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Justin K. Scheer, Taemin Oh, Justin S. Smith, Christopher I. Shaffrey, Alan H. Daniels, Daniel M. Sciubba, D. Kojo Hamilton, Themistocles S. Protopsaltis, Peter G. Passias, Robert A. Hart, Douglas C. Burton, Shay Bess, Renaud Lafage, Virginie Lafage, Frank Schwab, Eric O. Klineberg, Christopher P. Ames and the International Spine Study Group

OBJECTIVE

Pseudarthrosis can occur following adult spinal deformity (ASD) surgery and can lead to instrumentation failure, recurrent pain, and ultimately revision surgery. In addition, it is one of the most expensive complications of ASD surgery. Risk factors contributing to pseudarthrosis in ASD have been described; however, a preoperative model predicting the development of pseudarthrosis does not exist. The goal of this study was to create a preoperative predictive model for pseudarthrosis based on demographic, radiographic, and surgical factors.

METHODS

A retrospective review of a prospectively maintained, multicenter ASD database was conducted. Study inclusion criteria consisted of adult patients (age ≥ 18 years) with spinal deformity and surgery for the ASD. From among 82 variables assessed, 21 were used for model building after applying collinearity testing, redundancy, and univariable predictor importance ≥ 0.90. Variables included demographic data along with comorbidities, modifiable surgical variables, baseline coronal and sagittal radiographic parameters, and baseline scores for health-related quality of life measures. Patients groups were determined according to their Lenke radiographic fusion type at the 2-year follow-up: bilateral or unilateral fusion (union) or pseudarthrosis (nonunion). A decision tree was constructed, and internal validation was accomplished via bootstrapped training and testing data sets. Accuracy and the area under the receiver operating characteristic curve (AUC) were calculated to evaluate the model.

RESULTS

A total of 336 patients were included in the study (nonunion: 105, union: 231). The model was 91.3% accurate with an AUC of 0.94. From 82 initial variables, the top 21 covered a wide range of areas including preoperative alignment, comorbidities, patient demographics, and surgical use of graft material.

CONCLUSIONS

A model for predicting the development of pseudarthrosis at the 2-year follow-up was successfully created. This model is the first of its kind for complex predictive analytics in the development of pseudarthrosis for patients with ASD undergoing surgical correction and can aid in clinical decision-making for potential preventative strategies.

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Emily K. Miller, Brian J. Neuman, Amit Jain, Alan H. Daniels, Tamir Ailon, Daniel M. Sciubba, Khaled M. Kebaish, Virginie Lafage, Justin K. Scheer, Justin S. Smith, Shay Bess, Christopher I. Shaffrey, Christopher P. Ames and the International Spine Study Group

OBJECTIVE

The goal of this study was to analyze the value of an adult spinal deformity frailty index (ASD-FI) in preoperative risk stratification. Preoperative risk assessment is imperative before procedures known to have high complication rates, such as ASD surgery. Frailty has been associated with risk of complications in trauma surgery, and preoperative frailty assessments could improve the accuracy of risk stratification by providing a comprehensive analysis of patient factors that contribute to an increased risk of complications.

METHODS

Using 40 variables, the authors calculated frailty scores with a validated method for 417 patients (enrolled between 2010 and 2014) with a minimum 2-year follow-up in an ASD database. On the basis of these scores, the authors categorized patients as not frail (NF) (< 0.3 points), frail (0.3–0.5 points), or severely frail (SF) (> 0.5 points). The correlation between frailty category and incidence of complications was analyzed.

RESULTS

The overall mean ASD-FI score was 0.33 (range 0.0–0.8). Compared with NF patients (n = 183), frail patients (n = 158) and SF patients (n = 109) had longer mean hospital stays (1.2 and 1.6 times longer, respectively; p < 0.001). The adjusted odds of experiencing a major intraoperative or postoperative complication were higher for frail patients (OR 2.8) and SF patients ( 4.1) compared with NF patients (p < 0.01). For frail and SF patients, respectively, the adjusted odds of developing proximal junctional kyphosis (OR 2.8 and 3.1) were higher than those for NF patients. The SF patients had higher odds of developing pseudarthrosis (OR 13.0), deep wound infection (OR 8.0), and wound dehiscence (OR 13.4) than NF patients (p < 0.05), and they had 2.1 times greater odds of reoperation (p < 0.05).

CONCLUSIONS

Greater patient frailty, as measured by the ASD-FI, was associated with worse outcome in many common quality and value metrics, including greater risk of major complications, proximal junctional kyphosis, pseudarthrosis, deep wound infection, wound dehiscence, reoperation, and longer hospital stay.

