Prospective Multicenter Adult Spinal Deformity Research Articles

The T4-L1-Hip Axis: Sagittal Spinal Realignment Targets in Long-Construct Adult Spinal Deformity Surgery: Early Impact.

Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch. A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age. The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year. We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Influence of smoking on patient-reported outcome measures (PROMs) in patients undergoing surgery for adult spinal deformity: a propensity score-matched analysis.

The purpose of this study was to determine the isolated influence of smoking in patient-reported outcome measures (PROMs) for adult spinal deformity (ASD) surgery excluding known tobacco-related complications. Retrospective analysis of a prospective multicenter ASD database. Patients operated on ASD with 2year post-operative follow-up were included. Former smokers (non-active smokers) and patients developing mechanical or infectious complications were excluded. Changes of PROMs over time were analyzed using mixed models for repeated measures (MMRM). Propensity score matching (PSM) (1:1 ratio, caliper 0.10) was performed without replacement using optimum algorithm, tolerance ≤ 0.001, and estimated with 95% confidence interval (CI). PROMS in both groups were compared by paired t test or Wilcoxon signed-rank test. 692 out of 1246 surgical patients met our inclusion criteria. 153 smokers were matched with 153 non-smokers according to age, BMI, number of fused levels, and global tilt. After PSM both groups were homogeneous regarding baseline parameters, surgical data, and complications (mechanical complications and infection excluded). Smokers had worse baseline results for SRS-total, SRS-pain COMI-back, and ODI; smokers also showed worse 2-year outcomes for SRS-total, SRS-function, SRS-pain, SRS-self-image, and ODI. However, no differences between the two groups were found in the improvement from baseline to 2-year follow-up or in the timing of this improvement (MMRM). The proportion of patients reaching the minimal clinically important difference (MCID) after surgery was similar in the two groups, but the proportion of patients reaching patient acceptable symptom state (PASS) was significantly lower in smokers for SRS-Subtotal, SRS-function, and SRS-image. Even in the absence of smoking-related complications, smokers had worse PROMs at baseline and 2 years after surgery with less patients achieving PASS, but similar degrees on improvement compared to non-smokers. The proportion achieving MCID was also similar between the two cohorts.

143. Determining the best vertebra for measuring pelvic incidence and spinopelvic parameters in transitional anatomy

<h3>BACKGROUND CONTEXT</h3> Sacralization of L5 is a condition that affects 15% of the population. Because of the increased L5 articulations to the sacrum, it is unclear how pelvic incidence and spinopelvic parameters should be measured. <h3>PURPOSE</h3> Determine whether patients with L5 sacralization should be radiographically measured with relation to the L5 or S1 vertebrae. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis. <h3>PATIENT SAMPLE</h3> Prospective multicenter adult spinal deformity database. <h3>OUTCOME MEASURES</h3> ODI, SF36 PCS, radiographic spinopelvic parameters. <h3>METHODS</h3> Linear regression modeling was used to determine normative TPA and PI-LL based on PI and age in a database of asymptomatic subjects. In an adult spinal deformity database, patients with radiographic evidence of L5 sacralization, had PI, LL and TPA measured from the superior endplate S1 and then also from L5. Patients with instrumentation below L4 at baseline were excluded. The differences in TPA and PI-LL from normative were calculated in the sacralization cohort relative to L5 and S1 and correlated to ODI. Patients were grouped based on PI-LL Schwab modifier (0, +, ++) utilizing their L5 PI-LL and S1 PI-LL. Baseline ODI and SF36 PCS were compared across and within groups and their respective SRS Schwab class. <h3>RESULTS</h3> Among 1,179 ASD patients, 276 (23.4%) had transitional anatomy, 176 with sacralized L5 (14.9%) and 100 (8.48%) with lumbarization of S1. The 176 with sacralized L5 were analyzed. PI (24.5 ± 11.0 vs 55.7 ± 12.0, p=0.001), TPA (11.2 ± 12.0 vs 20.3 ± 12.5, p=0.001) and PI-LL (0.67 ± 21.1 vs 11.4 ± 20.8, p=0.001) measured utilizing the L5 superior endplate were significantly smaller than those who were measured relative to S1. When measured from S1, 76 (43. %) of patients were SRS Schwab 0, 45 (25.6%) were Class +, and 55 (31.3%) were class ++ compared to 124 (70.5%), 22 (12.5%), and 30 (17.0%) measured from L5 respectively. There were significant differences in ODI and PCS as the Schwab grade increased regardless of L5 or S1 measurement. The L5 group had higher PCS functional scores for Schwab 0 and ++ relative to same grades in the S1 group. Offset from normative TPA (0.5 ± 11.1 vs 9.6 ± 10.8, p=0.001) and PI-LL (0.67 ± 21.1 vs 11.4 ± 20.8, p=0.001) were smaller when measuring from L5. Moreover, S1 measurements were more correlated with disability by ODI (TPA offset from normative, S1: R=0.326 vs L5: R=0.285; PI-LL Offset from normative, S1: R=0.318 vs L5: R=0.274). <h3>CONCLUSIONS</h3> Measuring the PI at L5 in sacralized anatomy results in underestimating the PILL Schwab grade in a percentage of patients and less correlation with HRQLs. Patients with sacralized L5s should have spinopelvic parameters measured relative to S1. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P28. Complication rates following adult spinal deformity surgery: the category of complication dictates timing

