The case for decreased surgeon-reported complications due to surgical volume and fellowship status in the treatment of geriatric hip fracture: An analysis of the ABOS database.

INTRODUCTION: American orthopaedists are increasingly seeking fellowship sub-specialization. One proposed benefit of fellowship training is decrease in complications, however, few studies have investigated the rates of medical and surgical complications for hip fracture patients between orthopedists from different fellowship backgrounds. This study aims to investigate the effect of fellowship training and case volume on medical and surgical outcomes of patient following hip fracture surgical intervention.
METHODS: 1999-2016 American Board of Orthopedic Surgery (ABOS) Part II Examination Case List data were used to assess patients treated by trauma or adult reconstruction fellowship-trained orthopedists versus all-other orthopaedists. Rates of surgeon-reported medical and surgical adverse events were compared between the three surgeon cohorts. Using binary multivariate logistic regression to control of demographic factors, independent factors were evaluated for their effect on surgical complications.
RESULTS: Data from 73,427 patients were assessed. An increasing number of hip fractures are being treated by trauma fellowship trained surgeons (9.43% in 1999-2004 to 60.92% in 2011-2016). In multivariate analysis, there was no significant difference in type of fellowship, however, surgeons with increased case volume saw significantly decreased odds of complications (16-30 cases: OR = 0.91; 95% CI: 0.85-0.97; p = 0.003; 31+ cases: OR = 0.68; 95% CI: 0.61-0.76; p<0.001). Femoral neck hip fractures were associated with increased odds of surgical complications. DISCUSSION: Despite minor differences in incidence of surgical complications between different fellowship trained orthopaedists, there is no major difference in overall risk of surgical complications for hip fracture patients based on fellowship status of early orthopaedic surgeons. However, case volume does significantly decrease the risk of surgical complications among these patients and may stand as a proxy for fellowship training. Fellows required to take hip fracture call as part of their training regardless of fellowship status exhibited decreased complication risk for hip fracture patients, thus highlighting the importance of additional training.

Introduction

Hip fractures are a major source of morbidity and mortality affecting an estimated 340,000 persons annually and projected to grow to over 600,000 annually by 2040 in the United States [1, 2]. Usually arising after minor trauma, typically a fall from standing height [3], fragility hip fractures among elderly patients have been shown to seriously affect physical and mental functioning and severely impact their health status and health-related quality of life [3]. As such, proper treatment of hip fractures is essential to minimize complications, decrease length of stay, and maximize recovery [4].

Treatment for hip fractures varies from hospital to hospital, and often includes treatment by general orthopaedic surgeons, orthopaedic trauma surgeons, or other fellowship trained orthopaedic surgeons [5]. Research continues to evaluate the respective care provided as a result of sub-specialization training.

Over the past decade, orthopaedic surgery has become increasingly specialized for a variety of reasons: providing extra training in specific areas of interest, improving clinical expertise, and optimizing chances to ensure employment [6]. In 2012, it was estimated that 87.4% of orthopaedic graduates pursue additional training in a subspecialized fellowship [6, 7]. While orthopaedic residency exposes residents to generalized practices, fellowship can ensure subspecialized orthopaedic operative competency and increased caseloads to prepare surgeons for the evolving nature of the field [7, 8].

Increased surgical volume has been extensively studied across a wide variety of procedures to investigate the link between experience and surgeon skill and patient complications [9-15]. In the case of hip fractures specifically, greater surgical volume has shown mixed findings in relation to surgical complications [16-21]. While some studies show surgical volume to be associated with decreased mortality [17, 18], others have shown no such associations [20, 21]. Similarly, the treatment of hip fractures by fellowship trained surgeons and general orthopaedic surgeons has also shown mixed results. Treatment of intertrochanteric fractures by trauma and non-trauma orthopaedic surgeons showed no difference in complications [5], however another study comparing fellowship trained surgeons (trauma or arthroplasty) and general orthopaedic surgeons did show differences in complication rates and 1-year mortality following treatment via hemiarthroplasty [22]. While these findings debate the importance of surgical volume and fellowship training, the implications of the effect of surgical volume on early practice physicians requires further attention. Additionally, the act of fellowship training itself on post-operative complications remains understudied.

Due to this dearth of information, the current study aimed to identify the pertinent factors in the occurrence of surgeon-reported complications of hip fractures in the training, fellowship specialization type, and experience of early practice orthopaedic surgeons and trend those over an extended period of time. Utilization of data from 1999 through 2016 American Board of Orthopaedic Surgery (ABOS) database enables a large, longitudinal review of operative treatment and subsequent complications for hip fracture patients treated by different fellowship-trained surgeons. Such analysis will provide insight and direction for orthopaedic graduates and hospital administrators in an ever increasingly subspecialized field [23]. Continuous evaluation and assessment of orthopaedic fellowship sub-specialization aims to decrease complication rates for patients and ensure better training and preparation for orthopaedic residency graduates as they transition into their careers.

Material and methods

Background

In the United States, the American Board of Orthopaedic Surgery (ABOS) awards Board Eligibility and then Board Certification to physicians completing all necessary requirements after finishing a five-year accredited orthopaedic residency program in either the US or Canada. A major component of this certification is the successful completion of a two-part examination–Part I is given via a computer-based multiple-choice examination and Part II is given as an oral examination [24]. After finishing the computer-based Part I, applicants become ABOS Board Eligible and are required to submit a comprehensive list of all surgical procedures they perform over a period of six months during a practice period of 20 months at one practice location. They must submit a minimum of 35 cases for review [25-27]. The list of procedures is logged by the applicant and includes a wide range of data including the applicant’s fellowship status, patient demographics (e.g. patient age and gender) and information about the procedure (e.g. Current Procedural Terminology (CPT) codes, and anesthetic, medical, and surgical complications). Once this data is received and reviewed, applicants can be approved to take the ABOS Part II Oral Examination. All of the patient information submitted as a part of this process is then de-identified and made available for research purposes after application and approval through the ABOS Research Committee.

