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A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes
Journal of Clinical Neuroscience xxx (2017) xxx–xxx
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A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes Pavan S. Upadhyayula a,b,1, John K. Yue b,c,1, Erik I. Curtis a, Reid Hoshide a, Joseph D. Ciacci a,⇑ a b c
Department of Neurological Surgery, University of California, San Diego, La Jolla, CA, United States Brain and Spinal Injury Center, San Francisco General Hospital, San Francisco, CA, United States Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
a r t i c l e
i n f o
Article history: Received 30 January 2017 Accepted 22 April 2017 Available online xxxx Keywords: ACDF ACS-NSQIP CDA Cervical spine Spine surgery Operation time
a b s t r a c t Objective: Cervical disc arthroplasty (CDA) is a recent alternative to anterior cervical discectomy and fusion (ACDF) in patients suffering cervical disc herniation and degeneration. To date, a systematic analysis of their comparative advantages and risks following elective surgery remains elusive. Methods: Adult patients undergoing elective CDA or ACDF were extracted from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database years 2011–2014. A total of 19,369 patients were matched 1:1 by age, sex, functional status, charlson comorbidity index, ASA classification, BMI classification, and number of vertebral levels operated on during surgery. This matching process led to a final sample of 588 subjects (294 CDA, 294 ACDF). Multivariable regression was performed for five outcome measures: operation time, early complications, reoperation rates, hospital length of stay (HLOS), and discharge destination. Mean differences (B), odds ratios (OR) and associated 95% confidence intervals (CI) are reported. Results: Compared to ACDF, CDA was associated with decreased mean operation time (B = 18.78-min, 95% CI [29.13, 8.42]; p < 0.001), decreased HLOS (B = 0.44-days [0.77, 0.11]; p = 0.009), and increased likelihood of discharge to home (OR = 5.39 [1.14–25.43]; p = 0.033). No differences in reoperation rates and complications were found. Conclusion: In a matched cohort analysis, CDA performs comparably to ACDF and is associated with decreased operation time and HLOS, and increased likelihood of discharge to home, without differences in 30-day complications or reoperation rates. Future prospective studies are warranted. Published by Elsevier Ltd.
1. Introduction Degenerative cervical spine conditions will impact over 60% of the population at some point in life [1]. An aging population makes the number of patients requiring operative treatment more likely to rise [2,3]. Effective surgical techniques for symptomatic relief are important for both quality of life and economic measures. Anterior cervical discectomy and fusion (ACDF) is a procedure indicated for cervical disc herniation and cervical degeneration (e.g. spondylosis). ACDF is known for its low complication rate and
⇑ Corresponding author at: Neurological Surgery, Chief of Neurosurgery, UCSD VAMC, University of California, San Diego, 200 West Arbor Drive #8893, San Diego, CA 92103, United States. Fax: +1 858 534 8899. E-mail address: [email protected] (J.D. Ciacci). 1 These authors contributed equally to this work.
low rate of reoperation. The published rate of surgical complication from ACDF is around 2.4% [4]; low complication rates, high probability of fusion and resolution of symptoms have led ACDF to become the standard surgical technique for cervical radiculopathy and disc degeneration. A newer technique indicated in cervical disc herniation/degeneration patients is cervical disc arthroplasty (CDA). The first U.S. Food and Drug Administration (FDA) approval of artificial discs in the U.S. occurred in 2004 [5]. A systematic review of two FDA trials comparing CDA with ACDF found CDA associated with higher rates of operative success, greater improvement in neck disability and lower rates of adjacent segment disease [6]. Although popular abroad, the lower utilization level of CDA in the U.S. has been impacted by three factors: the relative novelty of the technology, high cost of prosthesis and lack of insurance coverage [4]. A 2013 cost-effectiveness study found that a CDA prosthesis would need
http://dx.doi.org/10.1016/j.jocn.2017.04.027 0967-5868/Published by Elsevier Ltd.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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to remain functional for 14 years to become more cost-effective than conventional ACDF [6]. Although a majority of published research comparing the two techniques discusses a slight benefit for CDA versus no difference, many surgeons anecdotally describe higher complication rates, device failure and neurologic deficit observed following CDA compared to ACDF [5,7,8]. A limitation of these previous studies includes small sample sizes and the reliance on retrospective data from FDA trials. Our goal was to collect and analyze data from the American College of Surgeons (ACS) National Surgical Quality Improvement Project (NSQIP) database across 435 centers. In utilizing ACS-NSQIP, we aim to describe and characterize the clinical presentations of elective ACDF and CDA, and determine the risk factors for perioperative outcome including operation time, early complications, reoperations, hospital length of stay (HLOS), and discharge destination. 2. Materials and methods 2.1. Data source NSQIP was created to improve surgical techniques and outcomes [9] and catalogs >300 variables on comorbidities, intraoperative events and 30-day outcomes using prospective random sampling [10,11]. This study is exempt from institutional review board (IRB) approval, as the ACS-NSQIP participant-use data files contain no protected health information. 2.2. Study population This study analyzes the NSQIP database from years 2011–2014 for patients undergoing elective ACDF or CDA. These NSQIP years were selected for the current analysis because the variables ‘emergncy’ (coding whether surgery was emergent) and ‘dischdest’ (coding whether patient was discharged to home, skilled nursing facility (SNF), rehabilitation unit, or other) were added to NSQIP starting in 2011 [12]. The ACDF and CDA patients were identified using common procedural terminology (CPT) codes. The CPT code for CDA was 22856 (‘total disc arthroplasty (artificial disc), anterior approach, including discectomy with end plate preparation (includes osteophytectomy for nerve root or spinal cord decompression and microdissection); single interspace, cervical’). ACDF was identified using CPT code 22551 (‘anterior interbody fusion, with discectomy and decompression; cervical below C20 ). Multilevel procedures were identified with additional CPT codes for each interspace. 22585 (‘‘Arthrodesis Anterior Interbody – Each Additional Interspace) and 22858 (‘‘Total disc arthroplasty (artificial disc), anterior approach; second level cervical.”). Of 19,369 initial subjects (CDA = 796, ACDF = 18,573), those undergoing emergency surgery (n = 1264) were excluded. Then patients were matched one-toone based off age, sex, ASA status, functional status, charlson comorbidity score, BMI classification and number of vertebral levels operated on. This led to a final cohort of 588 subjects (n = 294 each in CDA and ACDF surgical cohorts). 2.3. Outcome measures The primary outcome measures were operation time, complications, 30-day reoperations, HLOS and discharge destination. Operation time was defined as the total surgical time in minutes. HLOS was defined as the number of days between admission and date of post-surgery discharge. For univariate and multivariable analyses, operation time and HLOS were treated as continuous variables. Hospital discharge destination was categorized to home versus a facility of higher level of care, in all patients not reported to have died within 30 days. Due to the small numbers of 30-day complica-
tions and reoperations, outcome distributions are provided but multivariable analyses were not performed. 2.4. Statistical analysis Means and standard deviations (SD) are reported for continuous variables, and proportions are reported for categorical variables unless otherwise specified. Analysis of variance (ANOVA) and chi-squared tests were used to compare continuous and categorical variables, respectively, by surgery cohort (CDA, ACDF). Linear regressions were performed for operation time and HLOS, and logistic regressions were performed for discharge to home, with surgery cohort as the primary variable of interest. Due to high incidences and associations with negative outcomes in prior studies [13–16], hypertension and smoking were included as independent predictors. The factors patients were matched on were coded as follows. BMI was stratified to World Health Organization classifications (kg/m2; <18.5 = underweight, 18.5–29.9 = nonobese, 30– 34.9 = obese class I, 35 = obese class II/III) [17,18], per association with increased risk of poor outcome (e.g. airway compromise, extubation challenges, surgical site infection) [19–21]. The Charlson Comorbidity Index (CCI) [22], widely utilized in large retrospective spine studies, provides a numerical value of a patient’s comorbidity burden [23–26]. The American Society of Anesthesiologists physical classification (ASA) score is well-established in cervical spine literature as a predictor of poor outcome [27,28]. Whether the surgery was performed during inpatient stay or as an outpatient was also included and adjusted for in multivariable regressions. For linear regressions, the mean difference (B) and associated 95% confidence interval (95% CI) are reported for each predictor; for logistic regressions, the odds ratio (OR) and 95% CI are reported. Statistical significance was assessed at p < 0.05. All statistical analyses were performed using open source software in Python or R (SciPy, StatsModels, Sci-Kit-Learn and Resource Selection packages) [29–32].
