Vascular surgery training trends from 2001-2007: A substantial increase in total procedure volume is driven by escalating endovascular procedure volume and stable open procedure volume
Article Outline
Background
Endovascular procedure volume has increased rapidly, and endovascular procedures have become the initial treatment option for many vascular diseases. Consequently, training in endovascular procedures has become an essential component of vascular surgery training. We hypothesized that, due to this paradigm shift, open surgical case volume may have declined, thereby jeopardizing training and technical skill acquisition in open procedures.
Methods
Vascular surgery trainees are required to log both open and endovascular procedures with the Accreditation Council for Graduate Medical Education (ACGME). We analyzed the ACGME database (2001-2007), which records all cases (by Current Procedural Terminology [CPT] code) performed by graduating vascular trainees. Case volume was evaluated according to the mean number of cases performed per graduating trainee.
Results
The mean number of total major vascular procedures performed per trainee increased by 174% between 2001 and 2007 (from 298.3 to 519.2). Endovascular diagnostic and therapeutic procedures increased by 422% (from 63.7 to 269.1) and accounted for 93.0% of the increase in total procedures. The number of open aortic procedures (aneurysm, occlusive, mesenteric, renal) decreased by 17.1% (from 49.7 to 41.2), while the number of endovascular aortic aneurysm repair procedures increased by 298.8% (from 16.9 to 50.5). Specifically, open aortic aneurysm procedures decreased by 21.8%, aortobifemoral bypass increased by 3.2%, and open mesenteric or renal procedures decreased by 13%. Infrainguinal bypass procedures remained relatively constant (from 37.6 to 36.5, 2.9% decrease), and the number of carotid endarterectomy procedures performed did not change significantly (from 43.6 to 42.2, 3.2% decrease).
Conclusion
Vascular surgery trainees are performing a vastly increased total number of procedures. This increase in total procedure volume is almost entirely attributable to the recent increase in endovascular procedures. Aside from a small decline in open aortic procedures, the volume of open surgical procedures has largely remained stable. It is essential that vascular surgery training programs continue to focus on both endovascular and open surgical skills in order for vascular surgeons to remain the premier specialists to care for patients with vascular disease.
Endovascular techniques have dramatically transformed the field of vascular surgery. As an example, since the introduction of endovascular aortic aneurysm repair (EVAR) in 1991 by Parodi,1 and the United States Food and Drug Administration approval of the first EVAR devices in 1999, this less invasive technique has rapidly taken a firm hold. Recent national analyses of conventional open repair and EVAR for abdominal aortic aneurysms (AAA) revealed that prior to 2000, 99% of AAA repairs were performed with an open technique. By 2004, this proportion had steadily decreased to 48%; conversely, the percentage of patients undergoing AAA repair with EVAR had increased to 52%.2, 3
During the last decade, most literature relating to vascular surgery training has focused on methods to ensure that vascular surgery trainees (VST) are properly trained in this relatively new endovascular skill set.4, 5, 6 In contrast, few authors have addressed the continued importance of VST education in conventional open vascular techniques.7, 8, 9, 10, 11 Furthermore, most studies of reduced open surgical volume have focused on the effect on general surgery trainees7, 8, 9 rather than VSTs.10, 11 Program directors must remain mindful of the specific trends in the proportion of open vs endovascular procedures performed by their trainees, as a substantial number of studies across many surgical disciplines have shown that case volume (albeit when analyzing attending physicians) directly impacts morbidity and mortality.12, 13
We undertook this study to examine the trends in the proportion of open and endovascular procedures performed by VSTs in the United States from 2001 to 2007. We hypothesized that, while VSTs in the United States are performing increased numbers of endovascular cases, this experience has come at the expense of decreased open surgical case volume. If this is the case, VSTs may be receiving inadequate training in open surgery. The loss of adequate training in open surgical procedures might jeopardize the ability of recently trained vascular surgeons to continue to provide comprehensive vascular care at a high skill level. Recognition of such a trend would be critical, as combined skill in open and endovascular treatments is the key characteristic that sets vascular surgeons apart from all other specialists who treat patients with vascular disease.