Data

For the current study, we investigated the 1999–2016 databases for geriatric patients (defined as age > 65) who were treated for hip fracture by an ABOS candidate during this period. Patients were identified using the following CPT codes and author assigned categories: 27235 (simple percutaneous pinning hip fracture), 27236 (femoral neck hip fracture), or 27244/27245 (intertrochanteric hip fracture). Patients were then grouped based on fellowship status of the treating physician (trauma, adult reconstruction, or other). Physicians in the “other” fellowship category included any general orthopedist applicant (did not complete a fellowship) as well as candidates who had completed a fellowship in a field other than trauma or adult reconstruction. If a candidate had completed a fellowship in both trauma and adult reconstruction, their cases were excluded to ensure clarity of findings between the fellowships. Patients were also grouped by number of cases completed by the candidate during their collection period and put into the following groupings: 0–15 cases, 16–30 cases, and 31+ cases. Lastly, candidates were broken up by region of the United States based on the pre-defined regions as defined by the ABOS Research Committee (Fig 1).

Fig 1

Pre-defined regions of the United States for ABOS candidates.

Analysis

All available demographics for each patient was extracted including patient age and sex, geographic region, the year of the procedure, and procedural codes. As coding of complications has changed in the ABOS database in recent years, the current study identified surgeon-reported medical complications and surgeon-reported surgical complications that were collected across all years of data collection to ensure consistency of findings. Collected data that was not present across all years was excluded to ensure consistent complication rate data and comparisons. The medical complications recorded across all years and subsequently extracted for analysis were: death, myocardial infarction, stroke, renal failure, pulmonary embolism, congestive heart failure, pneumonia, and medical unspecified complications. The surgical complications recorded across all years were: bone fracture, dislocation, infection, nonunion/delayed union, skin ulcer/blister, implant failure, nerve palsy/injury, and vascular injury. Binary logistic regressions investigating likelihood of complication based on demographic covariates of patients and treating physician was then performed with patient age, patient sex, region, year of procedure, fellowship status, procedure type, and number of cases preformed.

IBM SPSS Statistics for Macintosh (version 26; IBM Corp., Armonk, NY) was used for all analysis. Chi-square tests were performed for the categorical variables between the three cohorts (both fellowship-type and case-number). Student t-test was utilized for continuous variables.

The ABOS Research Committee approved the current study and the study was classified as exempt by our institutional review board.

Results

The current study identified 73,427 hip fracture surgeries that fit inclusion criteria. Of these, trauma surgeons performed 14.67% (10,769), adult reconstruction performed 14.64% (10,748), and other fellowship trained surgeons performed the remaining 70.70% (51,910) hip fracture procedures (Table 1). Across surgeries performed, the average ages for cases were 82.17, 82.79, and 82.64 for trauma, adult reconstruction, and other surgeons respectively (p<0.001). A statistically significant but clinically insignificant difference in percent of surgeries performed in female patients was seen between the groups (between 71.59% and 73.46%, p < 0.001). From 1999–2016, trauma and adult reconstruction surgeons increased their share of hip fracture procedures while those surgeons in other fellowships saw a decline in their total hip fracture procedures in 2011–2016. Looking at breakdown of type of procedure done, surgeons in all fellowship categories performed the greatest percentage of intertrochanteric hip fractures in relation to all other cases they performed (Table 1).

Table 1

Demographics of hip fracture patients, organized by fellowship type of the treating physician and procedure type.

Type: Hip Fracture	Trauma	Adult Reconstruction	Other*	Univariate P-value
N = 73,427 (100%)	N = 10,769 (14.67%)	N = 10,748 (14.64%)	N = 51,910 (70.70%)
Age (SD)	82.17 (8.22)	82.79 (7.83)	82.64 (7.81)	<0.001
Sex
Male	3,060 (28.41%)	2,882 (26.81%)	13,778 (26.54%)	<0.001
Female	7709 (71.59%)	7,866 (73.19%)	38,132 (73.46%)
Region
Northeast	2,172 (20.17%)	2,941 (27.36%)	9,888 (19.05%)	<0.001
Northwest	461 (4.28%)	467 (4.34%)	3,401 (6.55%)
Midwest	2,325 (21.59%)	2,225 (20.70%)	10,768 (20.74%)
South	1,787 (16.59%)	1,539 (14.32%)	9,989 (19.24%)
Southeast	2,016 (18.72%)	1,910 (17.77%)	8,967 (17.27%)
Southwest	1,949 (18.10%)	1,650 (15.35%)	8,630 (16.62%)
Year of Procedure **
1999–2004	1,016 (6.79%)	1,894 (12.67%)	12,044 (80.54%)	<0.001
2005–2010	3,192 (11.13%)	4,004 (13.96%)	21,481 (74.91%)
2011–2016	6,561 (22.02%)	4,850 (16.28%)	18,385 (61.70%)
Procedure Type (CPT Code)
Simple Percutaneous Pinning Hip Fracture (27235)	1,125 (10.45%)	1,079 (10.04%)	5,821 (11.21%)	<0.001
Femoral Neck Hip Fracture (27236)	3,612 (33.54%)	4,028 (37.48%)	18,356 (35.36%)
Intertrochanteric Hip Fracture (27244, 27245)	6,032 (56.01%)	5,641 (52.48%)	27,733 (53.43%)

*Other fellowship specialties include: foot and ankle, pediatrics, sports medicine, hand/upper extremity, oncology, spine, and shoulder/elbow

**Percentages were calculated horizontally to better reflect changes in each time strata

In examining the incidence of surgeon-reported medical adverse events, fellowship training was not found to have any significant overall effect on most adverse medical events. However, in the case of renal failure (p<0.001), pulmonary embolism (p = 0.008), and pneumonia (p = 0.002), trauma surgeons were more likely to have such complications following hip fracture surgeries (Table 2).