<h3>BACKGROUND CONTEXT</h3> Adult spinal deformity (ASD) is a complex pathology associated with high complication rates. Although complication rates have been previously reported, the interplay between timing and type of complications has not been fully analyzed. <h3>PURPOSE</h3> Provide benchmarks for the rates of complications by type and timing. <h3>STUDY DESIGN/SETTING</h3> Prospective multicenter database. <h3>PATIENT SAMPLE</h3> Operatively treated ASD patients with 2-year follow-up. <h3>OUTCOME MEASURES</h3> Rates of medical complications (cardiac, GI, infection, pulmonary, renal) and surgical complications (implant-related, operative, neurologic, radiographic) within 2 years postsurgery <h3>METHODS</h3> In the context of a prospective multicenter ASD database, standardized forms were used to collect data on surgery-related complications. Onsite research coordinators and central auditing helped ensure data capture completeness. Inclusion criteria were age >18 years, ASD and minimum 2-year follow-up. Date and type of complication were collected and classified into three severity groups (minor, major, major leading to reoperation). Only complications occurring before the 2-year visit were retained for analysis. <h3>RESULTS</h3> A total of 997 out of 1,260 patients eligible for 2-year follow-up (79.1%) were captured. The mean age at the time of surgery was 60.4yo±14.3, 76.3% were female and 50.5% had a history of previous spine surgery. The vast majority of patients (98.9%) had treatment including a posterior procedure, 57.9% had decompression, 71.2% had at least one osteotomy, and 18.1% had a 3-column osteotomy. Interbody fusion (IBF) was used in 64.0%: 48.7% posterior (TLIF or PLIF), 38.3% anterior (ALIF) and 23.2% lateral (LLIF). The mean ASD surgical invasiveness index was 88.8±36.1; 66.3% of the patients were admitted postop to the ICU, with a median overall length of hospital stay of 7 days (IQR 5 to 9). The overall complication rate was 67.4% (N=672). A total of 247 patients (24.8%) experienced at least one complication the day of surgery (including intraoperatively), 359 (36.0%) between POD1 and 6-weeks postoperatively, 271 (27.2%) between 6 weeks and 1-year postoperatively, and finally 162 (16.3%) between 1- and 2-years postoperatively. Using Kaplan-Meier survival analysis, the rate of remaining complication-free was estimated at 70.9% by POD1, 59.0% by POD7, 51.4% by 30 days, 47.4% by 3 months, and 33.6% by 2-years postoperatively. Breakdown by severity of remaining complication-free revealed the following rates for minor | major | reop: by POD1=87.3% | 90.1% | 97.4%; by POD7=78.4% | 86.8% | 95.8%; by 3 months=71.6% | 81.0% | 86.7%; by 6 months = 70.3% | 80.1% | 86.7%; and by 2-years postop=64.5% | 75.1% | 77.0%. Stratification by type of complication demonstrated that most of the medical complications occurred within the first 60 days. Surgical complications followed two types of behavior: operative, wound and infection occurred early (within 60 days), while implant-related and radiographic complications happened at a constant rate over the 2-year period. Neurologic complications had a high occurrence with the first 60 days, followed by a continuous increase up to the 2-year visit. <h3>CONCLUSIONS</h3> Only one-third of ASD patients remained complication-free 2-years postoperatively. Two patients out of ten had a complication requiring a reoperation/revision. Estimation of timing and type of complication associated with surgical treatment is crucial when counseling patients and planning treatment cost-effectiveness. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

49. The impact of sagittal alignment on disability decreases after surgery as other factors become more influential: series of 925 patients with two-year follow-up

<h3>BACKGROUND CONTEXT</h3> The relationship of sagittal malalignment to outcomes has been emphasized in adult spinal deformity (ASD) surgery and it is known that sagittal parameters have some correlation to HRQOL measures overall. However, the specific relationship of HRQOL to postop sagittal alignment and changes in the strength of the relationship from preop to postop for deformity surgery has not been well defined. <h3>PURPOSE</h3> To determine how postop health-related quality of life (HRQOL) correlates to sagittal alignment. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis of a large prospective multicenter ASD database. <h3>PATIENT SAMPLE</h3> This study included 925 ASD patients. <h3>OUTCOME MEASURES</h3> HRQOL: Oswestry Disability Index (ODI), Short-Form-36 (SF-36), and Scoliosis Research Society-22r (SRS-22r). Radiographic sagittal alignment thresholds for C7-S1 sagittal vertical axis (SVA), pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL). <h3>METHODS</h3> Adult (=18yrs), Cobb angle=20°, SVA=5cm, PT=25°, and/or thoracic kyphosis=60°, 2-yr follow up. Pts were grouped by having met 2/3 of the sagittal alignment thresholds (SVA,PT, and/or PI-LL) at 2 years postop for either the SRS-Schwab values (+SS0) or age-adjusted values (+AGE). The age-adjusted values were calculated within +/-10 years of their actual age. The groups –SS0 and –AGE were patients who didn't meet 2/3 of the SRS-Schwab or the age-adjusted values, respectively. Baseline/2-year HRQOL were evaluated via linear regression for all groups based on 2-year correction. <h3>RESULTS</h3> Total 925 pts, mean age 60.1±14.2yrs, 602(65.1%)+SS0, 323(35.9%)-SS0, 199(21.5%)+AGE, and 283(30.6%)–AGE pts. The remaining age-adjusted pts were either overcorrected or did not have 2/3 sagittal values matched (n=443). All pts had significant improvement in all HRQOL at 2 years and for each of the subgroups (p <0.001 for all). The overall baseline R2 values for all pts for SVA, PI-LL and PT with ODI were (0.110, 0.072, 0.043, respectively) and at 2 years they were lower (0.049, 0.016, 0.008, respectively). Of the pts with pelvic fixation (n=635,68.6%), the same 2-year R2 values increased slightly but were still very weak (0.058, 0.028, 0.021, respectively). Of the pts who developed PJK, the 2-year R2 values were (PJK: 0.007, 0.024, 0.004, noPJK: 0.057, 0.017, 0.006, respectively). This same trend of low values was observed in +/-SS0 and +/-AGE pts. However, the R2 for 2-year ODI vs MCS, SRS appearance, and SRS mental, increased postop (0.19, 0.43, 0.22, respectively) compared with preop (0.17, 0.25, 0.17, respectively). <h3>CONCLUSIONS</h3> Sagittal alignment correlates weakly with preop HRQOL and postop HRQOL is improved. Preop SVA explains only 11% of preop ODI scores based on the R2 value and this decreases postop to 5%. After alignment correction, other patient factors become increasingly important such as the relationship between ODI and SRS appearance, SRS mental, and MCS. More work is necessary to better understand the postop HRQOL relationships including the possibility of a better measurement tool for surgical success. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Evolution of Proximal Junctional Kyphosis and Proximal Junctional Failure Rates Over 10 Years of Enrollment in a Prospective Multicenter Adult Spinal Deformity Database.

