Quality of provided care in vascular surgery : outcome assessment & improvement strategies
Flu, H.C.
Citation
Flu, H. C. (2010, March 24). Quality of provided care in vascular surgery : outcome assessment & improvement strategies. Retrieved from
https://hdl.handle.net/1887/15124
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Chapter 2
Assessing the Quality of Surgical Care in Vascular Surgery; Value of Process, Structure and Outcome Parameters
Ploeg AJ, Flu HC, Breslau PJ, Hamming JF, Lardenoye JHP
Submitted to the Annals of Vascular Surgery
ABSTRACT
Objectives: This study presents a review of prospective studies reporting on quality of care in vascular surgery. All articles were subsequently subscribed to one of the three components of quality of care, e.g. structure, process or outcome, in order to provide insight in the value of each of the three components in assessing quality of care in vascular surgery.
Materials and methods: Original data regarding quality of care were collected from MEDLINE and EMBASE databases. Data were extracted systematically and main out- comes were analyzed.
Results: 57 prospective articles were included, drawn from 859 eligible reports. Struc- ture as an indicator of quality of care was described in 19 reports, process in 7 reports and outcome in 31 reports. Most studies based on structural measures considered the introduction of a clinical pathway a registration system. Process measures showed promising results with a 60% decrease of operative risk in 1 study. Outcome as clinical indicator mainly focused on identifying risk factors for morbidity, mortality or failure of treatment
Conclusion: Outcome as an indicator of quality of care is described predominantly whereas structure and process indicators are evaluated scarcely in vascular surgery. Pro- cess, structure and outcome measures are interwoven and can not be seen separately.
Many studies in vascular surgery have been focused on outcomes as indicator of quality of care, but a shift towards process measures should be considered as focus of attention in the future.
INTRODUCTION
Safety and quality have become prominent criteria by which surgical care is evaluated.
In today’s medicine surgeons and hospitals are more and more asked to provide infor- mation about the quality of care that they are able to provide. Quality improvement programs have already been implemented successfully in thoracic surgery and subse- quent morbidity and mortality rates have decreased in the past decades 1-3. Assessment of quality of care can be divided into three components: Structure, process and outcome
4, 5. There remains considerable debate which measures should be used to reflect surgical quality 5.
Structural measures include a broad list of variables reflecting the setting or system in which care is delivered. Volume is an example of a structural measure as a surrogate for surgical care 6. Systems and structures play a critical role in the final outcome of surgical care and they represent ultimately the care which is delivered to the patients. Process variables describe the care that patients actually receive. Many processes of care are strongly associated with improved patient outcomes. Examples include tight postop- erative glycemic control or proper administration of perioperative antibiotics. Direct outcomes measurement is particularly appealing as measure of surgical quality of care, because it represents directly the bottom line of surgical care. Morbidity, mortality or reoperation rates represent direct outcome measurement.
Furthermore, registration of adverse events alone may improve outcomes 7. Vascular operations are associated with higher morbidity and mortality rates compared to general surgical operations 8 and therefore of special interest to reduce adverse outcomes and to improve quality of care. Patients undergoing revascularization procedures frequently suffer from extensive forms of generalized atherosclerosis with subsequent coronary sclerosis and risk of cardiovascular postoperative adverse events. Therefore an analysis of initiatives providing insight in quality of care in this specific high risk patient popu- lation is of high importance. Quality indicators for assessment of quality of care have been identified for cardiothoracic, vascular and general surgery. Unplanned reoperation has been applied as a quality indicator for both general 9 and vascular surgery 10. The National Surgical Quality Improvement Program (NSQIP) introduced in Veteran Affairs hospitals has been a successful example of quality improvement in general surgery 11, 12.
To our knowledge no previous study has been undertaken reviewing publications regarding quality of care for vascular surgery. This study presents a systematic review of studies reporting on quality of care after vascular surgery. All articles were subsequently subscribed to one of the three components of quality of care, e.g. structure, process or outcome in order to provide insight in the value of each of the three components in assessing quality of care in vascular surgery.