Table 2

Incidence of medical adverse events following all hip fracture surgeries, organized by fellowship type of the treating physician.

Type: Hip Fracture	Trauma	Adult Reconstruction	Other	Univariate P-value
N = 73,427 (100%)	N = 10,769 (14.67%)	N = 10,748 (14.64%)	N = 51,910 (70.70%)
Any Adverse Event	1,693 (15.72%)	1,697 (15.79%)	7,998 (15.41%)	0.491
Death	682 (6.33%)	686 (6.38%)	3,464 (6.67%)	0.289
Myocardial Infarction	107 (0.99%)	99 (0.92%)	505 (0.97%)	0.847
Stroke	69 (0.64%)	79 (0.74%)	336 (0.65%)	0.573
Renal Failure	180 (1.67%)	135 (1.26%)	595 (1.15%)	<0.001
Pulmonary Embolism	95 (0.88%)	62 (0.58%)	329 (0.63%)	0.008
Congestive Heart Failure	106 (0.98%)	122 (1.14%)	550 (1.06%)	0.558
Pneumonia	315 (2.93%)	266 (2.47%)	1,214 (2.34%)	0.002

In the setting of surgeon-reported surgical adverse events on the other hand, trauma surgeons were the least likely to have any surgical complications compared to the adult reconstruction and other fellowship trained counterparts with complication rates of 5.44%, 5.95%, and 6.19% respectively (p = 0.01) (Table 3). These differences in surgical complications were specifically attributed to dislocation (p<0.001), skin ulcer/blister (p = 0.006), and hemorrhage (p < 0.001). There were no significant differences detected in the rates of bone fracture, infection, nonunion/delayed union, implant failure, nerve palsy/injury, lib ischemia, tendon ligament/injury, compartment syndrome, wrong side/site surgery, or vascular injury. When compared by fracture pattern, trauma surgeons had a slightly statistically significant reduction in surgical adverse events when performing procedures on intertrochanteric hip fractures compared to their counterparts from adult reconstruction or other fellowship categories (Table 4).

Table 3

Incidence of surgical adverse events following all hip fracture surgeries, organized by fellowship type of the treating physician.

Type: Hip Fracture	Trauma	Adult Reconstruction	Other	Univariate P-value
N = 73,427 (100%)	N = 10,769 (14.67%)	N = 10,748 (14.64%)	N = 51,910 (70.70%)
Any Surgical Complication	586 (5.44%)	639 (5.95%)	3,215 (6.19%)	0.011
Bone Fracture	179 (1.66%)	164 (1.53%)	776 (1.49%)	0.435
Dislocation	47 (0.44%)	93 (0.87%)	261 (0.50%)	<0.001
Infection	141 (1.31%)	115 (1.07%)	651 (1.25%)	0.218
Nonunion/Delayed Union	42 (0.39%)	64 (0.60%)	277 (0.53%)	0.088
Skin Ulcer/Blister	40 (0.37%)	68 (0.63%)	324 (0.62%)	0.006
Implant Failure	147 (1.37%)	129 (1.20%)	723 (1.39%)	0.292
Nerve Palsy/Injury	20 (0.19%)	29 (0.27%)	125 (0.24%)	0.423
Hemorrhage	16 (0.15%)	20 (0.19%)	235 (0.45%)	<0.001
Limb Ischemia	1 (0.01%)	4 (0.04%)	7 (0.01%)	0.178
Tendon Ligament/Injury	2 (0.02%)	0 (0.00%)	9 (0.02%)	0.388
Compartment Syndrome	0 (0.00%)	0 (0.00%)	1 (0.00%)	0.813
Wrong Side/Site Surgery	1 (0.01%)	0 (0.00%)	3 (0.01%)	0.642
Vascular Injury	3 (0.03%)	3 (0.03%)	10 (0.02%)	0.771

Table 4

Incidence of surgical adverse events by fracture pattern, organized by fellowship type of the treating physician.

Type: Hip Fracture	Trauma	Adult Reconstruction	Other	Univariate P-value
N = 73,427 (100%)	N = 10,769 (14.67%)	N = 10,748 (14.64%)	N = 51,910 (70.70%)
Simple Percutaneous Pinning Hip Fracture (27235)	53 (4.71%)	46 (4.26%)	311 (5.34%)	0.270
Femoral Neck Hip Fracture (27236)	266 (7.36%)	311 (7.72%)	1,443 (7.86%)	0.590
Intertrochanteric Hip Fracture (27244, 27245)	267 (4.43%)	282 (5.00%)	1,461 (5.27%)	0.025

When reviewing surgeon-reported surgical adverse events by the treating physician’s case volume, increasing case volume, comparing 0–15 cases, 16–30 cases, and 31+ cases, significantly reduced surgical complications (p<0.001) (Table 5). In particular, surgical complications including bone fracture (p = 0.001), skin ulcer/blister (p = 0.008), implant failure (p<0.001), and hemorrhage (p<0.001) were significantly reduced with increased case volumes and nonunion/delayed union (p = 0.050) less significantly. The implications of case volume was further evident in the incidence of surgical adverse events in femoral neck hip fracture and intertrochanteric hip fracture procedures (p<0.001) (Table 6).

Table 5

Incidence of surgical adverse events following all hip fracture surgeries, organized by case volume of the treating physician.

