Retrospective review.
Develop a simplified frailty index for cervical deformity (CD) patients.
To improve preoperative risk stratification for surgical CD patients, a CD frailty index (CD-FI) ...incorporating 40 health deficits was developed. While novel, the CD-FI is clinically impractical due to the large number of factors needed for its calculation. To increase clinical utility, a simpler, modified CD-FI (mCD-FI) is necessary.
CD patients (C2-C7 Cobb>10°, CL>10°, cSVA>4 cm, or CBVA>25°) >18 year with preoperative CD-FI component factors. Pearson bivariate correlation assessed relationships between component deficits of the CD-FI and overall CD-FI score. Top deficits contributing to CD-FI score were included in multiple stepwise regression models. Deficits from model with largest R were dichotomized, and the mean score of all deficits calculated, resulting in mCD-FI score from 0 to 1. Patients were stratified by mCD-FI: Not Frail (NF, <0.3), Frail (0.3-0.5), Severely Frail (SF, >0.5). Means comparison tests established correlations between frailty category and clinical outcomes.
Included: 121 CD patients (61 ± 11 yr, 60%F). Multiple stepwise regression models identified 15 deficits as responsible for 86% of the variation in CD-FI; these factors were used to construct the mCD-FI. Overall, mean mCD-FI was 0.31 ± 0.14. Breakdown of patients by mCD-FI category: NF: 47.9%, Frail: 46.3%, SF: 5.8%. Compared with NF and Frail, SF patients had the longest inpatient hospital stays (P = 0.042), as well as greater baseline neck pain (P = 0.033), inferior Neck Disability Index scores (P<0.001) and inferior EQ-5D scores (P < 0.001). Frail patients had higher odds of superficial infection (OR:1.11.0-1.2), and SF patients had increased odds of mortality (OR:8.31.3-53.9).
Increased frailty, assessed by mCD-FI, correlated with increased length of stay, neck pain, and decreased health-related quality of life. Frail patients were at greater risk for infection, and severely frail patients had greater odds of mortality. This relationship between frailty and clinical outcomes suggests that mCD-FI offers clinical utility as a preoperative risk stratification tool.
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Multicenter, retrospective series.
To analyze the incidence, mode, and location of acute proximal junctional failures (APJFs) after surgical treatment of adult spinal deformity.
Early proximal ...junctional failures above adult deformity constructs are a serious clinical problem; however, the incidence and nature of early APJFs remain unclear.
A total of 1218 consecutive adult spinal deformity surgeries across 10 deformity centers were retrospectively reviewed to evaluate the incidence and nature of APJF, defined as any of the following within 28 weeks of index procedure: minimum 15° post-operative increase in proximal junctional kyphosis, vertebral fracture of upper instrumented vertebrae (UIV) or UIV + 1, failure of UIV fixation, or need for proximal extension of fusion within 6 months of surgery.
Sixty-eight APJF cases were identified out of 1218 consecutive surgeries (5.6%). Patients had a mean age of 63 years (range, 26-82 yr), mean fusion levels of 9.8 (range, 4-18), and mean time to APJF of 11.4 weeks (range, 1.5-28 wk). Fracture was the most common failure mode (47%), followed by soft-tissue failure (44%). Failures most often occurred in the thoracolumbar region (TL-APJF) compared with the upper thoracic region (UT-APJF), with 66% of patients experiencing TL-APJF compared with 34% experiencing UT-APJF. Fracture was significantly more common for TL-APJF relative to UT-APJF (P = 0.00), whereas soft-tissue failure was more common for UT-APJF (P < 0.02). Patients experiencing TL-APJF were also older (P = 0.00), had fewer fusion levels (P = 0.00), and had worse postoperative sagittal vertical axis (P < 0.01).
APJFs were identified in 5.6% of patients undergoing surgical treatment of adult spinal deformity, with failures occurring primarily in the TL region of the spine. There is evidence that the mode of failure differs depending on the location of UIV, with TL failures more likely due to fracture and UT failures more likely due to soft-tissue failures.
