Surgical Adult Spinal Deformity Patients Research Articles

28. Does baseline thoracolumbar shape influence patterns of cervical decompensation following surgical adult spinal deformity correction?

BACKGROUND CONTEXT Adult spinal deformity (ASD) surgery is complex and may lead to new-onset cervical malalignment and/or proximal junctional kyphosis (PJK). Roussouly et al describes variations in baseline thoracolumbar (TL) shape (Types 1-4), which have been shown to differentially influence surgical ASD outcomes. The effect of morphological shape on patterns of postoperative CD development remains underexplored. PURPOSE Stratify patients by Roussouly type and assess patterns of conversion from baseline (BL) cervical alignment to postoperative cervical deformity (CD) in patients undergoing thoracolumbar ASD surgery. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter database of ASD patients. PATIENT SAMPLE A total of 266 surgical ASD patients. OUTCOME MEASURES Rate and timing of conversion to CD, rate of PJK, radiographic alignment parameters. METHODS Operative ASD patients with complete radiographic data at baseline, 6W, 1Y, 2Y, & 3Y intervals were included. Patients were grouped by baseline PI and apex of LL into component types of the Roussouly classification system utilizing pelvic incidence as published by Pizones et al. Patients with no BL CD were postoperatively stratified by Ames CD criteria (TS-CL>20 °, cSVA>40mm), where CD was defined as fulfilling >1 criteria. Follow-up intervals were established post-ASD surgery, with 6W postop defined as “Early,” 6W-1Y “Intermediate,” 1-2Y “Late,” and 2-3Y “Long.” Univariate and Cox regression analyses identified CD conversion rate and PJK rate ( RESULTS A total of 266 surgical ASD patients (59.7yrs, 77.4% F) with complete radiographic data were included. By Roussouly classification, 9% were Type 1, 15.8% Type 2, 46.6% Type 3, and 28.6% Type 4. 28.6% of ASD patients converted to postop CD (Early: 14.3%, Intermediate: 5.3%, Late: 4.1%, Long: 4.9%). There were no significant differences in CD conversion rate across Roussouly types (1: 33.3%; 2: 28.6%; 3: 26.6%; 4: 30.3%, P=0.895). Types 2 (41.7%), 3 (60.6%), and 4 (43.5%) had their peak rates of conversion in the Early ( 1 year) than other types (50% vs 28.1%, P=0.135), while Type 1 patients trended higher rates of earlier CD conversion ( 0.05). There were no significant change in ODI, PCS, or SRS total among Roussouly Types in patients that converted to CD (p>0.05). Random forest analysis determined the top surgical (levels fused), radiographic (TS-CL), and demographic (frailty) factors associated with CD conversion. CONCLUSIONS Baseline thoracolumbar shape as described by the Roussouly classification has a differential effect on timing to CD conversion, though overall rates of CD conversion after TL-ASD correction were similar across Types 1-4. Type 1 patients with a lower apex of lumbar lordosis trended earlier conversion, while Type 2 patients with a higher apex of LL trended conversion beyond 1-year postop. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

A cost utility analysis of treating different adult spinal deformity frailty states

The aim of this study was to investigate the cost utility of treating non-frail versus frail or severely frail adult spinal deformity (ASD) patients. 79 surgical ASD patients >18 years with available frailty and ODI data at baseline and 2-years post-surgery (2Y) were included. Utility data was calculated using the ODI converted to the SF-6D. QALYs utilized a 3% discount rate to account for decline to life expectancy (LE). Costs were calculated using the PearlDiver database. ICER was compared between non-operative (non-op.) and operative (op.) NF and F/SF patients at 2Y and LE. When compared to non-operative ASD, the ICER was $447,943.96 vs. $313,211.01 for NF and F/SF at 2Y, and $68,311.35 vs. $47,764.61 for NF and F/SF at LE. Frail and severely frail patients had lower cost per QALY compared to not frail patients at 2Y and life expectancy, and had lower ICER values when compared to a non-operative cohort of ASD patients. While these results support operative correction of frail and severely frail patients, it is important to note that these patients are often at worse baseline disability, which is closely related to frailty scores, and have more opportunity to improve postoperatively. Furthermore, there may be a threshold of frailty that is not operable due to the risk of severe complications that is not captured by this analysis. While future research should investigate economic outcomes at extended follow up times, these findings support the cost effectiveness of ASD surgery at all frailty states.

Classifying Complications: Assessing Adult Spinal Deformity 2-Year Surgical Outcomes.