3. Results 3.1. Demographic and clinical characteristics The 588 included subjects (294 CDA, 294 ACDF) were matched one-to-one by age, BMI, sex, ASA classification, function status, number of vertebral levels operated, and CCI to limit differences between groups. Overall, subjects were 46.5 ± 11.4 years of age and 51.7% male. Notably, both groups showed zero incidence for a number of prior comorbidities (Table 1). The only comorbidity to differ significantly between surgical cohorts was smoking status (CDA 23.4%, ACDF 36.4%; p < 0.001). 3.2. Operation time and early complications Overall, 1.8% of subjects (n = 11) suffered 30-day complications (CDA 1.3%, ACDF 2.3%; p = 0.362). There were no deaths in the cohort. The overall mean operation time was 123.93 ± 64.64 min. On univariate analysis, CDA demonstrated shorter operation times compared to ACDF (114.84 ± 57.47 min vs. 133.01 ± 69.81 min); p < 0.001) (Table 2), which survived multivariable analysis to show a mean decrease of 18.78 min in the CDA cohort (95% CI [29.13, 8.43]; p < 0.001) (Table 3). Longer operation times were also experienced by inpatients (B = 24.69 min [13.25, 36.13]; p < 0.001) compared to outpatients.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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P.S. Upadhyayula et al. / Journal of Clinical Neuroscience xxx (2017) xxx–xxx Table 1 Comorbidities by surgery cohort. Comorbidity variable
Table 3 Multivariable linear regression for operation time. ACDF (n = 294)
CDA (n = 294)
Sig. (p)
0.10 (0.30)
0.10 (0.30)
1.00
0 (0.0%) 0 (0.0%) 0 (0.0%)
0 (0.0%) 0 (0.0%) 1 (0.3%)
1.00 1.00 0.316
1 (0.3%) 0 (0.0%)
0 (0.0%) 0 (0.0%)
0.316 1.00
Malignancy Weight loss > 10% (6-months) Metastasis
0 (0.0%) 0 (0.0%)
0 (0.0%) 0 (0.0%)
1.00 1.00
Neurological Transient ischemic attack Stroke
0 (0.0%) 0 (0.0%)
2 (0.6%) 0 (0.0%)
0.156 1.00
Paralysis Hemiparesis Paraplegia Quadriplegia
0 (0.0%) 1 (0.0%) 0 (0.0%)
0 (0.0%) 0 (0.0%) 0 (0.0%)
1.00 0.316 1.00
Pulmonary Dyspnea Steroid use (inhaler) COPD
12 (4.1%) 4 (1.3%) 8 (2.7%)
10 (3.4%) 1 (.3%) 4 (1.4%)
0.607 0.178 0.243
Coagulopathy Diabetes Mellitus Hypertension Renal failure Smoking
1 (0.3%) 22 (14.3%) 103 (35.0%) 0 (0.0%) 107 (36.4%)
0 (0.0%) 25 (4.2%) 88 (29.9%) 0 (0.0%) 69 (23.4%)
0.316 0.648 0.186 1.00 <0.001
Charlson Comorbidity Index Mean (SD) Cardiovascular Congestive heart failure Myocardial infarction Percutaneous coronary intervention Prior cardiac surgery Peripheral vascular disease
Distributions and proportions are shown for elective cervical spine surgery patients. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty; SD = standard deviation.
Table 2 Univariate distribution of outcomes by surgery cohort. Outcome variable Operation time Minutes, Mean (SD) Hospital length of stay (HLOS) Days, Mean (SD) Hospital discharge to home Home Skilled nursing facility/ rehabilitation
ACDF (n = 294)
CDA (n = 294)
Sig. (p)
133.01 (69.81)
114.84 (57.47)
<0.001
1.57 (2.71)
1.18 (0.97)
0.018
287 (97.6%) 7 (2.4%)
292 (99.3%) 2 (0.7%)
0.093
Predictor variable
B
95% CI
Sig. (p)
Surgery cohort ACDF CDA
Reference 18.78
– 29.13, 8.43
– <0.001
Patient type Inpatient Outpatient
Reference 24.69
– 36.13, 13.25
– <0.001
Hypertension No Yes
Reference 5.06
– 5.91, 16.03
– 0.365
Smoking No Yes
Reference 4.75
– 16.08, 6.57
– 0.410
Mean increase or decrease (B) and associated 95% confidence intervals (CI) are shown for each predictor. ACDF = anterior cervical discectomy and fusion; ASA = American Society of Anesthesiologists physical classification score; CDA = cervical disc arthroplasty; SE = standard error.
Table 4 Multivariable linear regression for hospital length of stay (HLOS). Predictor variable
B
95% CI
Sig. (p)
Surgery cohort ACDF CDA
Reference 0.44
– 0.77, 0.11
– 0.009
Patient type Inpatient Outpatient
Reference 0.79
– 1.15, 0.43
– <0.001
Hypertension No Yes
Reference 0.04
– 0.39, 0.30
– 0.79
Smoking No Yes
Reference 0.25
– 0.61, 0.112
– 0.177
Mean increase or decrease (B) and associated 95% confidence intervals (CI) are shown for each predictor. Patients who expired in-hospital and/or within 30-days of operation were excluded from the analysis. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty.
3.4. Reoperation rates
Distributions and proportions are shown for elective cervical spine surgery patients. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty; SD = standard deviation.
3.3. Hospital discharge destination and total hospital length of stay (HLOS) Overall HLOS was 1.38 ± 2.04 days. CDA demonstrated shorter univariate HLOS compared to ACDF (1.18 ± 0.97 days vs. 1.57 ± 2.71 days, p = 0.018). On multivariable analysis, a nonsignificant statistical trend was observed for CDA (B = 0.44 days [0.77, 0.11]; p = 0.009) (Table 4). Generally, longer HLOS were experienced by inpatients (B = 0.79 days [0.43, 1.15]; p < 0.001) compared to outpatients. Overall, 579 (98.4%) of patients were discharged to home from hospital (CDA 99.3%, ACDF 97.6%, p = 0.093). While marginally significant on univariate analysis, CDA subjects demonstrated greater multivariable likelihood of being discharged to home (OR = 5.39 [1.14, 25.43]; p = 0.03) (Table 5).
A total of 0.8% (n = 5) patients required spine reoperations within 30 days (CDA 1.0%, ACDF 0.7%; p = 0.658). 4. Discussion Adequate and timely surgical intervention for degenerative cervical spine pathology is required to optimize outcomes. Currently, 95% of males and 75% of females aged > 65-years experience symptoms related to degenerative changes in the cervical spine [33]. For the past 58 years, ACDF has been the standard method of surgical intervention for these patients [34]. ACDF accesses the spine anteriorly performing a discectomy at relevant vertebral levels. Osteophytes are removed and adjacent vertebra are prepared to accept the ACDF implant. Measurement of the intervertebral distance is performed to ensure appropriate implant sizing. An allograft is then placed and a titanium end-plate is used to stabilize the graft-vertebra joint. CDA surgeries use a similar approach. Once all disc material is removed, a device creates keel cuts into the adjacent vertebrae. These are necessary for placement of the arthroplasty joint that maintains mobility. Due to the low incidence of postsurgical complications and morbidity of ACDF, alternatives have been met with high scrutiny. CDA has shown promise as a suitable alternative in select patients,
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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P.S. Upadhyayula et al. / Journal of Clinical Neuroscience xxx (2017) xxx–xxx
4.2. Discharge destination
Table 5 Multivariable logistic regression for discharge to home. Predictor variable
OR
95% CI
Sig. (p)
Surgery cohort ACDF CDA
Reference 5.39
– 1.14, 25.43
– 0.033
Patient type Inpatient Outpatient
Reference 0.61
– 0.17, 2.14
– 0.439
Hypertension No Yes
Reference 0.99
– 0.28, 3.49
– 0.996
Smoking No Yes
Reference 5.63
– 0.70, 44.97
– 0.103
Odds ratios (OR) and associated 95% confidence intervals (CI) are shown for each predictor. Patients who expired in-hospital and/or within 30-days of operation were excluded from the analysis. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty.
associating with fewer surgical complications and decreased HLOS [33,35]. Using NSQIP data for elective operations, we demonstrate that the patients undergoing CDA experience decreased operation time, decreased HLOS, and increased likelihood of discharge to home, without changes in complications or 30-day reoperations. To our knowledge, this study is the first to characterize the presentation and predictors of early outcomes, including discharge destination, across these two surgical cohorts after elective surgery using a large national dataset.
