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Original Article
2022
:13;
300
doi:
10.25259/SNI_497_2022

# Cost analysis comparison between anterior and posterior cervical spine approaches

Corresponding author: Alvin Y. Chan, Department of Neurological Surgery, University of California, Irvine, UCI Medical Center, Orange, California, United States. alvinyc1@hs.uci.edu
Licence

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Chan AY, Himstead AS, Choi EH, Hsu Z, Kurtz JS, Yang C, et al. Cost analysis comparison between anterior and posterior cervical spine approaches. Surg Neurol Int 2022;13:300.

## Background:

The costs of cervical spine surgery have steadily increased. We performed a 5-year propensity scoring-matched analysis of 276 patients undergoing anterior versus posterior cervical surgery at one institution.

## Methods:

We performed propensity score matching on financial data from 276 patients undergoing 1–3 level anterior versus posterior cervical fusions for degenerative disease (2015–2019).

## Results:

We found no significant difference between anterior versus posterior approaches for hospital costs ($42,529.63 vs.$45,110.52), net revenue ($40,877.25 vs.$34,036.01), or contribution margins ($14,230.19 vs.$6,312.54). Multivariate regression analysis showed variables significantly associated with the lower contribution margins included age (β = −392.3) and length of stay (LOS; β = −1151). Removing age/LOS from the analysis, contribution margins were significantly higher for the anterior versus posterior approach ($17,824.16 vs.$6,312.54, P = 0.01).

## Conclusion:

Anterior cervical surgery produced higher contribution margins compared to posterior approaches, most likely because posterior surgery was typically performed in older patients requiring longer LOS.

## INTRODUCTION

Although comparisons between anterior and posterior cervical surgical approaches due to degenerative disease have been described in the literature, few studies have focused on relative costs.[3,4,6,8] Furthermore, few reports have investigated the revenue, profit, or contribution margins of either anterior or posterior cervical approaches. Here, we have performed a financial analysis of anterior versus posterior cervical surgical data coming from one institution over a 5-year period (2015–2019).

## MATERIALS AND METHODS

We analyzed the demographic and financial data for 276 patients undergoing anterior (223 patients) versus posterior (53 patients) 1–3 level cervical fusions for spondylosis between 2015 and 2019; circumferential approaches were excluded from the study [Table 1]. The following variables were collected: American Society of Anesthesiologists (ASA) score, age, gender, ethnicity, spinal levels, operating room (OR) minutes, estimated blood loss, myelopathy, radiculopathy, time of the past follow-up, and length of stay (LOS). Financial variables included: total charges, total costs, net revenue, and contribution margins (direct cost subtracted from net revenue). Follow-up was performed utilizing chart reviews. To perform this study, we used multiple guidelines following IRB approval [Table 2].

### Statistical analysis

The following statistical tests/analyses were utilized in this study: the unpaired t-test, Chi-squared analysis, and propensity scoring for matched cohorts (i.e., including assessment of multiple variables). Stata (StataCorp) was used for propensity score matched analysis, mean, and standard deviations [Table 1].

## RESULTS

There was no significant difference between the two cohorts regarding: age, ASA score, gender, and LOS. The length of stay was over twice as long for the posterior group versus the anterior (4.5 vs. 2.1, P < 0.01). The number of levels involved was significantly higher in the posterior versus the anterior group (2.1 vs. 1.6, P < 0.01). Summary of the key findings for cost of anterior and posterior cervical spine surgical procedures are presented [Table 6 ].

### Propensity score matching

Utilizing propensity score matching, (i.e., note the original data showed many more anterior [223] than posterior [53] surgical patients), there were 53 patients placed in each group [Tables 3 and 4]. For these two groups, there were no significant differences in hospital costs ($42,529.63 vs.$45,110.52), net revenue ($40,877.25 vs.$34,036.01), or contribution margins ($14,230.19 vs.$6,312.54). However, multivariate regression analysis with matched data showed that variables significantly associated with the lower contribution margins were age (β = −392.3) and LOS (β = −1151) [Table 5]. Nevertheless, after removing age and LOS from the propensity score matched analysis, there was still no significant difference in hospital costs ($38,816.83 vs.$45,110.52) or net revenue ($42,255.27 vs.$34,036.01), but contribution margins were significantly higher in the anterior versus posterior cohorts ($17,824.16 vs.$6,312.54).

## DISCUSSION

This single-institution propensity score-matched analysis compared financial data in anterior and posterior spine surgery over 5 years. We found no significant differences in total charges, costs, net revenue, or contribution margins between anterior and posterior approaches. However, after removal of variables associated with the lower contribution margins on multivariate analysis (age and LOS), the anterior group had significantly higher contribution margins than the posterior group ($17,824.16 vs.$6,312.54, P = 0.01). These findings suggest that the lower contribution margins seen in posterior approaches were caused by an older patient population and longer hospital stay. Here, the authors, along with those from many other studies concluded that the decision to perform anterior versus posterior surgery must be made on a case-by-case basis.[6,9,13]

### Financial parameters

Financial parameters include costs and charges to the patient and hospital, revenue, and contribution margins. While several studies found lower hospital charges and total payments in anterior approaches,[2,4,7,11,12] few prior studies have demonstrated significant associations between surgical approach and contribution margins. We found no significant differences in hospital charges or net revenue, but there were significantly higher contribution margins with anterior approaches after age and LOS were removed from propensity score matching; our results suggest that age and LOS raise variable costs, thereby lowering contribution margins. Advanced age is also associated with a higher comorbidity burden,[1] resulting in a multifactorial increase in variable costs.

### Higher costs of posterior cervical fusions

An association between longer LOS and increased costs was observed after posterior cervical surgery in several studies. A study from Washington found posterior fusions had higher total hospital charges ($23,400 vs.$14,300) and longer LOS (4.6 vs. 3.8 days) compared to anterior fusions.[7] This relationship was echoed in a National Inpatient Sample study in which higher in-hospital charges ($99,841 vs.$59,934, P < 0.001) and a longer LOS (6.5 vs. 4.3 days, P < 0.001) were observed for posterior versus anterior cervical procedures.[12] A propensity score matched analysis also determined that posterior procedures had longer LOS (3.8 vs. 2.3 days), higher hospital payments ($23,638 vs.$18,346), and higher total payments ($33,526 vs.$28,963) versus anterior cervical surgery.[4] The relationship between increased age and the posterior approach is less clear. Masaki et al. theorized that older patients were more likely to choose posterior surgery to avoid the lengthier postoperative cervical immobilization period required by anterior cervical fusion.[10]

### No significant differences in hospital costs or net revenue for either approach

The present study did not find significant differences in hospital costs or net revenue between anterior versus posterior cervical surgical groups. This may be explained by the smaller sample size or by geographic variation in the costs of spine surgery.[7] For example, Kalakoti et al. reported higher average hospital costs associated with anterior cervical discectomy and fusion performed in the Western United States compared to the rest of the country (+\$9300; P < 0.001).[5]

## CONCLUSION

We performed propensity matched scoring and multivariate regression analysis of financial data on 53 patients undergoing anterior versus posterior 1–3 level cervical fusions and found that anterior approaches showed that significantly higher contribution margins compared to posterior surgery after age and length of stay were removed.

### Declaration of patient consent

Patients’ consent not required as patients’ identities were not disclosed or compromised.

Nil.

### Conflicts of interest

There are no conflicts of interest.

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