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

The Relationship Between Hospital Procedure Volume and Outcomes After Endovascular or Open Surgical Revascularisation for Peripheral Arterial Disease: An Analysis of Health Insurance Claims Data

OBJECTIVE

There is a paucity of data on the relationship between hospital procedure volume and outcomes after inpatient treatment of symptomatic peripheral arterial disease (PAD). This study aimed to generate meaningful hypotheses to support the ongoing discussion.

METHODS

Data derived from BARMER, Germany's second largest insurance provider, were linked with nationwide hospital procedure volumes from mandatory hospital quality reports. All endovascular (EVR) and open surgical revascularisations (OSR) provided to patients (≥ 40 years) with symptomatic PAD between 1 January 2013 and 31 December 2018 were included. Hospital volume was defined as the number of procedures performed by a hospital in the previous calendar year (in quartiles). Freedom from re-intervention, amputation, and overall mortality rate within 12 months after discharge were analysed using multivariable Cox proportional hazards models. In hospital mortality was determined by generalised estimating equations logistic regression models.

RESULTS

There were 88 187 revascularisations (72.4% EVR; EVR: 72.7 years and 45.2% females; OSR: 71.9 years and 41.9% females) registered by 668 hospitals. No statistically significant association was found between 12 month freedom from re-intervention and hospital volume (EVR: 4; quartile HR 1.05; 95% CI 0.94 - 1.16. OSR: 4; quartile HR 1.05; 95% CI 0.92 - 1.21). Patients with OSR had a decreased hazard of 12 month mortality in a high volume hospital compared with a low volume hospital (HR 0.85; 95% CI 0.73 - 0.98), but not with EVR (HR 1.03; 95% CI 0.91 - 1.16). Patients who were treated in hospitals with highest volumes showed decreased hazards of 12 month freedom from amputation when compared with low volume hospitals (EVR: HR 0.72; 95% CI 0.52 - 0.99. OSR: HR 0.61; 95% CI 0.44 - 0.85).

CONCLUSION

This large retrospective analysis of insurance claims suggests that higher procedure volume is associated with lower major amputation rates, although there is a need for standardisation of the definition of volume stratification. Future studies should address the impact of subsequent outpatient care and surveillance to further examine the complex interaction between treatment and outcomes.

Delays to revascularization for patients with chronic limb-threatening ischaemia

BACKGROUND

Vascular services in England are organized into regional hub-and-spoke models, with hubs performing arterial surgery. This study examined time to revascularization for chronic limb-threatening ischaemia (CLTI) within and across different care pathways, and its association with postrevascularization outcomes.

METHODS

Three inpatient and four outpatient care pathways were identified for patients with CLTI undergoing revascularization between April 2015 and March 2019 using Hospital Episode Statistics data. Differences in times from presentation to revascularization across care pathways were analysed using Cox regression. The relationship between postoperative outcomes and time to revascularization was evaluated by logistic regression.

RESULTS

Among 16 483 patients with CLTI, 9470 had pathways starting with admission to a hub or spoke hospital, whereas 7013 (42.5 per cent) were first seen at outpatient visits. Among the inpatient pathways, patients admitted to arterial hubs had shorter times to revascularization than those admitted to spoke hospitals (median 5 (i.q.r. 2-10) versus 12 (7-19) days; P < 0.001). Shorter times to revascularization were also observed for patients presenting to outpatient clinics at arterial hubs compared with spoke hospitals (13 (6-25) versus 26 (15-35) days; P < 0.001). Within most care pathways, longer delays to revascularizsation were associated with increased risks of postoperative major amputation and in-hospital death, but the effect of delay differed across pathways.

CONCLUSION

For patients with CLTI, time to revascularization was influenced by presentation to an arterial hub or spoke hospital. Generally, longer delays to revascularization were associated with worse outcomes, but the impact of delay differed across pathways.

Configuration of vascular services: a multiple methods research programme

Background

Vascular services is changing rapidly, having emerged as a new specialty with its own training and specialised techniques. This has resulted in the need for reconfiguration of services to provide adequate specialist provision and accessible and equitable services.