MATERIALS AND METHODS
Literature search
MEDLINE and EMBASE databases were searched up to July 2008. The following string search was used for Medline as shown in Appendix 1. For Excerpta Medica database (EMBASE 1980 to date) the following string search was used as shown in Appendix 2.
Selection of articles
All titles and abstracts of the selected articles were read by two independent reviewers.
Inclusion criteria were a) description one of the three factors of quality of care, e.g. pro- cess, outcome or structure b) prospectively described. Full text versions were obtained of all articles that matched the inclusion criteria and were subsequently read by two independent reviewers. Excluded were all articles a) which did not present vascular sur- gery b) patients under 18 c) other language than English. Of each study author, subject, year of publication, mortality, morbidity and main outcome was noted.
RESULTS
The search strategy identified 859 eligible reports. 544 reports were not included for describing surgery other then vascular surgery and/or a different language other than English. 258 reports were not prospectively described studies. Finally 57 articles were included, divided in process, outcome or structure. Table 1 provides a summary of all studies included.
Structure
Structure as an indicator of quality of care is described in 19 reports 8, 11, 13-29. Details are described in Table 2. Five of 19 studies on structure were based on The National Surgical Quality Improvement Program Data 11, 24, 30, 31 (NSQIP). NSQIP studies use observed to expected (O/E) ratios for morbidity and mortality for quality improvement. In the Patient Safety in Surgery Study (PSS) methodology of the NSQIP study was applied successfully to private sector hospitals 16. Hutter and Johnson demonstrated incidence of postopera- tive morbidity lower in VA hospitals after vascular operations both in men and women
8, 15.
A successful introduction of a clinical pathway is shown in 4 studies 13, 22, 23, 25. Significant reduction in costs could be demonstrated in all studies mainly based on reduced length
Table 1. Main issues and outcomes of studies included. All articles were subscribed into process, outcome and structure.
Main issue N Main outcome Reference
Process
Carotid endarterectomy
Restricting working hours
Introduction vascular registry Cardiac risk assessment
1417
1546
6143 630
Routine shunting is cost saving, selective angiography accepted, routine monitoring 60%
decrease in operative risk
Restricting work hours did not compromise surgical quality
Improved preoperative medication usage Resulted in decreasing perioperative myocardial infarction
13, 18, 19
16, 17
15 14
Structure
Introduction and use of NSQIP
Patient safety in surgery Vascular access study Introduction of clinical pathways
Mortality scoring system
Introduction of audit on CEA
Development of predictive model regarding adverse events Centralization in treatment of ruptured abdominal aortic aneurysm
13725
38225 172 458
1368
333
25594
626
A significant reduction in postoperative adverse events and selective use of regional anesthetic reduced postoperative morbidity
Lower incidence of morbidity in vascular patients Conducting audit led to improvement in outcomes Resulted in decrease of hospital stay and costs
Causes of death could usually be identified without autopsy, autopsy essential for registration complications
Reduction of in-hospital stay and improvement in indication of operation
Resulted in accurate prediction scores
Positive effect on survival
11, 22
7, 23, 24 26, 35, 38 25, 32, 33, 34
27, 36
32, 37
30, 31
28
Outcome
Endovascular aneurysm repair
Outcomes of CEA
Diabetes as risk factor Infrainguinal bypass surgery
Abdominal aortic risk surgery
Vascular trauma Vascular surgical audit
Graft infection
7929
27338
17300 18647
8022
549 6842
1066
Acceptable morbidity and mortality after EVAR in patients with appropriate size of aneurysm, specific anatomic features predict clinical difficulties Low mortality comparable to international benchmarks, except for 1 study. Prospective outcome assessment essential to reconcile operation indications and outcome improvement Increased morbidity, mortality increased in 1 study Major postoperative events are serious in claudicants and a limited life expectancy should be taken into account
Mortality increased in the presence of commonly known risk factors
In older patients iatrogenic trauma plays a major role More patients were operated for critical ischemia instead of ischemia after the audit
MRSA most common culture in complex graft infections, prosthetic infection after CEA is rare
20, 45-47, 53, 56, 57
41, 44, 48, 49, 51, 52, 54, 58, 59, 62, 63
39, 40, 66 21, 50, 55
42, 65, 71
64 43
60, 61
NSQIP=national surgical quality improvement program data; EVAR= endovascular aneurysm repair;
CEA=carotid endarterectomy; MRSA= methicillin-resistant staphylococcus aureus
Table 2. Structure as indicator of quality of care.
