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 Table of Contents  
Year : 2020  |  Volume : 53  |  Issue : 3  |  Page : 87-92

Comparison case number of E-Da hospital neurosurgical residency training in spine and peripheral nerve cases to America's national data

1 Department of Neurosurgery, E-Da Hospital, Kaohsiung, Taiwan
2 Division of Infectious Diseases, Department of Internal Medicine, E-Da Hospital, Kaohsiung, Taiwan

Date of Submission25-Oct-2019
Date of Decision22-Jan-2020
Date of Acceptance19-Mar-2020
Date of Web Publication30-May-2020

Correspondence Address:
Dr. I-Fan Lin
No. 1, Yi-Da Road, Jiaosu Village, Yan-Chao District, Kaohsiung City 824
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/fjs.fjs_89_19

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Background: The purpose of this study was to evaluate the trends in adult spinal cases performed by E-Da hospital graduating neurological surgery residents, then comparing the case volumes against the national means in the US.
Materials and Methods: The E-Da surgical case volumes were extracted using the hospital billing system for the years 2008–2017. These logs were coded according to the Accreditation Council for Graduate Medical Education guideline, providing a fair comparison against US national means. Linear regression analyses were conducted to identify changes in spinal categories. Finally, an unpaired student t-test was performed to compare E-Da case volumes to America's national means.
Results: An average of 781.5 total spinal procedures were performed in the past 4 years of residency training for each of the four graduated E-Da neurosurgical residents, with the individual total caseload increasing by 38.07 cases each year (r2 = 0.40). The US national average was 427.72 spinal procedures for each of the 877 graduating residents, increasing by 19.96 cases every year (r2 = 0.95). E-Da has significantly more thoracic/lumbar instrumentation fusion procedures (mean 486.00 ± 90.27) and anterior cervical approach for decompression/stabilization and fusion procedures (mean 182.75 ± 42.91) than the US (means 145.95 ± 3.07 and 72.66 ± 4.62, respectively). The US has significantly more lumbar discectomy procedures (mean 125.70 ± 2.89), posterior cervical approach for decompression/stabilization and fusion procedures (mean 56.98 ± 3.73) and peripheral nerve procedures (mean 26.2 ± 0.79) than E-Da (means 64.5 ± 8.54, 39.75 ± 4.99, and 8.50 ± 5.07, respectively).
Conclusion: Neurosurgical residents' surgical case exposures to different spinal categories were very different in E-Da and the US. Case entry logs provide valuable information nationally and internationally.

Keywords: Accreditation council for graduate medical education, case logs, E-Da hospital, neurological surgery, residency, spine and peripheral nerve

How to cite this article:
Wu YY, Chen TY, Chen PY, Lu K, Liang CL, Tzeng WJ, Chye CL, Wang HK, Lin IF. Comparison case number of E-Da hospital neurosurgical residency training in spine and peripheral nerve cases to America's national data. Formos J Surg 2020;53:87-92

How to cite this URL:
Wu YY, Chen TY, Chen PY, Lu K, Liang CL, Tzeng WJ, Chye CL, Wang HK, Lin IF. Comparison case number of E-Da hospital neurosurgical residency training in spine and peripheral nerve cases to America's national data. Formos J Surg [serial online] 2020 [cited 2021 Aug 4];53:87-92. Available from: https://www.e-fjs.org/text.asp?2020/53/3/87/285402

  Introduction Top

The Accreditation Council for Graduate Medical Education (ACGME) assesses surgical residents' experience in America by setting a required case minimum [1] and mandating that residents log in all their case participation online. A study by Agarwal et al.[2] reviewed this ACGME Resident Case Log (ACGME log) from 2013 to 2017 and analyzed the US national trends in graduating neurosurgical resident exposure to adult spinal procedures. An average of 427.72 spinal procedures was performed by 877 graduating US neurosurgical residents between 2013 and 2017, with the mean number of procedures increased by 19.96 (r2 = 0.95) cases per year.

A national platform to track individual resident's case participation volume was yet to be established in Taiwan. This study aims to examine a similar neurosurgical resident spinal case log compiled in E-Da hospital, which is a medical center in Southern Taiwan, to gain an overview of the neurosurgical training program. Then, this study was compared the data against America's national means over the same period to evaluate the differences in procedural categories in the two countries, enunciating the importance of national case log platforms.