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David B. Bumpass, Lawrence G. Lenke, Jeffrey L. Gum, Christopher I. Shaffrey, Justin S. Smith, Christopher P. Ames, Shay Bess, Brian J. Neuman, Eric Klineberg, Gregory M. Mundis Jr., Frank Schwab, Virginie Lafage, Han Jo Kim, Douglas C. Burton, Khaled M. Kebaish, Richard Hostin, Renaud Lafage, Michael P. Kelly and for the International Spine Study Group

OBJECTIVE

Adolescent spine deformity studies have shown that male patients require longer surgery and have greater estimated blood loss (EBL) and complications compared with female patients. No studies exist to support this relationship in adult spinal deformity (ASD). The purpose of this study was to investigate associations between sex and complications, deformity correction, and health-related quality of life (HRQOL) in patients with ASD. It was hypothesized that male ASD patients would have greater EBL, longer surgery, and more complications than female ASD patients.

METHODS

A multicenter ASD cohort was retrospectively queried for patients who underwent primary posterior-only instrumented fusions with a minimum of 5 levels fused. The minimum follow-up was 2 years. Primary outcomes were EBL, operative time, intra-, peri-, and postoperative complications, radiographic correction, and HRQOL outcomes (Oswestry Disability Index, SF-36, and Scoliosis Research Society-22r Questionnaire). Poisson multivariate regression was used to control for age, comorbidities, and levels fused.

RESULTS

Ninety male and 319 female patients met the inclusion criteria. Male patients had significantly greater mean EBL (2373 ml vs 1829 ml, p = 0.01). The mean operative time, transfusion requirements, and final radiographic measurements did not differ between sexes. Similarly, changes in HRQOL showed no significant differences. Finally, there were no sex differences in the incidence of complications (total, major, or minor) at any time point after controlling for age, body mass index, comorbidities, and levels fused.

CONCLUSIONS

Despite higher EBL, male ASD patients did not experience more complications or require less deformity correction at the 2-year follow-up. HRQOL scores similarly showed no sex differences. These findings differ from adolescent deformity studies, and surgeons can counsel patients that sex is unlikely to influence the outcomes and complication rates of primary all-posterior ASD surgery.

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Taemin Oh, Justin K. Scheer, Justin S. Smith, Richard Hostin, Chessie Robinson, Jeffrey L. Gum, Frank Schwab, Robert A. Hart, Virginie Lafage, Douglas C. Burton, Shay Bess, Themistocles Protopsaltis, Eric O. Klineberg, Christopher I. Shaffrey, Christopher P. Ames and the International Spine Study Group

OBJECTIVE

Patients with adult spinal deformity (ASD) experience significant quality of life improvements after surgery. Treatment, however, is expensive and complication rates are high. Predictive analytics has the potential to use many variables to make accurate predictions in large data sets. A validated minimum clinically important difference (MCID) model has the potential to assist in patient selection, thereby improving outcomes and, potentially, cost-effectiveness.

METHODS

The present study was a retrospective analysis of a multiinstitutional database of patients with ASD. Inclusion criteria were as follows: age ≥ 18 years, radiographic evidence of ASD, 2-year follow-up, and preoperative Oswestry Disability Index (ODI) > 15. Forty-six variables were used for model training: demographic data, radiographic parameters, surgical variables, and results on the health-related quality of life questionnaire. Patients were grouped as reaching a 2-year ODI MCID (+MCID) or not (−MCID). An ensemble of 5 different bootstrapped decision trees was constructed using the C5.0 algorithm. Internal validation was performed via 70:30 data split for training/testing. Model accuracy and area under the curve (AUC) were calculated. The mean quality-adjusted life years (QALYs) and QALYs gained at 2 years were calculated and discounted at 3.5% per year. The QALYs were compared between patients in the +MCID and –MCID groups.

RESULTS

A total of 234 patients met inclusion criteria (+MCID 129, −MCID 105). Sixty-nine patients (29.5%) were included for model testing. Predicted versus actual results were 50 versus 40 for +MCID and 19 versus 29 for −MCID (i.e., 10 patients were misclassified). Model accuracy was 85.5%, with 0.96 AUC. Predicted results showed that patients in the +MCID group had significantly greater 2-year mean QALYs (p = 0.0057) and QALYs gained (p = 0.0002).

CONCLUSIONS

A successful model with 85.5% accuracy and 0.96 AUC was constructed to predict which patients would reach ODI MCID. The patients in the +MCID group had significantly higher mean 2-year QALYs and QALYs gained. This study provides proof of concept for using predictive modeling techniques to optimize patient selection in complex spine surgery.