Objectives

To identify the effects of service configuration on practice, resource use and outcomes. To model potential changes in configuration. To identify and/or develop electronic data collection tools for collecting patient-reported outcome measures and other clinical information. To evaluate patient preferences for aspects of services other than health-related quality of life.

Design

This was a multiple methods study comprising multiple systematic literature reviews; the development of a new outcome measure for users of vascular services (the electronic Personal Assessment Questionnaire – Vascular) based on the reviews, qualitative studies and psychometric evaluation; a trade-off exercise to measure process utilities; Hospital Episode Statistics analysis; and the development of individual disease models and a metamodel of service configuration.

Setting

Specialist vascular inpatient services in England.

Data sources

Modelling and Hospital Episode Statistics analysis for all vascular inpatients in England from 2006 to 2018. Qualitative studies and electronic Personal Assessment Questionnaire – Vascular evaluation with vascular patients from the Sheffield area. The trade-off studies were based on a societal sample from across England.

Interventions

The data analysis, preference studies and modelling explored the effect of different potential arrangements for service provision on the resource use, workload and outcomes for all interventions in the three main areas of inpatient vascular treatment: peripheral arterial disease, abdominal aortic aneurysm and carotid artery disease. The electronic Personal Assessment Questionnaire – Vascular was evaluated as a potential tool for clinical data collection and outcome monitoring.

Main outcome measures

Systematic reviews assessed quality and psychometric properties of published outcome measures for vascular disease and the relationship between volume and outcome in vascular services. The electronic Personal Assessment Questionnaire – Vascular development considered face and construct validity, test–retest reliability and responsiveness. Models were validated using case studies from previous reconfigurations and comparisons with Hospital Episode Statistics data. Preference studies resulted in estimates of process utilities for aneurysm treatment and for travelling distances to access services.

Results

Systematic reviews provided evidence of an association between increasing volume of activity and improved outcomes for peripheral arterial disease, abdominal aortic aneurysm and carotid artery disease. Reviews of existing patient-reported outcome measures did not identify suitable condition-specific tools for incorporation in the electronic Personal Assessment Questionnaire – Vascular. Reviews of qualitative evidence, primary qualitative studies and a Delphi exercise identified the issues to be incorporated into the electronic Personal Assessment Questionnaire – Vascular, resulting in a questionnaire with one generic and three disease-specific domains. After initial item reduction, the final version has 55 items in eight scales and has acceptable psychometric properties. The preference studies showed strong preference for endovascular abdominal aortic aneurysm treatment (willingness to trade up to 0.135 quality-adjusted life-years) and for local services (up to 0.631 quality-adjusted life-years). A simulation model with a web-based interface was developed, incorporating disease-specific models for abdominal aortic aneurysm, peripheral arterial disease and carotid artery disease. This predicts the effects of specified reconfigurations on workload, resource use, outcomes and cost-effectiveness. Initial exploration suggested that further reconfiguration of services in England to accomplish high-volume centres would result in improved outcomes, within the bounds of cost-effectiveness usually considered acceptable in the NHS.

Limitations

The major source of evidence to populate the models was Hospital Episode Statistics data, which have limitations owing to the complexity of the data, deficiencies in the coding systems and variations in coding practice. The studies were not able to address all of the potential barriers to change where vascular services are not compliant with current NHS recommendations.

Conclusions

There is evidence of potential for improvement in the clinical effectiveness and cost-effectiveness of vascular services through further centralisation of sites where major vascular procedures are undertaken. Preferences for local services are strong, and this may be addressed through more integrated services, with a range of services being provided more locally. The use of a web-based tool for the collection of clinical data and patient-reported outcome measures is feasible and can provide outcome data for clinical use and service evaluation.

Future work

Further evaluation of the economic models in real-world situations where local vascular service reconfiguration is under consideration and of the barriers to change where vascular services do not meet NHS recommendations for service configuration is needed. Further work on the electronic Personal Assessment Questionnaire – Vascular is required to assess its acceptability and usefulness in clinical practice and to develop appropriate report formats for clinical use and service evaluation. Further studies to assess the implications of including non-health-related preferences for care processes, and location of services, in calculations of cost-effectiveness are required.