  Methods Top

This study collected census of adult spinal procedures performed by all neurosurgical residents between 2008 and 2017 in E-Da hospital using E-Da procedure billing data, generating an E-Da Resident Case Log (E-Da log). Then, the spinal procedures were coded according to the ACGME case log guidelines and its defined case categories.[1],[3]

[Figure 1] illustrates the timeline when each of the four neurosurgical residents graduated in E-Da hospital from 2012 to 2017. According to the ACGME case log guideline, resident surgeon roles are defined into assistant, senior, and lead resident surgeon.[3] This role definition was not applied into E-Da log retrospectively. By default, this study only included case participation from the last 4 years of neurosurgical residency training to account for this surgical role maturation process. In the early years of training, residents took part in operations as assistant surgeons, whose case participation should be excluded as defined by ACGME.[3] Residents assumed the roles of lead resident surgeons in their final 4 years of training.
Figure 1: Timeline representing the month and year of neurosurgical residents graduating from E-Da hospital from 2012 to 2017. By default, only the procedures operated by graduating residents during the last 4 years before graduation were included in this study. For example, for “Resident A,” only cases participated by him from July 1, 2008 to June 30, 2012 were included

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The total spinal procedures and each of the five ACGME defined spinal case categories were evaluated using linear regression analysis to determine trends in residency case exposure, which are represented in [Figure 2] and [Table 1], respectively. The trend of total spinal procedures in the US was included in [Figure 2] to provide an overall comparison. Then, using unpaired Student's t-test, the mean numbers of spinal procedures in E-Da log were compared against the means in ACGME log collated by Agarwal et al.,[2] as shown in [Figure 3]. All calculations were performed using Microsoft Excel 365 (Microsoft; Redmond, WA, USA). Data collection required neither interaction with study participants nor identifiable private information.
Figure 2: Regression line representing the trend of total spinal procedures operated by graduating neurosurgical residents in E-Da hospital and the US over the years

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Table 1: Trends of spinal procedures performed by E-Da residents

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Figure 3: Mean number of spinal procedures performed by E-Da graduating neurosurgical residents, plotted with the standard error of the mean, compared to the national means of the US (data from Agarwal et al.). TL fusion had a difference in mean of 336.99–343.11 (95% confidence interval) and an accreditation council for graduate medical education case minimum of 20. Lumbar discectomy had a difference in mean of 64.08–58.32 (95% confidence interval) and an accreditation council for graduate medical education case minimum of 25. Anterior cervical discectomy and fusion had a difference in mean of 104.92–115.56 (95% confidence interval) and an accreditation council for graduate medical education case minimum of 25. Posterior cervical decompression and fusion had a difference in mean of 20.91–13.55 (95% confidence interval) and an accreditation council for graduate medical education case minimum of 15. Peripheral nerve procedures had a difference in mean of 18.53–16.87 (95% confidence interval) and an accreditation council for graduate medical education case minimum of 10. (Unpaired student t-test: **P < 0.0001) (CI: Confidence interval)

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  Results Top

A mean of 781.5 total spinal procedures were performed throughout residency training for each of the four residents graduating between 2012 and 2017. The number of procedures completed by graduating residents increased by 38.07 (r2 = 0.40) cases per year [Figure 2]. The ACGME defined spinal case categories did not show any statistically significant trend [Table 1].

The most performed procedures were thoracic/lumbar instrumentation fusion (TL fusion) and anterior cervical approach for decompression/stabilization and fusion (ACDF) with means of 486 and 182.75 procedures per resident, respectively. These comprised 62.19% and 23.38% of all spine procedures performed by neurosurgical residents, respectively. The lesser performed procedures were lumbar discectomy, posterior cervical approach for decompression/stabilization and fusion (PCDF) and peripheral nerve operations with means of 64.5, 39.75, and 8.5 procedures per resident, respectively. These comprised 8.25%, 5.09%, and 1.09% of all spine procedures performed by neurosurgical residents, respectively.

When compared with America's national mean, E-Da has significantly greater case volume in TL fusion (95% confidence interval [CI]: 336.99–343.11, P < 0.0001) and ACDF (95% CI: 104.92–115.26, P < 0.0001). On the other hand, E-Da has significantly lesser case volume in lumbar discectomy (95% CI: 64.08–58.32, P < 0.0001), PCDF (95% CI: 20.91–13.55, P < 0.0001) and peripheral nerve operations (95% CI: 18.53–16.87, P < 0.0001). The comparison chart between E-Da and the US is depicted in [Figure 2].

