Adolescent idiopathic scoliosis (AIS) is a 3-dimensional deformity of the spine with a reported prevalence of 0.47% to 5.2% in the pediatric population.1 Surgical management of AIS has the commonly accepted goals of arresting and correcting the spinal deformity while achieving spinal balance in the coronal and sagittal planes.2–7 Segmental spinal instrumentation with hybrid pedicle screw, hook, and/or wire constructs have become the common tools by which modern-day surgeons achieve the surgical goals of deformity correction and stabilization.2,3
Although the surgical management of AIS has uniform themes, a source of variability in North America is the training of the surgeons performing such procedures. Surgeons gain the expertise to manage complex pediatric spine deformity by (1) completing a pediatric orthopedic fellowship, preceded by an orthopedic surgery residency; (2) completing a spine fellowship, preceded by either an orthopedic surgery residency or a neurosurgical residency; or (3) acquiring the necessary skills during orthopedic or neurosurgical residency without formal subspecialty training. Vitale et al8 have demonstrated that training background may be correlated with AIS surgical volume in both New York and California, where surgeons with pediatric orthopedic fellowship training appear to perform a significantly greater number of posterior spine fusions for scoliosis than those without pediatric fellowship training. Although greater surgical volume can be correlated with lower morbidity rates in various orthopedic and nonorthopedic surgeries, no study has examined whether differences in training background can be associated with differences in early surgical outcomes for patients with AIS.9,10
This study used a national surgical quality data registry, the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP), to compare the 30-day morbidity and mortality for AIS patients receiving posterior spinal fusion (PSF) by surgeons with and without pediatric orthopedic fellowship training.
Materials and Methods
A retrospective review of the ACS NSQIP database for 2012 to 2016 was performed for this study. The Pediatric National Surgical Quality Improvement Project (P-NSQIP) is a subset of data collected from participating pediatric hospitals across the United States. Data collected and included for analysis include demographic data, medical comorbidities, procedures performed, surgeon data, complications, readmissions, and mortality during the initial 30-day postoperative period.
Patients from the P-NSQIP database were initially included for analysis if they underwent a PSF for AIS as determined by Current Procedural Terminology (CPT) codes 22800 (1–6 levels fused), 22802 (7–12 levels fused), and 22804 (13 or more levels fused). Additional inclusion criteria included (1) age at surgery between 10 and 18 years; (2) PSF as the primary procedure; and (3) complete demographic and morbidity and mortality data were available. Exclusion criteria included a nonidiopathic diagnosis, such as cerebral palsy or neuromuscular scoliosis, and the use of an anterior surgical approach. This group was then divided based on the sub-specialty training of the surgeon performing the procedure: pediatric orthopedic fellowship (ped+) or nonpediatric orthopedic fellowship (ped-).
A group of patients from the ped+ group was matched by age, sex, body mass index (BMI), race, and CPT code for number of levels fused to the patients in the ped- group. Outcome data of interest included mortality, wound infections, urinary tract infection (UTI), sepsis, pulmonary embolism (PE), blood loss and transfusion requirements, nerve injury, unplanned reoperation, and unplanned re-admission.
Statistical analysis was performed using SAS 9.3 (SAS Institute Inc, Cary, North Carolina). Continuous data were evaluated with a t test comparison and count data by chi-square contingency. Only variables with a P<.05 were considered significant.
A total of 14,194 patients were identified in the ACS NSQIP database as having undergone PSF for AIS between 2012 to 2016. Of these patients, 4780 met all inclusion and exclusion criteria. Pediatric-trained surgeons performed 4455 cases (ped+ group), and nonpediatric-trained surgeons performed 325 cases (ped-group). A cohort of 325 patients was selected from the ped+ group (ped+match group) and matched to the 325 patients from the ped- group. Demographic data of the groups are presented in Table 1, with no differences between ped+, ped+match, and ped- groups for all parameters, including age and ethnicity. The distribution of fusion levels between the 3 groups was also similar, with no significant differences identified (P=.43) (Table 2).
Demographics of the Study Population
Distribution of Levels Fused According to Group
Comparison of the ped+match group with the ped- group demonstrated that most perioperative adverse event (AE) parameters were similar between the 2 groups (Table 3). There was 1 (0.31%) superficial wound infection in the ped+match group and 2 (0.62%) in the ped- group, without significant difference in rates (P=.335). Two (0.62%) deep infections were noted in the ped+match group and 1 (0.31%) in the ped- group, without significant difference between groups (P=.335). There were no incidents of PE in either group and 1 (0.30%) UTI in each group (P=.998).