Study registration

This study is registered as PROSPERO CRD42016042570, CRD42016042573, CRD42016042574, CRD42016042576, CRD42016042575, CRD42014014850, CRD42015023877 and CRD42015024820.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 9, No. 5. See the NIHR Journals Library website for further project information.

Referral patterns for catheter-directed thrombolysis for iliofemoral deep venous thrombosis

OBJECTIVES

Post thrombotic syndrome (PTS) is a serious complication of deep venous thromboses (DVTs). PTS occurs more frequently and severely following iliofemoral DVT compared to distal DVTs. Catheter directed thrombolysis (CDT) of iliofemoral DVTs may reduce PTS incidence and severity.We aimed to determine the rate of iliofemoral DVT within our institution, their subsequent management, and compliance with NICE guidelines.

METHODS

Retrospective review of all DVTs diagnosed over a 3-year period was conducted. Cases of iliofemoral DVT were identified using ICD-10 codes from patient notes, and radiology reports of Duplex scans. Further details were retrieved, such as patient demographics and referrals to vascular services. NICE guidance was applied to determine if patients would have been suitable for CDT. A survey was sent to clinicians within medicine to identify awareness of CDT and local guidelines for iliofemoral DVT management.

RESULTS

225 patients with lower limb DVTs were identified. Of these, 96 were radiographically confirmed as iliofemoral DVTs. The median age was 77. 67.7% of iliofemoral DVTs affected the left leg. Right leg DVTs made up 30.2% and 2.1% were bilateral DVTs. Of the 96 iliofemoral DVTs, 21 were deemed eligible for CDT. Only 3 patients (14.3%) were referred to vascular services, and 3 received thrombolysis.From our survey, 95.5% of respondents suggested anticoagulation alone as management for iliofemoral DVT. Only one respondent recommended referral to vascular services. There was a knowledge deficiency regarding venous anatomy, including superficial versus deep veins.

CONCLUSIONS

CDT and other mechanochemical procedures have been shown to improve outcomes of patients post-iliofemoral DVT, however a lack of awareness regarding CDT as a management option results in under-referral to vascular services. We suggest closer relations between vascular services and their "tributary" DVT clinics, development of guidelines and robust care pathways in the management of iliofemoral DVT.

Association of hospital and surgeon volume with mortality following major surgical procedures: Meta-analysis of meta-analyses of observational studies

Accumulation of the literature has suggested an inverse association between healthcare provider volume and mortality for a wide variety of surgical procedures. This study aimed to perform meta-analysis of meta-analyses (umbrella review) of observational studies and to summarize existing evidence for associations of healthcare provider volume with mortality in major operations.We searched MEDLINE, SCOPUS, and Cochrane Library, and screening of references.Meta-analyses of observational studies examining the association of hospital and surgeon volume with mortality following major operations. The primary outcome is all-cause short-term morality after surgery. Meta-analyses of observational studies of hospital/surgeon volume and mortality were included. Overall level of evidence was classified as convincing (class I), highly suggestive (class II), suggestive (class III), weak (class IV), and non-significant (class V) based on the significance of the random-effects summary odds ratio (OR), number of cases, small-study effects, excess significance bias, prediction intervals, and heterogeneity.Twenty meta-analyses including 4,520,720 patients were included, with 19 types of surgical procedures for hospital volume and 11 types of surgical procedures for surgeon volume. Nominally significant reductions were found in odds ratio in 82% to 84% of surgical procedures in both hospital and surgeon volume-mortality associations. To summarize the overall level of evidence, however, only one surgical procedure (pancreaticoduodenectomy) fulfilled the criteria of class I and II for both hospital and surgeon volume and mortality relationships, with a decrease in OR for hospital (0.42, 95% confidence interval[CI] [0.35-0.51]) and for surgeon (0.38, 95% CI [0.30-0.49]), respectively. In contrast, most of the procedures appeared to be weak or "non-significant."Only a very few surgical procedures such as pancreaticoduodenectomy appeared to have convincing evidence on the inverse surgeon volume-mortality associations, and yet most surgical procedures resulted in having weak or "non-significant" evidence. Therefore, healthcare professionals and policy makers might be required to steer their centralization policy more carefully unless more robust, higher-quality evidence emerges, particularly for procedures considered as having a weak or non-significant evidence level including total knee replacement, thyroidectomy, bariatric surgery, radical cystectomy, and rectal and colorectal cancer resections.