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Justin S. Smith, Christopher I. Shaffrey, Eric Klineberg, Virginie Lafage, Frank Schwab, Renaud Lafage, Han Jo Kim, Richard Hostin, Gregory M. Mundis Jr., Munish Gupta, Barthelemy Liabaud, Justin K. Scheer, Bassel G. Diebo, Themistocles S. Protopsaltis, Michael P. Kelly, Vedat Deviren, Robert Hart, Doug Burton, Shay Bess and Christopher P. Ames

OBJECTIVE

Although 3-column osteotomy (3CO) can provide powerful alignment correction in adult spinal deformity (ASD), these procedures are complex and associated with high complication rates. The authors' objective was to assess complications associated with ASD surgery that included 3CO based on a prospectively collected multicenter database.

METHODS

This study is a retrospective review of a prospectively collected multicenter consecutive case registry. ASD patients treated with 3CO and eligible for 2-year follow-up were identified from a prospectively collected multicenter ASD database. Early (≤ 6 weeks after surgery) and delayed (> 6 weeks after surgery) complications were collected using standardized forms and on-site coordinators.

RESULTS

Of 106 ASD patients treated with 3CO, 82 (77%; 68 treated with pedicle subtraction osteotomy [PSO] and 14 treated with vertebral column resection [VCR]) had 2-year follow-up (76% women, mean age 60.7 years, previous spine fusion in 80%). The mean number of posterior fusion levels was 12.9, and 17% also had an anterior fusion. A total of 76 early (44 minor, 32 major) and 66 delayed (13 minor, 53 major) complications were reported, with 41 patients (50.0%) and 45 patients (54.9%) affected, respectively. Overall, 64 patients (78.0%) had at least 1 complication, and 50 (61.0%) had at least 1 major complication. The most common complications were rod breakage (31.7%), dural tear (20.7%), radiculopathy (9.8%), motor deficit (9.8%), proximal junctional kyphosis (PJK, 9.8%), pleural effusion (8.5%), and deep wound infection (7.3%). Compared with patients who did not experience early or delayed complications, those who had these complications did not differ significantly with regard to age, sex, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists score, smoking status, history of previous spine surgery or spine fusion, or whether the 3CO performed was a PSO or VCR (p ≥ 0.06). Twenty-seven (33%) patients had 1–11 reoperations (total of 44 reoperations). The most common indications for reoperation were rod breakage (n = 14), deep wound infection (n = 15), and PJK (n = 6). The 24 patients who did not achieve 2-year follow-up had a mean of 0.85 years of follow-up, and the types of early and delayed complications encountered in these 24 patients were comparable to those encountered in the patients that achieved 2-year follow-up.

CONCLUSIONS

Among 82 ASD patients treated with 3CO, 64 (78.0%) had at least 1 early or delayed complication (57 minor, 85 major). The most common complications were instrumentation failure, dural tear, new neurological deficit, PJK, pleural effusion, and deep wound infection. None of the assessed demographic or surgical parameters were significantly associated with the occurrence of complications. These data may prove useful for surgical planning, patient counseling, and efforts to improve the safety and cost-effectiveness of these procedures.

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Justin K. Scheer, Justin S. Smith, Frank Schwab, Virginie Lafage, Christopher I. Shaffrey, Shay Bess, Alan H. Daniels, Robert A. Hart, Themistocles S. Protopsaltis, Gregory M. Mundis Jr., Daniel M. Sciubba, Tamir Ailon, Douglas C. Burton, Eric Klineberg, Christopher P. Ames and The International Spine Study Group

OBJECTIVE

The operative management of patients with adult spinal deformity (ASD) has a high complication rate and it remains unknown whether baseline patient characteristics and surgical variables can predict early complications (intraoperative and perioperative [within 6 weeks]). The development of an accurate preoperative predictive model can aid in patient counseling, shared decision making, and improved surgical planning. The purpose of this study was to develop a model based on baseline demographic, radiographic, and surgical factors that can predict if patients will sustain an intraoperative or perioperative major complication.

METHODS

This study was a retrospective analysis of a prospective, multicenter ASD database. The inclusion criteria were age ≥ 18 years and the presence of ASD. In total, 45 variables were used in the initial training of the model including demographic data, comorbidities, modifiable surgical variables, baseline health-related quality of life, and coronal and sagittal radiographic parameters. Patients were grouped as either having at least 1 major intraoperative or perioperative complication (COMP group) or not (NOCOMP group). An ensemble of decision trees was constructed utilizing the C5.0 algorithm with 5 different bootstrapped models. Internal validation was accomplished via a 70/30 data split for training and testing each model, respectively. Overall accuracy, the area under the receiver operating characteristic (AUROC) curve, and predictor importance were calculated.