Study Design:Retrospective review of prospective database.Objective:Complication rates for adult spinal deformity (ASD) surgery vary widely because there is no accepted system for categorization. Our objective was to identify the impact of complication occurrence, minor-major complication, and Clavien-Dindo complication classification (Cc) on clinical variables and patient-reported outcomes.Methods:Complications in surgical ASD patients with complete baseline and 2-year data were considered intraoperatively, perioperatively (<6 weeks), and postoperatively (>6 weeks). Primary outcome measures were complication timing and severity according to 3 scales: complication presence (yes/no), minor-major, and Cc score. Secondary outcomes were surgical outcomes (estimated blood loss [EBL], length of stay [LOS], reoperation) and health-related quality of life (HRQL) scores. Univariate analyses determined complication presence, type, and Cc grade impact on operative variables and on HRQL scores.Results:Of 167 patients, 30.5% (n = 51) had intraoperative, 48.5% (n = 81) had perioperative, and 58.7% (n = 98) had postoperative complications. Major intraoperative complications were associated with increased EBL (P < .001) and LOS (P = .0092). Postoperative complication presence and major postoperative complication were associated with reoperation (P < .001). At 2 years, major perioperative complications were associated with worse ODI, SF-36, and SRS activity and appearance scores (P < .02). Increasing perioperative Cc score and postoperative complication presence were the best predictors of worse HRQL outcomes (P < .05).Conclusion:The Cc Scale was most useful in predicting changes in patient outcomes; at 2 years, patients with raised perioperative Cc scores and postoperative complications saw reduced HRQL improvement. Intraoperative and perioperative complications were associated with worse short-term surgical and inpatient outcomes.

Pelvic Incidence Affects Age-adjusted Alignment Outcomes in a Population of Adult Spinal Deformity.

A single-center retrospective cohort study. The objective of this study was to assess the effects of patient height and pelvic incidence (PI) on age-adjusted alignment outcomes of surgical adult spinal deformity (ASD) patients. Patient height and PI have yet to be evaluated for their individual effects on achieving age-adjusted alignment targets. Surgical ASD patients were grouped by percentile (low: <25th; normative: 25th-75th; high: >75th) for height and PI. Correction groups were generated at postoperative follow-up for actual alignment compared with age-adjusted ideal values for pelvic tilt (PT), pelvic incidence minus lumbar lordosis mismatch (PI-LL), and sagittal vertical axis, and PI-adjusted ideal alignment values for sacral slope (SS), as derived from clinically relevant formulas. Means comparison tests assessed differences in rates of matching ideal alignment (±10 y threshold for age-adjusted targets; -7 to 5 degrees measured minus ideal for SS) across height and PI groups. Breakdown of all included 198 patients by PI group: low (25%, 38±11 degrees), normative (50%, 57±5 degrees), high (25%, 75±7 degrees). Breakdown of patient height groups: low (25%, 1.52±0.04 m), normative (50% 1.64±0.05 m), and high (25%, 1.79±0.06 m). Overall, 29% of patients met postoperative age-adjusted alignment targets for PT, 23% for PI-LL, and 25% for sagittal vertical axis. Overall, 26% of patients met PI-adjusted SS alignment. There were no differences across patient height groups in rates of achieving adjusted alignment target (all P>0.05). Patients with high PI reached age-adjusted ideal alignment for PT at a lower rate (16%) than patients with normative (33%) or low PI (33%, P=0.056). Of patients that matched at least 1 ideal alignment target, those with high PI showed inferior preoperative to postoperative changes in EuroQol 5-dimension questionnaire as compared with normative and low PI patients (P=0.015). Patients with high PI reached ideal postoperative age-adjusted PT alignment at a lower rate than patients with normative and low PI. Height had no impact on postoperative age-adjusted alignment outcomes. Current postoperative ideal alignment targets may warrant an adjustment to account for PI.

Durability of Satisfactory Functional Outcomes Following Surgical Adult Spinal Deformity Correction: A 3-Year Survivorship Analysis.

Despite reports showing positive long-term functional outcomes following adult spinal deformity (ASD)-corrective surgery, it is unclear which factors affect the durability of these outcomes. To assess durability of functional gains following ASD-corrective surgery; determine predictors for postoperative loss of functionality. Surgical ASD patients>18 yr with 3-yr Oswestry Disability Index (ODI) follow-up, and 1-yr postoperative (1Y) ODI scores reaching substantial clinical benefit (SCB) threshold (SCB<31.3 points). Patients were grouped: those sustaining ODI at SCB threshold beyond 1Y (sustained functionality) and those not (functional decline). Kaplan-Meier survival analysis determined postoperative durability of functionality. Multivariate Cox regression assessed the relationship between patient/surgical factors and functional decline, accounting for age, sex, and levels fused. All 166 included patients showed baseline to 1Y functional improvement (mean ODI: 35.3±16.5-13.6±9.2, P<.001). Durability of satisfactory functional outcomes following the 1Y postoperative interval was 88.6% at 2-yr postoperative, and 71.1% at 3-yr postoperative (3Y). Those sustaining functionality after 1Y had lower baseline C2-S1 sagittal vertical axis (SVA) and T1 slope (both P<.05), and lower 1Y thoracic kyphosis (P=.035). From 1Y to 3Y, patients who sustained functionality showed smaller changes in alignment: pelvic incidence minus lumbar lordosis, SVA, T1 slope minus cervical lordosis, and C2-C7 SVA (all P<.05). Those sustaining functionality beyond 1Y were also younger, less frail at 1Y, and had lower rates of baseline osteoporosis, hypertension, and lung disease (all P<.05). Lung disease (Hazard Ratio:4.8 [1.4-16.4]), 1Y frailty (HR:1.4 [1.1-1.9]), and posterior approach (HR:2.6 [1.2-5.8]) were associated with more rapid decline. Seventy-one percent of ASD patients maintained satisfactory functional outcomes by 3Y. Of those who failed to sustain functionality, the largest functional decline occurred 3-yr postoperatively. Frailty, preoperative comorbidities, and surgical approach affected durability of functional gains following surgery.