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.
Abstract Background context Whereas the costs of primary surgery, revisions, and selected complications for adult spinal deformity (ASD) have been individually reported in the literature, the total ...costs over several years after surgery have not been assessed. The determinants of such costs are also not well understood in the literature. Purpose This study analyzes the total hospital costs and operating room (OR) costs of ASD surgery through extended follow-up. Study design/setting Single-center retrospective analysis of consecutive surgical patients. Patient sample Four hundred eighty-four consecutive patients undergoing surgical treatment for ASD from January 2005 through January 2011 with minimum three levels fused. Outcome measures Costs were collected from hospital administrative data on the total hospital costs incurred for the operation and any related readmissions, expressed in 2010 dollars and discounted at 3.5% per year. Detailed data on OR costs, including implants and biologics, were also collected. Methods We performed a series of paired t tests and Wilcoxon signed-rank tests for differences in total hospital costs over different follow-up periods. The goal of these tests was to identify a time period over which average costs plateau and remain relatively constant over time. Generalized linear model regression was used to estimate the effect of patient and surgical factors on hospital inpatient costs, with different models estimated for different follow-up periods. A similar regression analysis was performed separately for OR costs and all other hospital costs. Results Patients were predominantly women (n=415 or 86%) with an average age of 48 (18–82) years and an average follow-up of 4.8 (2–8) years. Total hospital costs averaged $120,394, with primary surgery averaging $103,143 and total readmission costs averaging $67,262 per patient with a readmission (n=130 or 27% of all patients). Operating room costs averaged $70,514 per patient, constituting the majority (59%) of total hospital costs. Average total hospital costs across all patients significantly increased (p<.01) after primary surgery, from $111,807 at 1-year follow-up to $126,323 at 4-year follow-up. Regression results also revealed physician preference as the largest determinant of OR costs, accounting for $14,780 of otherwise unexplained OR cost differences across patients, with no significant physician effects on all other non-OR costs (p<.05). Conclusions The incidence of readmissions increased the average cost of ASD surgery by more than 70%, illustrating the financial burden of revisions/reoperations; however, the cost burden resulting from readmissions appeared to taper off within 5 years after surgery. The estimated impact of physician preference on OR costs also highlights the variation in current practice and the opportunity for large cost reductions via a more standardized approach in the use of implants and biologics.
Despite the complexity of cervical spine deformity (CSD) and its significant impact on patient quality of life, there exists no comprehensive classification system. The objective of this study was to ...develop a novel classification system based on a modified Delphi approach and to characterize the intra- and interobserver reliability of this classification.
Based on an extensive literature review and a modified Delphi approach with an expert panel, a CSD classification system was generated. The classification system included a deformity descriptor and 5 modifiers that incorporated sagittal, regional, and global spinopelvic alignment and neurological status. The descriptors included: "C," "CT," and "T" for primary cervical kyphotic deformities with an apex in the cervical spine, cervicothoracic junction, or thoracic spine, respectively; "S" for primary coronal deformity with a coronal Cobb angle ≥ 15°; and "CVJ" for primary craniovertebral junction deformity. The modifiers included C2-7 sagittal vertical axis (SVA), horizontal gaze (chin-brow to vertical angle CBVA), T1 slope (TS) minus C2-7 lordosis (TS-CL), myelopathy (modified Japanese Orthopaedic Association mJOA scale score), and the Scoliosis Research Society (SRS)-Schwab classification for thoracolumbar deformity. Application of the classification system requires the following: 1) full-length standing posteroanterior (PA) and lateral spine radiographs that include the cervical spine and femoral heads; 2) standing PA and lateral cervical spine radiographs; 3) completed and scored mJOA questionnaire; and 4) a clinical photograph or radiograph that includes the skull for measurement of the CBVA. A series of 10 CSD cases, broadly representative of the classification system, were selected and sufficient radiographic and clinical history to enable classification were assembled. A panel of spinal deformity surgeons was queried to classify each case twice, with a minimum of 1 intervening week. Inter- and intrarater reliability measures were based on calculations of Fleiss k coefficient values.
