective or emergency. Risk-adjusted data were analysed through modelling of death rate, complication rate and length of admission with regard to the year of procedure and annual hospital volume of surgery. Hospitals with elevated death rates were identified and the evidence quantified that they had outlying mortality rates.

RESULTS

There were 280,081 diagnoses of extra-cranial atherosclerotic arterial disease in which 18,248 CEA were performed. The mean mortality rates were 1.04% for elective and 3.16% for emergency CEA. A volume-related improvement in mortality (p=0.047) was seen for elective CEA. Length of stay decreased as annual volume increased for elective and emergency CEA (p<0.001). 20% of the operations were performed in 67.1% of the hospitals, each of which performed fewer than 10 CEA per annum. A number of hospitals had elevated death rates.

CONCLUSIONS

Volume-related improvements in outcome were demonstrated for elective CEA. Minimum volume-criteria of 35 CEA per annum should be established in England. Hospitals performing low annual volumes of surgery should consider arrangements to network services.