4.1. Demographic differences, operation time and complications By matching our cohorts based on numerous demographic variables we were able to prevent demographic differences from altering our analysis of outcomes. The similar levels of clinical comorbidities and matching of patients based on age, sex, BMI, CCI, ASA status, functional status, and vertebral levels fused allows us to accurately compare the two surgical techniques. Our dataset also only had one and two level surgeries further ensuring outcomes were not altered by outliers associated with more difficult surgeries. CDA is associated with reduced operation time compared to ACDF. While this is contrary to the results found in a 2015 metaanalysis of randomized-controlled trials (RCTs) on the topic [36], it is likely that the difference is, at least in part, attributable to our objective to characterize elective surgeries instead of all surgeries. Characterization of the relevant risk profile is critical in assisting with the decision to operate for an emergency/lifesaving purpose versus one of harm reduction/quality of life improvement. This is an important distinction as demonstrated by the disparate comorbidity profiles between the surgery cohorts in our data. Fewer technical steps, coupled with reduced stressors in the nonemergency setting, may explain why elective CDA operation time is shorter than that of ACDF. Historical data gathered from FDA trials and RCTs comparing CDA and ACDF show no difference or a slight advantage for CDA with regards to post-surgical complication rates [37]. While the overall incidence of complications did not differ between CDA and ACDF in our study, we were in part constrained by the low number of CDA surgeries in NSQIP; whether this is attributable to a low absolute likelihood of complications after elective CDA or due to the smaller sample size of elective CDA patients in our study should be a topic of future meta-analyses or prospective investigations.
Discharge to higher levels of care increases the overall utilization of healthcare resources and subsequent public health cost and burden [38]. After controlling for demographics and comorbidities, CDA patients remained more likely to return home. Patients who are of higher baseline physical and cognitive status are more likely to return home after surgery [39–41]; we control for these variables in our study to further delineate the specific contribution of surgery type to outcomes. Discharge to care above that of home for an elective surgery confers a comparatively higher level of risk to quality of life, necessitating a discussion of risks and benefits with the patient and/or families. Such discussions require an improved understanding of the optimal indications for CDA surgery. 4.3. Cost and HLOS Cost also merits consideration. A recent analysis by Ghori et al. found the combined cost for a 45–60 year old patient was $24,119 for CDA versus $31,178 for ACDF when factoring in cost of surgery, lost productivity and rates of reoperation [39–42]. The nature of elective surgeries makes the cost of prosthesis an important determinant of out-of-pocket expenditures. A 2013 cost-effectiveness study found that CDA prostheses must remain functional for 14 years to become more cost-effective than conventional ACDF [6]. If CDA is to become a viable broadly indicated treatment for cervical degeneration issues of novelty and durability must be addressed. As it stands, the benefits to early outcomes associated with CDA may merit increased consideration and potential investment in further research and development. A number of RCTs demonstrate lower reoperation rates for CDA due to increased durability of the prosthesis [43,44]. The aging U.S. population demonstrates the need for surgical solutions capable of providing quantifiable long-term benefits. The decrease in HLOS for the CDA cohort was close to half a day, with an associated cost estimate of $500 to $5,000 for spine surgeries [45,46]. Although cost may be less important to the patient in need of surgery, it does provide an important point of consideration for hospital resource utilization and insurance organizations. The ability to safely discharge patients earlier is crucial to maximizing utility. 4.4. Limitations There are a number of limitations when conducting research using a retrospective database such as NSQIP. The NSQIP database has been known to have some limited reporting inaccuracies [47,48]. Campbell et al. documented the underrepresentation of complications solely based off of ICD-9 codes [49], and CPT coding does not capture the granularity of associated clinical conditions concurrent with the primary operation. Surgical cost, reimbursement potential, surgeon preference, and academic status and/or volume of the treating hospital may also influence the decision for surgery. While we matched one-to-one by age, sex, BMI, ASA classification, functional status and number of surgical levels, it is possible that we were limited in our drawing pool by the comparatively smaller sample size of total elective CDA surgeries contained in NSQIP compared to the more mainstream ACDF. We were also limited to the variables collected as part of NSQIP limiting conclusions to the 30-day perioperative window. Hilibrand and colleagues describe a 10-year, 25% incidence rate of adjacent disc cervical degeneration following ACDF [50]. Although beyond the scope of NSQIP and our current analysis, it would be of interest to investigate the incidence of long-term sequelae following elective ACDF and CDA.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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5. Conclusions Compared to ACDF, CDA is associated with decreased operative times and increased likelihood of being discharged home from the hospital following one-to-one matching by demographic and clinical variables. These data suggest the clinical relevance of exploring standard criteria for qualifying patients for CDA as a viable alternative to ACDF to optimize outcomes. Future prospective trials are needed to confirm these findings. References [1] Todd AG. Cervical spine: degenerative conditions. Curr Rev Musculoskelet Med 2011;4:168–74. [2] Okada E, Matsumoto M, Ichihara D, et al. Aging of the cervical spine in healthy volunteers: a 10-year longitudinal magnetic resonance imaging study. Spine 2009;34:706–12. [3] Marquez-Lara A, Nandyala SV, Fineberg SJ, et al. Current trends in demographics, practice, and in-hospital outcomes in cervical spine surgery: a national database analysis between 2002 and 2011. Spine 2014;39:476–81. [4] Smith JS, Fu K-MG, Polly Jr DW, et al. Complication rates of three common spine procedures and rates of thromboembolism following spine surgery based on 108,419 procedures: a report from the Scoliosis Research Society Morbidity and Mortality Committee. Spine 2010;35:2140–9. [5] Mummaneni PV, Amin BY, Wu J-C, et al. Cervical artificial disc replacement versus fusion in the cervical spine: a systematic review comparing long-term follow-up results from two FDA trials. Evid Based Spine Care J 2012;3:59–66. [6] Qureshi SA, McAnany S, Goz V, et al. Cost-effectiveness analysis: comparing single-level cervical disc replacement and single-level anterior cervical discectomy and fusion: clinical article. J Neurosurg Spine 2013;19:546–54. [7] Boselie TFM, Willems PC, van Mameren H, et al. Arthroplasty versus fusion in single-level cervical degenerative disc disease: a Cochrane review. Spine 2013;38. E1096–107. [8] Traynelis VC, Leigh BC, Skelly AC. Return to work rates and activity profiles: are there differences between those receiving C-ADR and ACDF? Evid Based Spine Care J 2012;3:47–52. [9] Ingraham AM, Richards KE, Hall BL, et al. Quality improvement in surgery: the American College of Surgeons National Surgical Quality Improvement Program approach. Adv Surg 2010;44:251–67. [10] Hall BL, Hamilton BH, Richards K, et al. Does surgical quality improve in the American College of Surgeons National Surgical Quality Improvement Program: an evaluation of all participating hospitals. Ann Surg 2009;250:363–76. [11] Hanauer DA, Englesbe MJ, Cowan Jr JA, et al. Informatics and the American College of Surgeons National Surgical Quality Improvement Program: automated processes could replace manual record review. J Am Coll Surg 2009;208:37–41. [12] American College of Surgeons, National Surgical Quality Improvement Project. User Guide for the 2013 ACS NSQIP Participant Use Data File 2014. https:// www.facs.org/~/media/files/quality%20programs/nsqip/acs_nsqip_puf_user_ guide_2013.ashx. [13] Kumagai G, Takeuchi K, Aburakawa S, et al. Perioperative cardiopulmonary complications after cervical spine surgery in the prone position: the relationship between age and preoperative testing. Arch Orthop Trauma Surg 2011;131:911–6. [14] Harris OA, Runnels JB, Matz PG. Clinical factors associated with unexpected critical care management and prolonged hospitalization after elective cervical spine surgery. Crit Care Med 2001;29:1898–902. [15] Lee JC, Lee S-H, Peters C, et al. Risk-factor analysis of adjacent-segment pathology requiring surgery following anterior, posterior, fusion, and nonfusion cervical spine operations: survivorship analysis of 1358 patients. J Bone Joint Surg Am 2014;96:1761–7. [16] Boakye M, Maxwell B, Ryan M, et al. Health-related quality-of-life status in Veterans with spinal disorders. Qual Life Res 2012;22:45–52. [17] World Health Organization. Obesity: preventing and managing the global epidemic; 2000. [18] Status P. The use and interpretation of anthropometry report of a WHO expert committee technical report series, No 854. Geneva: WHO; 1995. [19] Auffinger B, Lam S, Kraninger J, et al. The impact of obesity on surgeon ratings and patient-reported outcome measures after degenerative cervical spine disease surgery. World Neurosurg 2014;82:e345–52. [20] Olsen MA, Nepple JJ, Riew KD, et al. Risk factors for surgical site infection following orthopaedic spinal operations. J Bone Joint Surg Am 2008;90:62–9. [21] Cavallone LF, Vannucci A. Review article: extubation of the difficult airway and extubation failure. Anesth Analg 2013;116:368–83. [22] Charlson ME, Pompei P, Ales KL, et al. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373–83. [23] Marquez-Lara A, Nandyala SV, Hassanzadeh H, et al. Sentinel events in cervical spine surgery. Spine 2014;39:715–20.
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[24] Nandyala SV, Marquez-Lara A, Fineberg SJ, et al. Perioperative characteristics and outcomes of patients undergoing anterior cervical fusion in July: analysis of the ‘‘July effect”. Spine 2014;39:612–7. [25] Woods BI, Hohl JB, Braly B, et al. Mortality in elderly patients following operative and nonoperative management of odontoid fractures. J Spinal Disord Tech 2014;27:321–6. [26] Oglesby M, Fineberg SJ, Patel AA, et al. The incidence and mortality of thromboembolic events in cervical spine surgery. Spine 2013;38. E521–7. [27] Patel A, Amit P, Rasheed Z, et al. Conservative management of type II and III odontoid fractures in the elderly at a regional spine centre: a prospective and retrospective cohort study. Br J Neurosurg 2014;29:249–53. [28] Sebastian A, Huddleston 3rd P, Kakar S, et al. Risk factors for surgical site infection after posterior cervical spine surgery: an analysis of 5441 patients from the ACS-NSQIP 2005–2012. Spine J 2015. http://dx.doi.org/10.1016/j. spinee.2015.12.009. [29] Pedregosa F, Varoquaux G, Gramfort A, et al. Scikit-learn: machine learning in python. J Mach Learn Res 2011;12:2825–30. [30] Seabold S, Perktold J. Statsmodels: econometric and statistical modeling with Python; n.d. [31] Subhash R. Lele JLKAPS. resourceselection: resource selection (probability) functions for use-availability data. R. 2016. [32] Jones E, Oliphant T, Peterson P, et al. Open source scientific tools for Python; 2001. [33] Nandyala SV, Marquez-Lara A, Fineberg SJ, et al. Comparison of revision surgeries for one- to two-level cervical TDR and ACDF from 2002 to 2011. Spine J 2014;14:2841–6. [34] Smith GW, Robinson RA. The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am 1958;40-A:607–24. [35] Basho R, Hood KA. Cervical total disc arthroplasty. Global Spine J 2012;2:105–8. [36] Rao M-J, Nie S-P, Xiao B-W, et al. Cervical disc arthroplasty versus anterior cervical discectomy and fusion for treatment of symptomatic cervical disc disease: a meta-analysis of randomized controlled trials. Arch Orthop Trauma Surg 2015;135:19–28. [37] Burkus JK, Haid RW, Traynelis VC, et al. Long-term clinical and radiographic outcomes of cervical disc replacement with the Prestige disc: results from a prospective randomized controlled clinical trial. J Neurosurg Spine 2010;13:308–18. [38] Oldmeadow LB, McBurney H, Robertson VJ. Hospital stay and discharge outcomes after knee arthroplasty: implications for physiotherapy practice. Aust J Physiother 2002;48:117–21. [39] Campbell SE, Seymour DG, Primrose WR, et al. A multi-centre European study of factors affecting the discharge destination of older people admitted to hospital: analysis of in-hospital data from the ACMEplus project. Age Ageing 2005;34:467–75. [40] Sharareh B, Le NB, Hoang MT, et al. Factors determining discharge destination for patients undergoing total joint arthroplasty. J Arthroplasty 2014;29(1355– 8):e1. [41] Alrawashdeh MO, DeVito Dabbs A, Dew M, et al. (177) – Predictors of Discharge destination after lung transplantation. J Heart Lung Transplant 2015;34:S73. [42] Ghori A, Konopka JF, Makanji H, et al. Long term societal costs of anterior discectomy and fusion (ACDF) versus cervical disc arthroplasty (CDA) for treatment of cervical radiculopathy. Int J Spine Surg 2016;10:1. [43] Jackson RJ, Davis RJ, Hoffman GA, et al. Subsequent surgery rates after cervical total disc replacement using a Mobi-C Cervical Disc Prosthesis versus anterior cervical discectomy and fusion: a prospective randomized clinical trial with 5year follow-up. J Neurosurg Spine 2016:1–12. [44] Davis RJ, Nunley PD, Kim KD, et al. Two-level total disc replacement with Mobi-C cervical artificial disc versus anterior discectomy and fusion: a prospective, randomized, controlled multicenter clinical trial with 4-year follow-up results. J Neurosurg Spine 2015;22:15–25. [45] AANS – Spine Surgery Patients with Other Health Issues Incur Longer Hospital Stays and Increased Costs n.d. http://www.aans.org/Media/General%20Press% 20Releases/2010/May/Spine%20Surgery%20Patients%20with%20Other% 20Health%20Issues%20Incur%20Longer%20Hospital%20Stays%20and% 20Increased%20Costs.aspx?p=1 (accessed October 31, 2016). [46] Taheri PA, Butz DA, Greenfield LJ. Length of stay has minimal impact on the cost of hospital admission. J Am Coll Surg 2000;191:123–30. [47] Huffman KM, Cohen ME, Ko CY, et al. A comprehensive evaluation of statistical reliability in ACS NSQIP profiling models. Ann Surg 2015;261:1108–13. [48] Shiloach M, Frencher Jr SK, Steeger JE, et al. Toward robust information: data quality and inter-rater reliability in the American College of Surgeons National Surgical Quality Improvement Program. J Am Coll Surg 2010;210:6–16. [49] Campbell PG, Malone J, Yadla S, et al. Comparison of ICD-9-based, retrospective, and prospective assessments of perioperative complications: Assessment of accuracy in reporting: Clinical article. J Neurosurg Spine 2011;14:16–22. [50] Hilibrand AS, Carlson GD, Palumbo MA, et al. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 1999;81:519–28.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes Pavan S. Upadhyayula a,b,1, John K. Yue b,c,1, Erik I. Curtis a, Reid Hoshide a, Joseph D. Ciacci a,⇑ a b c
Department of Neurological Surgery, University of California, San Diego, La Jolla, CA, United States Brain and Spinal Injury Center, San Francisco General Hospital, San Francisco, CA, United States Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
a r t i c l e
i n f o
Article history: Received 30 January 2017 Accepted 22 April 2017 Available online xxxx Keywords: ACDF ACS-NSQIP CDA Cervical spine Spine surgery Operation time
a b s t r a c t Objective: Cervical disc arthroplasty (CDA) is a recent alternative to anterior cervical discectomy and fusion (ACDF) in patients suffering cervical disc herniation and degeneration. To date, a systematic analysis of their comparative advantages and risks following elective surgery remains elusive. Methods: Adult patients undergoing elective CDA or ACDF were extracted from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database years 2011–2014. A total of 19,369 patients were matched 1:1 by age, sex, functional status, charlson comorbidity index, ASA classification, BMI classification, and number of vertebral levels operated on during surgery. This matching process led to a final sample of 588 subjects (294 CDA, 294 ACDF). Multivariable regression was performed for five outcome measures: operation time, early complications, reoperation rates, hospital length of stay (HLOS), and discharge destination. Mean differences (B), odds ratios (OR) and associated 95% confidence intervals (CI) are reported. Results: Compared to ACDF, CDA was associated with decreased mean operation time (B = 18.78-min, 95% CI [29.13, 8.42]; p < 0.001), decreased HLOS (B = 0.44-days [0.77, 0.11]; p = 0.009), and increased likelihood of discharge to home (OR = 5.39 [1.14–25.43]; p = 0.033). No differences in reoperation rates and complications were found. Conclusion: In a matched cohort analysis, CDA performs comparably to ACDF and is associated with decreased operation time and HLOS, and increased likelihood of discharge to home, without differences in 30-day complications or reoperation rates. Future prospective studies are warranted. Published by Elsevier Ltd.