Type: Hip Fracture	0–15 Cases	16–30 Cases	31+ Cases	Univariate P-value
N = 73,427 (100%)	N = 36,679 (49.95%)	N = 26,792 (36.49%)	N = 9,956 (13.56%)
Any Surgical Complication	2,377 (6.48%)	1,605 (5.99%)	458 (4.60%)	<0.001
Bone Fracture	602 (1.64%)	407 (1.52%)	110 (1.10%)	0.001
Dislocation	183 (0.50%)	168 (0.63%)	50 (0.50%)	0.079
Infection	459 (1.25%)	327 (1.22%)	121 (1.22%)	0.924
Nonunion/Delayed Union	214 (0.58%)	128 (0.48%)	41 (0.41%)	0.050
Skin Ulcer/Blister	238 (0.65%)	156 (0.58%)	38 (0.38%)	0.008
Implant Failure	582 (1.59%)	320 (1.19%)	97 (0.97%)	<0.001
Nerve Palsy/Injury	92 (0.25%)	68 (0.25%)	14 (0.14%)	0.104
Hemorrhage	125 (0.34%)	133 (0.50%)	13 (0.13%)	<0.001
Limb Ischemia	6 (0.02%)	6 (0.02%)	0 (0.00%)	0.328
Tendon Ligament/Injury	7 (0.02%)	2 (0.01%)	2 (0.02%)	0.450
Compartment Syndrome	1 (0.00%)	0 (0.00%)	0 (0.00%)	0.606
Wrong Side/Site Surgery	3 (0.01%)	0 (0.00%)	1 (0.01%)	0.309
Vascular Injury	6 (0.02%)	6 (0.02%)	4 (0.04%)	0.359

Table 6

Incidence of surgical adverse events by fracture pattern, organized by case volume of the treating physician.

Type: Hip Fracture	0–15 Cases	16–30 Cases	31+ Cases	Univariate P-value
N = 73,427 (100%)	N = 36,679 (49.95%)	N = 26,792 (36.49%)	N = 9,956 (13.56%)
Simple Percutaneous Pinning Hip Fracture (27235)	235 (5.48%)	132 (4.84%)	43 (4.28%)	0.220
Femoral Neck Hip Fracture (27236)	1,001 (8.14%)	785 (7.87%)	234 (6.29%)	<0.001
Intertrochanteric Hip Fracture (27244, 27245)	1,141 (5.68%)	688 (4.88%)	181 (3.46%)	<0.001

Multivariate regression revealed four factors independently associated with reduced complication rates and three factors associated with increased complication rates. Patient age (OR 0.91; 95% CI: 0.88–0.95; p<0.001), male gender (OR 0.91; 95% CI: 0.85–0.97; p = 0.006), and case volume of either 16–30 cases (OR 0.91; 95% CI: 0.85–0.97; p = 0.003) or 31+ cases (OR 0.68; 95% CI: 0.61–0.76; p<0.001) were found to be protective factors against complications (Table 7). Patients treated in the Midwest (OR 1.21; 95% CI: 1.10–1.33; p<0.001) or South (OR 1.11; 95% CI: 1.00–1.22; p = 0.045) region of the United States were more likely to experience a complication than those treated in other regions. Finally, patients treated for a femoral neck hip fractures (OR 1.61; 95% CI: 1.44–1.80; p<0.001) were more likely to experience complications. Fellowship status did not appear to affect complication rates.

Table 7

Factors independently associated with surgical complications among all hip fracture surgeries.

Factor	Likelihood of Surgical Complication
N = 73,427 (100%)	OR	95% CI	P-value
Patient Age (per decade)	0.91	[0.88–0.95]	<0.001
Patient Sex
Female	1.00	–	–
Male	0.91	[0.85–0.97]	0.006
Region
Northeast	1.00	–	–
Northwest	1.10	[0.96–1.27]	0.185
Midwest	1.21	[1.10–1.33]	<0.001
South	1.11	[1.00–1.22]	0.045
Southeast	1.01	[0.91–1.12]	0.848
Southwest	1.03	[0.93–1.14]	0.609
Case Volume of Treating Physician
0–15 cases	1.00	–	–
16–30 cases	0.91	[0.85–0.97]	0.003
31+ cases	0.68	[0.61–0.76]	<0.001
Fellowship Status
Other	1.00	–	–
Trauma	0.97	[0.86–1.09]	0.613
Adult Reconstruction	0.99	[0.90–1.09]	0.827
Procedure Type
Simple Percutaneous Pinning Hip Fracture (27235)	1.00	–	–
Femoral Neck Hip Fracture (27236)	1.61	[1.44–1.80]	<0.001
Intertrochanteric Hip Fracture (27244, 27245)	1.02	[0.92–1.14]	0.692

Discussion

In recent years, the number of orthopaedic residency graduates seeking fellowship training increased significantly [23, 28]. In fact, orthopaedics has one of the highest fellowship participation rates across specialties–as high as 90% by some estimates [7, 28, 29]. Furthermore, physicians are more likely to perform procedures within their given specialty thus making patients with any given pathology more likely to be treated by a surgeon who was fellowship-trained in the most relevant specialty [23]. Given that fellowship training requires additional time and significant financial resources, it is becoming increasingly important to understand the effects of fellowship-training on surgeons’ clinical practice and the value for decreasing patient complications.

In this series of 73,427 hip fractures, patients treated by surgeons who were fellowship-trained in orthopaedic trauma were more likely to experience renal failure, pulmonary emboli, and pneumonia in the post-operative course than those treated by other specialties. We suspect this may be a reflection of traumatologists treating more acute and perhaps medically complex patients than other subspecialties, but in the absence of patient comorbidity data in the ABOS dataset, further information is required to support or negate this hypothesis.

Initial analysis also revealed that the trauma-trained physicians also had fewer overall surgical complications than the other cohorts. However, only three specific complications occurred at statistically different rates amongst the three groups. Dislocations, skin ulcers/blisters, and hemorrhage all occurred at a significantly lower frequencies in the trauma cohort than either the adult reconstruction or other categories. Subgroup analysis by fracture pattern revealed that only intertrochanteric hip fractures had differing rates of complication based on fellowship training, with trauma fellowship-trained surgeons experiencing the lowest complication rates.