RESULTS

Five hundred fifty-seven patients were included: 409 (73.4%) in the NOCOMP group, and 148 (26.6%) in the COMP group. The overall model accuracy was 87.6% correct with an AUROC curve of 0.89 indicating a very good model fit. Twenty variables were determined to be the top predictors (importance ≥ 0.90 as determined by the model) and included (in decreasing importance): age, leg pain, Oswestry Disability Index, number of decompression levels, number of interbody fusion levels, Physical Component Summary of the SF-36, Scoliosis Research Society (SRS)–Schwab coronal curve type, Charlson Comorbidity Index, SRS activity, T-1 pelvic angle, American Society of Anesthesiologists grade, presence of osteoporosis, pelvic tilt, sagittal vertical axis, primary versus revision surgery, SRS pain, SRS total, use of bone morphogenetic protein, use of iliac crest graft, and pelvic incidence–lumbar lordosis mismatch.

CONCLUSIONS

A successful model (87% accuracy, 0.89 AUROC curve) was built predicting major intraoperative or perioperative complications following ASD surgery. This model can provide the foundation toward improved education and point-of-care decision making for patients undergoing ASD surgery.

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Alexander A. Theologis, Gregory M. Mundis Jr., Stacie Nguyen, David O. Okonkwo, Praveen V. Mummaneni, Justin S. Smith, Christopher I. Shaffrey, Richard Fessler, Shay Bess, Frank Schwab, Bassel G. Diebo, Douglas Burton, Robert Hart, Vedat Deviren and Christopher Ames

OBJECTIVE

The aim of this study was to evaluate the utility of supplementing long thoracolumbar posterior instrumented fusion (posterior spinal fusion, PSF) with lateral interbody fusion (LIF) of the lumbar/thoracolumbar coronal curve apex in adult spinal deformity (ASD).

METHODS

Two multicenter databases were evaluated. Adults who had undergone multilevel LIF of the coronal curve apex in addition to PSF with L5–S1 interbody fusion (LS+Apex group) were matched by number of posterior levels fused with patients who had undergone PSF with L5–S1 interbody fusion without LIF (LS-Only group). All patients had at least 2 years of follow-up. Percutaneous PSF and 3-column osteotomy (3CO) were excluded. Demographics, perioperative details, radiographic spinal deformity measurements, and HRQoL data were analyzed.

RESULTS

Thirty-two patients were matched (LS+Apex: 16; LS: 16) (6 men, 26 women; mean age 63 ± 10 years). Overall, the average values for measures of deformity were as follows: Cobb angle > 40°, sagittal vertical axis (SVA) > 6 cm, pelvic tilt (PT) > 25°, and mismatch between pelvic incidence (PI) and lumbar lordosis (LL) > 15°. There were no significant intergroup differences in preoperative radiographic parameters, although patients in the LS+Apex group had greater Cobb angles and less LL. Patients in the LS+Apex group had significantly more anterior levels fused (4.6 vs 1), longer operative times (859 vs 379 minutes), and longer length of stay (12 vs 7.5 days) (all p < 0.01). For patients in the LS+Apex group, Cobb angle, pelvic tilt (PT), lumbar lordosis (LL), PI-LL (lumbopelvic mismatch), Oswestry Disability Index (ODI) scores, and visual analog scale (VAS) scores for back and leg pain improved significantly (p < 0.05). For patients in the LS-Only group, there were significant improvements in Cobb angle, ODI score, and VAS scores for back and leg pain. The LS+Apex group had better correction of Cobb angles (56% vs 33%, p = 0.02), SVA (43% vs 5%, p = 0.46), LL (62% vs 13%, p = 0.35), and PI-LL (68% vs 33%, p = 0.32). Despite more LS+Apex patients having major complications (56% vs 13%; p = 0.02) and postoperative leg weakness (31% vs 6%, p = 0.07), there were no intergroup differences in 2-year outcomes.

CONCLUSIONS

Long open posterior instrumented fusion with or without multilevel LIF is used to treat a variety of coronal and sagittal adult thoracolumbar deformities. The addition of multilevel LIF to open PSF with L5–S1 interbody support in this small cohort was often used in more severe coronal and/or lumbopelvic sagittal deformities and offered better correction of major Cobb angles, lumbopelvic parameters, and SVA than posterior-only operations. As these advantages came at the expense of more major complications, more leg weakness, greater blood loss, and longer operative times and hospital stays without an improvement in 2-year outcomes, future investigations should aim to more clearly define deformities that warrant the addition of multilevel LIF to open PSF and L5–S1 interbody fusion.