Retrospective cohort study. The aim of this study was to investigate the evolution of proximal junctional kyphosis (PJK) rate over 10-year enrollment period within a prospective database. PJK is a common complication following adult spinal deformity (ASD) surgery and has been intensively studied over the last decade. Patients with instrumentation extended to the pelvis and minimum 2-year follow-up were included. To investigate evolution of PJK/proximal junctional failure (PJF) rate, a moving average of 321 patients was calculated across the enrollment period. Logistic regression was used to investigate the association between the date of surgery (DOS) and PJK and/or PJF. Comparison of PJK/PJF rates, demographics, and surgical strategies was performed between the first and second half of the cohort. A total of 641 patients met inclusion criteria (age: 64±10 years, 78.2% female, body mass index: 28.3±5.7). The overall rate of radiographic PJK at 2 years was 47.9%; 12.9% of the patients developed PJF, with 31.3% being revised within 2-year follow-up. Stratification by DOS produced two halves. Between these two periods, rate of PJK and PJF demonstrated nonsignificant decrease (50.3%-45.5%, P =0.22) and (15.0%-10.9%, P =0.12), respectively. Linear interpolation suggested a decrease of 1.2% PJK per year and 1.0% for PJF. Patients enrolled later in the study were older and more likely to be classified as pure sagittal deformity ( P <0.001). There was a significant reduction in the use of three-column osteotomies ( P <0.001), an increase in anterior longitudinal ligament release ( P <0.001), and an increase in the use of PJK prophylaxis (31.3% vs 55.1%). Logistical regression demonstrated no significant association between DOS and radiographic PJK ( P =0.19) or PJF ( P =0.39). Despite extensive research examining risk factors for PJK/PJF and increasing utilization of intraoperative PJK prophylaxis techniques, the rate of radiographic PJK and/or PJF did not significantly decrease across the 10-year enrollment period of this ASD database.

Multicenter assessment of outcomes and complications associated with transforaminal versus anterior lumbar interbody fusion for fractional curve correction.

Few studies have compared fractional curve correction after long fusion between transforaminal lumbar interbody fusion (TLIF) and anterior lumbar interbody fusion (ALIF) for adult symptomatic thoracolumbar/lumbar scoliosis (ASLS). The objective of this study was to compare fractional correction, health-related quality of life (HRQL), and complications associated with L4-S1 TLIF versus those of ALIF as an operative treatment of ASLS. The authors retrospectively analyzed a prospective multicenter adult spinal deformity database. Inclusion required a fractional curve ≥ 10°, a thoracolumbar/lumbar curve ≥ 30°, index TLIF or ALIF performed at L4-5 and/or L5-S1, and a minimum 2-year follow-up. TLIF and ALIF patients were propensity matched according to the number and type of interbody fusion at L4-S1. Of 135 potentially eligible consecutive patients, 106 (78.5%) achieved the minimum 2-year follow-up (mean ± SD age 60.6 ± 9.3 years, 85% women, 44.3% underwent TLIF, and 55.7% underwent ALIF). Index operations had mean ± SD 12.2 ± 3.6 posterior levels, 86.6% of patients underwent iliac fixation, 67.0% underwent TLIF/ALIF at L4-5, and 84.0% underwent TLIF/ALIF at L5-S1. Compared with TLIF patients, ALIF patients had greater cage height (10.9 ± 2.1 mm for TLIF patients vs 14.5 ± 3.0 mm for ALIF patients, p = 0.001) and lordosis (6.3° ± 1.6° for TLIF patients vs 17.0° ± 9.9° for ALIF patients, p = 0.001) and longer operative duration (6.7 ± 1.5 hours for TLIF patients vs 8.9 ± 2.5 hours for ALIF patients, p < 0.001). In all patients, final alignment improved significantly in terms of the fractional curve (20.2° ± 7.0° to 6.9° ± 5.2°), maximum coronal Cobb angle (55.0° ± 14.8° to 23.9° ± 14.3°), C7 sagittal vertical axis (5.1 ± 6.2 cm to 2.3 ± 5.4 cm), pelvic tilt (24.6° ± 8.1° to 22.7° ± 9.5°), and lumbar lordosis (32.3° ± 18.8° to 51.4° ± 14.1°) (all p < 0.05). Matched analysis demonstrated comparable fractional correction (-13.6° ± 6.7° for TLIF patients vs -13.6° ± 8.1° for ALIF patients, p = 0.982). In all patients, final HRQL improved significantly in terms of Oswestry Disability Index (ODI) score (42.4 ± 16.3 to 24.2 ± 19.9), physical component summary (PCS) score of the 36-item Short-Form Health Survey (32.6 ± 9.3 to 41.3 ± 11.7), and Scoliosis Research Society-22r score (2.9 ± 0.6 to 3.7 ± 0.7) (all p < 0.05). Matched analysis demonstrated worse ODI (30.9 ± 21.1 for TLIF patients vs 17.9 ± 17.1 for ALIF patients, p = 0.017) and PCS (38.3 ± 12.0 for TLIF patients vs 45.3 ± 10.1 for ALIF patients, p = 0.020) scores for TLIF patients at the last follow-up (despite no differences in these parameters at baseline). The rates of total complications were similar (76.6% for TLIF patients vs 71.2% for ALIF patients, p = 0.530), but significantly more TLIF patients had rod fracture (28.6% of TLIF patients vs 7.1% of ALIF patients, p = 0.036). Multiple regression analysis demonstrated that a 1-mm increase in L4-5 TLIF cage height led to a 2.2° reduction in L4 coronal tilt (p = 0.011), and a 1° increase in L5-S1 ALIF cage lordosis led to a 0.4° increase in L5-S1 segmental lordosis (p = 0.045). Operative treatment of ASLS with L4-S1 TLIF versus ALIF demonstrated comparable mean fractional curve correction (66.7% vs 64.8%), despite use of significantly larger, more lordotic ALIF cages. TLIF cage height had a significant impact on leveling L4 coronal tilt, whereas ALIF cage lordosis had a significant impact on restoration of lumbosacral lordosis. The advantages of TLIF may include reduced operative duration and hospitalization; however, associated HRQL was inferior and more rod fractures were detected in the TLIF patients included in this study.

Obeid-Coronal Malalignment Classification Is Age Related and Independently Associated to Personal Reported Outcome Measurement Scores in the Nonfused Spine.

ObjectiveTo evaluate Obeid-coronal malalignment (O-CM) modifiers according to age, sagittal alignment, and patient-reported outcome measures (PROMs), in the mobile spine. MethodsRetrospective review of a prospective multicenter adult spinal deformity (ASD) database with 1,243 (402 nonoperative, 841 operative) patients with no prior fusion surgery. Patients were included if they were aged over 18 years and were affected by spinal deformity defined by one of: Cobb angle ≥ 20°, pelvic tilt ≥ 25°, sagittal vertical axis ≥ 5 cm, thoracic kyphosis ≥ 60°. Patients were classified according to the O-CM classification and compared to coronally aligned patients. Multivariate analysis was performed on the relationship between PROMs and age, global tilt (GT) and coronal malalignment (CM). ResultsFour hundred forty-three patients had CM of more than 2 cm compared to 800 who did not. The distribution of these modifiers was correlated to age. After multivariate analysis, using age and GT as confounding factors, we found that before the age of 50 years, 2A1 patients had worse sex life and greater satisfaction than patients without CM. After 50 years of age, patients with CM (1A1, 1A2) had worse self-image and those with 2A2, 2B had worse self-image, satisfaction, and 36-item Short Form Health Survey physical function. Self-image was the consistent determinant of patients opting for surgery for all ages. ConclusionCM distribution according to O-CM modifiers is age dependent. A clear correlation between the coronal malalignment and PROMs exists when using the O-CM classification and in the mobile spine, this typically affects self-image and satisfaction. Thus, CM classified according to O-CM modifiers is correlated to PROMs and should be considered in ASD.