Prior studies investigating fellowship status for hip fracture patients have shown mixed results. In a retrospective study of 298 femoral neck fractures, Mabry et al. found that adult reconstruction trained surgeons had shorter operative duration and less complications than those treated by general practice orthopaedic surgeons when performing hip hemiarthroplasty [22]. Decreased complications were also shown in a separate study for total hip arthroplasty [30]. Patients treated by trauma trained doctors had longer delays to surgery, possibly reflecting scheduling conflicts and adversely affecting complication incidence. Additionally, patients treated by traumatologists were significantly more likely to have suffered prior myocardial infarctions or be diagnosed with chronic obstructive pulmonary disease, presenting potential confounders [22]. In a conflicting retrospective study of 871 patients by Yuan and Kwek, they found reduced surgical delays and shorter surgical times for trauma surgeons when compared to non-trauma surgeons but found no difference in the incidence of postoperative complications and mortality [5]. However, both of these studies are single center studies, which may have limited external validity, as the skill sets and time restraints of individual surgeons at these respective centers may have influenced results.

The absence of effect of fellowship training on hip fracture surgeon-reported complications when compared to procedures such as joint arthroplasty may be attributable to the common practice of hip fracture call regardless of surgical subspecialty, which likely is a fundamental skill acquired during orthopaedic surgery residency training. While elective procedures like THA may largely be concentrated to adult reconstruction fellowship-trained surgeons in early practice, general orthopaedic or hip fracture call is broadly dispersed thus enabling surgeons from any subspecialty to gain considerable caseloads. This would not be true in reverse, thus muddling conclusions about value of fellowship training for hip fracture complications. Additionally, this current study uses data from ABOS candidates who are in their initial stages of their career and this finding may differ after years of being an attending physician.

Although fellowship status did not seem to significantly influence complication rates in the current study, surgeons’ annual hip fracture case volume did seem to influence the rates. Across the orthopedic literature, the relationship between surgeon and hospital volume and complications rates has been shown in the settings of hip or knee arthroplasty as well as for the operative treatment of scoliosis [31, 32]. In our study, surgeons treating more than 30 hip fractures during the collection period demonstrated an odds ratio of 0.68 in comparison to surgeons treating 15 fractures or less per year. This finding is similar to findings in studies about total knee arthroplasty (TKA) in which surgeons performing higher numbers of TKA’s reported fewer early complications than surgeons with less experience [33].

Our findings regarding case volume for hip fractures are in contrast to those by Okike et al., who used hip fracture registry data to assess the relationship between hospital or surgeon volume against patient morbidity and mortality [20]. In that study, there was no association between case volume and reoperation, medical complications, or readmissions, however, despite it being a registry study, the data is limited in number and to one geographic region. The discrepancy between these findings and those of the presently presented data warrants further exploration of the relationship between surgeon volume and complication rates.

Our findings also differ from those of Spaans et al. [21]. In their retrospective cohort from the Netherlands, patients who were treated for femoral neck fractures with hemiarthroplasty by low-volume surgeons, defined as less than 10 arthroplasties per year, were compared to those treated by moderate-volume (10–35 arthroplasties per year) and high-volume (35+ cases/year). The authors found that neither case volume nor surgeon experience correlated with hip prosthesis survival, patient mortality, surgical site infection, periprosthetic fracture, or prosthesis dislocation, however, this study too was limited in patient numbers (752 cases) and to one academic hospital.

Finally, in a recent systematic review by Wiegers et al., their findings were mixed with some findings supporting studies such as Okike and Spaans with no effect observed between hospital or surgeon volume on complications in the setting of hip fractures [34]. These associations were limited to morbidity and infectious complications, however. This finding does fall in line with some aspects of our results, in which infection was not found to be statistically different. Conversely, they did find a relationship between high surgeon volume and shorter lengths of stay [18, 35, 36]. As shorter lengths of stay after hip fractures have been shown to reduce rates of early mortality, this may also support the case volume findings of the current study [37, 38].

The presented project has several limitations. The inherent biases of any retrospective review hold true in this study. Moreover, the ABOS dataset does not provide granular patient comorbidity data thus limiting sub-group analysis conclusions. Additionally, because it is surgeon self-reported data there may be errors in inputting, missed cases, and/or complications may have been classified different depending on the orthopedist group; however, the ABOS database is considered to be highly reliable and extremely robust as the six months of case collection data is submitted as a mandatory part of the board certification for new orthopaedic surgeons, thus cases are inspected carefully and self-reported data is monitored [24]. Thus, the current study offers important insights into refuting the conclusions of previous studies wherein surgeon case volume did not affect complication rates and highlights the need for future research in this domain.

Conclusion

Based on our findings, fellowship status of training orthopaedic surgeons showed no major difference in the overall incidence of surgeon-reported surgical complications for hip fracture patients, and likely demonstrates the fundamental competence of orthopaedic surgeons in managing hip fractures following the successful completion of orthopaedic residency training. Despite such minor differences attributed to the fellowship type, case volume of the performing surgeon proved to have a more significant association with decreased risk of surgeon-reported surgical complications. The importance of case volume showcases the importance of additional training, thus potentially identifying the importance of concentrating hip fracture call in an early surgeon’s career. Future studies should review surgeon data later in their career to analyze these impact of early training and continued case volume as it pertains to more veteran surgeons and their medical and surgical complication rates in hip fracture procedures. Additional studies may want to further investigate the role of patient factors, including comorbidities and case acuity, as these may play a role in relation to surgeon factors, affecting the complexity and technical nature of the procedure.

8 Oct 2021

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Reviewers' comments:

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

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Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

**********

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Reviewer #1: No

Reviewer #2: No

**********

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Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear Editor,

It was a pleasure for me to review the above-mentioned manuscript for PLOS-ONE.

AIM OF THE STUDY

The aim of this study is important as the final goal of any fellowship training (providing better care to a defined sub-population of orthopaedic patients) still needs to be scientifically investigated, at least for trauma patients. Right now, fellowship is recognized as the “right to operate on some patients” by academics, hospital/clinic administrators and sometimes even by patients, but this “right” relies on few objective data.

LEVEL OF ENGLISH AND EDITION

Minimal corrections needed. See one of my comments.