Author Subject Year
of publication
Number of procedures
Main outcome
Choi Introduction of clinical pathways in infrainguinal reconstruction
2000 399 Length of stay decreased from 14.3 to 9.2 days
Freeman A prospective audit of surgery carried out to establish and maintain dialysis access
2008 172 Conducting an audit of surgical practice contributed to an improvement in outcomes for dialysis-dependant patients Johnson Comparison of morbidity
and mortality in vascular hospitals and university hospitals of vascular operations in women
2007 3993 Women in private sector
hospitals had higher incidence of comorbidities. vascular patients
Hutter Comparison of morbidity and mortality in vascular hospitals and university hospitals of vascular operations in men
2007 35233 Lower incidence of postoperative morbidity in vascular patients
Khuri Patient Safety in Surgery Study, comparison of morbidity and mortality postoperative between vascular hospitals and private sector
2007 39225 Successful implementation of National surgical Quality Improvement Program methodology
Klinkert Implementation of a mortality scoring system
2004 1022 Causes of death and the
shortcomings in medical care could usually be identified without the help of autopsy data
Laukontaus Centralization in treatment of ruptured abdominal aortic aneurysm
2007 626 Centralization of emergency
vascular services with availability of closed-unit postoperative critical care to achieve better results as these measures were associated with a positive impact on survival McCollum Introduction of vascular
database
1990 ND Improvement of communication
with general practitioner Neumayer Development of a predictive
model of surgical site infection
2007 25424 Development of an accurate prediction score for surgical site infection
Pomposelli SCOUT score: A new method to evaluate quality of care in vascular surgery
1997 170 The SCOUT score allows the surgeon to identify problem areas that can then be targeted for improvement to positively affect outcome.
Rowell Use of NSQIP Data as a Catalyst for Quality Improvement
2007 103 A siginificant reduction in postoperative adverse events
of stay and recommendations for change in treatment could be made. The introduc- tion of a vascular access quality program improved vascular access care, furthermore the authors state that it is of vital essence to have a standardized database system to collect prospective data 26. Introduction of a mortality scoring system led to a detailed insight and forms a base for further quality improvement 17, 27. A prospective audit was undertaken in three studies 14, 28, 29.
Author Subject Year
of publication
Number of procedures
Main outcome
Sandison Cost-effective CEA 2000 333 In-hospital stay has been reduced and the routine use of intensive care replaced by a 2-h stay in theatre recovery.
Schneider Introduction of a critical pathway for carotid endarterectomy
1997 ND CP resulted in a 0.5-day decrease in hospital stay overall
Stoner Use of NSQIP to identify high-risk patients and improve results
2006 13622 Use of regional anesthetic significantly reduced perioperative complications
Sweeney A review of the use of previously described integrated care pathways
2002 59 The use of care pathways leads to reduction in costs and hospital stay
Van Loon Implementation of a vascular access quality programme
2007 2300 A vascular access QIP resulted in placement of more autogenous AVFs, increased number of PTAs and surgical interventions
Vrancken Peeters
Introduction of a mortality- scoring system in patients undergoing abdominal aortic surgery
1999 346 Autopsy reports are essential for accurately estimating complication rates
Wong The influence of a prospective audit and educational campaign on the performance of CEA
1999 184 Prospective surveillance of CEA reduced the number of inappropriate operations
Young Hemodialysis vascular access preferences and outcomes in the DOPPS
2002 ND No evidence was found that graft outcomes are superior in facilities that prefer grafts to fistulae ND=not described; SCOUT=Surgical complication outcome; NSQIP=national surgical quality improvement program; CEA=carotid endarterectomy; AVF=arterio venous fistula; PTA=percutaneous transluminal angioplasty.
