Commentary: Utilization Trends of Cervical Disk Replacement in the United States

Influence of Surgeon Specialty on 30-day Outcomes Following Single-Level Cervical Disc Arthroplasty: A Propensity-Matched Analysis

STUDY DESIGN

Retrospective, propensity-matched analysis.

OBJECTIVES

Cervical disc arthroplasty (CDA) is being increasingly utilized for cervical disc generation. Surgeon specialty has been shown to influence the risk for postoperative complications in spine surgery, but this has not yet been explored for CDA. Thus, the purpose of this study is to determine whether there is any difference in 30-day complications between patients undergoing single-level CDA by neurosurgeons vs by orthopaedic surgeons.

METHODS

A retrospective, 1:1 propensity score matched analysis was performed using the NSQIP database from 2015 to 2020. Patient demographics, operative characteristics, and postoperative complications were recorded. Independent multivariate logistic regression models were constructed using the propensity-matched dataset to assess surgical specialty influence on any complication, any site complication, any operative infection, and any medical complications.

RESULTS

3179 single-level CDAs (28.8% orthopaedic surgery patients, 71.2% neurosurgery patients) were identified that met the inclusion criteria. Well-matched cohorts of 916 patients each were generated. After controlling for all possible confounders, orthopedic surgery specialty was not associated with a higher odds for any complication (OR: .87, 95% CI: .35 - 2.20, P = .7696), any site complication (OR: .32, 95% CI: .08 - 1.32, P = .1359), any operative infection (OR: .31, 95% CI: .07 - 1.34), P = .1172), nor any medical complication (OR: 2.11, 95% CI: .62 - 7.20, P = .2311) vs neurosurgery.

CONCLUSION

This is the first propensity-matched analysis to show that spine surgeon specialty does not influence the risk for any complication, any site complication, any operative infection, nor any medical complication following single-level CDA within the first 30 days after surgery.

Utilization Trends of Recombinant Human Bone Morphogenetic Protein in the United States

STUDY DESIGN

Retrospective.

OBJECTIVE

The aim of this study was to explore the utilization trends of recombinant human bone morphogenetic protein (rh-BMP) in the United States using the largest inpatient administrative database.

SUMMARY OF BACKGROUND DATA

Since 2002, the rh-BMP has been widely used by the surgical spine community in fusion surgery. In light of the rising evidence regarding the safety and efficacy of this novel and expensive bone biological technology, a comprehensive examination of its utilization in the American population is warranted.

METHODS

We queried the 2002-Q3 2015 National Inpatient Sample for patients that underwent spinal fusion with rh-BMP. We calculated population-level estimates of rh-BMP utilization trends per 100,000 spinal fusions. Trends were estimated for the overall use as well as broken down by primary versus revision fusion, fusion type, number of levels, age category, US region, and hospital type.

RESULTS

A total of 5,563,282 fusions were performed, of which 19.9% (n = 1,108,984) utilized rh-BMP. We detected an increase in rh-BMP use in spinal fusion surgery from 0.7% in 2002 to a peak of 29.5% in 2010, followed by a gradual decline till Q3 2015, where it represented 14.7% of all fusion surgeries. These trends paralleled all fusion types. It was most commonly used in fusions spanning two to three levels. The South remained the most common region, whereas West has recently surpassed the Midwest. Its use is becoming more pervasive among older patients, particularly in the 65- to 74 years' age group.

CONCLUSION

Further studies are needed to provide insights into the correlation of these trends with the technology's safety and efficacy profile in contemporary series.Level of Evidence: 3.

Accuracy of various fluoroscopic landmarks for determination of midline implant placement within the cervical disc space

PURPOSE

The traditional teaching has been that proper function of a cervical disc replacement is dependent upon appropriate placement, which includes centering the device in the coronal plane. The purpose of this study was to identify the most reliable anatomical landmark for determining midline placement of an implant within the cervical disc space under fluoroscopy.

