Faculty Bibliography

BACKGROUND CONTEXT: With the rise of health care costs and a focus on value-based outcomes, hospitals have become more cognizant on cost of revisions and complications. However, literature on the effect of distal junctional kyphosis in driving up health care costs is scarce. PURPOSE: To evaluate the effect of distal junctional kyphosis on the cost effectiveness of corrective cervical deformity surgery. STUDY DESIGN/SETTING: Retrospective review of a single surgeon database. PATIENT SAMPLE: This study included 123 cervical deformity patients. OUTCOME MEASURES: Cost per QALY.
METHOD(S): Cervical deformity patients with minimum 1-year HRQL follow-up were included. Means comparison tests assessed differences in baseline demographic and clinical data. Utility data was calculated using published conversion methods to convert NDI to SF-6D. QALYs utilized a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs was calculated using the PearlDiver database incorporating complications, comorbidities (CC), major complications, and comorbidities (MCC) were assessed according to CMS.gov manual definitions. 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) and death, cost per QALY at 2Y was calculated for revisions due to distal junctional kyphosis.
RESULT(S): A total of 123 cervical deformity patients met inclusion criteria (57.22yrs, 54%F, 29.0kg/m2). At baseline, patients presented radiographically as: PT (16.9+/-9.7), PI (54.7+/-11.4), PI-LL (-2.9+/-12.6), SVA (80.5+/-49.8), cSVA (28.4+/-20.6), TS-CL (26.6+/-14.4). Surgical details: EBL of 708 mL, operative time of 438.6 min, with 29.51% undergoing an anterior approach, 50.82% posterior-only approach, and 19.67% combined approach. Overall, 7.9% of patients developed DJK within two years postoperatively. Average cost of revision surgery due to DJK within 2years of index surgery was $50,736 +/- 31,467. Patients that developed DJK within 2years of index surgery trended toward having a greater baseline NDI (62.8 vs 55.47, p>0.05) and showed less improvement in NDI at 2 years (4 vs 16.6). Overall, cost per QALY was higher for patients developing DJK at 2 years ($28,483 vs $20,989).
CONCLUSION(S): Cervical deformity revisions due to distal junctional kyphosis had a cost per QALY of $28,483. Efforts to limit postoperative DJK after surgical intervention can further limit additional costs associated with revisions and complications. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Frailty has been utilized in cervical deformity (CD) to characterize the influence of preop health state on postop outcomes. Frailty severity may be an important determinant for impaired recovery after CD corrective surgery. No prior studies have examined the associations between increasingly frail states and the trajectory of recovery in CD realignment. PURPOSE: Evaluate postop clinical recovery among CD patients between frailty states undergoing primary procedures STUDY DESIGN/SETTING: Retrospective review of a prospective CD database PATIENT SAMPLE: A total of 106 CD patients. OUTCOME MEASURES: Baseline (BL) to 1-Year(1Y) HRQL Instruments: NDI, mJOA, EQ5D METHODS: Patients>18yrs undergoing surgery for CD (C2-7 Cobb>10degree, coronal Cobb>10degree, cSVA>4cm or TS-CL>10degree, or CBVA>25degree) with HRQL data at BL, 3M and 1Y postop intervals were identified. Patients were stratified by the modified CD frailty index (mCD-FI, Passias et al.) scale from 0-1 (no frailty:<0.3[NF], mild/severe: >0.3[F]). Patients in NF and F groups were propensity score matched (PSM) for TS-CL to control for baseline deformity. Demographics, alignment and Ames-ISSG deformity modifiers were assessed using chi-squared and paired t-tests to compare HRQL outcomes. HRQL outcomes were normalized by dividing BL and postop (3M, 1Y) outcomes by BL for each patient. Normalized scores (y-axis) were plotted against duration of follow-up (x-axis). AUC was calculated for follow-up time intervals; total area for each follow-up interval was divided by cumulative follow-up, determining overall normalized, time-adjusted HRQL outcomes (Integrated Health State [IHS]). IHS was compared between NF and F groups.
