Relation between rates of leg amputation and distal arterial reconstructive surgery. Oxford Regional Vascular Audit Group

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.

Quality improvement framework for major amputation: are we getting it right?

INTRODUCTION

The quality improvement framework for major amputation was developed with the aim of improving outcomes and reducing the perioperartive mortality to less than 5% by 2015. The aim of the study was to assess our compliance with the framework guidelines and look for the reasons for non-compliance.

METHOD

All major amputations performed between 2008 and 2010 were included. The following data were collected: presence of infection ± tissue loss, status of arterial supply, revascularisation attempts, time to surgery, type of amputation, morbidity and mortality.

RESULTS

A total of 81 patients were included (42 BKAs, 39 AKAs). Ninety percentage had formal preoperative arterial investigations and 84% had an attempted revascularisation procedure. Patients who were transferred late from non-vascular units (n = 12) had a 30-day mortality of 50% whereas patients who presented directly to our unit had a 30-day mortality of 7.2%. The number of amputations has decreased over the last 3 years from 34 to 21 per year, coinciding with the doubling of crural revascularisation procedures performed (from 60 to 120 per year). Ten patients underwent a revision from BKA to AKA because of an inadequate profunda femoris artery (PFA), whereas all those with a healed BKA stump either had a good PFA or a named crural vessel.

CONCLUSION

The overall number of amputations is decreasing from year to year. By doubling our crural revascularisation procedures we are saving more limbs. Thirty-day mortality is higher than expected, particularly in patients who present late. Expeditious referral may potentially improve the mortality rate among this group of patients.

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.

Provider volume and outcomes for abdominal aortic aneurysm repair, carotid endarterectomy, and lower extremity revascularization procedures

BACKGROUND

Intuitively, vascular procedures performed by high-volume vascular subspecialists working at high-volume institutions should be associated with improved patient outcome. Although a large number of studies assess the relationship between volume and outcome, a single contemporary compilation of such studies is lacking.

METHODS

A review of the English language literature was performed incorporating searches of the Medline, EMBASE, and Cochrane collaboration databases for abdominal aortic aneurysm repair (elective and emergent), carotid endarterectomy, and arterial lower limb procedures for any volume outcome relationship. Studies were included if they involved a patient cohort from 1980 onwards, were community or population based, and assessed health outcomes (mortality and morbidity) as a dependent variable and volume as an independent variable.

RESULTS

We identified 74 relevant studies, and 54 were included. All showed either an inverse relationship of variable magnitude between provider volume and mortality, or no volume-outcome effect. The reduction in the risk-adjusted mortality rate (RAMR) for high-volume providers was 3% to 11% for elective abdominal aortic aneurysm (AAA) repair, 2.5 to 5% for emergent AAA repair, 0.7% to 4.7% carotid endarterectomy, and 0.3% to 0.9% for lower limb arterial bypass procedures. Subspeciality training also conferred a considerable morbidity and mortality benefit for emergent AAA repair, carotid endarterectomy, and lower limb arterial procedures.

CONCLUSION

High-volume providers have significantly better outcomes for vascular procedures both in the elective and emergent setting. Subspeciality training also has a considerable impact. These data provide further evidence for the specialization of vascular services, whereby vascular procedures should generally be preformed by high-volume, speciality trained providers.

Is there a positive volume-outcome relationship in peripheral vascular surgery? Results of a systematic review

OBJECTIVES

to examine the evidence for the existence, or otherwise, of a positive volume-outcome relationship in the area of peripheral vascular surgery.

DESIGN

systematic overview of prospective or retrospective volume-outcome studies.

DATA SOURCES

seven bibliographic databases were searched for English-language articles published between 1986 and 1998.

STUDY SELECTION

thirty-six articles published in peer-reviewed journals; excluding editorials, letters or abstracts; and addressing volume and outcome in peripheral vascular surgery. Criteria were applied and agreed by consensus between two of the authors.

DATA EXTRACTION

the articles identified were independently assessed by two of the authors. Studies were categorised into three distinct areas - carotid endarterectomy- (17 studies), abdominal aortic aneurysm repair (16 studies) and other vascular interventions (four studies). Within each category studies were further classified according to full adjustment, partial adjustment or no adjustment for case mix. Where discrepancies arose, decisions were referred to a third author for arbitration.

DATA SYNTHESIS

findings for carotid endarterectomy identified a positive volume-outcome relationship for both mortality and stroke at the physician level. There was less support for a positive relationship for mortality at the hospital level, and no evidence of benefits for stroke in higher volume hospitals. If only studies making a full adjustment for case mix are included, there is no clear support from statistically significant evidence for or against a positive volume-outcome relationship. For repair of unruptured abdominal aortic aneurysms there is evidence of a positive volume-outcome relationship at both the physician and hospital level, with evidence being particularly strong at the level of the hospital. For ruptured aneurysms the evidence is suggestive of there not being a positive volume-outcome relationship at the hospital level, while for physicians the evidence is more balanced with no clear support either way. For other vascular interventions there were insufficient studies (n=4) from which to draw meaningful conclusions.