METHODS

Digital fluoroscopy images were taken for each cervical level at 0 °, 2.5 °, 5 °, 7.5 °, 10 °, and 15 ° from the mid-axis by rotating the C-arm beam of six cadavers. Thin-slice CT scanning of the same levels was subsequently performed. Three independent reviewers measured the distance between anatomic structures: (a) tip of the right uncinate; (b) medial border of the right pedicle; and (c) center of the spinous processes for different x-ray angles across cervical levels C3-7.

RESULTS

Both the uncinate and pedicle demonstrated superior overall accuracy to that of the spinous process (p ≤ 0.02) at all angles except at 0 ° for the pedicle where the difference was not statistically significant. Overall (pooled C3-7), the accuracy of the uncinate did not differ significantly from that of the pedicle at any fluoroscopic angle. The center of the spinous process measurement was particularly sensitive to deviations from the perfect anteroposterior fluoroscopy image.

CONCLUSIONS

The results of this investigation suggest that the tip of the uncinate and the medial border of the pedicle are more accurate measures of midline in the cervical spine than the center of the spinous process and are less susceptible to inadvertent off-axis imaging.

Prevalence and Trends in Management of Idiopathic Normal Pressure Hydrocephalus in the United States: Insights from the National Inpatient Sample

BACKGROUND

Over the past 2 decades, management of idiopathic normal pressure hydrocephalus (iNPH) has evolved significantly. In the current study, we sought to evaluate the national prevalence and management trends of iNPH in the United States using a national database.

METHODS

The National Inpatient Sample was queried for patients with an International Classification of Diseases diagnosis code for iNPH from 2007 to 2017. Trends in prevalence and procedure type were evaluated per 100,000 discharges and as a percentage of discharges, using weighted discharges. Utilization of procedure type across U.S. regions and hospital types was also compared.

RESULTS

From 2007 to 2017, 302,460 weighted discharges with any diagnosis code for iNPH, aged ≥60 years, were identified. Prevalence ranged from 0.04% to 0.20% (41/100,000 to 202/100,000) among admitted patients ≥60 years old, giving an average prevalence during the study duration of 0.18% (179/100,000). Of 66,759 weighted discharges with a primary diagnosis code of iNPH undergoing surgical management, ventriculoperitoneal shunt (72.0% of discharges, n = 48,977) was most commonly used; of these, 9.3% (n = 4567) were performed laparoscopically. This result was followed by lumbar peritoneal shunt (15.1% of discharges, n = 10,441). Up to 15.1% (n = 9990) of discharges reported only a lumbar puncture, assumed to be only diagnostic, for screening, or part of serial cerebrospinal fluid removal procedures. Significant discrepancies in procedure utilization were also identified among hospitals in the Western, Southern, Northeast and Midwest regions, as well as between urban and rural hospitals (P < 0.05).

CONCLUSIONS

We have summarized the national prevalence of iNPH, trends in its management over the previous decade and trends by region and hospital type.

Predictors of adverse outcomes and cost after surgical management for idiopathic normal pressure hydrocephalus: Analyses from a national database

INTRODUCTION

We utilized a national administrative database to investigate drivers of immediate adverse economic and hospital outcomes, including non-routine discharge, prolonged length of stay (LOS), and admission costs among patients undergoing surgery for idiopathic normal pressure hydrocephalus (iNPH).

METHODS

The National Inpatient Sample (NIS) was queried from 2007 to 2017 for patients aged ≥60 with a diagnosis code for iNPH undergoing surgery. Multivariable logistic-regression models and Wald χ2 were used to identify drivers of non-routine discharge, prolonged length of stay (LOS) (>75th percentile) and higher admission costs (>90th percentile).