Overall, resident mean caseloads during residency in both countries were found to be significantly greater than ACGME required minimums, except peripheral nerve operations in E-Da hospital. Only one resident reached case minimum (Resident B's recorded peripheral nerve case number was 16), while the other three residents failed to attain case minimum set by ACGME, with recorded case numbers ranging from 5 to 7.

  Discussion Top

Trends in Taiwan and the US

The mean spinal procedures performed by graduating E-Da resident was 781.5, which was close to twice the national mean of the US at 427.72 spinal procedures per graduating resident.[2] As shown in [Figure 2], there was an increasing trend in total spine procedures performed by graduating E-Da neurosurgery residents from 2012 to 2017. Even though there are mixed findings in trend for every spine category, it is reasonable to conclude that all trends are generally stationary, with slight upward fluctuation in TL fusion and ACDF only [Table 1]. This is different from the trends observed in the US, where there are significant increase in total spine procedures and every spine category, except peripheral nerve procedures.[2]

One explanation to this observation is the good accessibility, short waiting times, low cost, and high coverage rate of Taiwan's National Health Insurance (NHI) system,[4] which was introduced in 1995, covering 99% of the population. Surgical case volumes in Taiwan might have plateaued at the highest number attainable by a medical center under the affordable and extensive NHI coverage.

Another possibility is the increase in compliance of US residents to update their ACGME log. Many studies have shown that resident case logs are inaccurate reflection of the actual procedural history.[5],[6] In general, resident case volumes are under-reported into case log system.[7] It is a reasonable speculation that more US residents are getting familiar with the ACGME log guideline and online logging system over the years, thus more residents are logging in their case count timely and accurately. With the decrease in under-reporting of procedures, case volume trends in the US will appear to be rising. E-Da log did not inherit this resident-managed case log error since the data was extracted directly from the hospital billing system.

Lumbar spine surgeries

According to ACGME guideline, each resident may only claim credit for one Common Procedural Terminology (CPT) code per case.[3] In other words, even though lumbar discectomy is usually performed concurrently with TL fusion, only a single CPT, which is TL fusion, will be credited. The discrepancy in the mean number of TL fusion and lumbar discectomy procedures between E-Da and the US [Figure 3] can be largely explained by the difference in procedural preferences between the two countries. It has been shown in numerous studies that lumbar discectomy is associated with spinal instability and increased likelihood of a patient undergoing a TL fusion surgery in future.[8],[9] On the other hand, TL fusion is associated with instrumentation failures and adjacent segment diseases, with the fusion length being the most significantly related factor.[10] The ongoing debate about which is the better treatment strategy is beyond the scope of discussion in this study. It can be inferred that under the accessible, efficient and affordable NHI system in Taiwan, neurosurgeons and patients are more likely to opt for a major single surgery, which is TL fusion, to manage lumbar radiculopathy thoroughly and extensively, as opposed to a minor procedure and possible future ones, such as lumbar discectomies.

Cervical spine surgeries

ACDF and PCDF are both safe and effective treatments for cervical radiculopathy.[11] ACDF has the advantage of easier and wider exposure of the cervical intervertebral space and less patient discomfort. However, it has fusion-related complications such as pseudoarthrosis and instrumentation failure, which was avoided in PCDF.[12],[13] The ongoing debate about which is the better treatment option is beyond this study as well. E-Da residents are exposed to significantly more ACDF procedures than the US average, while the opposite trend observed in PCDF [Figure 3]. A reasonable explanation is that Taiwan neurosurgeons, or surgeons in general, fall back to old habits and routine practices during clinical decision making. The study by Agarwal et al.[2] might have case volume data more evenly distributed across the two spinal categories since it was a nationwide survey. The E-Da log, on the other hand, reflected the practice of a single medical center. Thus, a single dominant procedure method, which is ACDF, is evident.

Profit-driven factor

In Taiwan, a global budget is implemented on all hospitals as a policy to keep the cost of NHI down. Healthcare providers are paid through a mix of fee-for-service and other payment systems using a “floating” point-value scale.[14] This is incentive for hospitals to promote surgeries involving patient-charged medical devices while cutting down all other medical expenditures, such as imaging, pharmacy, laboratory, and facility costs. TL fusion is more profitable because it has much higher cost of hardware than lumbar discectomy.[15],[16] Similarly, the direct cost of ACDF is significantly higher than PCDF, consisting mainly of instrumentation costs.[17],[18] Furthermore, ACDF has a shorter length of hospital stay compared to PCDF.[19] Evidence has even demonstrated that ACDF can be safely performed in outpatient settings.[20] Thus, from a profit-making point of view, E-Da hospital, being a private healthcare provider with stiff competition from other hospitals, will favor TL fusion and ACDF heavily over lumbar discectomy and PCDF, respectively.