Twenty spinal deformity surgeons participated in this study. Interrater reliability (Fleiss k coefficients) for the deformity descriptor rounds 1 and 2 were 0.489 and 0.280, respectively, and mean intrarater reliability was 0.584. For the modifiers, including the SRS-Schwab components, the interrater (round 1/round 2) and intrarater reliabilities (Fleiss k coefficients) were: C2-7 SVA (0.338/0.412, 0.584), horizontal gaze (0.779/0.430, 0.768), TS-CL (0.721/0.567, 0.720), myelopathy (0.602/0.477, 0.746), SRS-Schwab curve type (0.590/0.433, 0.564), pelvic incidence-lumbar lordosis (0.554/0.386, 0.826), pelvic tilt (0.714/0.627, 0.633), and C7-S1 SVA (0.071/0.064, 0.233), respectively. The parameter with the poorest reliability was the C7-S1 SVA, which may have resulted from differences in interpretation of positive and negative measurements.
The proposed classification provides a mechanism to assess CSD within the framework of global spinopelvic malalignment and clinically relevant parameters. The intra- and interobserver reliabilities suggest moderate agreement and serve as the basis for subsequent improvement and study of the proposed classification.
Proximal junctional failure (PJF) should be distinguished from proximal junctional kyphosis, which is a recurrent deformity with limited clinical impact. PJF includes mechanical failure, and is a ...significant complication following adult spinal deformity surgery with potential for neurologic injury and increased need for surgical revision. Risk factors for PJF include age, severity of sagittal plane deformity, and extent of operative sagittal plane realignment. Techniques for avoiding PJF will likely require refinements in both perioperative and surgical strategies.
Readmissions following adult spinal deformity surgical procedures frequently occur, placing a substantial burden on patients and providers. Existing literature on readmission costs, including ...reason-specific readmission costs, is limited. The purposes of this study were to determine the most expensive reasons for readmission, to assess the impact of reasons and timing on readmission costs, and to estimate the drivers of total costs associated with adult spinal deformity surgical procedures.
We performed a retrospective review of 695 patients with adult spinal deformity (≥18 years of age) who underwent a corrective spine surgical procedure at a single center from 2005 to 2013. Demographic, surgical, and direct cost data expressed in 2010 dollars for the entire inpatient episode of care were obtained from the hospital administrative database. A multivariable linear regression model with a gamma distribution and log-link function was used to estimate the impact of reasons and timing on readmission costs and to identify the primary drivers of long-term costs.
The mean age (and standard deviation) of the patients was 50.6 ± 15.8 years, 589 patients (85%) were women, and 637 patients (92%) were Caucasian. The observed readmission rates were 24% overall (costing $10.1 million), 8.8% for 30 days (costing $3.2 million), and 11.7% for 90 days (costing $4.6 million). The most expensive readmissions and their mean readmission cost were pseudarthrosis ($92,755), infection ($75,172), and proximal junctional kyphosis ($66,713), after adjusting for patient and surgical factors. The mean readmission cost after 2 years was $86,081. Older age (p = 0.001), ≥8 levels fused (p = 0.01), and length of index stay at the hospital (p < 0.0001) were independently associated with higher total cost. Surgical procedures in patients with a thoracic-only curve (p = 0.004) or a double curve (p = 0.05) and a surgical approach that was anterior-only (p < 0.0001) or posterior-only (p = 0.01) were independently associated with lower total costs.
Compared with readmission cost due to medical reasons, readmission due to pseudarthrosis increases mean readmission cost by 105%, readmission due to infection increases mean readmission cost by 72%, and readmission due to proximal junctional kyphosis increases mean readmission cost by 63%. Together, these 3 reasons accounted for 73% of readmission costs. This study identifies potential areas for cost reduction and opportunities for reducing readmission rates.