RESULTS

A total of 13,363 patients with iNPH undergoing surgical management were identified. The most common comorbidity reported in the cohort was a cardiovascular pathology (56.9 %, n = 7,787), followed by urinary pathology (37.2 %, n = 5,084), osteoarthritis (7.8 %, n = 1,071), Alzheimer's disease (4.6 %, n = 626) and cerebrovascular pathology (4.2 %, n = 569). The most frequently employed procedure was ventriculo-peritoneal (VP) shunt placement (65.6 %, n = 8,942) of which 89.8 % (n = 8,027) were performed open and 10.2 % (n = 915) laparoscopically. This was followed by lumbo-peritoneal (LP) shunting (15.5 %, n = 2,115), lumbar puncture alone (screened, serial CSF removal) (14.8 %, n = 2,013), endoscopic third ventriculostomy (ETV) (2%, n = 274), ventriculo-atrial (VA) shunt (0.95 %, n = 130) and ventriculo-pleural (Vpleural) shunt (0.46 %, n = 64). The median (IQR) LOS was 3 days (2-5), the rate of non-routine discharge was 37.3 % and median (IQR) cost was $11,230 ($7,735-15,590). On multivariable-analysis, emergent-admission (OR 2.91), older age (76-90: OR 1.55; 90+: OR 2.66), VP shunt (open: OR 3.09; laparoscopic: OR 2.32), ETV (OR 3.16), VA/VPleural shunt (OR 2.73) and hospital admission in Northeast-region compared to Midwest (OR 1.27) were found to be associated with increased risk of non-routine discharge. Some of the highly significant associated factors for prolonged LOS included emergent-admission (OR 11.34), ETV (OR 10.92), VA/VPleural shunt (OR 7.79) and open VP shunt (OR 8.24). For increased admission costs, some of the highly associated factors included VA/VPleural shunt (OR 18.48), laparoscopic VP shunt (OR 9.92), open VP shunt (OR 12.72) and ETV (OR 9.34). Predictor importance analysis revealed emergent admission, number of diagnosis codes (comorbidities) open VP shunt, hospital region, age] and revision or removal of shunt to be the most important drivers of these outcomes.

CONCLUSION

Analyses from a national database indicate that among patients with iNPH, an emergent-admission may be the most significant risk-factor of adverse economic outcomes and higher costs.

Assessing the Effects of Publication Bias on Reported Outcomes of Cervical Disc Replacement and Anterior Cervical Discectomy and Fusion: A Meta-Epidemiologic Study

BACKGROUND

There have been several clinical trials as well as observational studies that have compared the outcomes of different cervical disc replacement (CDR) devices with anterior cervical disc replacement and fusion (ACDF). Although the results of these studies have provided sufficient evidence for the safety of CDR, there is still a lack of consensus in terms of longer-term outcomes, with studies providing equivocal results for the 2 procedures. In the current study, we used a novel methodology, a meta-epidemiologic study, to investigate the impact of study characteristics on the observed effects in the literature on CDR and ACDF.

METHODS

Data were abstracted from available meta-analyses regarding author, study author, year, intervention events, control events, and sample size, as well as year and geographic location of each study within the meta-analyses. We grouped the studies based on median year of publication as well as the region of the submitting author(s). Odds ratios, 95% confidence intervals (CIs), and standard errors of individual studies were calculated based on the number of events and sample size for each arm (ACDF or CDR). Further, results of outcomes from individual studies were pooled and a meta-analysis was conducted. Ratio of odds ratio (ROR) was used to assess the impact of each of these factors on estimates of the study for CDR versus ACDF.

RESULTS

A total of 13 meta-analyses were analyzed after exclusions. Using the results from 10 meta-analyses, we found that studies published before 2012 reported significantly lower odds of a reoperation after CDR (vs. ACDF), compared with studies published after 2012 (ROR, 0.51; 95% CI, 0.38-0.67; P < 0.001). We did not observe a significant impact of study year on difference in estimates between CDR and ACDF for adjacent segment disease (ROR, 0.99; 95% CI, 0.64-1.55; P = 0.465). The region of submitting author was also found to have no impact on results of published studies.

CONCLUSIONS

These results indicate that there may be a publication bias regarding the year of publication, with earlier studies reporting lower reoperation rates for CDR compared with ACDF.