CEA=carotid endarterectomy; DOPPS=dialysis outcomes and practice patterns study; ND=not described.
Process
Table 3 shows details of all 7 reports concerning process 32-38. Process as indicator of quality of care is least described with only 7 studies included. Remarkably in this group, 4 studies were conducted in order to show that adjustment of daily practice did not compromise quality of care, mainly in teaching hospitals 32, 36, 37, 39. A 60% decrease in operative risk could be achieved by introducing a program of perioperative monitoring for patients undergoing carotid surgery 38.
Table 3. Process as indicator of quality of care.
Author Subject Year
of publication
Number of procedures
Main outcome
Bastounis Routine use of shunting in CEA
2001 423 The routine use of shunting resulted in cost saving
Cronenwett Introduction of regional registry for vascular procedures
2007 6143 Improved preoperative medication usage
Bunt The role of a defined protocol for cardiac risk assessment in decreasing perioperative myocardial infarction
1992 630 Preoperative cardiac assessment combined with aggressive perioperative management could indeed reduce perioperative myocardial infarction rates Evans Effect of reducing working
hours on the outcome following AAA repair
1999 1136 Supervised trainees can perform an increasing proportion of AAA surgery without increasing operative mortality
Kaafarani Impact of restricting surgical resident work hours on postoperative outcomes
2005 410 Restricted resident work hour schedule did not significantly affect postoperative outcomes
Loftus To evaluate a policy of adopting routine duplex instead of angiography in CEA
1998 494 A policy of selective angiography does not compromise patient safety or operability
Naylor Reducing the risk of carotid surgery: A 7-year audit of the role of monitoring and quality control assessment
2000 500 A program of monitoring and
quality control assessment has been associated with a 60% decrease in the operative risk in comparison with that observed before implementation of the protocol CEA=carotid endarterectomy
Outcome
The majority of studies in this review concern outcome as indicator of quality of care:
31 out of 57 30, 31, 40-67; details are described in Table 4. These 31 studies describe different subjects from different perspectives. Main issues are EVAR, carotid endarterectomy and peripheral arterial bypass surgery. Not surprising is EVAR as a relatively new technique in this era a frequently described subject in 7 studies 30, 46-48, 54, 57, 58. These studies showed that short term results were reported as from good to excellent in high-risk patients in different studies Carotid endarterectomy in 11 studies reflects the more recent change in approach of patients with carotid artery stenosis 42, 45, 49, 50, 52, 53, 55, 59, 60, 63. Carotid endar- terectomy was performed at acceptable rates of postoperative morbidity and mortality.
Diabetes as a perioperative risk factor in 3 studies 40, 41, 67 and lower extremity revascular- ization in 3 studies 31, 51, 56, abdominal aortic aneurysm repair in 3 studies 35, 43, 66. Outcome as clinical indicator mainly focused on identifying risk factors for morbidity, mortality or failure of treatment based on reported numbers for morbidity and/or mortality.
Table 4. Outcome as indicator of quality of care (1.3).
Author Subject Year
of publication
Number of procedures
Main outcome
AhChong DM and the outcome of infrainguinal bypass for CLI
2004 265 DM adversely affects hospital mortality and long-term survival. Graft patency and limb salvage are not compromised by the presence of DM
Axelrod Perioperative cardiovascular risk stratification of patients with diabetes who undergo elective major vascular surgery
2002 16035 After controlling for specific comorbid conditions, the only independent association was between patients with insulin treatment and the risk of cardiovascular complications
Axelrod Risk for stroke after elective non-carotid vascular surgery
2004 19475 Stroke after non-carotid peripheral vascular surgery is uncommon, but results in markedly increased mortality and length of stay. Stroke risk is most strongly associated with previous stroke history and greater degree of illness.