1. Introduction Degenerative cervical spine conditions will impact over 60% of the population at some point in life [1]. An aging population makes the number of patients requiring operative treatment more likely to rise [2,3]. Effective surgical techniques for symptomatic relief are important for both quality of life and economic measures. Anterior cervical discectomy and fusion (ACDF) is a procedure indicated for cervical disc herniation and cervical degeneration (e.g. spondylosis). ACDF is known for its low complication rate and
⇑ Corresponding author at: Neurological Surgery, Chief of Neurosurgery, UCSD VAMC, University of California, San Diego, 200 West Arbor Drive #8893, San Diego, CA 92103, United States. Fax: +1 858 534 8899. E-mail address: [email protected] (J.D. Ciacci). 1 These authors contributed equally to this work.
low rate of reoperation. The published rate of surgical complication from ACDF is around 2.4% [4]; low complication rates, high probability of fusion and resolution of symptoms have led ACDF to become the standard surgical technique for cervical radiculopathy and disc degeneration. A newer technique indicated in cervical disc herniation/degeneration patients is cervical disc arthroplasty (CDA). The first U.S. Food and Drug Administration (FDA) approval of artificial discs in the U.S. occurred in 2004 [5]. A systematic review of two FDA trials comparing CDA with ACDF found CDA associated with higher rates of operative success, greater improvement in neck disability and lower rates of adjacent segment disease [6]. Although popular abroad, the lower utilization level of CDA in the U.S. has been impacted by three factors: the relative novelty of the technology, high cost of prosthesis and lack of insurance coverage [4]. A 2013 cost-effectiveness study found that a CDA prosthesis would need
http://dx.doi.org/10.1016/j.jocn.2017.04.027 0967-5868/Published by Elsevier Ltd.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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to remain functional for 14 years to become more cost-effective than conventional ACDF [6]. Although a majority of published research comparing the two techniques discusses a slight benefit for CDA versus no difference, many surgeons anecdotally describe higher complication rates, device failure and neurologic deficit observed following CDA compared to ACDF [5,7,8]. A limitation of these previous studies includes small sample sizes and the reliance on retrospective data from FDA trials. Our goal was to collect and analyze data from the American College of Surgeons (ACS) National Surgical Quality Improvement Project (NSQIP) database across 435 centers. In utilizing ACS-NSQIP, we aim to describe and characterize the clinical presentations of elective ACDF and CDA, and determine the risk factors for perioperative outcome including operation time, early complications, reoperations, hospital length of stay (HLOS), and discharge destination. 2. Materials and methods 2.1. Data source NSQIP was created to improve surgical techniques and outcomes [9] and catalogs >300 variables on comorbidities, intraoperative events and 30-day outcomes using prospective random sampling [10,11]. This study is exempt from institutional review board (IRB) approval, as the ACS-NSQIP participant-use data files contain no protected health information. 2.2. Study population This study analyzes the NSQIP database from years 2011–2014 for patients undergoing elective ACDF or CDA. These NSQIP years were selected for the current analysis because the variables ‘emergncy’ (coding whether surgery was emergent) and ‘dischdest’ (coding whether patient was discharged to home, skilled nursing facility (SNF), rehabilitation unit, or other) were added to NSQIP starting in 2011 [12]. The ACDF and CDA patients were identified using common procedural terminology (CPT) codes. The CPT code for CDA was 22856 (‘total disc arthroplasty (artificial disc), anterior approach, including discectomy with end plate preparation (includes osteophytectomy for nerve root or spinal cord decompression and microdissection); single interspace, cervical’). ACDF was identified using CPT code 22551 (‘anterior interbody fusion, with discectomy and decompression; cervical below C20 ). Multilevel procedures were identified with additional CPT codes for each interspace. 22585 (‘‘Arthrodesis Anterior Interbody – Each Additional Interspace) and 22858 (‘‘Total disc arthroplasty (artificial disc), anterior approach; second level cervical.”). Of 19,369 initial subjects (CDA = 796, ACDF = 18,573), those undergoing emergency surgery (n = 1264) were excluded. Then patients were matched one-toone based off age, sex, ASA status, functional status, charlson comorbidity score, BMI classification and number of vertebral levels operated on. This led to a final cohort of 588 subjects (n = 294 each in CDA and ACDF surgical cohorts). 2.3. Outcome measures The primary outcome measures were operation time, complications, 30-day reoperations, HLOS and discharge destination. Operation time was defined as the total surgical time in minutes. HLOS was defined as the number of days between admission and date of post-surgery discharge. For univariate and multivariable analyses, operation time and HLOS were treated as continuous variables. Hospital discharge destination was categorized to home versus a facility of higher level of care, in all patients not reported to have died within 30 days. Due to the small numbers of 30-day complica-
tions and reoperations, outcome distributions are provided but multivariable analyses were not performed. 2.4. Statistical analysis Means and standard deviations (SD) are reported for continuous variables, and proportions are reported for categorical variables unless otherwise specified. Analysis of variance (ANOVA) and chi-squared tests were used to compare continuous and categorical variables, respectively, by surgery cohort (CDA, ACDF). Linear regressions were performed for operation time and HLOS, and logistic regressions were performed for discharge to home, with surgery cohort as the primary variable of interest. Due to high incidences and associations with negative outcomes in prior studies [13–16], hypertension and smoking were included as independent predictors. The factors patients were matched on were coded as follows. BMI was stratified to World Health Organization classifications (kg/m2; <18.5 = underweight, 18.5–29.9 = nonobese, 30– 34.9 = obese class I, 35 = obese class II/III) [17,18], per association with increased risk of poor outcome (e.g. airway compromise, extubation challenges, surgical site infection) [19–21]. The Charlson Comorbidity Index (CCI) [22], widely utilized in large retrospective spine studies, provides a numerical value of a patient’s comorbidity burden [23–26]. The American Society of Anesthesiologists physical classification (ASA) score is well-established in cervical spine literature as a predictor of poor outcome [27,28]. Whether the surgery was performed during inpatient stay or as an outpatient was also included and adjusted for in multivariable regressions. For linear regressions, the mean difference (B) and associated 95% confidence interval (95% CI) are reported for each predictor; for logistic regressions, the odds ratio (OR) and 95% CI are reported. Statistical significance was assessed at p < 0.05. All statistical analyses were performed using open source software in Python or R (SciPy, StatsModels, Sci-Kit-Learn and Resource Selection packages) [29–32].