Association of Treatment for Critical Limb Ischemia with Gender and Hospital Volume

Critical limb ischemia (CLI) is a frequent and major vascular problem and can lead to amputation and death despite surgical revascularization. Women have been shown to have 3 to 4 per cent lower revascularization rates for CLI compared with men as well as inferior outcomes. We hypothesize that this difference is a result of women being more likely admitted to low-volume hospitals, which in turn perform fewer revascularizations. Prospective cohort study. Data from the Nationwide Inpatient Sample 2007 to 2010 were used to identify admissions with primary International Classification of Diseases-9 codes for CLI (International Classification of Diseases-9 codes: 440.22, 440.23, 440.24, 707.1, 707.10–707.15, or 707.19). Hospitals were grouped in quintiles by annual revascularization procedures. Bivariate analyses were performed and multivariable logistic regression was used to analyze the odds of revascularization, amputation, and mortality while controlling for patient and hospital-level factors. Of 113,631 admissions, 54,370 (47.8%) were women, who were more likely admitted to low-volume hospitals (very low: 49.6% vs very high: 47.1%; P < 0.001). Revascularization rates were lower in women (31.6% vs 35.1%, P < 0.001) across all volume quintiles, whereas the difference was greatest in the use of open surgical revascularization (12.5% vs 16.0%, P < 0.001). In multivariable analysis, female gender [odds ratio (OR) 0.87, 95% confidence interval (CI) 0.83–0.92, P < 0.001] and very-low hospital volume (OR 0.21, 95% CI 0.17–0.26, P < 0.001) were both significantly associated with lower rates of revascularization. Women had lower odds of major amputation compared with men (OR 0.75, 95% CI 0.69–0.82, P < 0.001), whereas treatment in a very high-volume hospital was associated with increased odds for amputation (OR 1.37, 95% CI 1.09–1.73, P = 0.008). Neither gender nor hospital volume were independently associated with in-hospital mortality in the multivariable regression model. Women are more likely to be admitted to low-volume hospitals for treatment of CLI. Because of this, they are less likely to undergo revascularization, although they also had lower rates of major amputation.

Surgeon, not institution, case volume is associated with limb outcomes after lower extremity bypass for critical limb ischemia in the Vascular Quality Initiative

OBJECTIVE

Studies from large administrative databases have demonstrated associations between institutional case volume and outcomes after lower extremity bypass (LEB). We hypothesized that increased institutional and surgeon volume would be associated with improved outcomes after LEB. Using a national, prospectively collected clinical database, the objective of this study was to determine the effects of both surgeon and institutional volume on outcomes after LEB.

METHODS

The Vascular Quality Initiative (VQI) was queried to identify all LEBs for critical limb ischemia or claudication between 2004 and 2014. Average annual case volume was calculated by dividing an institution's or surgeon's total LEB volume by the number of years they reported to the VQI. Institutional and surgeon volumes were analyzed as continuous variables to determine the impact of volume on major adverse cardiac events (MACEs), major adverse limb events (MALEs), graft patency, and amputation-free survival. Hierarchical regression models were used with cases clustered by surgeon and center. Time-dependent outcomes were evaluated with multivariable shared frailty Cox proportional hazards models.

RESULTS

From 2004 to 2014, there were 14,678 LEB operations performed at 114 institutions by 587 surgeons. Average annual institutional volume ranged from 1.0 to 137.5 LEBs per year, with a median of 26.9 (interquartile range, 14-45.3). Average annual surgeon volume ranged from 1 to 52 LEBs per year with a median of 5.7 (interquartile range, 2.5-9.3). Institutional LEB volume was not associated with MACEs or MALEs or with loss of patency. However, average annual surgeon volume was independently associated with reduced MALEs and improved primary patency. Institutional and surgeon volume did not predict MACEs.