Bayly In-hospital mortality from abdominal aortic surgery in Great Britain and Ireland
2001 933 Mortality rate increased considerably when commonly encountered risk factors were present.
Bergqvist Vascular surgical audit during a 5-year period
1994 6842 Decision making among vascular surgeons in Sweden appears to have improved as proportionally fewer patients are operated on for acute ischaemia, more for critical ischaemia with possibly an improved outcome.
Author Subject Year of publication
Number of procedures
Main outcome
Bond Clinical and radiographic risk factors for operative stroke and death in the European Carotid Surgery Trial
2002 1729 Several baseline patient characteristics predict surgical risk and it may be possible to use these characteristics to aid patient selection and surgical audit.
Boult Australian audit for the endoluminal repair of abdominal aortic aneurysm: The first 12 months
2002 830 Good compliance has been obtained from vascular surgeons for submission of the operative data sets.
Boult Endoluminal repair of abdominal aortic aneurysm - Contemporary Australian experience
2004 950 Mortality rates are low, given the elderly population in question and morbidity rates acceptable
Boult Predictors of success following endovascular aneurysm repair: Mid- term results
2006 961 Predictors of clinical failure or need for re-intervention include large aneurysm size, neck angulation 45 degrees and short infrarenal neck
Burns South Australian CEA study
1991 239 CEA did not diminish the expected stroke and death incidence after one year
Bush Performance of endovascular aortic aneurysm repair in high- risk patients: Results from the Veterans Affairs National
Surgical Quality Improvement Program
2007 2368 In veterans deemed high-risk for surgical therapy, outcomes after elective EVAR are excellent, and the procedure is relatively safe in this special patient population
Davies CEA under cervical plexus block - A prospective clinical audit
1990 128 CEA under superficial and deep cervical plexus blocks was associated with a high patient acceptance, low neurological complication rate and an acceptable rate of cardiovascular AEs Dawson Vascular morbidity
and mortality during long-term follow-up in claudicants selected for peripheral bypass surgery
1998 155 Major vascular AEs and additional interventions are common and serious in claudicants.
Debing Does the type, number or combinations of traditional cardiovascular risk factors affect early outcome after CEA?
2006 1002 Traditional cardiovascular risk factors significantly affect the 30-day stroke and death rate after CEA
Author Subject Year of publication
Number of procedures
Main outcome
Evans The influence of gender on outcome after ruptured abdominal aortic aneurysm
2000 692 Gender has no influence on either short- term or long-term outcome for patients undergoing operative repair of RAAA
Frawley Risk factors for peri- operative stroke complicating CEA Selective analysis of a prospective audit of 1000 consecutive operations
2000 1000 Prospective audit is a useful tool for identifying causes of peri-operative stroke and indicating the need for modifications to surgical clinical management which might improve outcomes for CEA
Golledge The outcome of endovascular repair of small abdominal aortic aneurysms
2007 478 At present, widespread treatment of small AAAs by EVAR would appear inappropriate
Hertzer Early outcome assessment for 2228 consecutive CEA procedures:
The cleveland clinic experience from 1989 to 1995
1997 2228 Prospective outcome assessment is essential to reconcile the indications for CEA with its actual results, and it may lead incidentally to important observations concerning patient care
Holdsworth Results and resource implications of treating end-stage limb ischaemia
1997 275 An acceptable limb-salvage rate can be achieved although there is a high initial mortality. In view of the poor overall survival any benefits for these patients should be viewed as relatively short- term objectives
Hua Early outcomes of endovascular versus open AAA repair in the NSQIP-PS
2005 1042 Significant morbidity accompanies AAA repair, even at major academic medical centers. These data strongly endorse EVAR as the preferred approach in the presence of significant cardiopulmonary or renal comorbidities, or poor preoperative functional status Johnson Propensity score
analysis in observational studies: outcomes after abdominal aortic aneurysm repair
2006 3091 Patients who underwent elective EVAR had substantially lower perioperative mortality and morbidity rates compared with patients having open repair
McCollum CEA in the U.K. and Ireland: Audit of 30-day outcome
1997 709 Members of the vascular society of U.K.
and Ireland have a very low morbidity/
mortality rate for performing carotid surgery
Author Subject Year of publication
Number of procedures
Main outcome
Middleton Outcomes of CEA: How does the Australian state of New South Wales compare with international benchmarks?