RESULT(S): A total of 106 CD patients included (61.7yrs, 66% F, 27.7kg/m2). By frailty group: 52.8% NF, 47.2% F. After PSM for TS-CL (mean: 38.1degree), 38 patients remained in each of the NF and F groups. By surgical approach, 46.1% underwent posterior approach, 19.7% anterior, and 34.2% combined; which was not significant between the frailty groups(p>0.05). At baseline, cervical and spinopelvic radiographic parameters were not significant, except for the C7-S1 SVA (NF: -26.5mm vs F: 15.2mm, p=0.007). According to BL HRQLs, F patients displayed significantly worse NDI scores (NF: 36.8 F: 55.4; p<0.001), mJOA (NF: 14.7, F: 12.7; p=0.002), and EQ5D (NF: 0.78, F: 0.69; p<0.001). All frailty groups exhibited BL to 1Y improvement in NDI, EQ5D and NRS Neck Pain (all p<0.001). After HRQL normalization, F patients had more improvement in mJOA scores at 3M (p=0.065) as well as NDI (p=0.096) and EQ5D (p=0.016). IHS-adjusted HRQL outcomes from BL to 1Y showed a significant difference in EQ5D scores (NF: 1.02, F: 1.07, P=0.016). No significant differences were found in the IHS NDI and mJOA between frailty groups (p>0.05). F patients had more postop major complications (31.3%) compared to the NF (8.9%), p=0.004, though DJK occurrence and reoperation between the groups was not significant.
CONCLUSION(S): While all groups exhibited improved postop disability/pain scores, frail patients recovered better in overall health state. Despite frail patients having more complications, they seem to have overall better patient-reported outcomes, signifying that with frailty severity, patients have more room for improvement postop compared to baseline quality of life. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Proximal junctional failure (PJF) is a common and particularly adverse complication of adult spinal deformity (ASD) surgery. There is evidence that the rigidity of posterior spinal constructs may impact risk of PJF. PURPOSE: We hypothesized that lower mean screws per level and decreased rod stiffness would be associated with lower incidence of PJF. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Patients with ASD and 2-year minimum follow-up were included. Only patients undergoing fusion of >=5 levels, and with LIV at the sacro-pelvis were included. Patients undergoing revision surgery were excluded. In total, 420 patients were analyzed. OUTCOME MEASURES: The primary outcome variable was PJF, defined using previously published radiographic criteria (PJ angle >28degreeand PJ angle >22degree, and >=8mm/>=3mm listhesis at upper thoracic / thoracolumbar levels, respectively).
METHOD(S): The primary independent variables were the mean number of screws per level fused analyzed with a cutoff of 1.8 (determined by ROC analysis) and rod material/diameter. Multivariable logistic regression was utilized to investigate confounding factors, including age, history of osteoporosis, BMI, gender, CCI, preoperative Schwab modifiers, preoperative TPA, postoperative change in lumbar lordosis, upper instrumented vertebra, osteotomy, approach, UIV type (ie, pedicle screw vs other), and number of levels fused.
RESULT(S): Of the total patients, 78.8% were female. PJF occurred in 14.1% of patients. The mean screws per level was 1.7 (SD 0.2), and 57.6% of patients had <1.8 screws per level. PJF occurred in 19.4% vs 9.8% of patients with >=1.8 vs <1.8 screws per level, respectively (p<0.01). In multivariable analysis, patients with <1.8 screws per level exhibited lower odds of PJF (OR 0.39, p<0.01). Rod material and diameter (both p>0.2) were not significantly associated with PJF. Screw density specifically adjacent to the UIV was not related to PJF (p>0.2).
CONCLUSION(S): Among ASD patients undergoing long-segment primary fusion to the pelvis, the risk of PJF was lower among patients with <1.8 screws per level. Rod diameter and material, however, were not significantly associated with PJF. This finding may be related to construct rigidity. It is possible that residual confounding by other patient and surgeon-specific characteristics may exist. Further biomechanical and clinical studies exploring the relationship between screw density and PJK/PJF are warranted. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: While advances have been made in the surgical management of distal junctional kyphosis (DJK), complication rates remain high. Although individual factors related to its occurrence have been cited, many of these cases are mild and have no clinical relevance nor have these been combined into a formal predictive model, particularly for cases that are clinically impactful. PURPOSE: Develop a formal predictive model distinguishing between symptomatic and asymptomatic DJK. STUDY DESIGN/SETTING: Retrospective review PATIENT SAMPLE: A total of 99 cervical deformity patients (CD) with 1 year (1Y) follow up OUTCOME MEASURES: Complications; reoperations; HRQL, alignment METHODS: CD patients (pts) were stratified into asymptomatic (Asym) and symptomatic (Sym) DJK. DJK angle (DJKA) was defined >10degree change in kyphosis between LIV and LIV-2 and a >10degree index angle. Asym: DJK to be>10degree in the absence neurologic sequelae. Sym: 1) DJKA> 10degree and either reop due to DJK or >one new-onset neurological sequelae related to DJK or 2) pts who had either a DJKA > 20degree or DJKA > 20degree. Stepwise logistic regressions were used to identify patient-specific, surgical, radiographic and HRQL factors that were associated with these types of DJK. Decision tree analysis established cut-offs for the continuous variables.