SRS-22r legacy scores can be accurately translated to PROMIS scores in adult spinal deformity patients

BACKGROUND CONTEXTPatient-Reported Outcomes Measurement Information System (PROMIS) facilitates comparisons of treatment effectiveness across populations and diseases. In adult spinal deformity (ASD), the disease-specific Scoliosis Research Society-22r (SRS-22r) tool assesses outcomes. Existing data must be translated to PROMIS to make comparisons. PURPOSETo develop and validate a method to translate SRS-22r scores to PROMIS scores in surgical ASD patients. STUDY DESIGNRetrospective cohort study. PATIENT SAMPLEA total of 158 ASD surgery patients from an ongoing registry of patients who underwent spine surgery at a tertiary care center from 2015 to 2017 were included. OUTCOME MEASURESPROMIS and SRS-22r questionnaires were completed at 387 visits (150 preoperative [derivation sample]; 237 postoperative [validation sample]). METHODSUsing the derivation sample, we modeled PROMIS domains as functions of age and SRS-22r domains using linear regression. The most parsimonious model was selected. In the validation cohort, we used the derived regression equations to estimate PROMIS scores from SRS-22r scores. RESULTSThe following significant associations were found (p<.001): PROMIS Pain Interference is dependent on age and SRS-22r Pain, Physical Function, and Patient Satisfaction; PROMIS Physical Function is dependent on age and SRS-22r Pain and Physical Function; PROMIS Anxiety is dependent on SRS-22r Mental Health; PROMIS Depression is dependent on age and SRS-22r Mental Health; and PROMIS Satisfaction with Social Roles is dependent on age and SRS-22r Pain, Physical Function (p=.011), Mental Health, and Patient Satisfaction. Correlations were strong to very strong between estimated and actual PROMIS scores in the validation cohort (p<.001): Pain Interference, r=0.78; Physical Function, r=0.66; Anxiety, r=0.83; Depression, r=0.80; and Satisfaction with Social Roles, r=0.71. CONCLUSIONSPROMIS scores estimated from SRS-22r scores using our model correlate strongly with actual PROMIS scores. SRS-22r scores may be translated to PROMIS scores in all evaluated domains for ASD patients. Orthopedic surgeons can use this method to compare legacy measures with PROMIS scores.

210. Comparing and contrasting the clinical utility of sagittal spine alignment classification frameworks: Roussouly vs SRS-Schwab

BACKGROUND CONTEXT For surgical adult spinal deformity (ASD) patients, incorporating restoration of appropriate Roussouly Classificaion shape into surgical planning may improve outcomes. With the introduction and use of the SRS-Schwab ASD classification system, it is important to compare the utility of both classification frameworks as they relate to surgical outcomes. PURPOSE Compare outcomes of surgical ASD patients classified by both Roussouly and Schwab systems. STUDY DESIGN/SETTING Retrospective review of prospective ASD database. PATIENT SAMPLE A total of 515 ASD patients. OUTCOME MEASURES Complications; Health-related quality of life (HRQL): ODI, SF-36 PCS, SRS-22r. METHODS ASD patients with pre- and 2-year postop (2Y) radiographic/HRQL data were grouped by “theoretical” Roussouly type (Type 1: PI 60°) and “current” Roussouly type (1: SS 45°), as published. Means comparison tests assessed outcomes of those that mismatched “theoretical” and “current” types at both pre- and 2Y intervals (mismatched) to those of preoperative mismatched patients that matched at 2-years (matched). Subanalysis assessed outcomes of patients that improved in Schwab modifiers, and patients that both improved in both Schwab modifiers and matched Roussouly type by 2Y. RESULTS Included 515 ASD patients (59±14yrs, 80%F). The overall cohort showed moderate preoperative global and lumbo-pelvic deformity: SVA(64mm±73), PT(25°±11), PI-LL(16°±21). Preoperative breakdown of “current” Roussouly types: Type 1 (10%), Type 2 (54%), Type 3 (24%), Type 4 (12%). Preoperative mismatch between “current” and “theoretical” types was 60%. By 2Y, 16% of patients matched Roussouly types. Matched and Mismatched groups did not differ in rates of reaching MCID for any HRQL metrics by 2Y(all p>0.1). Reop, PJK and complications did not differ between matched and mismatched(all p>0.1), though mismatched patients showed a trend of increased instrumentation failure(17% vs 26%, p=0.080). By 2Y, 28% of patients improved in PT Schwab modifier, 37% in SVA, and 46% in PI-LL. Patients that improved in PT modifier had lower instrumentation failure rates (16% vs 24%) and higher rates of reaching 2Y MCID for ODI (58% vs 48%) and SRS Activity (75% vs 64%) than patients that did not improve. Patients that both Matched Roussouly at 2Y and improved in all Schwab modifiers met MCID for ODI and SRS Activity at higher rates than patients that did not. Roussouly Match patients that improved in Schwab PT met SRS Activity MCID at a higher rate, and had less renal, infection, and neurologic complications than patients that did not. Roussouly Match patients that improved in Schwab SVA also had superior SF-36 scores and fewer cardiopulmonary complications(all p CONCLUSIONS For surgical ASD patients, isolated restoration of sagittal spinal shape per the Roussouly system was not associated with superior clinical outcomes or complications by 2 years. In contrast, improvement in PT, per the SRS-Schwab system, was associated with substantial improvement in low-back disability by 2 years. Collectively, patients that both matched Roussouly sagittal type and improved in Schwab modifiers had superior complication and patient-reported outcomes by 2 years. These results suggest that concurrent consideration of both existing systems may offer utility in establishing optimal realignment targets. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

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.