2002 689 30-day outcomes comparable with international benchmarks
Naylor A prospective audit of complex wound and graft infections in
2001 75 WI, 55 GI MRSA was the commonest single organism cultured in patients with complex wound and graft infections after vascular surgery.
Naylor U.K. and Ireland: The emergence of MRSA Prosthetic patch infection after CEA
2002 936 Prosthetic patch infection after CEA is rare. This study emphasises the importance of close surveillance of early wound AEs
O’Hare Impact of renal insufficiency on short-term morbidity and mortality after LEAR: Data from the Department of Veterans Affairs’ NSQIP
2003 18217 Efforts to improve pre-and post- operative care in patients with renal insufficiency undergoing LEAR should take into account the increased incidence of postoperative death and cardiopulmonary AEs in this group in addition to more traditional concerns about operative site AEs
Oliver A regional collaborative audit of the practice and outcome of CEA in the U.K.
2000 139 In the study area CEA was performed predominantly on high-risk patients with low subsequent surgical mortality.
Taylor The pitfalls of establishing a statewide vascular registry:
The South Carolina experience
1997 652 Excellent outcomes after carotid endarterectomy are not limited to a few select centers and can be accomplished by adequately trained surgeons in a variety of institutional settings.
Thomson Vascular trauma in New Zealand: An 11-year review of NZVASC, the New Zealand Society of Vascular Surgeons’ audit database
2004 549 While programmes to slow down and sober up road users help reduce injuries in the younger age groups, it lies in the hands of our own profession to reduce the iatrogenic injuries in the older patients
Vemuri Effect of increasing patient age on complication rates following intact AAA repair in the USA
1994 6397 Quality improvement efforts must focus on minimizing complication rates in elderly patients undergoing common vascular surgical procedures including AAA repair
DISCUSSION
The need for hospitals and surgeons to present the quality of care that they provide is now stronger than ever as is requested by patients, but also by other health care provid- ers and payers in public and private sectors. Effective measurement of quality of care is of high importance, but before improvement of quality of care can be achieved, one first has to decide how to measure quality of care. Indicators for performance and outcome measurement allow the quality of care and services to be measured, they provide a quantative basis for clinicians, organizations and planners aiming to achieve improve- ment in care and the process by which patient care is provided 68. A natural starting place would be the Donabedian paradigm of structure, process and outcomes in order to assess quality of care 4, 5.
Vascular surgery differs from general surgery for a number of reasons. First of all, pa- tients have more comorbid illnesses and are at higher risk for development of adverse events. Furthermore a range of therapeutic options is available; open vs. endovascular vs.
conservative treatment. The continuous search for improving quality of care combined with these specific features of vascular surgery, make it of special interest to investigate which quality initiatives have been deployed so far and the amount of success and recommendations for the future to be made.
Structure as indicator of quality of care in vascular surgery
Structure represents the system in which care for the patient is delivered such as the physical resources of the hospital, but as well staff expertise and organization. Because of the complexity of vascular patients it seems appealing to introduce structural mea- sures to influence care of the vascular patient because of the multidisciplinary nature of
Author Subject Year
of publication
Number of procedures
Main outcome
Virkkunen Diabetes as an independent risk factor for early postoperative AEs in CLI
2004 5709 Diabetes was not an independent risk factor for early postoperative mortality in CLI as there was an increased morbidity in diabetics associated with old age, male gender, known coronary artery disease, and renal insufficiency, as well as urgent surgery
DM=diabetes mellitus; CLI=critical limb ischaemia; CEA=carotid endarterectomy; EVAR=endovascular aneurysm repair; AE=adverse events; RAAA= renal abdominal aortic aneurysm; AAA=abdominal aortic aneurysm; NSQIP-PS=National Surgical Quality Improvement Program-Private Sector; WI=wound infection; GI=graft infection; MRSA= methicillin-resistant staphylococcus aureus
the care process around the vascular patient. The introduction of a clinical pathway is a successful example of a structural measure 13, 22, 23, 25.