3. Results 3.1. Demographic and clinical characteristics The 588 included subjects (294 CDA, 294 ACDF) were matched one-to-one by age, BMI, sex, ASA classification, function status, number of vertebral levels operated, and CCI to limit differences between groups. Overall, subjects were 46.5 ± 11.4 years of age and 51.7% male. Notably, both groups showed zero incidence for a number of prior comorbidities (Table 1). The only comorbidity to differ significantly between surgical cohorts was smoking status (CDA 23.4%, ACDF 36.4%; p < 0.001). 3.2. Operation time and early complications Overall, 1.8% of subjects (n = 11) suffered 30-day complications (CDA 1.3%, ACDF 2.3%; p = 0.362). There were no deaths in the cohort. The overall mean operation time was 123.93 ± 64.64 min. On univariate analysis, CDA demonstrated shorter operation times compared to ACDF (114.84 ± 57.47 min vs. 133.01 ± 69.81 min); p < 0.001) (Table 2), which survived multivariable analysis to show a mean decrease of 18.78 min in the CDA cohort (95% CI [29.13, 8.43]; p < 0.001) (Table 3). Longer operation times were also experienced by inpatients (B = 24.69 min [13.25, 36.13]; p < 0.001) compared to outpatients.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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P.S. Upadhyayula et al. / Journal of Clinical Neuroscience xxx (2017) xxx–xxx Table 1 Comorbidities by surgery cohort. Comorbidity variable
Table 3 Multivariable linear regression for operation time. ACDF (n = 294)
CDA (n = 294)
Sig. (p)
0.10 (0.30)
0.10 (0.30)
1.00
0 (0.0%) 0 (0.0%) 0 (0.0%)
0 (0.0%) 0 (0.0%) 1 (0.3%)
1.00 1.00 0.316
1 (0.3%) 0 (0.0%)
0 (0.0%) 0 (0.0%)
0.316 1.00
Malignancy Weight loss > 10% (6-months) Metastasis
0 (0.0%) 0 (0.0%)
0 (0.0%) 0 (0.0%)
1.00 1.00
Neurological Transient ischemic attack Stroke
0 (0.0%) 0 (0.0%)
2 (0.6%) 0 (0.0%)
0.156 1.00
Paralysis Hemiparesis Paraplegia Quadriplegia
0 (0.0%) 1 (0.0%) 0 (0.0%)
0 (0.0%) 0 (0.0%) 0 (0.0%)
1.00 0.316 1.00
Pulmonary Dyspnea Steroid use (inhaler) COPD
12 (4.1%) 4 (1.3%) 8 (2.7%)
10 (3.4%) 1 (.3%) 4 (1.4%)
0.607 0.178 0.243
Coagulopathy Diabetes Mellitus Hypertension Renal failure Smoking
1 (0.3%) 22 (14.3%) 103 (35.0%) 0 (0.0%) 107 (36.4%)
0 (0.0%) 25 (4.2%) 88 (29.9%) 0 (0.0%) 69 (23.4%)
0.316 0.648 0.186 1.00 <0.001
Charlson Comorbidity Index Mean (SD) Cardiovascular Congestive heart failure Myocardial infarction Percutaneous coronary intervention Prior cardiac surgery Peripheral vascular disease
Distributions and proportions are shown for elective cervical spine surgery patients. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty; SD = standard deviation.
Table 2 Univariate distribution of outcomes by surgery cohort. Outcome variable Operation time Minutes, Mean (SD) Hospital length of stay (HLOS) Days, Mean (SD) Hospital discharge to home Home Skilled nursing facility/ rehabilitation
ACDF (n = 294)
CDA (n = 294)
Sig. (p)
133.01 (69.81)
114.84 (57.47)
<0.001
1.57 (2.71)
1.18 (0.97)
0.018
287 (97.6%) 7 (2.4%)
292 (99.3%) 2 (0.7%)
0.093
Predictor variable
B
95% CI
Sig. (p)
Surgery cohort ACDF CDA
Reference 18.78
– 29.13, 8.43
– <0.001
Patient type Inpatient Outpatient
Reference 24.69
– 36.13, 13.25
– <0.001
Hypertension No Yes
Reference 5.06
– 5.91, 16.03
– 0.365
Smoking No Yes
Reference 4.75
– 16.08, 6.57
– 0.410
Mean increase or decrease (B) and associated 95% confidence intervals (CI) are shown for each predictor. ACDF = anterior cervical discectomy and fusion; ASA = American Society of Anesthesiologists physical classification score; CDA = cervical disc arthroplasty; SE = standard error.
Table 4 Multivariable linear regression for hospital length of stay (HLOS). Predictor variable
B
95% CI
Sig. (p)
Surgery cohort ACDF CDA
Reference 0.44
– 0.77, 0.11
– 0.009
Patient type Inpatient Outpatient
Reference 0.79
– 1.15, 0.43
– <0.001
Hypertension No Yes
Reference 0.04
– 0.39, 0.30
– 0.79
Smoking No Yes
Reference 0.25
– 0.61, 0.112
– 0.177
Mean increase or decrease (B) and associated 95% confidence intervals (CI) are shown for each predictor. Patients who expired in-hospital and/or within 30-days of operation were excluded from the analysis. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty.
3.4. Reoperation rates
Distributions and proportions are shown for elective cervical spine surgery patients. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty; SD = standard deviation.
3.3. Hospital discharge destination and total hospital length of stay (HLOS) Overall HLOS was 1.38 ± 2.04 days. CDA demonstrated shorter univariate HLOS compared to ACDF (1.18 ± 0.97 days vs. 1.57 ± 2.71 days, p = 0.018). On multivariable analysis, a nonsignificant statistical trend was observed for CDA (B = 0.44 days [0.77, 0.11]; p = 0.009) (Table 4). Generally, longer HLOS were experienced by inpatients (B = 0.79 days [0.43, 1.15]; p < 0.001) compared to outpatients. Overall, 579 (98.4%) of patients were discharged to home from hospital (CDA 99.3%, ACDF 97.6%, p = 0.093). While marginally significant on univariate analysis, CDA subjects demonstrated greater multivariable likelihood of being discharged to home (OR = 5.39 [1.14, 25.43]; p = 0.03) (Table 5).
A total of 0.8% (n = 5) patients required spine reoperations within 30 days (CDA 1.0%, ACDF 0.7%; p = 0.658). 4. Discussion Adequate and timely surgical intervention for degenerative cervical spine pathology is required to optimize outcomes. Currently, 95% of males and 75% of females aged > 65-years experience symptoms related to degenerative changes in the cervical spine [33]. For the past 58 years, ACDF has been the standard method of surgical intervention for these patients [34]. ACDF accesses the spine anteriorly performing a discectomy at relevant vertebral levels. Osteophytes are removed and adjacent vertebra are prepared to accept the ACDF implant. Measurement of the intervertebral distance is performed to ensure appropriate implant sizing. An allograft is then placed and a titanium end-plate is used to stabilize the graft-vertebra joint. CDA surgeries use a similar approach. Once all disc material is removed, a device creates keel cuts into the adjacent vertebrae. These are necessary for placement of the arthroplasty joint that maintains mobility. Due to the low incidence of postsurgical complications and morbidity of ACDF, alternatives have been met with high scrutiny. CDA has shown promise as a suitable alternative in select patients,
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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4.2. Discharge destination
Table 5 Multivariable logistic regression for discharge to home. Predictor variable
OR
95% CI
Sig. (p)
Surgery cohort ACDF CDA
Reference 5.39
– 1.14, 25.43
– 0.033
Patient type Inpatient Outpatient
Reference 0.61
– 0.17, 2.14
– 0.439
Hypertension No Yes
Reference 0.99
– 0.28, 3.49
– 0.996
Smoking No Yes
Reference 5.63
– 0.70, 44.97
– 0.103
Odds ratios (OR) and associated 95% confidence intervals (CI) are shown for each predictor. Patients who expired in-hospital and/or within 30-days of operation were excluded from the analysis. ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty.
associating with fewer surgical complications and decreased HLOS [33,35]. Using NSQIP data for elective operations, we demonstrate that the patients undergoing CDA experience decreased operation time, decreased HLOS, and increased likelihood of discharge to home, without changes in complications or 30-day reoperations. To our knowledge, this study is the first to characterize the presentation and predictors of early outcomes, including discharge destination, across these two surgical cohorts after elective surgery using a large national dataset.