322. Equilibrating SRS sagittal deformity grades with the PROMIS physical health domain in adult spinal deformity

BACKGROUND CONTEXT The Patient-Reported Outcomes Measurement Information System (PROMIS) is a comprehensive self-report measurement tool with patient functions, symptoms, behaviors, and mental health outcomes. Little work has been done correlating PROMIS physical health domain metrics with established adult spinal deformity (ASD) classifications such as SRS-Schwab. PURPOSE To correlate sagittal alignment components via the SRS-Schwab classification system with established PROMIS domains in a cohort of ASD patients. STUDY DESIGN/SETTING Retrospective review of a single-center stereoradiographic database. PATIENT SAMPLE A total of 41 ASD patients with complete baseline radiographic and PROMIS data. OUTCOME MEASURES PROMIS physical health domain metrics (Pain Intensity [PI], Physical Function [PF], Pain Interference [Interference]), SRS-Schwab modifiers (SVA, PI-LL, PT) METHODS Surgical ASD patients (SVA≥5cm, PT≥25° or TK ≥60°) ≥18 years old with available baseline (BL) radiographic and PROMIS data were isolated in the single-center comprehensive Spine Quality Database (Quality). Patients were classified according to SRS-Schwab deformity modifiers(0,+,++) for SVA, PI-LL and PT. Descriptives and univariate analyses compared population-weighted PROMIS scores for PI, PF and Interference across ASD deformity modifiers. Conditional Tree Analysis (CTA) with logistic regression sampling established cut-off points for PROMIS scores predicting severe malalignment (++) at BL compared to mild or moderate (0,+). RESULTS A total of 41 patients (58.95 yrs,75.6%F,29.1kg/m2) met inclusion criteria. BL SRS modifiers were as follows: SVA 51.2%, 2.4%, 46.3% (0,+,++); PI-LL 27.3%, 12.1%, 60.6%(0,+,++); PT 18.2%, 36.4%, 45.5% (0,+,++). Mean cohort PI score was 94.2±6.0, mean PF score 8.95±10.1, mean Inter score 57.84±5.46. PF and Interference differed significantly across low and high SVA groups, with low SVA having significantly higher PF (13.50 vs 3.68,p 0.05). Low PI-LL pts had significantly higher PF than pts with ++PI-LL (19.3 vs 4.15,p=0.001) and trended lower PI and Inter without significance. No significant differences in PI, PF or Inter were found across PT groups (all p>0.05). CTA found a PI score>98 or PF score 98) and PF ( 0.05). Pain Interference did not predict SRS metrics to a significant degree (all p>0.05). CONCLUSIONS Inferior PROMIS scores of pain intensity and physical function predicted increasingly severe SRS sagittal modifiers at baseline, specifically severe sagittal vertical axis and lumbopelvic mismatch. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

68. Early patient-reported outcomes can be used to identify patients at risk for poor 1-year outcomes in adult spinal deformity

BACKGROUND CONTEXT The progression of patient-reported outcomes (PRO) scores postoperatively in adult spinal deformity (ASD) is not well understood. Estimating when outcomes plateau and when minimum clinically important differences (MCIDs) are achieved could result in early identification of patients at risk for poor outcomes, and allow for early intervention. It may also help set patient expectations on when they will experience the benefits of surgery. This study examines the relationship between early and 1-year postoperative PROMIS outcomes scores. It further evaluates whether early assessments can predict failure to achieve PROMIS minimal clinically important differences (MCIDs) at 1 year. PURPOSE To determine whether failure to achieve MCIDs at 3 months leads to lower likelihood to achieve them after 1 year. STUDY DESIGN/SETTING Retrospective review. PATIENT SAMPLE Seventy-eight ASD patients. OUTCOME MEASURES PROMIS domains, achievement of MCIDs. METHODS Surgical ASD patients from 2015-2018 with 3-month and 1-year postoperative follow-up were evaluated. PROMIS scores were obtained preoperatively, at all follow-up appointments. PROMIS domains assessed were pain interference, physical function, anxiety, depression, fatigue, sleep disturbance and satisfaction with participation in social roles. First, we correlated assessments at 3 months to those at 1 year. Then, to determine whether failure to achieve MCIDs at 3 months postoperatively resulted in a lower likelihood to achieve them after 1 year, we performed a logistic regression for each PROMIS domain, adjusting for age, gender, race and preoperative scores. MCIDs used for this purpose, specifically computed for the ASD population, were: pain interference, -6.4; physical function, 4.8; anxiety, -6.5; depression, -5.7; fatigue, -6.4; sleep disturbance, -5.6; satisfaction with participation in social roles, 6.0. RESULTS Seventy-eight ASD patients (mean age 59.2 years) undergoing surgery for ASD were included. There were moderate correlations between 3-month and 1-year assessments in all domains (0.45 CONCLUSIONS Patients who fail to achieve PROMIS MCIDs by 3 months postoperatively are unlikely to achieve them after 1 year in domains of pain interference, physical function, anxiety and depression. Thus, early assessments allow identification of patients at risk for poor outcomes and present an opportunity for early intervention. They can also be used to set patient expectations after surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters

BACKGROUND CONTEXT Current preoperative planning for surgical adult spinal deformity (ASD) patients takes into account patient age when establishing postoperative alignment targets for sagittal vertical axis (SVA), pelvic tilt (PT) and spino-pelvic-mismatch (PI-LL). Patient height and pelvic incidence (PI), however, have yet to be evaluated for their individual effects on achieving age-adjusted alignment targets. PURPOSE This study assesses the individual effects of patient height and PI on age-adjusted alignment outcomes of surgical ASD patients. STUDY DESIGN/SETTING Single center retrospective review. PATIENT SAMPLE A total of 205 operative ASD patients. OUTCOME MEASURES Postoperative alignment parameters (PT, SVA, PI-LL, and SS); health-related quality of life (HRQL) scores. METHODS Surgical ASD patients >18 years with full-body stereographic x-ray imaging at baseline (BL) and early postoperative follow-up ( 75th) for both BL height and PI. Correction groups were generated at postoperative follow-up for actual alignment compared to age-adjusted ideal values for PT, PI-LL, and SVA, and PI-adjusted ideal alignment values for SS, as derived from clinically relevant formulas. Chi-squared tests assessed differences in rates of matching age-adjusted alignment ideal (±10years threshold for age-adjusted targets; −7° to 5° measured minus ideal for SS target) across height and PI groups. Subanalysis of patients matching age-adjusted alignment ideal used ANOVA to compare clinical outcomes across height and PI groups. RESULTS Included: 205 ASD patients (59±16 year, 64% F, 27±6 kg/m2). Following surgery, patients showed significant improvement in PT, PI-LL and SVA (all p .05). Height groups also did not differ in age or BMI (all p>.05), although female patients comprised a greater proportion of the low (96% F vs. 4% M) and normative (75% F vs. 25% M) height groups (p 0.05). Although there were no differences across PI groups in rates of achieving ideal alignment for PI-LL, SVA or SS (all p>.05), patients with high PI reached age-adjusted ideal alignment for PT at a significantly lower rate (15%) than patients with normative (36%) or low PI (33%, p=.031). Of the 58% of patients that matched any adjusted alignment target in early follow-up, there were no significant differences in postoperative HRQL outcomes across patient height or PI groups (all p>.05). CONCLUSIONS Patients with high pelvic incidence reached ideal postoperative age-adjusted PT alignment at a significantly lower rate than patients with normative and low pelvic incidence. In contrast, patient height had no impact on postoperative age-adjusted alignment outcomes. These results suggest that current postoperative ideal alignment targets may warrant adjustment to account for the morphological factor of pelvic incidence.

Saturday, September 29, 2018 9:00 am–10:00 am Impact of Adult Deformity Correction: 266. Durability of satisfactory functional outcomes following surgical adult spinal deformity correction: a 3-year survivorship analysis

BACKGROUND CONTEXT Despite reports showing positive long-term functional outcomes following adult spinal deformity (ASD) corrective surgery, it is still unclear which factors may impact the durability of these outcomes. PURPOSE Assess durability of functional gains following ASD-corrective surgery, and determine predictors for postoperative loss of functionality. STUDY DESIGN/SETTING Retrospective review of prospective, multi-center ASD patient database. PATIENT SAMPLE A total of 166 surgical ASD patients (57±15 year, 75%F, BMI: 26.7±6.1). OUTCOME MEASURES Oswestry Disability Index (ODI), modified frailty index (mFI). METHODS Included: surgical ASD patients (scoliosis≥20°, SVA≥5 cm, PT≥25° and/or TK>60°)≥18years with 3-year ODI follow-up, and 1-year postop (1 year) ODI scores reaching substantial clinical benefit threshold(SCB, RESULTS All 166 included surgical ASD patients(11±4 lvls; 68% posterior approach, 2% anterior, 31% combined; 64% of cases involved osteotomy, 55% decompression), showed baseline (BL) to 1 year functional improvement (mean ODI: 35.3±16.5 to 13.6±9.2, P 2 vs. 28, P=0.010), and lower rates of reoperation past 1Y(9% vs. 23%, P=.011), BL osteoporosis (9% vs. 23%, P=.019), cancer(4% vs. 19%, P=.002), heart disease (6% vs. 21%, P=.004), hypertension (28% vs. 54%, P=.001), and lung disease (1% vs. 6%, P=.040). Multivariate analysis showed lung disease (HR:4.8 [1.4-16.4]), 1 year frailty(HR:1.4 [1.1-1.9]), and posterior approach (HR:2.6 [1.2-5.8]) as associated with shorter time to functional decline. CONCLUSIONS A total of 71% of surgical ASD patients maintained satisfactory functional outcomes by 3-year postoperative. Of those who failed to sustain satisfactory functionality, the largest functional decline was observed at the 3-year postop interval. Patient frailty, preoperative comorbidity burden, and surgical approach all affected the durability of functional gains following ASD-corrective surgery. Evidence of functional deterioration in patients with these factors should be taken into account to improve patient counseling. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Wednesday, September 26, 2018 2:00 PM – 3:00 PM Integrating Technology into Practice: 60. Utilization of artificial intelligence-based hierarchical cluster analysis of patient baseline characteristics and surgical invasiveness provides novel insights on 2-year outcomes and complications through pattern recognition