RESULT(S): A total of 99 CD pts were included (60yrs, 26.5kg/m2, 66.7%F). Surgical characteristics: 7.4+/-4 levels fused, 47.5% posterior, 18.2% anterior, and 34.3% combined. Overall, 32.2% developed DJK (34.3% Asym, 65.7% Sym). 37.5% of Asym pts received a reop vs 62.5% Sym pts. At BL, Asym pts had a greater BMI (28.5 vs 23kg/m2) and NSR back pain (5.2 vs 4.6; all p<0.05). Decision tree analysis identified osteoporosis, UIV level, and the apex of the region of the spine where the primary deformity is located to predict Sym pts. Top factors predicting Sym pts over Asym were BL EQ5D>0.65, UIV cephalad to C2, and C2-C7 apex caudal to C5. Multivariate analysis identified independent radiographic and surgical factors for developing Sym DJK: [Radiographic] BL PI (1.02[0.9-1.07]), preop cervical flexibility (1.04[1.01-1.07]); [Surgical] combined approach (6.2[1.4-27]; all p<0.05). Having abnormal hyper kyphosis in the thoracic spine, more so than abnormal cervical lordosis, was an independent factor for developing Sym when analyzed against Asym pts (1.2[0.01-115]). Predictive modeling identified factors that were predictive of Sym against no DJK pts such as having myelopathy (mJOA score:12-14), combined approach, UIV=C3 or C4, preoperative hypermobility, and >7 levels fused (AUC: 0.89). A predictive model for Sym versus Asym pts yielded an AUC of 85% and included being frail, having a TS-CL>20, and a PI>46.3. Controlling for BL deformity and disability, Sym pts had greater cSVA(4-8cm: 47.6%vs 27%) and were more maligned according to their SRS-SVA (0.1[0.76-0.02]) than non DJK pts at 1Y (all p<0.05). Despite their symptomatology and higher re-operation rate, outcomes equilibrated in the Sym cohort at 1Y following revision.
CONCLUSION(S): Overall 32.2% cervical deformed patients suffered from DJK most of which were clinically significant. Severe symptomatic DJK can be predicted with high reliability using combined determinants of baseline spinal cord dysfunction, mobility, frailty, and surgical factors including end levels, number of levels fused and use of a combined approach. It can be further distinguished from asymptomatic occurrences by taking into account pelvic incidence and baseline cervicothoracic deformity severity. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT/BACKGROUND:Considerable debate exists regarding the optimal surgical approach for adult spinal deformity (ASD). It remains unclear which approach, posterior-only or combined anterior-posterior (AP), is more cost-effective. Our goal is to determine the 2-year cost per quality-adjusted life year (QALY) for each approach. PURPOSE/OBJECTIVE:To compare the 2-year cost-effectiveness of surgical treatment for ASD between the posterior-only approach and combined AP approach. STUDY DESIGN/METHODS:Retrospective economic analysis of a prospective, multicenter database PATIENT SAMPLE: From a prospective, multicenter surgical database of ASD, patients undergoing 5 or more level fusions through a posterior-only or AP approach were identified and compared. METHODS:QALYs gained were determined using baseline, 1-year, and 2-year post-operative Short Form 6D. Cost was calculated from actual, direct hospital costs including any subsequent readmission or revision. Cost-effectiveness was determined using cost/QALY gained. RESULTS:The AP approach showed significantly higher index cost than the posterior-only approach ($84,329 vs $64,281). This margin decreased at 2-year follow-up with total costs of $89,824 and $73,904, respectively. QALYs gained at two years were similar with 0.21 and 0.17 in the posterior-only and the AP approaches, respectively. The cost/QALY at two years after surgery was significantly higher in the AP approach ($525,080) than in the posterior-only approach ($351,086). CONCLUSIONS:We assessed 2-year cost-effectiveness for the surgical treatment through posterior-only and AP approaches. The posterior-only approach is less expensive both for the index surgery and at 2-year follow-up. The QALY gained at 2-years was similar between the two approaches. Thus, posterior-only approach was more cost-effective than the AP approach under our study parameters. However, both approaches were not cost-effective at 2-year follow-up.