CONCLUSIONS

our results show that evidence of a relationship between volume and outcome in peripheral vascular surgery may be attributable to factors such as lack of adjustment for case-mix, different definitions of volume and poor quality of studies, especially those of retrospective design. Future studies should address these deficiencies by making full adjustment for case mix and by being prospective in design.

Survey of changes in the provision of vascular surgical services in the Oxford Region over 5 years

AIM

This study aimed to examine changes in the provision of vascular services in the Oxford region over 5 years.

METHODS

A questionnaire was sent to all general surgeons in the region asking of their involvement in vascular surgery. Data were obtained from the Department of Health concerning vascular procedures and inpatient codes for each district in the Oxford Region from 1990-1991 to 1994-1995. Office of Population Censuses and Surveys (OPCS) data for abdominal aortic aneurysm repair and femoral artery reconstruction were validated against data collected prospectively for West Berkshire.

RESULTS

Eighteen of 45 surgeons who replied to the questionnaire carried out elective and emergency arterial work. All were members of the Vascular Surgical Society of Great Britain and Ireland (VSS). All but one took part in the general surgical rota. Eight surgeons carried out emergency arterial surgery only; only two of these were members of the VSS. Of 19 surgeons undertaking no arterial surgery, 15 operated on primary and 11 on recurrent varicose veins. The number of arterial reconstructions rose from 20.8 per 100000 population to 28 per 100000 throughout the study. The greatest increase occurred in districts where a new vascular consultant had been appointed. Similar results were obtained with endovascular procedures. The number of major amputations remained fairly constant at approximately 11 per 100000 population. The number of inpatient episodes for arterial disease also rose, from 35.7 to 47.6 per 100000. In validating OPCS codes against prospectively collected data, discrepancies for individual years were noted but the annual trend was reflected fairly accurately by the codes.

CONCLUSION

There has been an increase in vascular activity in the region, but variations still exist between different districts.

Factors affecting the results of surgery for chronic critical leg ischemia--a nationwide survey. Finnvasc Study Group

PURPOSE

To assess the factors affecting immediate outcome of surgery for chronic critical leg ischemia, especially the influence of surgeon's caseload and hospital volume.

METHODS

The data of Finnvasc registry were retrospectively analyzed. A total of 11,747 surgical vascular reconstructions included 1,761 operations for chronic critical leg ischemia during 1991 to 1994.

RESULTS

The 30-day postoperative leg amputation rate was 7.5% and the mortality rate 4.7%. Diabetes, previous vascular surgery or amputation, preoperative ulcer or gangrene, a surgeon's annual caseload fewer than 10 operations, and hospital volume fewer than 20 operations for chronic critical leg ischemia adversely affected amputation rates. The presence of coronary artery disease and renal dysfunction increased postoperative mortality rates. Both amputation rates and postoperative mortality rates were affected by the type of procedure.

CONCLUSIONS

A surgeon's caseload and hospital volume affect amputation rate, but not mortality rate, in patients operated for chronic critical leg ischemia.

Effects of vascular surgery on amputation rates and mortality

OBJECTIVES

To study the relation between rates of vascular interventions, amputations and mortality in a defined population.

DESIGN

Retrospective comparison between two consecutive 4-year periods.

SETTING

Swedish district hospital covering a population of 125,000.

MATERIAL

Three hundred and sixty-seven lower limb amputations and 1080 vascular procedures.

RESULTS

The number of legs treated for limb-threatening ischaemia with either revascularisation or amputation increased from 269 to 289. The rate of vascular interventions for limb-threatening ischaemia increased from the first to the second period by 65%, while the rate of amputations decreased by 23%. Limb salvage rate at 30 months increased from 37% to 53% (p < 0.0000). The reduced amputation rate was entirely related to primary amputations. The adjusted risk of amputation for patients treated in the second period was half of that for patients treated in the first period (relative risk = 0.49, p = 0.0001), while mortality was similar in both periods. Among survivors, the proportion of patients with intact legs was higher in the second period than in the first, while no difference was found between the two periods among deceased patients.

CONCLUSIONS

Increased vascular intervention leads to improved limb salvage rates and reduced amputation rates. It is important for both ethical and economical reasons to identify good responders to revascularisation, because the choice of initial treatment will only influence limb salvage but not survival.

General surgery with a special interest in vascular surgery: changing patterns of workload

Prospective surveys of workload were carried out during 1989, 1990 and 1995. Analysis of outpatient referrals, inpatients and operations performed over periods of 3 months was undertaken and the changing patterns of general surgical and vascular surgical workload noted. The number of outpatient referrals rose throughout the study period because of a significant increase in the number of patients with both varicose veins and other vascular problems. There was an increase in the number of emergency admissions for vascular disease. The number of patients having general surgical operations fell; there was a corresponding increase in the number for arterial and venous disease. The general surgical component of a general surgical unit with a vascular interest is gradually declining, as increased numbers of patients with vascular problems are being referred and managed.