BACKGROUND CONTEXT Adult spinal deformity (ASD) is a highly heterogeneous condition with a broad range of surgical options. Unsupervised machine-based pattern clustering of patient types based on radiographic parameters and quality of life measures alongside combinations of surgical options may simplify ASD patient types, procedures and outcomes. Artificial intelligence (AI) based pattern recognition may provide augmented preoperative decision analysis to surgeons in real time. PURPOSE Subtle similarity patterns may exist across patient and surgery types that may not be specified but may significantly influence surgical outcomes and major complication (MC) rates. Our objective was to explore whether AI may potentially augment our decision-making capability by identifying similarity patterns in patient types when combined with procedure groups. STUDY DESIGN/SETTING Retrospective analysis of prospectively collected data. PATIENT SAMPLE Adult spinal deformity patients from two prospective observational cohorts. OUTCOME MEASURES Major complication rates, SF36v2, Scoliosis Research Society-22R (SRS-22R). METHODS Two prospective observational cohorts were queried for surgical ASD patients with SRS-22/ODI/SF-36v2 data at baseline, 1 year and 2 years. Two dendrograms on the same observations were fitted, one with surgical features and the other with patient characteristics. Both were built with Ward distances and optimized with the Gap method. For each of the possible n patient clusters by m surgeries, normalized average improvement at 2 years and adjusted MC rates were computed. RESULTS A total of 570 patients were included in the analysis. Three optimal patient types were identified: young with coronal plane deformity (YC)(n=195), older with prior spine surgeries (ORev) (n=194) and Older without prior spine surgeries (OPrim)(n=218). Osteotomy type, instrumentation and interbody fusion were identified and combined to define four optimal average surgical options. Two-year normalized average improvement ranged from −0.074% for SF36v2 MCS score in cluster (1,3) to 100.21% for SRS self-image score in cluster (2,1). MC rates at 2 years ranged from 0% to 51.8%. CONCLUSIONS Unsupervised AI hierarchical clustering can identify subtle data patterns and classification clusters that may augment preoperative decision-making through construction of a 2-year risk/benefit grid. In addition to enhancing outcome and complication prediction, pattern identification may facilitate treatment optimization by educating surgeons on which treatment patterns yield optimal improvement with lowest risk. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P81. Successful creation of deployable preoperative predictive risk calculators for individual patient event-free survivorship for major complications, hospital readmissions and unplanned surgery following adult spinal deformity (ASD) surgery

BACKGROUND CONTEXT Few predictive models allow for proper patient selection, adjustment of invasiveness and patient frailty optimization to predict and reduce postoperative major complications (MC), hospital readmissions (READMIT), and unplanned surgery (UNPLAN). PURPOSE The objective of this project is to create accurate predictive models for the occurrence and timing of MC, READMIT, and UNPLAN following ASD surgery. STUDY DESIGN/SETTING Retrospective analysis of two independent prospective, multicenter ASD databases with identical fixed data fields. PATIENT SAMPLE Data from 1,018 ASD surgically treated patients (57 surgeons, 24 sites, and 5 countries) were used to build MC, READM and UNPLAN risk calculating models with proved successful model fit. OUTCOME MEASURES Postoperative major complications (MC), hospital readmissions (READMIT), unplanned surgery (UNPLAN). METHODS Surgical ASD patients with >2yFU were identified. Patient demographic, radiographic, operative, baseline PROMs, and complications data were analyzed to build event free survival curves for MC, READMIT and UNPLAN, and to create predictive models by means of a random survival forest with 80/20 train or test sets. 101 variables were used. Missing value imputation was performed with the missForest package. RESULTS A total of 1,018 ASD patients treated surgically before September-2014 (77.7% women, 55.5 mean age, 10.7 levels fused segments, 55.5% pelvic fixation, 21.2% 3CO) by 57 surgeons at 24 sites in 5 countries (2 continents), with 2,047.9 observation-years, were included in the analysis. Missing value imputation was 14.59%. C-statistic value (70.6%) proved successful model fit. Models demonstrate that 87.9% of patients are MC-free at 10days postop, 78.5% at 90days and 63% at 2years. Surgical invasiveness (LIV-pelvic fixation, length of fusion, prior surgery), age, magnitude of sagittal deformity, patient frailty (walking and lifting capacity) and blood loss most strongly predict MC. Surgeon and site most strongly predict READMIT and UNPLAN. Curves show a continued survivorship decrease for event free MC, READMIT and UNPLAN beyond >2yFU. CONCLUSIONS Risk calculating models for event-free MC, READMIT and UNPLAN following ASD surgery demonstrate that patient-related factors, >1/3 of which are modifiable, account for 55% of the MC predictive model weight. Surgeon and site represent 4% for MC, but are most relevant for READMIT and UNPLAN.

Medical Complications After Adult Spinal Deformity Surgery: Incidence, Risk Factors, and Clinical Impact.