However most structural measures can only be assessed in observational studies, such as the vascular access studies 14, 26 and this is a potential disadvantage. Furthermore out- come of structural measures reflects the result of variables and not for a single variable.
Therefore, it is difficult to point out the origin of improvement after structural measures have been implemented and to evaluate structure as indicator of quality of care the introduction of a clinical database is required. In this study only one study was included concerning volume, showing that centralization of emergency vascular services led to a positive impact on survival 18.
Over the past years more studies have been undertaken to show a favourable effect of high hospital or surgeon volume but are criticized for not using prospective collected administrative data as a base for evidence 69.
In several hospitals postoperative adverse events were significantly reduced, by using the NSQIP database as a catalyst for quality improvement11. In this review all studies us- ing structural measures to improve quality of care demonstrated a favourable result, but not always a statistically significant effect. This shows the difficulty of using structural measures to improve quality of care because the exact focus of structural measures is difficult to point out.
Process as indicator of quality of care in vascular surgery
Process of care measures are appealing to use because they represent the care that patients actually receive, for example the routine use of shunting in carotid endarterec- tomy. Secondly process measures are more immediately actionable than outcome mea- sures, as is demonstrated by Cronenwett et al. who focused on process improvement (e.g. the optimal preoperative medication use) while waiting for risk-adjusted analysis of major AEs 12, 34, furthermore process measures can be applied by all hospitals unlike some structural indicators such as hospital volume. Many processes of care are strongly associated with improved patient outcomes. It is suggested that process measures may be better applied in general medicine than in surgery because process is easier to define in general medicine and cardiology patients 69.
For vascular surgery only few authors have described processes of care, and surgical process measures are in short supply as stated by Birkmeyer 12. Process measures are perhaps right applicable to vascular patients because of the category of patients who are high-risk patients with more concomitant diseases. In this category of patients proper treatment of these diseases, such as diabetes and secondary prevention of cardiovas- cular diseases are of utmost importance. This strongly suggests room for improvement in the care for these patients and strengthens the potential of process measures on
improving quality of care. The Vascular Study Group of Northern New England showed a successful implementation of process measures in daily practice in different hospitals 34. Although not many studies have been performed using process measures as a tool for improving quality of care in vascular patients, the results published so far are promising.
Outcome as indicator of quality of care in vascular surgery
Outcome as clinical indicator was most commonly used in the past decades and al- ready is demonstrated for general surgery that registration of complications provides detailed insight in postoperative adverse events and care delivered to the patient 5, 9. Furthermore type of procedure performed is directly related to morbidity, mortality and excess hospital days 70. For cardiac surgery measurement of direct outcomes has led to improvement in surgical outcomes and this has formed the base for the start of all NSQIP studies focused on general and vascular surgery 5.
Outcome as indicator of quality of care is particular appealing for surgical procedures since it represents the bottom line of surgery, as stated earlier. A disadvantage could include sample size. Sample sizes are frequently too small in individual hospitals, for example zero mortality in a small hospital does not represent perfect care 69, 71.
Outcomes analysis is important for hospital credentialing and surgeon selection, but is critical for quality improvement, especially if it allows regional benchmarking and comparing processes of care that define best practice as is shown by reports concern- ing outcome assessment of carotid endarterectomy 53, 55. However patient selection, decision making, and processes of care could have an important impact on clinical outcomes 34. Outcomes are a function of patient characteristics (risk factors), type of surgery performed, quality (surgeon and hospital factors) and chance (random varia- tion) 69. Furthermore, one of the key issues of reporting on outcomes is to identify risk factors which could lead to improvement in quality of care. Main patient related risk fac- tors are diabetes and renal insufficiency in vascular patients and this could be a starting point for improvement of quality of care. Identification of risk factors of clinical failure of endovascular aortic aneurysm repair or for stroke or death in the ESCT trial form an example of the use of an outcome measure to improve quality of care 45, 48.