QUALITY OF THE STUDY/MANUSCRIPT

-General:

On the Plos One Editorial Manager page, corresponding author is Jonathan N Grauer, whereas on the title page, corresponding author is Taylor D Ottesen. Please correct one of these statements to be consistent throughout the manuscript.

-ABSTRACT:

-Lines 47-48: “no prior study has investigated…”; however, in the Introduction, the authors cite references 5 & 23 (lines 114-117). Please modify the abstract, stating something like “Rare studies…” or “Scarce studies…” or something else.

-Line 61: after reading the Methods and the Results chapters, “1994-2004” should be replaced by “1999-2004”. Also see my comments on percentages (9.43% -> 6.8%, 60.92% -> 22%) on Results/Table 1.

-MANUSCRIPT

-Introduction:

-Line 95: replace “including” by “includes”.

-Lines 120-121: the statement should be mitigated, as references 5 & 23 studied this point.

-Materials and methods:

-Line 149: define the abbreviation “CPT” at its first appearance (line 149), not at its second appearance (Line 158).

-“Data” section: please define which states are included in each of the 6 regions. This might be obvious for US (and maybe Canadian) readers, but not for the rest of the world. As a non-US reviewer, I am for instance interested in incongruous/off-the-grid questions, such as: to which region belong Alaska and Hawaii? Were data from Puerto Rico, US Virgin Islands and other overseas territories included? This could be described in a Figure or a Table to save word count.

-“Data” section: “Number of cases completed by the candidate during…”. Does this number really reflect the volume? Might underestimation be possible? Please add a short statement about this issue, either in the M&M chapter, or in the limitation section.

Results:

-I am a little bit surprised by the fact that the tiny differences in ages (82.2 +/- 8.2 vs. 82.8 +/- 7.8 vs. 82.6 +/- 7.8, Line 199) and gender repartition (71,6% female vs. 73.2% vs. 73.5%, Line 201) among different fellowship groups reaches statistical significance which such mighty p-values. I would simply ask the authors to double-check these results (this also applies to Table 1).

-Lines 201-204/Table 1:

1° see my comment on abstract Line 61.

2° I think percentages in Table 1 should be corrected. For example: In years 1999-2004, 14954 procedures were performed (1016 + 1894 + 12044), meaning that Trauma fellowship trained surgeons performed 6.8% of the procedures (1016 out of 14954, not 1016 out of 10796), Adult reco 12.7% of the procedures (1894 out of 14954) and others 80.5% (12044 out of 14954). For years 2005-2010, my calculations result in 11.1%, 14% and 74.9% respectively. For years 2011-2016, 22%, 16.3% and 61.7% respectively; P-value should thus be recalculated, but the interpretative text is probably still ok.

-Table 1:

1° I think after calculation that N for “Other” should be 51910 rather than 60612. However, percentages for the whole column seem to be generally correct:

Total N for Sex/Other, Year/Other and Procedure type/Other is 51910-ok;

Total N for Region/Other is 51643-please correct or add a line for “n.a. region” or “other region”.

P-values might have to be corrected.

2° Total N for Region/Trauma is 10710 and does not correspond to 10769: please correct or add a line for “n.a. region” or “other region”.

3° Total N for Region/Adult reco is 10732 and does not correspond to 10748: please correct or add a line for “n.a. region” or “other region”.

-Table 2: I think after calculation that N for other should be 51910 rather than 60612. However, percentages for the whole column seem to be correct. P-values might have to be corrected.

-Tables 3a and 3b: I think after calculation that N for other should be 51910 rather than 60612. However, percentages for the whole column seem to be correct. P-values might have to be corrected.

Discussion:

-As long as corrections following my remarks on the Results section and Tables do not provoke unexpected changes in the interpretation of results, this section won’t need any corrections to be performed.

Reviewer #2: Dear Editor,

Dear Authors,

Thank you very much for the opportunity to review this interesting manuscript. Authors could show decreased surgeon reported complications due to surgical volume. This is a nicely written paper. I would like to suggest to address the following issues in order to improve the quality of the manuscript.

Introduction:

- Aims of the study were described.

Methods:

- Did all patients signed the informed consent?

- Do you need to have ethical approval to use this data?

- Authors should note that the statistical analysis in big data is not always useful. Beside the regression analysis, other statistics has mainly a descriptive character.

Results

- What about the time point of surgery? Is it known (< 24 h) or later?

- The regression analysis is the main part of results.

Discussion

- Nice Discussion and description of limitations

**********

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Reviewer #1: Yes: Axel GAMULIN

Reviewer #2: Yes: Roman Pfeifer

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Submitted filename: Review_PLOS_ONE.docx

Click here for additional data file.

10 Jan 2022

Dear Editorial Board,

Attached is a copy of our revised manuscript entitled “The Case for Decreased Surgeon-reported Complications Due to Surgical Volume and Fellowship Status in the Treatment of Geriatric Hip Fracture: An Analysis of the ABOS Database”. We wish to thank you and the reviewers for their time and effort in their critical review of our manuscript. We have responded to the requested changes as detailed below and believe the reviewers’ comments have allowed us to substantially improve the quality of the manuscript. Our responses are recorded in italics with changes to the manuscript documented in bold.

Thank you for your time and consideration.

Warmly,

Taylor D. Ottesen, M.D., M.B.A

Jonathan N. Grauer, MD

Lee E. Rubin, M.D. FAAOS, FAAHKS, FAOA

Response to Reviewers:

Reviewer #1:

-General:

On the Plos One Editorial Manager page, corresponding author is Jonathan N Grauer, whereas on the title page, corresponding author is Taylor D Ottesen. Please correct one of these statements to be consistent throughout the manuscript.

Thank you for identifying this discrepancy. We have corrected the cover letter submitted with the most recent version of the manuscript to identify Dr. Jonathan N Grauer as the corresponding author. The title page and PLOS One Editorial Manager page are now in agreement with the designation.