Retrospective review of a prospective multicenter database evaluating surgical adult spinal deformity (ASD) patients. This study aims to identify risk factors for medical complications in ASD patients undergoing surgery. ASD surgery is known for its high complication rate. This study examines baseline patient characteristics for predictors of medical complications in surgical ASD patients. Intra and perioperative medical complications were included. Medical complications were: infection, pneumonia, urinary tract infection, c-difficile, sepsis, stroke, delirium, deep venous thrombosis, pulmonary embolism, myocardial infarction, arrhythmia, congestive heart failure, pneumothorax, atelectasis, adult respiratory distress syndrome, bowel obstruction, ileus, and renal failure. Potential predictors were identified using univariate testing. Multivariate Poisson regression was used to determine independent predictors of medical complications. Health-related quality of life (HRQL) was measured using the Oswestry Disability Index and SF-36. Multivariate repeated measures mixed models were used to examine HRQL. Four hundred forty-eight patients were included. The incidence of patients with at least one medical complication was 26.8%. Potential predictors included: age, BMI, anemia, arthritis, depression, cardiac history, hypertension, lung disease, history of PVD, Charlson Comorbidity Index, ASA, smoking, sex, and the number of years with spine problems. Independent predictors identified on multivariate logistic regression modeling included hypertension (IRR 2.43 P = 0.0001), smoking (IRR 2.49 P = 0.0001), and number of years with spine problems (IRR 1.23 P = 0.03). Despite medical complications, patients experienced significant improvements in HRQL, as measured by the SF-36 (P = 0.0001) and oswestry disability index (P = 0.0001). The rate of improvement and overall improvement compared with baseline were not statistically different than that of patients who did not experience medical complications. Risk factors for the development of postoperative medical complications after correction of ASD include smoking, hypertension, and duration of symptoms. Patients who have one or more of these risk factors should be identified and informed during informed consent of their increased risks. They should be optimized preoperatively, and followed closely during the postoperative period. 3.

Introducing dynamic balance assessment in Adult Spinal Deformity

Over the past decade, the number of adult spinal deformity (ASD) surgeries has more than doubled in the United States. The complex surgeries needed to manage ASD are associated with significant resource utilization and high cost, making them a primary target for increased scrutiny. Accordingly, it is important to not only demonstrate value in ASD surgery as clinical effectiveness but also to translate outcome assessment to cost-effectiveness.To compare the difference between Medicare allowable rates and the actual, direct hospital costs for ASD surgeries.Longitudinal cohort.Consecutive patients enrolled in an ASD database from a single institution.Short Form (SF)-6D.Consecutive patients enrolled in an ASD database from a single institution from 2008 to 2013 were identified. Direct hospital costs were collected from hospital administrative records for the entire inpatient episode of surgical care. Medicare allowable rates were calculated for the same inpatient stays using the year-appropriate Center for Medicare-Medicaid Services Inpatient Pricer Payment System Tool. The SF-6D, a utility index derived from the SF-36v1, was used to determine quality-adjusted life years (QALY). Costs and QALYs were discounted at 3.5% annually.Of 580 surgical ASD patients eligible for 2-year follow up, 346 (60%) had complete baseline and 2-year data, and 60 were Medicare beneficiaries comprising the cohort for the present study. Mean SF-6D gained is 0.10 during year 1 after surgery and 0.02 at year 2, resulting in a cumulative SF-6D gain of 0.12 over 2 years. Mean Medicare allowable rate over the 2 years is $82,050 (range $42,383 to $220,749) and mean direct cost is $99,114 (range $28,447 to $217,717). Mean cost per QALY over 2 years is $683,750 using Medicare allowable rates and $825,950 using direct costs. This difference of $17,181 between the 2 cost calculation represents a 17% difference, which was statistically significant (p<.001).There is a significant difference in direct hospital costs versus Medicare allowable rates in ASD surgery and in turn, there is a similar difference in the cost per QALY calculation. Utilizing Medicare allowable rates not only underestimates (17%) the cost of ASD surgery, but it also creates inaccurate and unrealistic expectations for researchers and policymakers.

Impact of cost valuation on cost-effectiveness in adult spine deformity surgery

Background ContextOver the past decade, the number of adult spinal deformity (ASD) surgeries has more than doubled in the United States. The complex surgeries needed to manage ASD are associated with significant resource utilization and high cost, making them a primary target for increased scrutiny. Accordingly, it is important to not only demonstrate value in ASD surgery as clinical effectiveness but also to translate outcome assessment to cost-effectiveness. PurposeTo compare the difference between Medicare allowable rates and the actual, direct hospital costs for ASD surgeries. Study DesignLongitudinal cohort. Patient SampleConsecutive patients enrolled in an ASD database from a single institution. Outcome MeasuresShort Form (SF)-6D. MethodsConsecutive patients enrolled in an ASD database from a single institution from 2008 to 2013 were identified. Direct hospital costs were collected from hospital administrative records for the entire inpatient episode of surgical care. Medicare allowable rates were calculated for the same inpatient stays using the year-appropriate Center for Medicare-Medicaid Services Inpatient Pricer Payment System Tool. The SF-6D, a utility index derived from the SF-36v1, was used to determine quality-adjusted life years (QALY). Costs and QALYs were discounted at 3.5% annually. ResultsOf 580 surgical ASD patients eligible for 2-year follow up, 346 (60%) had complete baseline and 2-year data, and 60 were Medicare beneficiaries comprising the cohort for the present study. Mean SF-6D gained is 0.10 during year 1 after surgery and 0.02 at year 2, resulting in a cumulative SF-6D gain of 0.12 over 2 years. Mean Medicare allowable rate over the 2 years is $82,050 (range $42,383 to $220,749) and mean direct cost is $99,114 (range $28,447 to $217,717). Mean cost per QALY over 2 years is $683,750 using Medicare allowable rates and $825,950 using direct costs. This difference of $17,181 between the 2 cost calculation represents a 17% difference, which was statistically significant (p<.001). ConclusionsThere is a significant difference in direct hospital costs versus Medicare allowable rates in ASD surgery and in turn, there is a similar difference in the cost per QALY calculation. Utilizing Medicare allowable rates not only underestimates (17%) the cost of ASD surgery, but it also creates inaccurate and unrealistic expectations for researchers and policymakers.