Contemporary trends in extracranial-intracranial bypass utilization: analysis of data from 2008 to 2016

OBJECTIVE

The impact of FDA approval of flow-diversion technology for the treatment of supraclinoid internal carotid artery aneurysms and the publication of the Carotid Occlusion Surgery Study, both of which occurred in 2011, on the utilization of extracranial-intracranial (EC-IC) bypasses is not known.

METHODS

The National Inpatient Sample (NIS) was queried for hospitalizations for EC-IC bypass performed from 2008 to 2016. Diagnoses of interest included an unruptured intracranial aneurysm (UIA), subarachnoid hemorrhage (SAH), carotid occlusive disease (COD), and moyamoya disease. The authors assessed trends in EC-IC bypass utilization for these diagnoses and the incidence of adverse discharges, defined as discharge to locations other than home, and the rate of mortality.

RESULTS

A total of 1640 EC-IC bypass procedures were performed at 558 hospitals during the study period, with 1148 procedures at 448 hospitals performed for a diagnosis of interest. The most frequent surgical indication was moyamoya disease (65.7%, n = 754), followed by COD (23.2%, n = 266), SAH (3.2%, n = 37), and a UIA (7.9%, n = 91). EC-IC bypass utilization for COD decreased from 0.21 per 100 admissions of COD in 2010 to 0.09 per 100 admissions in 2016 (p = 0.023). The frequency of adverse discharges increased during the study period from 22.3% of annual admissions in 2008 to 31.2% in 2016 (p = 0.030) when analysis was limited to procedures performed for a diagnosis of interest. Per volume, the top 5th percentile of hospitals, on average, performed 18.4 procedures (SD 13.2) per hospital during the study period, compared to 1.3 procedures (SD 1.3) that were performed in hospitals within the bottom 95th percentile. The rate of adverse discharges was higher at low-volume institutions when compared to that at high-volume institutions (33.8% vs 28.7%; p = 0.029). Over the study period, the authors noted a trend toward a reduced percentage of total surgical volume performed at high-volume hospitals (p < 0.001).

CONCLUSIONS

The authors observed a decrease in the utilization of EC-IC bypass for COD during the study period. An increase in the rate of adverse discharges was also noted, coinciding with more procedures being performed at lower-volume centers.

Artificial Discs in Cervical Disc Replacement: A Meta-Analysis for Comparison of Long-Term Outcomes

BACKGROUND

Cervical disc replacement (CDR) has emerged as an alternative to anterior cervical discectomy and fusion for the surgical treatment of degenerative cervical disc disease. Although comparison of the 2 techniques has been studied in the literature, a thorough assessment of all artificial discs between each has not been performed. The objective of the present study was to examine the long-term outcomes of 5 artificial discs.

METHODS

An electronic literature search was conducted for studies of CDR devices for all years available. Only articles in English were included. Heterotopic ossification, adjacent segment disease, and reoperation comprised the primary outcomes of interest. Pooled descriptive statistics with effect size (ES) and 95% confidence interval were used to synthesize the outcomes for each device.

RESULTS

Sixty-five studies (n = 5785) were included in the analysis. Comparison of the incidence of grade III/IV heterotopic ossification showed a significant variability between the 5 devices (P < 0.001) with ProDisc-C (ES, 38%; 95% confidence interval [CI], 24%-54%) having the highest incidence rate. Overall rate of adjacent segment disease was 14% (95% CI, 7%-23%) with significant associated heterogeneity (P < 0.001). Regarding 2-year reoperation risk, the overall incidence rate was 2% (95% CI, 1%-3%), with nonsignificant variability between devices (P = 0.63). The highest rate was observed in the Discover group (ES, 4%; 95% CI, 0%-13%).

CONCLUSIONS

The results of the present meta-analysis indicate that surgical and clinical outcomes may differ among different CDR devices. These findings may assist surgeons in tailoring their decision making to specific patient profiles. Future multicenter efforts are needed to validate associations found in this study.