31. Evolution of proximal junctional kyphosis and proximal junctional failure rates over 10 years of enrollment in a prospective multicenter adult spinal deformity database

<h3>BACKGROUND CONTEXT</h3> Proximal junctional kyphosis (PJK) is one of the most common complications following adult spinal deformity (ASD) surgery and has been intensively studied over the last decade. <h3>PURPOSE</h3> This study aims to investigate the evolution of PJK rate over a 10-year enrollment period within a prospective database of ASD patients. The hypothesis is that the rate of PJK and PJF will decrease across time. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospective multicenter database. <h3>PATIENT SAMPLE</h3> A total of 641 ASD patients with minimum 2-year follow-up. <h3>OUTCOME MEASURES</h3> Rate of PJK and PJF. <h3>METHODS</h3> ASD patients with a fusion extended to pelvis and a minimum of 2-year follow-up were included. To investigate a continuous evolution of the PJK/PJF rate, a moving average of 321 patients was calculated across the entire enrollment period, allowing for 95% CI on rate for an incidence of 30% or less. Radiographic PJK was defined as a PJA>10° at 2Y and ΔPJA>10° between preoperative and 2-year follow-up. PJF was defined as either revised for PJK before 2-year visit or Severe radiographic PJK at 2-year follow-up (PJA>28° & ΔPJA>22°). Logistic regression was used to investigate association between date of surgery and PJK and/or PJF. Comparison of PJK rate, demographics and surgical strategies was performed between the first and second half of the cohort. <h3>RESULTS</h3> A total of 641 patients met inclusion criteria (age: 64±10yo, 78.4% F, BMI: 28.3±5.7). The overall rate of radiographic PJK at 2-year was 48.2% (N=309/641); 12.9% (N=83/641) of the patients developed a PJF, with 31.3% (N=26/83) being revised within 2-year. The stratification by date of surgery (DOS) yielded 2 timeframes: First=Oct 2008 to Jul 2014 (with a median DOS of Sep 2011), and Second=Jun 2014 to Apr 2018 (with a median DOS of Aug 2016). Between these 2 periods, the rate of radiographic PJK demonstrated a nonsignificant decrease from 50.3% to 45.5% (p=0.22) and PJF from 15.0% to 10.9% (p=0.12). Linear interpolation of the rate of PJK and PJF by enrollment using a moving average suggested a decrease of 1.1% PJK per year and 1.0% PJF per year. Over the study period, patients became continuously older (from 62.6±10.3 to 65.5±8.7 p<0.001) and were more likely be classified as a pure sagittal deformity (SRS Type N from 31.2% to 47.4% p<0.001). Across the enrollment period, there was a shift in surgical strategy, with a significant reduction of 3CO use (35.1% vs 20.8% p<0.001), an increase in ALL release (0% vs 18.4% p<0.001), a decrease in the number of levels fused (12.2±3.5 vs 11.7±3.9 p=0.016), and an increase in the use of PJK prophylaxis (31.3% vs 55.1%). Logistical regression analysis demonstrated no significant association between date of surgery and radiographic PJK (p=0.19) or PJF (p=0.39). <h3>CONCLUSIONS</h3> Despite extensive research examining risk factors for PJK/PJF and increasing utilization of intraoperative PJK prophylaxis techniques, the rate of radiographic PJK and/or PJF did not significantly decrease across the 10-year enrollment period of this ASD database. The increase in patient risk factors (older) was probably balanced by changes in surgical strategy and preoperative optimization. Continuous enrollment and follow-up will allow ongoing study which may eventually lead to significant decreases in the rate of PJK and PJF. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

179. Correcting ASD patients to normative alignment results in no functional benefit but more PJK and PJF

<h3>BACKGROUND CONTEXT</h3> A previous study utilized normative alignment to determine overcorrections and predict mechanical complications in adult spinal deformity (ASD) surgery. Other studies have recommended alignment targets that optimize age-appropriate physical function. The difference in functional outcomes and mechanical complications between these prescribed alignment targets has not been explored. This study utilizes a component angle of the T1 pelvic angle (TPA) within the fusion to compare normative and age-pelvic incidence (PI) optimal alignment in terms of proximal junctional kyphosis (PJK), proximal junctional failure (PJF) and health related quality of life measures (HRQL). Using the component of TPA within the fusion, the T4-pelvic angle (T4PA), allows for the measurement spinopelvic alignment separate from that of the unfused thoracic spine and any PJK that may occur postoperatively. <h3>PURPOSE</h3> To compare ASD patients corrected to normative alignment vs age-PI optimal alignment in terms of PJK/PJF and outcomes. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis of a prospective multicenter ASD database and a database of asymptomatic subjects. <h3>PATIENT SAMPLE</h3> This study included 1,916 ASD patients and 118 asymptomatic subjects for formula development; 288 ASD patients with 2-year X-ray and HRQL follow-up. <h3>OUTCOME MEASURES</h3> SF36-PCS, ODI, SRS-22, NRS back/leg, PJK (change in UIV to UIV+2 >10°), PJF (defined as severe PJK with change >21.6°, or UIV olisthesis, or proximal junctional fracture). <h3>METHODS</h3> Baseline relationships between age, PI and T4PA, were analyzed in the ASD patients and compared to the asymptomatic subjects. Linear regression modeling was used to determine alignment based on PI and age in asymptomatic subjects (normative alignment), and in ASD patients, alignment corresponding to age-appropriate functional status (optimal alignment). ASD patients with UIV above T4 were grouped based on their corrections: normative vs optimal. Extreme over or under corrected patients were excluded (greater than or less than 2SD from mean postop T4PA). For each group, the rate of PJK and PJF were determined. <h3>RESULTS</h3> In the multilinear regression analysis of the 119 asymptomatic subjects, T4PA correlated with age and PI, r=.713, p<.0001. 1916 ASD patients were included in the optimal formula development. In the 288 ASD patients included in the pre- to postop analysis (137 normative, 151 optimal), there was no difference in baseline alignment or HRQL between the groups. At 6 weeks, the normative aligned group had smaller T4PA (4.45 vs 14.1) and PI-LL (-7.24 vs 7.4), all p<.0001. Normative aligned patients had the higher PJK rate (40% vs 27.2%, p=.03) compared with optimal; and a higher PJF rate (17% vs 6.8%, p=.008). PJF patients had -1.2°of T4PA offset from normative alignment and -5.2°of offset from optimal alignment. By contrast, no PJF patients had 3.8° of T4PA offset from normative alignment and -0.42° of offset from optimal alignment. There was a trend toward worse 2-year SF36-PCS in patients who suffered PJF (37.7 vs 41.6, p=.09). Both the Normative and Optimal groups improved in outcomes from baseline to 2-year (p<.001) with no difference in 2-year HRQL. <h3>CONCLUSIONS</h3> Correcting ASD patients to normative alignment resulted in higher rates of PJK and PJF without improvements in HRQL. ASD patients should not be corrected to match the alignment of their asymptomatic unfused peers, rather they should be realigned optimally to match age-appropriate physical function. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