BACKGROUND CONTEXT: Age-adjusted alignment targets for adult spinal deformity (ASD) patients have the potential to reduce the incidence of PJK while ensuring optimal HRQL. Previous studies demonstrated the interplay between lumbar lordosis (LL) and thoracic kyphosis (TK) and their relationship with pelvic morphology as measured by the plevic incidence (PI). In clinical practice, reaching this ideal alignment remains challenging as the relationship between lordosis and kyphosis is not clearly elucidated. PURPOSE: This study aimed at developing a pragmatic formula on how much lumbar lordosis is needed based on the patient age, PI and exiting thoracic kyphosis. STUDY DESIGN/SETTING: Multicenter retrospective review of a prospective database. PATIENT SAMPLE: A total of 347 adult spinal deformity patients reaching age-adjusted alignment at 1-year post surgery. OUTCOME MEASURES: Sagittal alignment and internal validation of predictive formula.
METHOD(S): Surgical ASD patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regressions analysis was used to identify the relationship between regional curvatures (LL &TK) permitting to reach a given global alignment (TPA) based on pelvic incidence.
RESULT(S): The 347 patients included (60 years old, 72% female, BMI 29+/-6.2) had a significant improvement in all sagittal parameters from pre-op to 1Y (p<0.001 except PI). Multilinear regression predicting L1-S1 based on TK, TPA and PI demonstrated excellent results (R2=0.85). Similar results were found when regressions were conducted for each TPA percentile group (R2 ranging from 0.83 to 0.87). Simplification of the coefficients of prediction led to the following equation: LL = PI + 0.3

PURPOSE/OBJECTIVE:Analysis of interactions of spinal alignment metrics may uncover novel alignment parameters, similar to PI-LL. This study utilized a data-driven approach to hypothesis generation by testing all possible division interactions between spinal alignment parameters. METHODS:This study was a retrospective cohort analysis. In total, 1439 patients with baseline ODI were included for hypothesis generation. In total, 666 patients had 2-year postoperative follow-up and were included for validation. All possible combinations of division interactions between baseline metrics were assessed with linear regression against baseline ODI. RESULTS:From 247 raw alignment metrics, 32,398 division interactions were considered in hypothesis generation. Conceptually, the TPA divided by PI is a measure of the relative alignment of the line connecting T1 to the femoral head and the line perpendicular to the sacral endplate. The mean TPA/PI was 0.41 at baseline and 0.30 at 2 years postoperatively. Higher TPA/PI was associated with worse baseline ODI (p < 0.0001). The change in ODI at 2 years was linearly associated with the change in TPA/PI (p = 0.0172). The optimal statistical grouping of TPA/PI was low/normal (≤ 0.2), medium (0.2-0.4), and high (> 0.4). The R-squared for ODI against categorical TPA/PI alone (0.154) was directionally higher than that for each of the individual Schwab modifiers (SVA: 0.138, PI-LL 0.111, PT 0.057). CONCLUSION/CONCLUSIONS:This study utilized a data-driven approach for hypothesis generation and identified the spino-pelvic ratio (TPA divided by PI) as a promising measure of sagittal spinal alignment among ASD patients. Patients with SPR > 0.2 exhibited inferior ODI scores. LEVEL OF EVIDENCE/METHODS:III.