Methods
All VSTs seeking board certification are required by the Accreditation Council for Graduate Medical Education (ACGME) to log their open and endovascular procedures. These data are aggregated by the Residency Review Committee (RRC) into an annual summary report, detailing the national average case volume for all VSTs. While each individual annual dataset reflects the total procedure volume for all graduating VSTs during a single academic year (July 1st through June 30th), the reported procedure volume per trainee is derived from the entire time spent in accredited vascular training (one or two years, depending on the program and year; Fig 1). The seven annual reports between 2001 and 2007 for all graduates of traditional vascular fellowships (ie, vascular training preceeded by five years of general surgery training) were reviewed in their entirety and form the basis of this study (Table).
Fig 1.
Bar graph demonstrating the number of accredited vascular surgery training programs with one and two clinical years from 2001 to 2007.
Table. The mean number (± standard deviation) of procedures performed by all graduating accredited vascular surgery trainees from 2001 to 2007
| 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | P-value⁎ | |
|---|---|---|---|---|---|---|---|---|
| Total primary major operations | 298.3 ±96 | 335.9±126 | 378.0±136 | 430.2±142 | 471.3±155 | 515.6±157 | 519.2±144 | <.01 |
| Open | 234.7±133 | 233.9±147 | 238.2±142 | 242.5±164 | 245.1±144 | 252.6±148 | 250.1±141 | <.01 |
| Endovascular diagnostic | 22.2±31 | 43.1±42 | 61.6±46 | 86.0±53 | 100.4±54 | 113.1±66 | 104.7±53 | <.01 |
| Endovascular therapeutic | 41.5±34 | 58.9±41 | 78.2±49 | 101.7±53 | 125.7±62 | 149.8±69 | 164.4±71 | <.01 |
| Total open aortic surgery | 49.7±35 | 46.2±40 | 45.2±35 | 43.3±34 | 41.4±33 | 41.1±35 | 41.2±33 | <.01 |
| Infrarenal aortic aneurysm | 25.9±17 | 24.1±14 | 22.2±12 | 21.9±12 | 20.0±11 | 18.6±11 | 18.1±11 | <.01 |
| Suprarenal aortic aneurysm | 3.0±3 | 3.5±4 | 3.3±4 | 3.2±4 | 3.9±4 | 4.4±6 | 4.1±6 | .25 |
| Thoracic aortic aneurysm | 1.1±2 | 1.1±3 | 0.9±2 | 1.0±2 | 0.6±1 | 0.5±1 | 0.8±2 | .26 |
| Thoracoabdominal aortic aneurysm | 4.4±7 | 4.7±8 | 3.6±6 | 4.0±5 | 3.5±5 | 3.5±6 | 3.4±4 | .60 |
| Aorto-iliac/femoral bypass | 9.3±6 | 7.8±6 | 9.9±5 | 8.3±6 | 8.8±7 | 9.0±6 | 9.6±6 | .16 |
| Mesenteric bypass/endarterectomy | 4.3±4 | 3.5±3 | 4.0±4 | 3.7±3 | 3.4±3 | 4.3±4 | 4.3±3 | .23 |
| Renal bypass/endarterectomy | 1.7±2 | 1.5±2 | 1.3±2 | 1.2±2 | 1.2±2 | 0.8±1 | 0.9±1 | <.01 |
| Endovascular aneurysm repair | 16.9±16 | 22.0±17 | 26.3±16 | 29.9±21 | 35.7±23 | 44.5±25 | 50.5±31 | <.01 |
| Total open infrainguinal bypass | 37.6±25 | 35.9±26 | 36.0±25 | 35.8±25 | 36.9±27 | 36.5±26 | 36.5±26 | .35 |
| Femoral-popliteal bypass | 15.6±12 | 14.8±12 | 14.5±11 | 15.3±11 | 15.7±11 | 16.8±12 | 17.1±12 | .52 |
| Infrapopliteal bypass | 22.0±13 | 21.1±14 | 21.5±14 | 20.5±14 | 21.2±16 | 19.6±14 | 19.4±14 | .11 |
| Carotid endarterectomy | 43.6±20 | 43.6±19 | 45.9±20 | 43.7±18 | 42.8±18 | 43.4±19 | 42.2±21 | .89 |
⁎ANOVA used to compare means across 7 years. |
For the purpose of this study, only data pertaining to cases that were logged as a primary procedure were analyzed (cases logged as a teaching assistant or secondary procedures were not included). In order to preserve the absolute number of separate operative encounters, cases involving more than one RRC category (ie, iliac stent placement at the time of an infrainguinal bypass) were analyzed according to the designated primary procedure. As a result, every individual component of a case may not have been captured, but the absolute number of each operative encounter was preserved.