51. Is percutaneous pedicle screw (PPS) fixation associated with minimized risk of perioperative proximal junctional kyphosis (PJK) in adult spinal deformity?

BACKGROUND CONTEXT Numerous strategies are used to minimize PJK in (ASD). The use of PPS is one such strategy. Studying this topic is difficult as there is a lack of homogeneity in the patient population being studied. PURPOSE Investigate if PPS minimizes the risk of perioperative PJK compared to traditional open techniques. STUDY DESIGN/SETTING Retrospective review of prospective multicenter adult spinal deformity database PATIENT SAMPLE Inclusion criteria are age >18, and one of the following: PT>25, PI-LL>10, or SVA>5 cm. OUTCOME MEASURES NRS leg, ODI, SF-12, EQ5D, SRS-22. METHODS A prospective database was retrospectively reviewed. Inclusion criteria are age >18, and one of the following: PT>25, PI-LL>10, or SVA>5 cm. Patients were grouped as MIS (all PPS no open component) or OPEN. Propensity matching was used to create 2 equal groups controlling for: age, BMI, Preop (PI-LL, PI, TPA), and post op (PI-LL correction and posterior levels fused). PJK was evaluated in 2 groups: Mild (PJK10) 10° change from preop and severe (PJK20) a 20° change, as previously reported. RESULTS A total of 1,023 patients met criteria: 114 MIS and 909 OPEN. MIS were older with higher BMI. No significant difference was found between groups in preop alignment or SRS Schwab classification. OPEN had more levels fused (11.3 vs 5.5), change in PI-LL (14.9 vs 9.3) and LL (16.2 vs 9.7; all p 0.59). PJK20 was 2.6% in OPEN vs 3.9% in MIS at 1YR (p=1). The PJK angle was not different (4.3 v 4.2). MIS had less EBL (510 v 1574 cc; p=0.000) longer OR time (448 v 373 min; p=0.022) and more interbodies (3.4 vs 2.1; p=0.000). There was no difference in rate of revision surgery (14.3% OPEN vs 10.4%). Major complications occurred more frequently in OPEN (23.4% vs 9.1%). CONCLUSIONS While the use of percutaneous fixation intuitively seems protective for PJK, our study found that when controlling for radiographic deformity, deformity correction, demographics and the magnitude of surgical intervention that percutaneous fixation is equivalent to open techniques in rate of perioperative PJK. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

94. What is the difference in patient outcomes in circumferential minimally invasive (cMIS) vs open correction of adult scoliosis?

BACKGROUND CONTEXT Circumferentially minimally invasive (cMIS) correction techniques of adult scoliosis have advanced, but it is unclear how outcomes compare to open correction. PURPOSE To compare health related quality of life (HRQL) measures and surgical parameters between the two modalities. STUDY DESIGN/SETTING Retrospective review of prospective multicenter adult spinal deformity database. PATIENT SAMPLE Inclusion criteria are age >18, and one of the following: PT>25, PI-LL>10, or SVA>5 cm. OUTCOME MEASURES NRS leg, ODI, SF-12, EQ5D, SRS-22. METHODS A prospective database was retrospectively reviewed. Inclusion criteria were age >18, and one of the following: PT>25, PI-LL>10, or SVA>5 cm. Patients were grouped as cMIS (percutaneous screws) or OPEN. Propensity matching was used to create two equal groups controlling for: age, BMI, preop (PI-LL, PI, TPA), and number of posterior levels fused. RESULTS A total of 154 (77 cMIS, 77 OPEN) patients were included after matching for age, BMI, PI-LL (15 vs 17°), PI (54° vs 54°), TPA (21° vs 22°), and mean number of levels fused (6 vs 6), for cMIS and OPEN, respectively. 3-column osteotomies were excluded. Baseline and postop ODI, SRS total, EQ5D were not different between MIS and OPEN (p=0.50, 0.45, 0.33). Maximum Cobb angles were similar for OPEN and cMIS, respectively, at baseline (26.3°, 25.9°, p=0.85) and at 1-yr postop (17.5°, 15.0°, p=0.17). Patients reaching minimal clinically important difference (MCID) were 58.3% for OPEN and 64.4% for cMIS (p=0.31) at 1 year. At 1 year, no difference was observed between PI-LL, SVA, PT, or Cobb (p=0.71, 0.46, 0.9, 0.20). OPEN vs MIS had greater EBL (1.36L vs 0.524L, p CONCLUSIONS When comparing cMIS to OPEN adult scoliosis correction with propensity matching, HRQL improvement, spino-pelvic parameters, revision surgery rates, and patients reaching MCID were not different between cohorts. However, cMIS had lower blood loss with comparable results in well-selected patients, but longer OR time. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