Early Complications After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis
No differences were noted between ped+match and ped- in terms of length of hospital stay or readmissions (Table 3). There were 5 (1.54%) unplanned returns to the operating room in each group (P=1.000), with no difference in average days until return to the operating room (ped+match=13.2 days vs ped-=5.4 days, P=.193). There were 4 (1.23%) unplanned readmissions in the ped+match group and 8 (2.46%) in the ped- group, without significant difference between groups (P=.583). No significant difference was noted for reported neurologic complications (ped+match=3 [0.92%] vs ped- group=2 [0.62%], P=.654).
Average blood loss in the ped+match group was significantly less than the ped-group (326±337 mL vs 516±517 mL, P<.001). The number of patients requiring transfusion was also significantly less in the ped+match group (207 [63.69%] vs 231 [71.08%], P=.045).
When compared with the ped- group, the complete group of patients treated by pediatric-trained surgeons (ped+) demonstrated significantly lower rates of transfusion (64.31% vs 71.08%, P<.01) and average volume of blood loss (230±449 mL vs 516±517 mL, P<.01). A significantly greater rate of neurologic injury was also noted for the ped- group when compared with the ped+ group (0.62% vs 0.09%, P<.01). However, a similar difference was noted when comparing the ped+ group with the ped+match group (0.09% vs 0.92%, P<.01). No significant differences between the ped+ group and ped- group were identified for rates of superficial infection, deep wound infection, reoperation, or unplanned readmissions.
Posterior spinal fusion for AIS is an invasive procedure that has myriad potential reported complications, inclusive of superficial wound infection, deep wound infection, neurologic injury, prolonged hospital stay, unanticipated readmission, and blood loss requiring transfusion.11–26 In North America, the treatment of AIS patients with PSF is tasked to physicians with varied surgical training backgrounds. The current study compared differences in early postoperative outcomes for patients operated on by surgeons with and without pediatric fellowship training.
The results demonstrated that the vast majority of AEs were similar between surgeons with and without pediatric fellowship training. Overall, pediatric fellowship training was not associated with differences in rates of superficial or deep wound infection (0.3% to 0.6%), UTI (0.3%), hospital stays greater than 30 days (0% to 0.1%), or reoperations (1.5% to 2.0%). Superficial or deep wound infection rates in the current study appear to be lower than the rates generally reported in the literature, which range from 1.4% to 8.5%.11,18,19,26–30 Such a difference in reported rates may result from the restriction of the P-NSQIP database to tertiary-level, high-volume children’s hospitals, which may have a more robust surgical experience and more developed, protocol/checklist-driven operating room processes.31 In addition, the current data set was collected from 2012 to 2016 and may therefore reflect the most recent advances in intraoperative and perioperative infection prevention, such as use of antibiotic powder in wounds.32
The data further verified that neurologic injury rates in PSF for AIS are generally low and were similar between surgeons with or without pediatric fellowship training. The overall neurologic complication rate in the current study was found to range from 0.09% to 0.92%, with no statistical difference between the matched cohort group (ped+match) and the group without pediatric fellowship training (ped-). The reported rate is consistent with previously published rates of 0.3% to 0.5% for PSF procedures.30,33 Interestingly, neurologic injury rates were significantly greater in the group with pediatric fellowship training as a whole than the ped+match and ped- groups. This identified difference may have little clinical significance because overall rates of such events are low. Further, without detailed information on the types of neurologic injury and the completeness of the injury, both of which represent data that are absent from P-NSQIP, one runs the risk of drawing conclusions based on clinical events that are not equivalent in severity.
Interestingly, the current data suggest that there is a significant difference in blood loss when comparing PSF surgeries performed by surgeons with pediatric fellowship training and those without. The ped- group had a significantly greater average blood loss volume and a significantly higher rate of transfusion than the group of patients treated by surgeons with pediatric training (ped+) or the matched cohort subset (ped+match). This difference in blood loss and transfusion rates between the 2 groups implies that surgeons with pediatric fellowship training may more effectively minimize intraoperative blood loss and decrease transfusion frequency than those without pediatric training. Although it is understood that objective factors such as curve magnitude, nonidiopathic scoliosis etiology, and number of levels fused are correlated with blood loss for scoliosis surgery, this is the first evidence to suggest that surgeon habit and training may heavily influence early postoperative outcome parameters.14,23,34–36
If one considers the myriad differences in surgeon behaviors that could potentially influence blood loss, spanning the gamut from soft tissue handling and bone preparation techniques to “acceptable” blood loss totals and “reasonable” transfusion triggers, the majority of differences may well be traced to the surgeon’s training. If surgical technique and algorithmic decision making learned by surgeons during their training has a significant role in the cumulative blood loss and transfusion rates, additional research may be valuable in identifying training differences and possibly standardizing the educational pathways for pediatric fellowship and nonpediatric fellowship spine surgeons.