The RRC utilizes Current Procedural Technology (CPT) codes in order to ensure case specificity when logging cases. While these codes are extremely specific for open surgical procedures, they tend to be very broad for endovascular interventions. As an example, the case log system in place during the study period grouped all stent procedures, regardless of location, under a single code (37205, transcatheter placement of an intravascular stent). Accepting this limitation, we evaluated three primary types of procedures, as indicated by CPT code: aortic repair, lower extremity bypass, and carotid endarterectomy. Definitions pertaining to case categories are consistent with previous reports using RRC data.14 We defined the total number of primary major operations for each trainee as the sum of all open major cases, endovascular diagnostic cases, and endovascular therapeutic cases. Total open aortic surgery was defined as the sum of open aortic aneurysm repairs (thoracic, thoracoabdominal, suprarenal, and infrarenal), aortoiliac and aortofemoral bypasses, mesenteric artery bypasses/endarterectomies, and renal artery bypasses/endarterectomies. Endovascular aortic aneurysm repair was defined as the sum of infrarenal and thoracic endovascular aneurysm repairs. Total open infrainguinal bypass was defined as the sum of all prosthetic and autogenous bypasses with the graft origin in the lower extremity. With regards to peripheral endovascular interventions, the classification of cases has been much less specific. For example, until 2008, all angioplasty procedures, regardless of locations, were categorized as balloon angioplasty. All stent procedures were also treated in the same manner.
Analysis of variance (ANOVA) was used to compare the mean number of cases performed by VSTs over the seven years analyzed. All means are represented as the mean ± standard deviation. Comparisons between two individual years (2001 vs 2007) were analyzed with a paired t test. All tests were considered statistically significant at an alpha level of 0.05 (P = .05, two-tailed). All analyses were performed using SAS version 9.1 (Cary, NC).
Results
During the study period, 2001 to 2007, the number of ACGME accredited vascular training programs increased by 14.5% (83 in 2001 to 95 in 2007), with a corresponding 15.6% increase in the number of graduating vascular trainees (96 in 2001 to 111 in 2007). The increase in the number of trainees was outpaced by the concurrent increase in overall vascular volume; graduating trainees logged 298.3 ± 96 mean total primary operations in 2001 and 519.2 ± 144 mean total primary operations in 2007 (174% increase, P < .01). This increase in total primary major operations was attributable to a 6.7% increase in open cases and to a 422% increase in endovascular cases (Fig 2).
Fig 2.
A, Bar graph demonstrating the total mean number of major procedures and B, demonstrating the total mean number of endovascular therapeutic and diagnostic procedures performed by accredited vascular surgery trainees from 2001 to 2007.