93. Cost utility analysis of a combined approach for surgical correction of adult spinal deformity

BACKGROUND CONTEXT With the increasing emphasis on value-based outcomes in health care, there has been an increased focus on the cost of surgical intervention in patients with adult spinal deformity (ASD). However, there is a paucity of literature on the economic impact of a surgeon's surgical approach for corrective ASD surgery. PURPOSE To investigate the cost-utility associated with surgical approach. STUDY DESIGN/SETTING Retrospective cohort study of a prospective multicenter ASD database. PATIENT SAMPLE This study included 208 ASD patients. OUTCOME MEASURES Oswestry Disability Index (ODI), SF-6D, cost per quality adjusted life years (QALY). METHODS ASD patients with no previous history of fusions, complete radiographic, and HRQL data at baseline and 2 years were included. Patients were propensity score matched for age, CCI, levels fused, frailty, SVA, PI-LL and osteotomies. Means comparison tests and ANOVA chi-squared analyses assessed differences in baseline demographic and clinical data between cohorts. Utility data were calculated using ODI converted to SF-6D using published conversion methods. QALYs utilized a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs were calculated using the PearlDiver database incorporating complications, comorbidities (CC), major complications, and comorbidities (MCC) were assessed according to CMS.gov manual definitions. Two-year reimbursement consisted of a standardized estimate using regression analysis of Medicare pay-scales for all services rendered within a 30-day window, including estimates regarding costs of postoperative complications, outpatient health care encounters, revisions and medical related readmissions. After accounting for CC, MCC, length of stay (LOS), revisions, and death, cost per QALY at 2 years and life expectancy were calculated for surgical approach. RESULTS A total of 208 PSM ASD patients were included (62.2yrs, 84% F, 26.9 kg/m2). Patients undergoing a combined approach had a longer LOS (6.55 vs 8.15), greater operative time, and experienced significantly greater blood loss (all p 0.05). Despite initial higher costs of a combined approach, the average cost of ASD surgery at 2 years follow-up for posterior-only approach was greater compared to a combined approach ($72,749 vs $65,073). Furthermore, the cost per QALY was higher for posterior-only patients at 2 years compared to patients undergoing a combined approach ($363,910 vs $333,981). If utility gained is sustained to life expectancy, the cost per QALY was $54,027 for posterior-only and $49,584 for combined. CONCLUSIONS In a matched cohort of adult spinal deformity patients, a combined approach trended toward a lower average cost of surgery at 2 years, lower cost per QALY, significantly lower rates of operative complications and revisions. Although improvement after surgical intervention was similar between the two approaches, cost per QALY of posterior-only approach was slightly greater primarily driven by increased operative complications and rates of revisions. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Incidence of Acute, Progressive, and Delayed Proximal Junctional Kyphosis Over an 8-Year Period in Adult Spinal Deformity Patients.

Proximal junctional kyphosis (PJK) is a common radiographic complication of adult spinal deformity (ASD) corrective surgery. Although previous literature has reported a 5 to 61% incidence of PJK, these studies are limited by small sample sizes and short-term follow-up. To assess the incidence of PJK utilizing a high-powered ASD database. Retrospective review of a prospective multicenter ASD database. Operative ASD patients>18 yr old from 2009 to 2017 were included. PJK was defined as≥10° for the sagittal Cobb angle between the inferior upper instrumented vertebra (UIV) endplate and the superior endplate of the UIV+2. Chi-square analysis and post hoc testing assessed annual and overall incidence of acute (6-wk follow-up [f/u]), progressive (increase in degree of PJK from 6 wk to 1 yr), and delayed (1-yr, 2-yr, and 3-yr f/u) PJK development. A total of 1005 patients were included (age: 59.3; 73.5% F; body mass index: 27.99). Overall PJK incidence was 69.4%. Overall incidence of acute PJK was 48.0%. Annual incidence of acute PJK has decreased from 53.7% in 2012 to 31.6% in 2017 (P=.038). Overall incidence of progressive PJK was 35.0%, with stable rates observed from 2009 to 2016 (P=.297). Overall incidence of 1-yr-delayed PJK was 9.3%. Annual incidence of 1-yr-delayed PJK has decreased from 9.2% in 2009 to 3.2% in 2016 (P<.001). Overall incidence of 2-yr-delayed PJK development was 4.3%. Annual incidence of 2-yr-delayed PJK has decreased from 7.3% in 2009 to 0.9% in 2015 (P<.05). Overall incidence of 3-yr-delayed PJK was 1.8%, with stable rates observed from 2009 to 2014 (P=.594). Although progressive PJK has remained a challenge for physicians over time, significantly lower incidences of acute and delayed PJK in recent years may indicate improving operative decision-making and management strategies.

Effective Prevention of Proximal Junctional Failure in Adult Spinal Deformity Surgery Requires a Combination of Surgical Implant Prophylaxis and Avoidance of Sagittal Alignment Overcorrection.

Propensity score matched analysis of a multi-center prospective adult spinal deformity (ASD) database. Evaluate if surgical implant prophylaxis combined with avoidance of sagittal overcorrection more effectively prevents proximal junctional failure (PJF) than use of surgical implants alone. PJF is a severe form of proximal junctional kyphosis (PJK). Efforts to prevent PJF have focused on use of surgical implants. Less information exists on avoidance of overcorrection of age-adjusted sagittal alignment to prevent PJF. Surgically treated ASD patients (age ≥18 yrs; ≥5 levels fused, ≥1 year follow-up) enrolled into a prospective multi-center ASD database were propensity score matched (PSM) to control for risk factors for PJF. Patients evaluated for use of surgical implants to prevent PJF (IMPLANT) versus no implant prophylaxis (NONE), and categorized by the type of implant used (CEMENT, HOOK, TETHER). Postoperative sagittal alignment was evaluated for overcorrection of age-adjusted sagittal alignment (OVER) versus within sagittal parameters (ALIGN). Incidence of PJF was evaluated at minimum 1 year postop. Six hundred twenty five of 834 eligible for study inclusion were evaluated. Following PSM to control for confounding variables, analysis demonstrated the incidence of PJF was lower for IMPLANT (n = 235; 10.6%) versus NONE (n = 390: 20.3%; P < 0.05). Use of transverse process hooks at the upper instrumented vertebra (HOOK; n = 115) had the lowest rate of PJF (7.0%) versus NONE (20.3%; P < 0.05). ALIGN (n = 246) had lower incidence of PJF than OVER (n = 379; 12.0% vs. 19.2%, respectively; P < 0.05). The combination of ALIGN-IMPLANT further reduced PJF rates (n = 81; 9.9%), while OVER-NONE had the highest rate of PJF (n = 225; 24.2%; P < 0.05). Propensity score matched analysis of 625 ASD patients demonstrated use of surgical implants alone to prevent PJF was less effective than combining implants with avoidance of sagittal overcorrection. Patients that received no PJF implant prophylaxis and had sagittal overcorrection had the highest incidence of PJF. 3.