CONCLUSIONS

In contradistinction to previous studies, there was no relationship in this study between institutional LEB volume and outcomes after LEB. However, greater average annual surgeon volume was associated with improved primary patency and decreased risk of MALEs. Open LEB remains a safe and effective procedure for limb salvage. Limb-related outcomes in critical limb ischemia and claudication will be optimized if surgeons maintain adequate volume of LEB.

Hospital volume and mortality for 25 types of inpatient treatment in German hospitals: observational study using complete national data from 2009 to 2014

OBJECTIVES

To explore the existence and strength of a relationship between hospital volume and mortality, to estimate minimum volume thresholds and to assess the potential benefit of centralisation of services.

DESIGN

Observational population-based study using complete German hospital discharge data (Diagnosis-Related Group Statistics (DRG Statistics)).

SETTING

All acute care hospitals in Germany.

PARTICIPANTS

All adult patients hospitalised for 1 out of 25 common or medically important types of inpatient treatment from 2009 to 2014.

MAIN OUTCOME MEASURE

Risk-adjusted inhospital mortality.

RESULTS

Lower inhospital mortality in association with higher hospital volume was observed in 20 out of the 25 studied types of treatment when volume was categorised in quintiles and persisted in 17 types of treatment when volume was analysed as a continuous variable. Such a relationship was found in some of the studied emergency conditions and low-risk procedures. It was more consistently present regarding complex surgical procedures. For example, about 22 000 patients receiving open repair of abdominal aortic aneurysm were analysed. In very high-volume hospitals, risk-adjusted mortality was 4.7% (95% CI 4.1 to 5.4) compared with 7.8% (7.1 to 8.7) in very low volume hospitals. Theminimum volume above which risk of death would fall below the average mortality was estimated as 18 cases per year. If all hospitals providing this service would perform at least 18 cases per year, one death among 104 (76 to 166) patients could potentially be prevented.

CONCLUSIONS

Based on complete national hospital discharge data, the results confirmed volume-outcome relationships for many complex surgical procedures, as well as for some emergency conditions and low-risk procedures. Following these findings, the study identified areas where centralisation would provide a benefit for patients undergoing the specific type of treatment in German hospitals and quantified the possible impact of centralisation efforts.

Influence of hospital volume on nephrectomy mortality and complications: a systematic review and meta-analysis stratified by surgical type

OBJECTIVES

The provision of complex surgery is increasingly centralised to high-volume (HV) specialist hospitals. Evidence to support nephrectomy centralisation however has been inconsistent. We conducted a systematic review and meta-analysis to determine the association between hospital case volumes and perioperative outcomes in radical nephrectomy, partial nephrectomy and nephrectomy with venous thrombectomy.

METHODS

Medline, Embase and the Cochrane Library were searched for relevant studies published between 1990 and 2016. Pooled effect estimates for nephrectomy mortality and complications were calculated for each nephrectomy type using the DerSimonian and Laird random-effects model. Sensitivity analyses were performed to examine the effects of heterogeneity on the pooled effect estimates by excluding studies with the heaviest weighting, lowest methodological score and most likely to introduce bias from misclassification of standardised hospital volume.

RESULTS

Some 226 372 patients from 16 publications were included in our review and meta-analysis. Considerable between-study heterogeneity was noted and only a few reported volume-outcome relationships specifically in partial nephrectomy or nephrectomy with venous thrombectomy.HV hospitals were correlated with a 26% and 52% reduction in mortality for radical nephrectomy (OR 0.74, 95% CI 0.61 to 0.90, p<0.01) and nephrectomy with venous thrombectomy (OR 0.48, 95% CI 0.29 to 0.81, p<0.01), respectively. In addition, radical nephrectomy in HV hospitals was associated with an 18% reduction in complications (OR 0.82, 95% CI 0.73 to 0.92, p<0.01). No significant volume-outcome relationship in mortality (OR 0.84, 95% CI 0.31 to 2.26, p=0.73) or complications (OR 0.85, 95% CI 0.55 to 1.30, p=0.44) was observed for partial nephrectomy.