Peripheral nerve surgery

Peripheral nerve surgeries were strikingly limited in E-Da due to several reasons. First, E-Da neurosurgical department did not specialize in complex peripheral nerve surgeries. These cases were referred elsewhere. Second, simple peripheral nerve procedures, such as median nerve neurolysis, were done in outpatient settings. Since the patients were awake in outpatient settings, attending surgeons would most likely perform the entirety of the procedure as requested by patients. Residents were excluded from outpatient procedures.

A well-constructed surgical training program should allow adequate case participation in all case varieties. E-Da residents could seek exchange programs to other medical centers where complex peripheral nerve surgeries were emphasized. Resident's involvement in awake procedures could be improved through methods described by Smith et al.[21] Educational techniques during awake surgery include preprocedural communication between attending surgeons and patients, nonverbal signaling during procedures, and involvement of the patient in the education process. Extra efforts by the attending neurosurgeons in these areas could make the inclusion of neurosurgical residents in awake procedures possible.


This study collected resident case entry volumes of a single medical center in Taiwan, which was not representative of Taiwan. To date, there were a total of 19 neurosurgical programs in Taiwan.

Only the cases participated by E-Da residents in the past 4 years of neurosurgical training were included in this study. Thus, this E-Da log is under-reported despite its accuracy. The decision to universally define first 3 years of residency to be assistant surgeons, whose case participations were not credited, was made by study design. First, this can account for the case entries where the neurosurgical residents assumed the role of assistant surgeons in their early years, which was an accurate reflection of reality. Second, it has been shown in other studies that resident-managed case logs, such as ACGME log, are under-reported.[5],[6],[7] Collectively, this study compared case logs from neurological residents, who graduated in the same year span and subjected to some degrees of under-reporting. Ultimately, the comparisons carried out in this study between E-Da hospital and the US was fair.

Future directions

Only spinal and peripheral nerve entries were discussed in this study. The case log can be expanded into other surgical case categories, such as cranial and pediatrics procedures, using similar methods.

A similar national online case entry reporting platform should be established in Taiwan, generating valuable information regarding resident training. Besides the quantity of operations performed by residents, the quality of operations could be gathered by such national online case log system as well. Factors such as the complication rates and postoperation hospital stays could be prospectively logged into the system. Meaningful studies could be conducted to evaluate these vital components in surgical graduate medical education.

This study provided a glimpse at the amount of information that could be generated when case logs were compared internationally. Most importantly, case log could provide individual residents general overview of their current training status, identify inadequacy in their specific surgical categories, and implement complimentary measures.

  Conclusion Top

This study evaluated the spinal and peripheral nerve case volumes participated by graduating neurosurgical residents in E-Da hospital and comparing them against America's national means. E-Da neurosurgical residents were generally well-trained in all spinal procedure categories with abundant case exposures, especially in TL fusion and ACDF. The overwhelming differences in case volume were heavily influenced by the NHI-governed medical environment in Taiwan and shared-decision making process between surgeons and patients. E-Da residents were under-trained in peripheral nerve procedures, which was a similar observation in the US, but to a much greater extent. Most importantly, this study advocates the establishment of a national online case logging platform in Taiwan.

Financial support and sponsorship


Conflicts of interests

There are no conflicts of interest.

  References Top

Accreditation Council for Graduate Medical Education: Neurological Surgery Case Log Defined Case Categories and Required Minimum Numbers. Available from: https://www.acgme.org/Portals/0/PFAssets/ProgramResources/160_Neurological_Surgery_Defined_Case_Categories_and_Required_Minimum_Numbers.pdf. [Last accessed on 2019 Mar 10].  Back to cited text no. 1
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Accreditation Council for Graduate Medical Education: Case Log Guidelines. Available from: https://www.acgme.org/Portals/0/PFAssets/ProgramResources/Case_Log_Guidelines.pdf?ver=2016-04-19-140246-217. [Last accessed on 2019 Mar 10].  Back to cited text no. 3
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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]


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