160. Increasing cost efficiency in adult spinal deformity surgery: identifying predictors of lower total costs

BACKGROUND CONTEXT Adult spinal deformity (ASD) surgery often involves complex deformity correction. It's unknown which baseline (BL) patient factors predict lower total costs in ASD surgery. PURPOSE Identify predictors of lower total surgery costs for ASD patients. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter adult spinal deformity database. PATIENT SAMPLE A total of 311 operative ASD patients ≥18 years old with baseline and 3Y demographic, surgical, and frailty data. OUTCOME MEASURES Schwab sagittal vertebral axis (SVA) modifier grade, Owestry Disability Index (ODI), costs of ASD surgery, predictors of lower costs. METHODS Inclusion criteria included surgical ASD (scoliosis ≥20°, SVA ≥5cm, PT ≥25°, or thoracic kyphosis ≥60°) patients >18 years with available frailty, demographic, and radiographic data at BL and 1 year postop. Descriptive analyses assessed mean age, frailty, and surgical data. Total costs for surgery were calculated using the PearlDiver database. A conditional variable importance table used nonreplacement sampling set of 20,000 conditional inference trees to identify the top factors associated with lower cost surgery for low (LSVA), moderate (MSVA), and high (HSVA) Schwab modifier grades. LSVA were SVA 9.5 cm. Linear and logistic regression assessed the relationship between significant predictors and the odds of lower cost surgery. RESULTS Of the 322 total ASD patients, 322 met inclusion criteria. Descriptive statistics were: age 58.9 ± 14.9, 76% women, BMI 27.8 ± 6.2, 62% osteotomy, 54% decompression, and 11.0 ± 4.1 average levels fused. At 3yrfollow-up, the potential cost of ASD surgery ranged from $57,606.88 to $116,312.54. There were 152 LSVA patients, 53 MSVA patients, and 111 HSVA patients. For all patients, BL ODI 1.5 (2.62 [1.402-4.875], p=0.002], no previous spine surgery (1.77 [1.22-2.58], p=0.003), frailty scores 1.5 (6.76 [1.68-27.18] p=0.007), age 2.38 (3.93 [1.54-10.18] p=0.004), frailty scores CONCLUSIONS For ASD patients, low frailty, no prior spine surgery, no depression, and higher baseline SRS activity scores were predictive of lower total surgery costs. When assessed by baseline deformity, decreased frailty and the lack of comorbidities and risk factors such as cancer, smoking, or high BMI, were associated with lower costs. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

66. Preop opioid use is associated with worse postop outcomes and chronic opioid use in nonrevision adult scoliosis patients: corroboration of two independent multicenter studies

BACKGROUND CONTEXT Sagittal malalignment and failed surgery are established etiologies for pain in adult spinal deformity (ASD). However, pain in primary adult scoliosis with good sagittal alignment is poorly understood. Opioids may be administered to control pain in adult scoliosis but are controversial and may negatively impact patient outcome. Evaluation of two independent ASD datasets may reduce bias and help understand the impact of preop opioid therapy on postop outcomes. PURPOSE Compare datasets from two independent ASD studies to evaluate the impact that the presence and frequency of opioid use has upon postop outcomes in adult scoliosis patients who have no prior history of spine surgery and no sagittal malalignment. STUDY DESIGN/SETTING Comparative analysis of datasets from two prospective multicenter ASD studies. PATIENT SAMPLE ASD patients with no history of prior spine surgery and no sagittal malalignment (as defined by the Scoliosis Research Society ASD Classification) enrolled into two independent multicenter databases and subsequently surgically treated for adult scoliosis OUTCOME MEASURES Scoliosis Research Society-22r questionnaire (SRS-22r), SF-36 and SF-12 Physical Component Score (PCS) and Mental Component Score (MCS), numeric rating scale (NRS) back and leg pain METHODS Adult scoliosis patients age >18 years, no history of spine surgery, and presence of thoracic, lumbar or double scoliosis (as per SRS deformity type) were identified from 2 independent prospective databases and assessed for preop non-opioid (NON) vs opioid use and amount of use (DAILY vs WEEKLY). Mixed and sagittal deformities were eliminated to reduce confounding pain impact of sagittal malalignment. Patients were treated surgically and pre- and postop demographic, radiographic data, patient-reported outcome measures and postop opioid usage were evaluated, minimum 2-year follow-up. RESULTS Database 1 (D1; 102/102 patients; mean follow up 2.1+0.2yr) and Database 2 (D2; 116/168 patients, mean follow-up 3.3 years) demonstrated similar preop demographic, depression history, smoking history and radiographic parameters for NON, DAILY and WEEKLY (p>0.05; Table). DAILY had greater preop NRS back and leg pain, and worse preop PCS and MCS than NON (p 0.05). At last follow-up, DAILY had worse postop NRS back pain (D1=4.1, D2=4.9), worse PCS (D1=38.8, D2=41.9), and worse MCS (D1=49.7, D2=45.4) than NON and WEEKLY (p CONCLUSIONS Comparison of datasets from two independent, multicenter prospective ASD studies demonstrated dataset agreement that preop opioid use and increased frequency of preop opioid use in adult scoliosis patients with no history of prior surgery and no sagittal malalignment is associated with worse postop pain, outcomes and continued opioid use. Attempts should be made, including program development, to aid in the discontinuation of preop and postop opioid usage for adult scoliosis to help improve postop outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