4.1. Demographic differences, operation time and complications By matching our cohorts based on numerous demographic variables we were able to prevent demographic differences from altering our analysis of outcomes. The similar levels of clinical comorbidities and matching of patients based on age, sex, BMI, CCI, ASA status, functional status, and vertebral levels fused allows us to accurately compare the two surgical techniques. Our dataset also only had one and two level surgeries further ensuring outcomes were not altered by outliers associated with more difficult surgeries. CDA is associated with reduced operation time compared to ACDF. While this is contrary to the results found in a 2015 metaanalysis of randomized-controlled trials (RCTs) on the topic [36], it is likely that the difference is, at least in part, attributable to our objective to characterize elective surgeries instead of all surgeries. Characterization of the relevant risk profile is critical in assisting with the decision to operate for an emergency/lifesaving purpose versus one of harm reduction/quality of life improvement. This is an important distinction as demonstrated by the disparate comorbidity profiles between the surgery cohorts in our data. Fewer technical steps, coupled with reduced stressors in the nonemergency setting, may explain why elective CDA operation time is shorter than that of ACDF. Historical data gathered from FDA trials and RCTs comparing CDA and ACDF show no difference or a slight advantage for CDA with regards to post-surgical complication rates [37]. While the overall incidence of complications did not differ between CDA and ACDF in our study, we were in part constrained by the low number of CDA surgeries in NSQIP; whether this is attributable to a low absolute likelihood of complications after elective CDA or due to the smaller sample size of elective CDA patients in our study should be a topic of future meta-analyses or prospective investigations.
Discharge to higher levels of care increases the overall utilization of healthcare resources and subsequent public health cost and burden [38]. After controlling for demographics and comorbidities, CDA patients remained more likely to return home. Patients who are of higher baseline physical and cognitive status are more likely to return home after surgery [39–41]; we control for these variables in our study to further delineate the specific contribution of surgery type to outcomes. Discharge to care above that of home for an elective surgery confers a comparatively higher level of risk to quality of life, necessitating a discussion of risks and benefits with the patient and/or families. Such discussions require an improved understanding of the optimal indications for CDA surgery. 4.3. Cost and HLOS Cost also merits consideration. A recent analysis by Ghori et al. found the combined cost for a 45–60 year old patient was $24,119 for CDA versus $31,178 for ACDF when factoring in cost of surgery, lost productivity and rates of reoperation [39–42]. The nature of elective surgeries makes the cost of prosthesis an important determinant of out-of-pocket expenditures. A 2013 cost-effectiveness study found that CDA prostheses must remain functional for 14 years to become more cost-effective than conventional ACDF [6]. If CDA is to become a viable broadly indicated treatment for cervical degeneration issues of novelty and durability must be addressed. As it stands, the benefits to early outcomes associated with CDA may merit increased consideration and potential investment in further research and development. A number of RCTs demonstrate lower reoperation rates for CDA due to increased durability of the prosthesis [43,44]. The aging U.S. population demonstrates the need for surgical solutions capable of providing quantifiable long-term benefits. The decrease in HLOS for the CDA cohort was close to half a day, with an associated cost estimate of $500 to $5,000 for spine surgeries [45,46]. Although cost may be less important to the patient in need of surgery, it does provide an important point of consideration for hospital resource utilization and insurance organizations. The ability to safely discharge patients earlier is crucial to maximizing utility. 4.4. Limitations There are a number of limitations when conducting research using a retrospective database such as NSQIP. The NSQIP database has been known to have some limited reporting inaccuracies [47,48]. Campbell et al. documented the underrepresentation of complications solely based off of ICD-9 codes [49], and CPT coding does not capture the granularity of associated clinical conditions concurrent with the primary operation. Surgical cost, reimbursement potential, surgeon preference, and academic status and/or volume of the treating hospital may also influence the decision for surgery. While we matched one-to-one by age, sex, BMI, ASA classification, functional status and number of surgical levels, it is possible that we were limited in our drawing pool by the comparatively smaller sample size of total elective CDA surgeries contained in NSQIP compared to the more mainstream ACDF. We were also limited to the variables collected as part of NSQIP limiting conclusions to the 30-day perioperative window. Hilibrand and colleagues describe a 10-year, 25% incidence rate of adjacent disc cervical degeneration following ACDF [50]. Although beyond the scope of NSQIP and our current analysis, it would be of interest to investigate the incidence of long-term sequelae following elective ACDF and CDA.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027
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5. Conclusions Compared to ACDF, CDA is associated with decreased operative times and increased likelihood of being discharged home from the hospital following one-to-one matching by demographic and clinical variables. These data suggest the clinical relevance of exploring standard criteria for qualifying patients for CDA as a viable alternative to ACDF to optimize outcomes. Future prospective trials are needed to confirm these findings. References [1] Todd AG. Cervical spine: degenerative conditions. Curr Rev Musculoskelet Med 2011;4:168–74. [2] Okada E, Matsumoto M, Ichihara D, et al. Aging of the cervical spine in healthy volunteers: a 10-year longitudinal magnetic resonance imaging study. Spine 2009;34:706–12. [3] Marquez-Lara A, Nandyala SV, Fineberg SJ, et al. Current trends in demographics, practice, and in-hospital outcomes in cervical spine surgery: a national database analysis between 2002 and 2011. Spine 2014;39:476–81. [4] Smith JS, Fu K-MG, Polly Jr DW, et al. Complication rates of three common spine procedures and rates of thromboembolism following spine surgery based on 108,419 procedures: a report from the Scoliosis Research Society Morbidity and Mortality Committee. Spine 2010;35:2140–9. [5] Mummaneni PV, Amin BY, Wu J-C, et al. Cervical artificial disc replacement versus fusion in the cervical spine: a systematic review comparing long-term follow-up results from two FDA trials. Evid Based Spine Care J 2012;3:59–66. [6] Qureshi SA, McAnany S, Goz V, et al. Cost-effectiveness analysis: comparing single-level cervical disc replacement and single-level anterior cervical discectomy and fusion: clinical article. J Neurosurg Spine 2013;19:546–54. [7] Boselie TFM, Willems PC, van Mameren H, et al. Arthroplasty versus fusion in single-level cervical degenerative disc disease: a Cochrane review. Spine 2013;38. E1096–107. [8] Traynelis VC, Leigh BC, Skelly AC. Return to work rates and activity profiles: are there differences between those receiving C-ADR and ACDF? Evid Based Spine Care J 2012;3:47–52. [9] Ingraham AM, Richards KE, Hall BL, et al. Quality improvement in surgery: the American College of Surgeons National Surgical Quality Improvement Program approach. Adv Surg 2010;44:251–67. [10] Hall BL, Hamilton BH, Richards K, et al. Does surgical quality improve in the American College of Surgeons National Surgical Quality Improvement Program: an evaluation of all participating hospitals. Ann Surg 2009;250:363–76. [11] Hanauer DA, Englesbe MJ, Cowan Jr JA, et al. Informatics and the American College of Surgeons National Surgical Quality Improvement Program: automated processes could replace manual record review. J Am Coll Surg 2009;208:37–41. [12] American College of Surgeons, National Surgical Quality Improvement Project. User Guide for the 2013 ACS NSQIP Participant Use Data File 2014. https:// www.facs.org/~/media/files/quality%20programs/nsqip/acs_nsqip_puf_user_ guide_2013.ashx. [13] Kumagai G, Takeuchi K, Aburakawa S, et al. Perioperative cardiopulmonary complications after cervical spine surgery in the prone position: the relationship between age and preoperative testing. Arch Orthop Trauma Surg 2011;131:911–6. [14] Harris OA, Runnels JB, Matz PG. Clinical factors associated with unexpected critical care management and prolonged hospitalization after elective cervical spine surgery. Crit Care Med 2001;29:1898–902. [15] Lee JC, Lee S-H, Peters C, et al. Risk-factor analysis of adjacent-segment pathology requiring surgery following anterior, posterior, fusion, and nonfusion cervical spine operations: survivorship analysis of 1358 patients. J Bone Joint Surg Am 2014;96:1761–7. [16] Boakye M, Maxwell B, Ryan M, et al. Health-related quality-of-life status in Veterans with spinal disorders. Qual Life Res 2012;22:45–52. [17] World Health Organization. Obesity: preventing and managing the global epidemic; 2000. [18] Status P. The use and interpretation of anthropometry report of a WHO expert committee technical report series, No 854. Geneva: WHO; 1995. [19] Auffinger B, Lam S, Kraninger J, et al. The impact of obesity on surgeon ratings and patient-reported outcome measures after degenerative cervical spine disease surgery. World Neurosurg 2014;82:e345–52. [20] Olsen MA, Nepple JJ, Riew KD, et al. Risk factors for surgical site infection following orthopaedic spinal operations. J Bone Joint Surg Am 2008;90:62–9. [21] Cavallone LF, Vannucci A. Review article: extubation of the difficult airway and extubation failure. Anesth Analg 2013;116:368–83. [22] Charlson ME, Pompei P, Ales KL, et al. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373–83. [23] Marquez-Lara A, Nandyala SV, Hassanzadeh H, et al. Sentinel events in cervical spine surgery. Spine 2014;39:715–20.