There were several limitations to this study. First, this was a retrospective review of patients undergoing PSF for AIS and was subject to the potential inaccuracies and biases from information gathered in the ACS NSQIP database. Second, the ACS NSQIP database comprises participating institutions in the United States and may not be representative of all patients undergoing PSF for AIS or of all surgeons performing these procedures. There is a lack of data on specific surgeon training and the exact differences between pediatric-trained and non-pediatric-trained surgeons. Finally, the ACS NSQIP database does not identify preoperative curve magnitudes, despite allowing for stratification based on number of levels fused, and may confound both the results for blood loss as well as rates of neurologic injury. However, the reported transfusion rates, neurologic injury rates, and average blood loss values match the numbers available in literature for AIS, suggesting a degree of external consistency.22,34,37
This study had several strengths. Despite the potential limitations inherent to a national registry, other investigators have shown the ACS NSQIP database to be highly reliable, with an interobserver agreement of 98.4%.38 Further, the large number of patients in the current work allows for a strongly powered comparison of groups and the creation of a select, well-matched cohort according to patient and surgical parameters.
Examination of the ACS NSQIP database from 2012 to 2016 revealed that the frequency of postoperative AEs following PSF for AIS were mostly similar between surgeons with a variety of training backgrounds. However, surgeons with pediatric fellowship training performing PSF have a significantly lower average blood loss and a decreased need for allogeneic blood transfusion when compared with surgeons without such training. The data imply there may be intrinsic differences in the various training pathways for surgeons interested in pediatric spine deformity and that such differences in training may significantly impact early postoperative outcomes. Additional research should identify such training differences in the hopes of making more uniform the skill set of physicians managing pediatric spinal deformity.
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Demographics of the Study Populationa
|Age, mean±SD, y||14.3±1.8||14.2±1.7||14.2±1.7||.44|
|Height, mean±SD, in||62.3±4.8||62.2±4.2||62.3±4.5||.60|
|Weight, mean±SD, lb||123.4±37.1||122.3±33||124±34||.16|
|Body mass index, mean±SD, kg/m2||22.8±6.7||22.1±5.1||22.6±8.5||.79|
| Native American||13||2||2|
Distribution of Levels Fused According to Groupa,b
|Ped+ (n=4455)||Ped+Match (n=325)||Ped- (n=325)|
|1–6||225 (5.1%)||16 (4.9%)||16 (4.9%)|
|7–12||2957 (66.4%)||204 (62.8%)||204 (62.8%)|
|≥13||1273 (28.6%)||105 (32.3%)||105 (32.3%)|
Early Complications After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosisa
|Complication||Ped+ (n=4455)||Ped+Match (n=325)||Ped- (n=325)||Pb|
|Superficial infection, No.||28 (0.63%)||1 (0.31%)||2 (0.62%)||.335|
|Deep infection, No.||23 (0.52%)||2 (0.62%)||1 (0.31%)||.335|
|Neurologic injury, No.||4 (0.09%)||3 (0.92%)||2 (0.62%)||.654|
|Pulmonary embolism, No.||0||0||0||NA|
|Urinary tract infection, No.||14 (0.31%)||1 (0.31%)||1 (0.31%)||.998|
|Systemic infection, No.||13 (0.29%)||1 (0.31%)||0||NA|
|Death, No.||1 (0.02%)||0||0||NA|
|Hospital stay >30 d, No.||3 (0.07%)||0||0||NA|
|Reoperation, No.||87 (1.95%)||5 (1.54%)||5 (1.54%)||1.000|
|Unplanned readmission, No.||97 (2.18%)||4 (1.23%)||8 (2.46%)||.583|
|Time from initial surgery to reoperation, mean±SD, d||13.1±8.8||13.2±10.8||5.4±4.2||.193|
|Time from initial surgery to readmission, mean±SD, d||14.5±13.8||22.8±2.4||15.2±3.1||.085|
|Length of stay, mean±SD, d||5.5±9.1||5.5±8.8||5.5±4.7||.842|
|Patients requiring transfusion, No.||2865 (64.31%)||207 (63.69%)||231 (71.08%)||.045c|
|Blood loss, mean±SD, mL||230±449||326±337||516±517||<.001c|