Aortic procedures
Vascular surgery trainees logged 17.1% fewer total open aortic procedures in 2007 than in 2001 (41.2 ± 33 vs 49.7 ± 35, P < .01) (Fig 3, A). This decrease was primarily attributable to the decrease in open infrarenal aortic aneurysm procedures (18.1 ± 11 vs 25.9 ± 17, 30.1% decrease, P < .01) and renal artery procedures (bypasses or endarterectomy) (0.9 ± 1 vs 1.7 ± 2, 47.5% decrease, P < .01). The number of open suprarenal aortic aneurysm procedures, open thoracic aortic aneurysm procedures, thoracoabdominal aortic aneurysm procedures, aortoiliac and aortofemoral bypass procedures, and mesenteric artery procedures (bypasses or endarterectomy) remained constant. The mean number of EVAR procedures steadily increased from 16.9 ± 16 cases per trainee in 2001 to 50.5 ± 31 cases per trainee in 2007 (299% increase, P < .01) (Fig 3, B).
Fig 3.
A, Bar graph demonstrating the total mean number of open aortic procedures and B, demonstrating the total mean number of open and endovascular infrarenal aortic aneurysm procedures performed by accredited vascular surgery trainees from 2001 to 2007.
Lower extremity bypass procedures
The mean total number of lower extremity bypass procedures performed by vascular surgery trainees did not change significantly (36.5 ± 26 vs 37.6 ± 25, 2.9% decrease, P = .35). While the mean number of femoral to popliteal artery bypass procedures increased by 9.6% (P = .52), the mean number of infrapopliteal artery bypass procedures decreased by 11.8% (P = .11; Fig 4).
Fig 4.
Bar graph demonstrating the total mean number of infrainguinal bypass procedures performed by accredited vascular surgery trainees from 2001 to 2007.
Carotid endarterectomy procedures
During the seven years surveyed, the overall mean number of CEA procedures performed by vascular surgery trainees did not change significantly (43.6 ± 20 vs 42.2 ± 21, 3.2% decrease, P = .89; Fig 5).
Fig 5.
Bar graph demonstrating the total mean number of carotid endarterectomy procedures performed by accredited vascular surgery trainees from 2001 to 2007.
Discussion
This report reviewed the last seven years of available data (2001-2007) providing case volume for all graduating VSTs in the United States. The most notable finding is the tremendous increase in VST total case volume (174%). This increase is largely secondary to the greater than four-fold increase in the volume of endovascular diagnostic and therapeutic procedures. While the volume of all types of open aortic procedures has decreased significantly (50 to 41 mean cases per graduating fellow), examination of the specific types of aortic procedures demonstrates that the decrease in total open aortic procedure volume is primarily attributable to the decrease in open infrarenal AAA repair (26 to 18 mean cases per graduating fellow). The volume of other open aortic procedures, as well as the volume of infrainguinal bypass and carotid endarterectomy, has not changed enough to be considered clinically significant.
Our findings indicate that while the introduction of EVAR has had a dramatic effect on reducing the number of open AAA procedures available for training, other endovascular procedures have not had as significant an impact. Specifically, the increasing role of endovascular aortoiliac, mesenteric, renal, carotid, and infrainguinal intervention do not appear to have reduced the number of corresponding open procedures to the extent that training is in jeopardy. Unfortunately, the data provided by the RRC are descriptive and do not explain the factors accounting for this increase in endovascular procedures and the absence of a corresponding decrease in open procedures. We can only speculate on possible explanations; these include an aging population, increased referral patterns to centers with training programs, a decrease in open major vascular procedures performed by general surgery residents, and physicians offering “minimally invasive” endovascular procedures to patients that otherwise would have been treated medically.
Several single institution reports7, 8, 9, 10, 11 and one state-level report15 have examined the effect of EVAR on open AAA training. Our analysis confirms the results of these earlier reports and extends the findings to the national level, again indicating that while the number of EVAR procedures performed by VSTs continues to increase, the number of open AAA procedures performed by VSTs continues to decrease.
