Meta-analysis and systematic review of the relationship between surgeon annual caseload and mortality for elective open abdominal aortic aneurysm repairs

Reproducibility of ultrasound measurement of the abdominal aorta

BACKGROUND

Abdominal aortic aneurysm (AAA) screening and surveillance programmes use ultrasound imaging to measure the anteroposterior (AP) diameter of the infrarenal aorta. The aim of this study was to examine potential observer bias and variability in ultrasound measurements.

METHODS

Studies were identified for review via a MEDLINE database search (1966-2009). References supplied in accessed papers were also checked for potential relevance. Consistent search terminology, and inclusion and exclusion criteria were used to ensure quality of data. Nine papers were available to review.

RESULTS

Variation in intraobserver repeatability and interobserver reproducibility was identified. Six studies reported intraobserver repeatability coefficients for AP aortic diameter measurements of 1·6-4·4 mm. These were below the 5-mm level regarded as acceptable by the UK and USA AAA screening programmes. Five studies had interobserver reproducibility below the level of 5 mm. Four studies, however, reported poor reproducibility (range from -2 to +5·2 to -10·5 to +10·4); these differences may have had a significant clinical impact on screening and surveillance.

CONCLUSION

The studies used different methodologies with no standardized measurement techniques. Measurements were taken by observers from different medical disciplines of varying grade and levels of training. Standard training and formal quality assurance of ultrasound measurements are important components of an effective AAA screening programme.

Surgeon case volume, not institution case volume, is the primary determinant of in-hospital mortality after elective open abdominal aortic aneurysm repair

OBJECTIVE

Studies analyzing the effects of volume on outcomes after abdominal aortic aneurysm (AAA) repair have primarily centered on institutional volume and not on individual surgeon volume. We sought to determine the relative effects of both surgeon and institution volume on mortality after open and endovascular aneurysm repair (EVAR) for intact AAAs.

METHODS

The Nationwide Inpatient Sample (2003-2007) was queried to identify all patients undergoing open repair and EVAR for nonruptured AAAs. To calculate surgeon and institution volume, 11 participating states that record a unique physician identifier for each procedure were included. Surgeon and institution volume were defined as low (first quintile), medium (second, third, or fourth quintile), and high (fifth quintile). Stratification by institution volume and then by surgeon volume was performed to analyze the primary endpoint: in-hospital mortality. Multivariable models were used to evaluate the association of institution and surgeon volume with mortality for open repair and EVAR, controlling for potential confounders.

RESULTS

During the study period, 5972 open repairs and 8121 EVARs were performed. For open AAA repair, a significant mortality reduction was associated with both annual institution volume (low <7, medium 7-30, and high >30) and surgeon volume (low ≤ 2, medium 3-9, and high >9). High surgeon volume conferred a greater mortality reduction than did high institution volume. When low and medium volume institutions were stratified by surgeon volume, mortality after open AAA repair was inversely proportional to surgeon volume (8.7%, 3.6%, and 0%; P < .0001, for low, medium, and high-volume surgeons at low-volume institutions; and 6.7%, 4.8%, and 3.3%; P = .02, for low, medium, and high-volume surgeons at medium-volume institutions). High-volume institutions stratified by surgeon volume demonstrated the same trend (5.1%, 3.4%, and 2.8%), but this finding was not statistically significant (P = .57). Multivariable analysis was confirmatory: low surgeon volume independently predicted mortality (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.3-3.1; P < .001); low institution volume did not (P = .1). For EVAR, neither institution volume nor surgeon volume influenced mortality (univariate or multivariable).

CONCLUSION

The primary factor driving the mortality reduction associated with case volume after open AAA repair is surgeon volume, not institution volume. Regionalization of AAAs should focus on open repair, as EVAR outcomes are equivalent across volume levels. Payers may need to re-evaluate strategies that encourage open AAA repair at high-volume institutions if specific surgeon volume is not considered.

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.

Centralization harnessing volume-outcome relationships in vascular surgery and aortic aneurysm care should not focus solely on threshold operative caseload

There has been great interest in the setting of threshold operative volumes for safety to guide centralisation of vascular surgical services by healthcare commissioners. This editorial examines the evidence for designing services around a numeric safety threshold in the relationship between volume and outcome in vascular surgery. Thresholds should be aimed at the best outcomes and equity of care. Equity means access to the most up-to-date technology and all the relevant support services for elective and emergency cases. The relationship of volume and outcome with quality is complex, and demands a shift in focus to infrastructural and procedural improvements that drive high-quality services rather than the concentration of planning exclusively around an operative volume threshold.

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.

Propensity scored analysis of outcomes after ruptured abdominal aortic aneurysm

Background

This study examined the population outcome of ruptured abdominal aortic aneurysm (rAAA) in England, the role of endovascular repair (EVAR), and the relationship between outcome and hospital workload.

Methods

Data were retrieved from Hospital Episode Statistics between 1 April 2003 and 31 March 2008. Propensity scoring was used to compare the outcomes of stratified patients undergoing EVAR and open repair. The relationship between workload and outcome was determined.

Results

Some 3725 urgent and 4414 rAAA repairs were included. Mortality rates were 21·3 per cent for urgent repair and 46·3 per cent for rAAA repair. EVAR was employed for 16·3 and 7·6 per cent of urgent and rAAA repairs respectively. EVAR was associated with significantly reduced mortality for urgent repair (odds ratio (OR) 0·531, 95 per cent confidence interval 0·415 to 0·680; P &lt; 0·001) and rAAA repair (OR 0·527, 0·416 to 0·668; P &lt; 0·001). A propensity scored analysis confirmed the benefit of EVAR for rAAA repair (P &lt; 0·001). Repair of rAAA at hospitals with a higher elective aneurysm workload was associated with lower mortality rates irrespective of the mode of treatment (P &lt; 0·001). Higher-volume hospitals were more likely to operate on rAAA (P = 0·033).