Corresponding Author:

Jonathan N. Grauer, M.D.

Professor of Orthopaedics & Rehabilitation; Associate Dean, Faculty Affairs; Director of Orthopaedic Spine Service, Orthopaedics & Rehabilitation

Department of Orthopaedics and Rehabilitation, Yale School of Medicine

800 Howard Avenue, New Haven, CT 06519, USA

Phone: 203-228-2622

Email: Jonathan.grauer@yale.edu

Abstract:

-Lines 47-48: “no prior study has investigated…”; however, in the Introduction, the authors cite references 5 & 23 (lines 114-117). Please modify the abstract, stating something like “Rare studies…” or “Scarce studies…” or something else.

Thank you for this comment. We agree that clarifying the existence of scarce studies as opposed to the previously stated no studies better reports the current state of the literature. To correct this statement, we have reframed the sentence to identify the scarcity of studies that exist in the literature and the importance of further examination of the subject. Below, we have included the modified sentence as it now reads. We thank the reviewer for bringing this to our attention.

One proposed benefit of fellowship training is decrease in complications, however, scarce studies has investigated the rates of medical and surgical complications for hip fracture patients between orthopedists from different fellowship backgrounds.

-Line 61: after reading the Methods and the Results chapters, “1994-2004” should be replaced by “1999-2004”. Also see my comments on percentages (9.43% -> 6.8%, 60.92% -> 22%) on Results/Table 1.

Thank you to the reviewer for their careful review. We agree the year included (1994) was an oversight in this line of text and should correctly read 1999. We have modified this year, and we have included the corrected sentence below for reference. We thank the reviewer for noting these important details.

An increasing number of hip fractures are being treated by trauma fellowship trained surgeons (9.43% in 1999-2004 to 60.92% in 2011-2016).

Manuscript

-Introduction:

-Line 95: replace “including” by “includes”.

-Lines 120-121: the statement should be mitigated, as references 5 & 23 studied this point.

Thank you to the reviewer for these comments. We agree the word “including” should be replaced by the word “includes”. We have made the respective change and provided the updated sentence as it reads below. Additionally, we agree with the point regarding the nature of the current literature on the relationship between fellowship training and post-operative complications. To add clarity, we have reframed the sentence to acknowledge the presence of research but more importantly highlight the insufficient evaluation that exists thus far. This paper and further papers are required to further understand the role of fellowship in the training of orthopaedic surgeons as it pertains to outcomes and complications. With this rationale, we have opted for the word “understudied” to highlight this point with the emphasis on this paper and future papers to continue to broaden the literature on this topic. We have included the updated sentence as it reads in the text now. We thank the reviewer for their comments.

Treatment for hip fractures varies from hospital to hospital, and often includes treatment by general orthopaedic surgeons, orthopaedic trauma surgeons, or other fellowship trained orthopaedic surgeons

Additionally, the act of fellowship training itself on post-operative complications remains understudied.

Materials and methods:

-Line 149: define the abbreviation “CPT” at its first appearance (line 149), not at its second appearance (Line 158).

Thank you to the reviewer for this comment. We agree with the importance of identifying abbreviations at their first appearance. We have modified the sentences accordingly to define the abbreviation in full at its first appearance and the removal of the definition in its previous location. We have provided the updated sentence as it now reads with the definition provided at its first appearance. We thank the reviewer for catching these details.

The list of procedures is logged by the applicant and includes a wide range of data including the applicant’s fellowship status, patient demographics (e.g. patient age and gender) and information about the procedure (e.g. Current Procedural Terminology (CPT) codes, and anesthetic, medical, and surgical complications).

-“Data” section: please define which states are included in each of the 6 regions. This might be obvious for US (and maybe Canadian) readers, but not for the rest of the world. As a non-US reviewer, I am for instance interested in incongruous/off-the-grid questions, such as: to which region belong Alaska and Hawaii? Were data from Puerto Rico, US Virgin Islands and other overseas territories included? This could be described in a Figure or a Table to save word count.

Thank you for this suggestion. We agree that this is helpful for a global audience. Below are the different regions and the associated states which we have put into a figure form and included in the text in line 181 and included as Figure 1:

Northeast - Connecticut, Massachusetts, Maine, New Hampshire, Rhode Island, Vermont, New Jersey, New York, Puerto Rico, Delaware, Maryland, Pennsylvania, DC

Southeast - Virginia, West Virginia, North Carolina, South Carolina, Florida, Georgia

South - Alabama, Kentucky, Mississippi, Tennessee, Arkansas, Louisiana, Texas

Southwest - New Mexico, Oklahoma, Arizona, California, Hawaii, Nevada, Colorado

Northwest - Alaska, Idaho, Oregon, Washington, Montana, North Dakota, South Dakota, Utah, Wyoming

Midwest - Iowa, Kansas, Nebraska, Missouri, Illinois, Indiana, Michigan, Minnesota, Ohio, Wisconsin

-“Data” section: “Number of cases completed by the candidate during…”. Does this number really reflect the volume? Might underestimation be possible? Please add a short statement about this issue, either in the M&M chapter, or in the limitation section.

Yes, this number should truly reflect volume. ABOS candidates are required to enter every surgical case from every hospital/surgery center in which they operate during the entire case collection period. If they fail to do this, they may be ineligible for certification. Further, hospitals submit their logs of all cases done and these must match. However, as the reviewer points out, there is always a possibility that case documentation could be missed. We have added this to the limitations section of the manuscript.

Results:

-I am a little bit surprised by the fact that the tiny differences in ages (82.2 +/- 8.2 vs. 82.8 +/- 7.8 vs. 82.6 +/- 7.8, Line 199) and gender repartition (71,6% female vs. 73.2% vs. 73.5%, Line 201) among different fellowship groups reaches statistical significance which such mighty p-values. I would simply ask the authors to double-check these results (this also applies to Table 1).