209. Global spinal deformity from the upper cervical perspective: what is “abnormal” in the upper cervical spine?

BACKGROUND CONTEXT Reciprocal changes in cervical alignment occur with incremental degrees of adult spinal deformity (ASD) severity, or across different sagittal morphotypes as described respectively by Schwab and Roussouly systems. The extent to which these systems relate changes in the upper cervical spine remains underexplored. PURPOSE To investigate quantitative anatomical relationships with regards to abnormal alignment in the upper cervical spine. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter ASD database. PATIENT SAMPLE A total of 343 patients who met criteria for ASD. OUTCOME MEASURES Cervical alignment parameters (C2-C7 angle, C2 slope, McGregor's Slope, CBVA when available, segmental tilt), Ostrow Disability Index (ODI) METHODS Patients >18 years with ASD (scoliosis≥20°, SVA≥5cm, PT≥25°, or thoracic kyphosis ≥60°) and complete radiographic data at baseline (BL) & 1-year (1Y) were identified. Patients were grouped by BL PI and apex of LL into component types of the Roussouly classification system (Type 1: PI 65°). Patients were categorized by increasing severity of SRS-Schwab modifiers at BL (0, +, ++) and further grouped by anatomical malalignment, moving cranially (P: pelvic only; LP: lumbopelvic; TL: thoracolumbopelvic; C: subaxial & thoracolumbo-pelvic). Analysis of variance (ANOVA) tests assessed differences in BL upper cervical alignment parameters (C0-C2, C0 slope, McGregor's slope, CBVA) and ODI scores across Roussouly and Schwab modifier groups. RESULTS A total of 343 ASD patients were analyzed. Schwab modifiers at BL were as follows: SVA (0: 45.8%, +: 20.3%, ++: 33.9%), PI-LL (0: 42.3%, +: 20.7%, ++: 37.0%), PT (0: 38.6%, +: 36.2%, ++: 25.3%). By Roussouly classification, 4.2% were Type 1, 19.3% were Type 2, 43.1% were Type 3, and 33.3% were Type 4. Moving cranially up the spine, Group P (10.6%), Group LP (54.7%) and Group TL (8.5%) did not differ in C0-C2 angle, C0 slope, MGS or CBVA (all P>0.05). Group C (26.2%) had a significantly smaller C0-C2 angle, and more negative MGS, C0 slope, and CBVA than non-cervical groups. By Roussouly type, Type 1 trended slightly higher CBVA and MGS than types 2-4 without statistical significance (all P>0.05). No differences in CL, C0-C2, or C0S were found between Types 1-4 (all P>0.05). McGregor's slope (r=-0.131, P=0.015), CBVA (r=-0.473, P 34mm predicted a 1 unit(°) decrease in MGS (OR: 0.970 [0.948 – 0.993], p=0.010), while cSVA>51mm predicted a 1 unit increase in MGS (OR: 1.25[1.12-1.38], p CONCLUSIONS Our present study suggests that upper cervical alignment remains relatively stable through most broad variations of adult thoracolumbar deformity. Changes in SVA correlated most with upper cervical changes compared to other TL modifiers. Incremental trends in upper cervical alignment changes were observed as TL deformity extended cranially, with greatest variation in pts who also had subaxial malalignment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

212. Giving patients the info they want: practical answers to FAQs for shared decision-making in ASD surgery

BACKGROUND CONTEXT The shared decision-making (SDM) process is an opportunity to deliver answers to frequently asked questions (FAQs) in adult spinal deformity (ASD) surgery. PURPOSE Our goal was to present a concise list of answers to these FAQs to aid in SDM counseling. STUDY DESIGN/SETTING Retrospective analysis of a prospective multi-center ASD database. PATIENT SAMPLE Adult spinal deformity patients undergoing surgical correction enrolled into a prospective, multicenter surgical database from 2008-2016. OUTCOME MEASURES Health related quality of life (HRQOL) outcome measures were collected such as Oswestry Disability Index (ODI), SF-36 PCS, and SF-36 MCS. METHODS Adult patients undergoing ≥ 5 level fusion with minimum 2-year follow up were included. We purposely included all deformity types (heterogeneity) to provide general applicability. We compiled a list of FAQs by patients undergoing ASD surgery and utilized a retrospective analysis to provide answers. All responses are reported as either means or reaching minimal clinically important difference (MCID) at the 2-year follow-up interval. RESULTS Out of 689 ASD patients eligible for 2-year follow-up, 521 (76%) had complete follow-up. The majority were female (77%) with mean age of 58.5 years and BMI of 27.5. Mean levels fused were 11.3 with 52% being primary vs 48% revision surgeries. Will my pain improve? Back (7.2 to 3.6) and leg (4.7 to 2.6) pain were both reduced by ∼50%. Will my activity level improve? A total of 63.9% reached MCID for SRS-22r activity. Will I feel better about myself? A total of 71.2% reached MCID for SRS-22r appearance. Is there a chance I'm worse? A total of 4.1% of patients were worse (ODI). What is the likelihood I have a complication? A total of 52.9% of patients have at least 1 complication and 29.6% have a major complication. Will I need another surgery? A total of 29.6% of patients have a reoperation within 2 years. Will I regret having surgery? A total of 32% would not choose the same treatment. Will I get a blood transfusion? A total of 79.1% of patients receive a blood transfusion. How long will I stay in the hospital? Study showed 9.9 days. Will I have to go to the ICU? A total of 79.1% of patients require an ICU stay. Will I be able to return to work? A total of 71% returned to full-time work at 2 years. Will I be taller after surgery? Yes, 1.4cm was the average CONCLUSIONS The above list provides concise, practical answers to FAQs encountered in the SDM process while counseling patients for ASD surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P84. Predicting ASD surgeries that exceed Medicare allowable payment thresholds: a comparison of hospital costs to what the government will actually pay

BACKGROUND CONTEXT Adult Spinal Deformity (ASD) surgery is associated with a high cost. Previous studies have suggested that the actual direct hospital cost of ASD surgery is higher than the Medicare Allowable (MA) rate. MA rates are becoming the benchmark reimbursement target for hospital accounting systems. It is important to determine what factors can predict which ASD patients have actual costs below Medicare reimbursement. PURPOSE Our goal is to (1) determine if we can develop a model to predict when index episode of care (iEOC) surgical costs of ASD surgeries are below the MA threshold and (2) to identify potentially modifiable variables. STUDY DESIGN/SETTING Retrospective analysis of a prospective multi-center ASD database. PATIENT SAMPLE Adult spinal deformity patients undergoing surgical correction enrolled into a prospective, multicenter surgical database from 2008-2014. OUTCOME MEASURES Primary outcome measure is iEOC costs and patient and hospital-specific MA reimbursements, but other baseline HRQOL outcome measures were collected such as Oswestry Disability Index (ODI), SF-36 PCS, and SF-36 MCS. METHODS From a prospective, multicenter ASD surgical database, patients undergoing long instrumented fusions (>4 level) with cost data were identified. Index episode of care (iEOC) cost was calculated by utilizing actual direct hospital cost. MA rates were calculated using the year-appropriate CMS Inpatient Pricer Payment System Tool and were hospital specific. Demographic, baseline HRQOL, radiographic and surgical variables were analyzed. A predictive model was developed to identify variables that can predict iEOC RESULTS Administrative direct cost data was obtained from 4 of 11 centers with a total of 195 patients included in the model. A total of 109 (55%) patients had iEOC below the MA threshold. There was significant variation across the 4 centers in both the mean iEOC cost ($56,788 to $78,878,p CONCLUSIONS There is significant institutional variation in ASD cost and reimbursement with an increased likelihood of 56.8% getting reimbursed more than the cost of surgery (iEOC FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.