Conclusion

EVAR offered a survival advantage over open repair for non-elective aneurysm procedures. Services for the treatment of rAAA should incorporate access to EVAR and would benefit from being based in units with a high elective caseload.

Surgical options for ulnar nerve entrapment: an example of individualized decision analysis

The decision-making process in the diagnosis and treatment of an ulnar nerve entrapment (UNE) at the elbow is presented from the viewpoint of the patient and from that of a physician who in this case, were the same individual. The problems of diagnosis and the selection of the appropriate therapy-conservative or surgical and the choice of a particular surgical approach are discussed in the light of recent evidence-based medicine (EMB) literature.

Initiation of a pediatric mock code program at a children's hospital

BACKGROUND

Pediatric cardiopulmonary arrests are rare. Mock codes were instituted to bridge the gap between opportunity and reality.

AIM

The goal was to improve medical caregivers' skills in pediatric resuscitation.

METHODS

All pediatric and internal medicine/pediatric (med/peds) residents were anonymously surveyed pre- and post-intervention about confidence level about codes and code skills. Twenty mock codes were conducted during the 1 year intervention period. Statistical comparisons were made between each resident pre- and post-survey, graduating third-year residents (PGY3s) prior to intervention versus PGY3s with mock codes and pediatric versus med/peds residents.

RESULTS

All residents significantly improved in their perception of overall skill level during the study (p < 0.0001). PGY3s were significantly more confident in their skills than PGY2s or PGY1s and PGY2s were significantly more confident than PGY1s both pre- and post-mock codes (p < 0.0001). Med/peds residents were significantly more confident in their skills than pediatric residents both pre- (p = 0.041) and post-intervention (p = 0.016). The two skills with the lowest score post-intervention were the ability to place an interosseous line and the ability to manage cardiac dysrhythmias.

CONCLUSIONS

Pediatric mock codes can improve resident confidence and self-assessment of their resuscitation skills. Data from surveys such as this can be used to design future skill-based educational initiatives.

The impact of surgeon specialization on patient mortality: examination of a continuous Herfindahl-Hirschman index

OBJECTIVE

To examine the effect of surgeon specialization on patient outcomes, controlling for volume.

BACKGROUND

There is great interest in the degree to which surgical specialization affects outcomes, particularly considering drives to measure and reward quality in healthcare. Although surgical specialization has been previously analyzed with respect to outcomes, most studies have treated it as a dichotomous variable based on academic credentials. We treat it here as a continuous variable defined quantitatively by procedural diversity.

METHODS

We used 2002 to 2005 patient data from the National Surgical Quality Improvement Program for the Department of Surgery, Barnes Jewish Hospital, St. Louis, Missouri. To quantitate procedural specialization, Herfindahl-Hirschman indices for surgeons were calculated using billing codes. These indices were calculated according to 3 different levels of procedural aggregation. Using conditional logit models, we examined the relationship between these indices and 30-day postoperative mortality rates.

RESULTS

Surgeon specialization was inversely related to mortality rates after adjusting for case volume when indices were calculated using medium procedural aggregation (odds ratio for mortality = 0.580 per 0.1 unit Herfindahl increase; P = 0.025) or low aggregation (odds ratio for mortality = 0.510 per 0.1 unit Herfindahl increase; P = 0.015). No relationship was observed at the high level of aggregation.

CONCLUSIONS

The procedural concentration component of surgical specialization is correlated with improved mortality rates independently of case volume. However, how broadly or narrowly "specialization" is defined has an impact on this relationship.

Surgeon volume impacts hospital mortality for pancreatic resection

OBJECTIVE

Improved outcomes after pancreatic resection (PR) by high volume (HV) surgeons have been reported in single center studies, which may be confounded with potential selection and referral bias. We attempted to determine if improved outcomes by HV surgeons are reproducible when patient demographic factors are controlled at the population level.

METHODS

Using the Nationwide Inpatient Sample, discharge records with surgeon identifiers for all nontrauma PR (n = 3581) were examined from 1998 to 2005. Surgeons were divided into 2 groups: (HV; > or = 5 operations/year) or low volume (LV; <5 operations/year). We created a logistic regression model to examine the relationship between surgeon type and operative mortality while accounting for patient and hospital factors. To further eliminate differences in cohorts and determine the true effect of surgeon volume on mortality, case-control groups based on patient demographics were created using propensity scores.

RESULTS

One hundred thirty-four HV and 1450 LV surgeons performed 3581 PR in 742 hospitals across 12 states that reported surgeon identifier information over the 8-year period. Patients who underwent PR by HV surgeons were more likely to be male, white raced, and a resident of a high-income zip code (P < 0.05). Significant independent factors for in-hospital mortality after PR included increasing age, male gender, Medicaid insurance, and surgery by HV surgeon. HV surgeons had a lower adjusted mortality compared with LV surgeons (2.4% vs. 6.4%; P < 0.0001).

CONCLUSIONS

After controlling for patient demographics and factors, pancreatic resection by a HV surgeon in this case-controlled cohort was independently associated with a 51% reduction in in-hospital mortality.

Improving quality of care by system change

Change based on evidence

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.