We sincerely thank this reviewer for their astute review of the manuscript’s tables and figures. The mean age and the standard deviation for each fellowship subgroup was re-checked, in addition to the accompanying ANOVA test p-value used to assess statistical significance. No difference was noted. This finding appears to be statistically significant likely due to the sheer size of the database utilized. However, we acknowledge that this finding is difficult to interpret and does not appear to have any meaningful clinical significance.

-Lines 201-204/Table 1:

1° see my comment on abstract Line 61.

This was corrected in the abstract per your suggestion. Thank you!

2° I think percentages in Table 1 should be corrected. For example: In years 1999-2004, 14954 procedures were performed (1016 + 1894 + 12044), meaning that Trauma fellowship trained surgeons performed 6.8% of the procedures (1016 out of 14954, not 1016 out of 10796), Adult reco 12.7% of the procedures (1894 out of 14954) and others 80.5% (12044 out of 14954). For years 2005-2010, my calculations result in 11.1%, 14% and 74.9% respectively. For years 2011-2016, 22%, 16.3% and 61.7% respectively; P-value should thus be recalculated, but the interpretative text is probably still ok.

Thank you for the thoughtful approach of how percentages should be calculated in Table 1 for the “year of procedure”. The decision to calculate percentages vertically (within each fellowship type), or horizontally (within each 5-year time period) was a difficult one that our research team debated for quite some time. We agree with your assessment, and have recalculated percentages and p-values accordingly and put a note at the bottom of the table. Notably, the P-value for this chi-square analysis remained significant (p<0.001). The interpretative text of this trend analysis will thus remain the same.

-Table 1:

1° I think after calculation that N for “Other” should be 51910 rather than 60612. However, percentages for the whole column seem to be generally correct:

Total N for Sex/Other, Year/Other and Procedure type/Other is 51910-ok;

Total N for Region/Other is 51643-please correct or add a line for “n.a. region” or “other region”.

P-values might have to be corrected.

2° Total N for Region/Trauma is 10710 and does not correspond to 10769: please correct or add a line for “n.a. region” or “other region”.

3° Total N for Region/Adult reco is 10732 and does not correspond to 10748: please correct or add a line for “n.a. region” or “other region”.

Thank you for the astute observations here. The N for the “Other” column has been adjusted, and the percentages have remained the same. A line for “Other” has been added to the region analysis. Notably, P-values have been recalculated, but remain the same in all instances (P<0.001), given the small amount of missing data.

-Table 2: I think after calculation that N for other should be 51910 rather than 60612. However, percentages for the whole column seem to be correct. P-values might have to be corrected.

Thank you once again for the astute observations. The N for the “Other” column has once again been adjusted, and the percentages have remained the same. The percentages and accompanying p-values were correct as initially stated and thus have not changed.

-Tables 3a and 3b: I think after calculation that N for other should be 51910 rather than 60612. However, percentages for the whole column seem to be correct. P-values might have to be corrected.

The same suggested changes for table 2 have been made for table 3 as well. Thank you!

Discussion:

-As long as corrections following my remarks on the Results section and Tables do not provoke unexpected changes in the interpretation of results, this section won’t need any corrections to be performed.

Given that the percentages and accompanying p-values were correct as initially stated and thus have not changed, the interpretation of the results has not changed either and has been left the same. Thank you for your help to make this manuscript the best it can be and pointing out important and necessary changes and edits. We appreciate it!

Reviewer #2:

Dear Authors,

Thank you very much for the opportunity to review this interesting manuscript. Authors could show decreased surgeon reported complications due to surgical volume. This is a nicely written paper. I would like to suggest to address the following issues in order to improve the quality of the manuscript.

Thank you so much for reviewing our manuscript and the resulting suggestions. We appreciate the reviewer taking the time to help make our manuscript the best it can be.

Introduction:

- Aims of the study were described.

Thank you!

Methods:

- Did all patients signed the informed consent?

The current study is using the American Board of Orthopaedic Surgeons (ABOS) dataset which is blinded data from across the country. All data entered into this database is done by ABOS examinees for which patients had to sign consent for the surgery and utilization of these details for reporting purposes.

- Do you need to have ethical approval to use this data?

Yes. The ABOS Research Committee approved the current study and the study was classified as exempt and received ethical approval by our institutional review board.

- Authors should note that the statistical analysis in big data is not always useful. Beside the regression analysis, other statistics has mainly a descriptive character.

Thank you for the comment. We agree that big data is not always useful, however, the current study tried to use the most appropriate statistical tests for the situation and to control for all available factors to try to give the most accurate interpretation of the data. We feel the findings support important training trends and the need for specialty specific fellowship exposure.

Results

- What about the time point of surgery? Is it known (< 24 h) or later?

Unfortunately this is a limitation of the dataset. It is not recorded at what time point the patient received surgery following the injury. This is a good question for future studies.

- The regression analysis is the main part of results.

Thank you for this comment. Due to the limited nature of the dataset, this analysis was the most complete statistical test to explore associations between data points.

Discussion

- Nice Discussion and description of limitations

Thank you for the feedback! We appreciate your support.

Submitted filename: PLOS_Response to Reviewer Geriatric Hip Manuscript.docx

Click here for additional data file.

20 Jan 2022

The Case for Decreased Surgeon-reported Complications Due to Surgical Volume and Fellowship Status in the Treatment of Geriatric Hip Fracture: An Analysis of the ABOS Database

PONE-D-21-28043R1

Dear Dr. Grauer,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Hans-Peter Simmen, M.D., Professor of Surgery

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

14 Feb 2022

PONE-D-21-28043R1

The Case for Decreased Surgeon-reported Complications Due to Surgical Volume and Fellowship Status in the Treatment of Geriatric Hip Fracture: An Analysis of the ABOS Database

Dear Dr. Grauer:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

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Thank you for submitting your work to PLOS ONE and supporting open access.

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on behalf of

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Academic Editor

PLOS ONE