Although reducing the 30-day and 90-day readmission rates and costs are important; adult spinal deformity surgery is unique, because the most common and most expensive complications occur after 1 year. We believe that our paper is clinically relevant as it will help to guide clinical focus on the most impactful complications.
Retrospective cohort study.
Determine whether screws per level and rod material/diameter are associated with incidence of proximal junctional kyphosis (PJF).
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.
Patients with ASD and 2-year minimum follow-up were included. Only patients undergoing primary fusion of more than or equal to five levels with lower instrumented vertebrae (LIV) at the sacro-pelvis were included. Screws per level fused was analyzed with a cutoff of 1.8 (determined by receiver operating characteristic curve (ROC) analysis). Multivariable logistic regression was utilized, controlling for age, body mass index (BMI), 6-week postoperative change from baseline in lumbar lordosis, number of posterior levels fused, sex, Charlson comorbidity index, approach, osteotomy, upper instrumented vertebra (UIV), osteoporosis, preoperative TPA, and pedicle screw at the UIV (as opposed to hook, wire, etc.).
In total, 504 patients were included. PJF occurred in 12.7%. The mean screws per level was 1.7, and 56.8% of patients had less than 1.8 screws per level. No differences were observed between low versus high screw density groups for T1-pelvic angle or magnitude of lordosis correction (both P > 0.15). PJF occurred in 17.0% versus 9.4% of patients with more than or equal to 1.8 versus less than 1.8 screws per level, respectively (P < 0.05). In multivariable analysis, patients with less than 1.8 screws per level exhibited lower odds of PJF (odds ratio (OR) 0.48, P < 0.05), and a continuous variable for screw density was significantly associated with PJF (OR 3.87 per 0.5 screws per level, P < 0.05). Rod material and diameter were not significantly associated with PJF (both P > 0.1).
Among ASD patients undergoing long-segment primary fusion to the pelvis, the risk of PJF was lower among patients with less than 1.8 screws per level. This finding may be related to construct rigidity. Residual confounding by other patient and surgeon-specific characteristics may exist. Further biomechanical and clinical studies exploring this relationship are warranted.Level of Evidence: 3.
Economic modeling of data from a multicenter, prospective registry.
The aim of this study was to analyze the cost utility of recombinant human bone morphogenetic protein-2 (BMP) in adult spinal ...deformity (ASD) surgery.
ASD surgery is expensive and presents risk of major complications. BMP is frequently used off-label to reduce the risk of pseudarthrosis.
Of 522 ASD patients with fusion of five or more spinal levels, 367 (70%) had at least 2-year follow-up. Total direct cost was calculated by adding direct costs of the index surgery and any subsequent reoperations or readmissions. Cumulative quality-adjusted life years (QALYs) gained were calculated from the change in preoperative to final follow-up SF-6D health utility score. A decision-analysis model comparing BMP versus no-BMP was developed with pseudarthrosis as the primary outcome. Costs and benefits were discounted at 3%. Probabilistic sensitivity analysis was performed using mixed first-order and second-order Monte Carlo simulations. One-way sensitivity analyses were performed by varying cost, probability, and QALY estimates (Alpha = 0.05).
BMP was used in the index surgery for 267 patients (73%). The mean (±standard deviation) direct cost of BMP for the index surgery was $14,000 ± $6400. Forty patients (11%) underwent revision surgery for symptomatic pseudarthrosis (BMP group, 8.6%; no-BMP group, 17%; P = 0.022). The mean 2-year direct cost was significantly higher for patients with pseudarthrosis ($138,000 ± $17,000) than for patients without pseudarthrosis ($61,000 ± $25,000) (P < 0.001). Simulation analysis revealed that BMP was associated with positive incremental utility in 67% of patients and considered favorable at a willingness-to-pay threshold of $150,000/QALY in >52% of patients.
BMP use was associated with reduction in revisions for symptomatic pseudarthrosis in ASD surgery. Cost-utility analysis suggests that BMP use may be favored in ASD surgery; however, this determination requires further research.
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