Ankle foot orthoses for calf muscle weakness: Effect on ankle angle and knee moment

Over the past decade, the number of adult spinal deformity (ASD) surgeries has more than doubled in the United States. The complex surgeries needed to manage ASD are associated with significant resource utilization and high cost, making them a primary target for increased scrutiny. Accordingly, it is important to not only demonstrate value in ASD surgery as clinical effectiveness but also to translate outcome assessment to cost-effectiveness.To compare the difference between Medicare allowable rates and the actual, direct hospital costs for ASD surgeries.Longitudinal cohort.Consecutive patients enrolled in an ASD database from a single institution.Short Form (SF)-6D.Consecutive patients enrolled in an ASD database from a single institution from 2008 to 2013 were identified. Direct hospital costs were collected from hospital administrative records for the entire inpatient episode of surgical care. Medicare allowable rates were calculated for the same inpatient stays using the year-appropriate Center for Medicare-Medicaid Services Inpatient Pricer Payment System Tool. The SF-6D, a utility index derived from the SF-36v1, was used to determine quality-adjusted life years (QALY). Costs and QALYs were discounted at 3.5% annually.Of 580 surgical ASD patients eligible for 2-year follow up, 346 (60%) had complete baseline and 2-year data, and 60 were Medicare beneficiaries comprising the cohort for the present study. Mean SF-6D gained is 0.10 during year 1 after surgery and 0.02 at year 2, resulting in a cumulative SF-6D gain of 0.12 over 2 years. Mean Medicare allowable rate over the 2 years is $82,050 (range $42,383 to $220,749) and mean direct cost is $99,114 (range $28,447 to $217,717). Mean cost per QALY over 2 years is $683,750 using Medicare allowable rates and $825,950 using direct costs. This difference of $17,181 between the 2 cost calculation represents a 17% difference, which was statistically significant (p<.001).There is a significant difference in direct hospital costs versus Medicare allowable rates in ASD surgery and in turn, there is a similar difference in the cost per QALY calculation. Utilizing Medicare allowable rates not only underestimates (17%) the cost of ASD surgery, but it also creates inaccurate and unrealistic expectations for researchers and policymakers.

The effect of antifibrinolytic therapy on complications, blood product utilization, and fusion in adult spinal deformity

Antifibrinolytic therapy (AF) has been shown to be effective in preventing blood loss in some settings. Its effect in patients undergoing adult spinal deformity (ASD) surgery remains unclear. This study looks at the use of antifibrinolytic therapy in adult spinal deformity surgery and its effect on major and minor perioperative complications, blood product utilization, vascular events and postoperative fusion. A multicenter prospective consecutive database of surgical ASD patients was reviewed. Complications were divided into intra-operative and perioperative (within 6 weeks). Parameters of blood product utilization included the rate of transfusion, and the units of PRBCs and FFP transfused. Thromboembolic events included stroke, deep venous thrombosis (DVT) and pulmonary embolus (PE). Fusion rates at 2 years were measured on AP and lateral radiographs at using the Lenke classification. The impact of AF use on complications, blood product utilization, vascular events and fusion rates was studied using multivariate logistic, ordinal logistic, or poisson regression, as appropriate. Models accounted for confounders as determined by univariate analysis and expert opinion. In total, 403 patients were included, 137 patients received aminocaproic acid (ACA), 81 received tranexamic acid (TXA), 185 received no AF, 227 patients had two-year radiographic data. The use of AF was associated with a decrease in transfusion (ACA OR 0.38 P = 0.043, TXA 0.31 P = 0.047), a decrease in the number of units of PRBCs transfused (ACA IRR 0.45 P = 0.0005, TXA IRR 0.7 P = 0.0005), and a decrease in the number of FFP transfused (ACA IRR 0.65 P = 0.003, TXA IRR 0.67 P = 0.006). The use of TXA (but not ACA) was associated with a decrease the incidence of major perioperative complications compared to no AF (IRR 0.37, P = 0.019). AF use was not associated with an increase in thromboembolic events. The use of AF did not impact the fusion rates at 2 years. The use of TXA or ACA was associated with increased minor intra-operative complications. TXA was associated with decreased major perioperative complications. AF was associated with decreased utilization of blood products without an increased rate of thromboembolic events. Given the observational nature of this study, transfusion threshold was not standardized across the study sites. Future studies with rigid criteria for transfusion should be prospectively performed to better evaluate AF use in ASD.