PURPOSE/OBJECTIVE:Coronal malalignment (CM) causes pain, impairment of function and cosmetic problems for adult spinal deformity (ASD) patients in addition to sagittal malalignment. Certain types of CM are at risk of insufficient re-alignment after correction. However, CM has received minimal attention in the literature compared to sagittal malalignment. The purpose was to establish reliability for our recently published classification system of CM in ASD among spine surgeons. METHODS:Fifteen readers were assigned 28 cases for classification, who represented CM with reference to their full-length standing anteroposterior and lateral radiographs. The assignment was repeated 2 weeks later, then a third assignment was done with reference to additional side bending radiographs (SBRs). Intra-, inter-rater reliability and contribution of SBRs were determined. RESULTS:Intra-rater reliability was calculated as 0.95, 0.86 and 0.73 for main curve types, subtypes with first modifier, and subtypes with two modifiers respectively. Inter-rater reliability averaged 0.91, 0.75 and 0.52. No differences in intra-rater reliability were shown between the four expert elaborators of the classification and other readers. SBRs helped to increase the concordance rate of second modifiers or changed to appropriate grading in cases graded type A in first modifier. CONCLUSIONS:Adequate intra- and inter-rater reliability was shown in the Obeid-CM classification with reference to full spine anteroposterior and lateral radiographs. While side bending radiographs did not improve the classification reliability, they contributed to a better understanding in certain cases. Surgeons should consider both the sagittal and coronal planes, and this system may allow better surgical decision making for CM.

BACKGROUND CONTEXT: Opioid use prior to surgery is associated with worse postop outcomes. Little is known regarding the economic impact that preop opioid use has upon patient preferred health state, quality adjusted life years (QALYs) and the cost/QALY of surgical treatment for adult spinal deformity (ASD). PURPOSE: Compare the health state preference values, QALYs, and cost/QALY for operatively treated ASD patients that used opioids vs did not use opioids prior to surgery. STUDY DESIGN/SETTING: Cost/QALY analysis of operatively treated patients identified from a prospective, multi-center ASD study. PATIENT SAMPLE: Propensity score matched (PSM) cohorts of patients that used opioids (OPIOID) vs nonusers (NON) prior to ASD surgery, at 1- and minimum 2-year follow up. OUTCOME MEASURES: Short Form-36v2 questionnaire (SF-36), SF6D derived from SF-36, hospital costs for operative treatment of ASD based on CMS DRG reimbursements, QALYs, cost/QALY for index surgery, perioperative complications, and 1- and 2-year postop opioid use.
METHOD(S): ASD patients (age>18 years) enrolled into a prospective multicenter ASD database were divided into preop opioid (OPIOID) vs nonopioid (NON) users. PSM was performed to control for confounding demographic, radiographic, and surgical variables. Preop, 1-year, and minimum 2-year postop SF6D values obtained, 1- and 2-year post QALYs were calculated using SF6D change from baseline, hospital costs at the time of index surgery were calculated using CMS DRG reimbursements adjusted for inflation to 2019 US dollars, cost/QALY evaluated at 1- and 2-years postop, perioperative complications, and 1- and 2-year postop opioid use was evaluated for OPIOID vs NON.
RESULT(S): DRG data was available for 182/262 patients meeting inclusion criteria. Following PSM, preoperative demographics, radiographic parameters, surgical treatment, and mean follow up (3.4 vs 3.3 years) were similar for OPIOID (n=68) vs NON (n=114), respectively (p>0.05). OPIOID had longer ICU (49 vs 23 hours) and hospital stay (9.7 vs 6.8 days) than NON, respectively (p<0.05). SF6D was worse for OPIOID at preop (0.521 vs 0.598), 1-year (0.613 vs 0.749), and 2-years postop (0.626 vs 0.749) than NON, respectively (p<0.05). QALYs were worse at 1- (0.567 vs 0.674) and 2-years postop (0.674 vs 0.825) for OPIOID vs NON, respectively (p<0.05). Cost of care at index surgery was greater for OPIOID ($83,363.02) vs NON ($70,281.17). Cost/QALY was higher for OPIOID at 1-year ($150,294.51vs $107,947.19) and 2-years postoperative ($69,615.78 vs $48,761.14) than NON (p<0.05). Perioperative complications were similar for OPIOID vs NON (p>0.05). Continued opioid use at 2-years postop was greater for OPIOID (52.4%) vs NON (8.7%; p>0.05).
CONCLUSION(S): Opioid use prior to ASD surgery is associated with worse patient perceived health state and greater costs to society. After controlling for patient demographics, deformity magnitude, and type of surgery, OPIOID had greater cost of care, despite similar perioperative complication rates. At 2-years postop both OPIOID and NON demonstrated cost effectiveness of index surgery (cost/QALY<$100,000), however the residual cost to society was $21,300 greater for OPIOID vs NON. Over 52% of OPIOD had continued opioid usage at 2-years postop compared to 8.7% of NON. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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