CONCLUSIONS

Our findings suggest that patients undergoing radical nephrectomy have improved outcomes when treated by HV hospitals. Evidence of this in partial nephrectomy and nephrectomy with venous thrombectomy is however not yet clear and could be secondary to the low number of studies included and the small patient number in our analyses. Further investigation is warranted to establish the full potential of nephrectomy centralisation particularly as existing evidence is of low quality with significant heterogeneity.

Variation in survival after surgery for peri-ampullary cancer in a regional cancer network

BACKGROUND

Centralisation of specialist surgical services requires that patients are referred to a regional centre for surgery. This process may disadvantage patients who live far from the regional centre or are referred from other hospitals by making referral less likely and by delaying treatment, thereby allowing tumour progression. The aim of this study is to explore the outcome of surgery for peri-ampullary cancer (PC) with respect to referring hospital and travel distance for treatment within a network served by five hospitals.

METHODS

Review of a unit database was undertaken of patients undergoing surgery for PC between January 2006 and May 2014.

RESULTS

394 patients were studied. Although both the median travel distance for patients from the five hospitals (10.8, 86, 78.8, 54.7 and 89.2 km) (p < 0.05), and the annual operation rate for PC (2.99, 3.29, 2.13, 3.32 and 3.07 per 100,000) (p = 0.044) were significantly different, no correlation was noted between patient travel distance and population operation rate at each hospital. No difference was noted between patients from each hospital in terms of resection completion rate or pathological stage of the resected tumours. The median survival after diagnosis for patients referred from different hospitals ranged from 1.2 to 1.7 years and regression analysis revealed that increased travel distance to the regional centre was associated with a small survival advantage.

CONCLUSION

Although variation in the provision and outcome of surgery for PC between regional hospitals is noted, this is not adversely affected by geographical isolation from the regional centre.

TRIAL REGISTRATION

This study is part of post-graduate research degree project. The study is registered with ClinicalTrials.gov (unique identifier NCT02296736 ) November 18, 2014.

Dutch evidence-based guidelines for amputation and prosthetics of the lower extremity: Amputation surgery and postoperative management. Part 1

BACKGROUND

Surgeons still use a range of criteria to determine whether amputation is indicated. In addition, there is considerable debate regarding immediate postoperative management, especially concerning the use of 'immediate/delayed fitting' versus conservative elastic bandaging.

OBJECTIVES

To produce an evidence-based guideline for the amputation and prosthetics of the lower extremities. This guideline provides recommendations in support of daily practice and is based on the results of scientific research and further discussions focussed on establishing good medical practice. Part 1 focuses on amputation surgery and postoperative management.

STUDY DESIGN

Systematic literature design.

METHODS

Literature search in five databases. Quality assessment on the basis of evidence-based guideline development.

RESULTS

An evidence-based multidisciplinary guideline on amputation and prosthetics of the lower extremity.

CONCLUSION

The best care (in general) for patients undergoing amputation of a lower extremity is presented and discussed. This part of the guideline provides recommendations for diagnosis, referral, assessment, and undergoing amputation of a lower extremity and can be used to provide patient information.

CLINICAL RELEVANCE

This guideline provides recommendations in support of daily practice and is based on the results of scientific research and further discussions focussed on establishing good medical practice.

Distal bypasses in patients with diabetes and infrapopliteal disease: technical considerations to achieve success

The combination of diabetes and peripheral arterial disease (PAD) is challenging in many ways. The characteristic and complex distal distribution of PAD often encountered in patients with diabetes means that bypass surgery in this context is technically challenging. In addition, many of these patients have a burden of serious comorbidities that must be optimized and managed concurrently. While the authors acknowledge that "achieving success" in distal bypass relies on much more than technical expertise, there are some technical aspects that should be considered when planning surgery on these patients. This article outlines some important issues in the treatment pathway of a patient with diabetes and PAD requiring distal bypass surgery--from selection and optimization of the patient (in the context of a multidisciplinary team) and preoperative workup, to the operative strategy planning, technical tips, and nonoperative adjuncts. These considerations, as well as sound knowledge of the underlying disease process, confounding medical factors and awareness of the difficulty in predicting treatment outcomes, should help maximize the chances of success.

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.