It is worthwhile to note that, although several authors have also shown that the number of open aortic procedures continues to decline, the level of complexity for these open AAA procedures appears to be increasing, presumably, as more straight-forward infrarenal AAAs are being treated with EVAR.8, 10, 11 At the Ochsner Clinic, Sternbergh and colleagues reported that, of the open AAA treated, the number of more complex juxtarenal and pararenal AAA repairs increased from 2.9% in 1996 to 23.3% in 2000.8 At Stanford University Medical Center, Arko and colleagues reported that the number of suprarenal AAA treated by their graduating vascular fellow increased from 9 in 1994 to 26 in 2000.11 Similarly, at Washington University Medical Center, Choi and colleagues reported that the percentage of infrarenal AAA repairs requiring suprarenal clamping increased from 21% in 1998 to 30% in 2000. In addition, the number of suprarenal AAA treated by their graduating vascular fellow increased from 4 in 1998 to 24 in 2000.10 These analyses indicate that as the number of open AAA procedures performed by VSTs decrease, those cases that are performed are increasingly complex. This finding of increased AAA complexity and associated technical challenges underscores the need to maintain the required high skill level in the performance of open aortic procedures.
To our knowledge, only one prior study, published by Cronenwett14 in 2003, has taken this broad approach to analyzing the trends in the proportion of open vs endovascular procedures performed by VSTs in the endovascular era. Similar to the approach in our study, Cronenwett used a national database to analyze a diverse array of vascular procedures and similarly did not concentrate solely on EVAR and open AAA. In that analysis, which also used RRC datasets (1994-2003), Cronenwett showed an increase in the number of total major cases attributable to an increase in endovascular procedures (5 cases in 1994, 140 cases in 2003) and relatively stable major open procedure volume (161 cases in 1994, 172 cases in 2003). The results presented in this study build on these findings by extending the analysis to 2007 (the most recent available data) and by focusing specifically on the volume of procedures available for VSTs (as opposed to the effect on general surgery resident training).
It is important to reiterate that the data analyzed in this study were gathered exclusively from institutions in the United States with accredited vascular surgery training programs. As mentioned, during this study period, many of the training programs transitioned from one clinical year to two clinical years, and the findings should be interpreted in this context. In other words, these case volume trends are specific to VSTs and may reflect either one or two years of clinical activity. Therefore, based on these data, we are unable to comment on open and endovascular procedure volume trends in the United States as a whole and intentionally limit our discussion to focus on VSTs.
Although these results demonstrate that open surgical case volume for VSTs has been stable between 2001 and 2007, we remain cautious in concluding that all future vascular surgeons will continue to be adequately trained in open techniques. Currently, vascular surgery training paradigms are changing dramatically with the introduction of programs that no longer include completing a general surgery residency. The new training programs consist of partial training in general surgery, either completing only three years of general surgery residency and three years of vascular surgery residency or an integrated residency, where there is no formal participation in a general surgery residency program. These residents spend five years in a vascular surgery residency that includes rotations onto general surgery and an array of other disciplines. In this study, all VSTs completed five full years of general surgery training prior to starting their vascular surgery training. The volume of open cases necessary to train residents who lack a strong foundation in open general surgery remains unknown–both time and a commitment to rigorous monitoring of technical skills and outcomes will be necessary to address this critical question.
Conclusions
Vascular surgery trainees are performing vastly increased total numbers of procedures. This increase in procedure volume is almost entirely attributable to the adoption of endovascular techniques. Aside from a small decline in open aortic procedures, the volume of open surgical procedures has largely remained stable. As endovascular procedures are used increasingly as the initial treatment option for many patients with vascular disease, it is essential that vascular surgery training programs develop methods to maintain the open surgical skills of their trainees; maintaining this combined skill set is imperative for vascular surgeons to remain the premier specialists to care for patients with vascular disease.
Author contributions
References
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Competition of interest: none.
PII: S0741-5214(08)02206-4
doi:10.1016/j.jvs.2008.12.019
© 2009 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