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[24] Nandyala SV, Marquez-Lara A, Fineberg SJ, et al. Perioperative characteristics and outcomes of patients undergoing anterior cervical fusion in July: analysis of the ‘‘July effect”. Spine 2014;39:612–7. [25] Woods BI, Hohl JB, Braly B, et al. Mortality in elderly patients following operative and nonoperative management of odontoid fractures. J Spinal Disord Tech 2014;27:321–6. [26] Oglesby M, Fineberg SJ, Patel AA, et al. The incidence and mortality of thromboembolic events in cervical spine surgery. Spine 2013;38. E521–7. [27] Patel A, Amit P, Rasheed Z, et al. Conservative management of type II and III odontoid fractures in the elderly at a regional spine centre: a prospective and retrospective cohort study. Br J Neurosurg 2014;29:249–53. [28] Sebastian A, Huddleston 3rd P, Kakar S, et al. Risk factors for surgical site infection after posterior cervical spine surgery: an analysis of 5441 patients from the ACS-NSQIP 2005–2012. Spine J 2015. http://dx.doi.org/10.1016/j. spinee.2015.12.009. [29] Pedregosa F, Varoquaux G, Gramfort A, et al. Scikit-learn: machine learning in python. J Mach Learn Res 2011;12:2825–30. [30] Seabold S, Perktold J. Statsmodels: econometric and statistical modeling with Python; n.d. [31] Subhash R. Lele JLKAPS. resourceselection: resource selection (probability) functions for use-availability data. R. 2016. [32] Jones E, Oliphant T, Peterson P, et al. Open source scientific tools for Python; 2001. [33] Nandyala SV, Marquez-Lara A, Fineberg SJ, et al. Comparison of revision surgeries for one- to two-level cervical TDR and ACDF from 2002 to 2011. Spine J 2014;14:2841–6. [34] Smith GW, Robinson RA. The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am 1958;40-A:607–24. [35] Basho R, Hood KA. Cervical total disc arthroplasty. Global Spine J 2012;2:105–8. [36] Rao M-J, Nie S-P, Xiao B-W, et al. Cervical disc arthroplasty versus anterior cervical discectomy and fusion for treatment of symptomatic cervical disc disease: a meta-analysis of randomized controlled trials. Arch Orthop Trauma Surg 2015;135:19–28. [37] Burkus JK, Haid RW, Traynelis VC, et al. Long-term clinical and radiographic outcomes of cervical disc replacement with the Prestige disc: results from a prospective randomized controlled clinical trial. J Neurosurg Spine 2010;13:308–18. [38] Oldmeadow LB, McBurney H, Robertson VJ. Hospital stay and discharge outcomes after knee arthroplasty: implications for physiotherapy practice. Aust J Physiother 2002;48:117–21. [39] Campbell SE, Seymour DG, Primrose WR, et al. A multi-centre European study of factors affecting the discharge destination of older people admitted to hospital: analysis of in-hospital data from the ACMEplus project. Age Ageing 2005;34:467–75. [40] Sharareh B, Le NB, Hoang MT, et al. Factors determining discharge destination for patients undergoing total joint arthroplasty. J Arthroplasty 2014;29(1355– 8):e1. [41] Alrawashdeh MO, DeVito Dabbs A, Dew M, et al. (177) – Predictors of Discharge destination after lung transplantation. J Heart Lung Transplant 2015;34:S73. [42] Ghori A, Konopka JF, Makanji H, et al. Long term societal costs of anterior discectomy and fusion (ACDF) versus cervical disc arthroplasty (CDA) for treatment of cervical radiculopathy. Int J Spine Surg 2016;10:1. [43] Jackson RJ, Davis RJ, Hoffman GA, et al. Subsequent surgery rates after cervical total disc replacement using a Mobi-C Cervical Disc Prosthesis versus anterior cervical discectomy and fusion: a prospective randomized clinical trial with 5year follow-up. J Neurosurg Spine 2016:1–12. [44] Davis RJ, Nunley PD, Kim KD, et al. Two-level total disc replacement with Mobi-C cervical artificial disc versus anterior discectomy and fusion: a prospective, randomized, controlled multicenter clinical trial with 4-year follow-up results. J Neurosurg Spine 2015;22:15–25. [45] AANS – Spine Surgery Patients with Other Health Issues Incur Longer Hospital Stays and Increased Costs n.d. http://www.aans.org/Media/General%20Press% 20Releases/2010/May/Spine%20Surgery%20Patients%20with%20Other% 20Health%20Issues%20Incur%20Longer%20Hospital%20Stays%20and% 20Increased%20Costs.aspx?p=1 (accessed October 31, 2016). [46] Taheri PA, Butz DA, Greenfield LJ. Length of stay has minimal impact on the cost of hospital admission. J Am Coll Surg 2000;191:123–30. [47] Huffman KM, Cohen ME, Ko CY, et al. A comprehensive evaluation of statistical reliability in ACS NSQIP profiling models. Ann Surg 2015;261:1108–13. [48] Shiloach M, Frencher Jr SK, Steeger JE, et al. Toward robust information: data quality and inter-rater reliability in the American College of Surgeons National Surgical Quality Improvement Program. J Am Coll Surg 2010;210:6–16. [49] Campbell PG, Malone J, Yadla S, et al. Comparison of ICD-9-based, retrospective, and prospective assessments of perioperative complications: Assessment of accuracy in reporting: Clinical article. J Neurosurg Spine 2011;14:16–22. [50] Hilibrand AS, Carlson GD, Palumbo MA, et al. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 1999;81:519–28.
Please cite this article in press as: Upadhyayula PS et al. A matched cohort comparison of cervical disc arthroplasty versus anterior cervical discectomy and fusion: Evaluating perioperative outcomes. J Clin Neurosci (2017), http://dx.doi.org/10.1016/j.jocn.2017.04.027