Limitations of the study
Only prospective studies were included, because of the essence of a prospectively kept complication registration system, as we previously have demonstrated7. Furthermore we excluded all other languages than English to provide clear inclusion criteria. To provide a clear insight in studies published concerning improvement in quality of care for vascular surgery prospectively kept studies were divided into structural, outcome
or process measures, but there is considerable overlap between these three measures.
For example Cronenwett introduced a regional cooperative data registry for Vascular Procedures in Northern New England and focused mainly on optimizing preoperative medication usage and succeeded, this study was marked as focused on process. On the other hand; Freeman carried out a prospective audit of surgery for vascular access which improved outcomes for dialysis dependent patients; this study was marked as focused on structure. All NSQIP studies were subscribed to structural measures because of the NSQIP system which was introduced into all participating hospitals, while NSQIP studies mainly focused on outcome measurement.
More important it is to acknowledge the direct link between structural, outcome and process measures. In order to improve quality of care using process measures, one first has to evaluate outcomes in order to define what improvements can be made and which process measures should be developed. After the introduction of a process measure, outcome evaluation is essential to demonstrate a potential favourable effect.
CONCLUSION
In this study, we evaluated studies assessing quality of care in vascular surgery. Out- come as an indicator of quality of care is described predominantly whereas structure and process indicators are evaluated scarcely in vascular surgery. In our opinion process, structure and outcome measures are interwoven and can not be seen separately. Many studies in vascular surgery have been focused on outcomes as indicator of quality of care, but a shift towards process measures should be considered as focus of attention in the future. This study provides a detailed insight in which studies have been undertaken and on which grounds recommendations are made to improve quality of care.
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Appendix 1. The Medline search strategy.
(“cardiovascular surgical procedures/adverse effects”[Majr] OR “cardiovascular surgical procedures/
mortality”[Majr] OR ((Cardiovascular[ti] OR vascular[ti]) AND (surgery[ti] OR surgical[ti]))) AND (“Medical audit”[Mesh] OR audit[tiab] OR “Risk adjustment”[Mesh] OR “risk adjustment”[tiab] OR “risk-adjusted”[tiab] OR
“Quality of Health Care/methods”[Majr:noexp] OR “Quality of Health Care/standards”[Majr:noexp] OR “Quality of Health Care/statistics and numerical data”[Majr:noexp] OR “Outcome Assessment (Health Care)/methods”[Majr]
OR “Outcome Assessment (Health Care)/statistics and numerical data”[Mesh] OR “Outcome Assessment (Health Care)/standards”[Majr] OR “outcome assessment”[tiab] OR “Quality Indicators, Health Care”[Majr] OR “health care quality indicators”[tiab] OR (“Quality”[ti] AND (“improvement”[ti] OR “improving”[ti])) OR “databases, factual”[Mesh])
Appendix 2. The Embase search strategy.
(*health care quality/ OR health care quality.ti,ab OR Medical Audit/ OR audit.ti,ab OR exp *risk assessment/
or risk adjustment.ti,ab OR *outcome assessment/ OR outcome assessment.ti,ab OR treatment failure.ti,ab OR
*Treatment failure/ OR *Total Quality Management/ OR quality management.ti,ab or quality improvement.ti,ab OR factual database/ OR factual database.ti,ab) AND ((exp *Cardiovascular Surgery/ AND (exp *Complication/
OR complication*.ti,ab or mortality.ti,ab)) OR ((heart.ti,ab OR cardiac.ti,ab OR vascular.ti,ab OR cardiovascular.
ti,ab) AND ((exp *Surgery/ ) OR surgery.ti,ab OR surgical.ti,ab) AND (exp *Complication/ OR complication*.ti,ab or mortality.ti,ab)))
