Surgical treatment of posttraumatic spinal cord tethering and syringomyelia: a retrospective cohort investigation of cost, reimbursement, and financial sustainability

Abstract

Background

Posttraumatic spinal cord tethering and syringomyelia are considered disabling diseases in patients with spinal cord injury. In symptomatic patients, surgical management can achieve promising clinical outcomes. As the raising economic pressure might jeopardize optimal and thus personalized patient care, we aimed to exemplify expenses of surgical treatment in contrast to reimbursement by the Swiss diagnosis related group (DRG) system.

Methods

This retrospective investigation includes 60 patients who underwent surgery for spinal cord tethering and syringomyelia. The duration of surgeries was used to estimate the costs of care in the operating room (OR) considering established bench marks. Coverage of costs was calculated by comparing Swiss DRG reimbursements with the expenses from the investigated cases.

Results

The mean duration of surgeries was 251.0 ± 93.5 min while 2.8 ± 1.4 vertebral segments were treated by spinal cord untethering. The mean OR costs (in USD) were $9,401.2±$3,500.2 (range $4,119.5 to $20,223.0). The mean reimbursement and the ratio of OR costs to reimbursement (in USD) were $24,122.5±$7,409.3 (range $17,249.8 to $31,977.1) and 0.41 ± 0.15 (range 0.14 to 0.74) for standard, and $39,106.0±$4,028.6 (range $35,369.1 to $43,376.8) and 0.24 ± 0.08 (range 0.10 to 0.47) for complex cases, respectively. The estimated costs of surgeries were different from reimbursements (p = 0.005).

Conclusions

Although the cost of surgical management of patients with posttraumatic spinal cord tethering and syringomyelia are principally covered, it remains questionable if total hospital expenses are sufficiently outweighed by the current reimbursement system. This could potentially limit the availability of best medical care and might endanger personalized patient management.

Introduction

Spinal cord injury (SCI) imposes a significant and lifelong socioeconomic burden on both patients and society [1]. Although considered rare diseases, posttraumatic spinal cord tethering and syringomyelia are disabling post-injury pathologies in SCI patients which can lead to progressive neurologic loss in symptomatic cases even years after SCI [2]. Various treatment strategies are available and ranging from conservative to complex surgical management like extensive arachnolysis or shortening osteotomies [3,4,5]. Although and according to a consensus panel in 2010 a weak recommendation exists to perform spinal cord untethering and expansion duraplasty in symptomatic patients [6], the effectiveness of surgical management is intensively debated [7]. However, in progressive cases, surgery has proven effective in at least arresting further deterioration of clinical symptoms [6, 8, 9]. Nevertheless, surgical management of these pathologies is often complex and consequently time-consuming and expensive. As the economic pressure on health care is continuously rising, this might force health care providers into ethically delicate situations. The raising costs of health care systems along with the growing economic pressure have further triggered the implementation of diagnosis related groups (DRG) reimbursement systems with the objective of stabilizing expenditures while improving transparency and quality of health care [10]. Although the DRG reimbursement system contains costs of inpatient care, a shift in overall costs was witnessed with raising expenditure in outpatient care and higher rehospitalization rates due to early discharge with an overall negative impact to quality of care [11, 12]. Unfortunately, the implementation of DRG-based reimbursement systems as replacement for fee-for-service remuneration was only partially successful in reducing overall increase of health care costs [13]. A major challenge in DRG systems applies for patients with unusual or complex diseases such as posttraumatic spinal cord tethering and syringomyelia. As a consequence, the treatment of these patients confronts hospitals with challenging decisions when it comes down to cost-effectiveness and avoiding uncovered expenses. This might endanger both quality of health care but also optimal and thus personalized patient care.

In this investigation, we aimed to retrospectively analyze the cost of care in a cohort of surgically treated patients with posttraumatic spinal cord tethering and syringomyelia in contrast to the Swiss DRG reimbursement system along with the consecutive financial burden exerted on the center of care. For this purpose, we estimated expenses resulting from the operating room (OR) for each patient and extrapolated the total cost of care based on established bench marks. The hypothesis was that in a rare disease like spinal cord tethering and syringomyelia, the coverage of expenses resulting from surgical treatment is insufficient.

Materials and methods

Study population and data gathering

This study is considered a retrospective cohort investigation at a single tertiary care center for spine pathologies in Switzerland. After exclusion of 7 patients due to missing documentation of the duration of conducted surgeries from an existing patient cohort published elsewhere [9], we included 60 patients (49 men and 11 women) for further analysis. The included data in this investigation was collected from electronic medical records. Each patient was either treated surgically by spinal cord untethering and/or followed up between 2012 and 2022 in our outpatient clinic at the Swiss Paraplegic Center. The local ethics committee waived the need for informed consent and approved the collection of the used data for research purposes (Ethikkommission Nordwest- und Zentralschweiz, EKNZ; KEK-2021-00890). Each analysis was performed in accordance with the declaration of Helsinki (as revised in 2013) and respects ethical principles for medical research involving human subjects.

Calculation of OR cost of care and Swiss DRG reimbursement

The duration of surgeries (excluding same stay revisions) was used to estimate cost of care in the OR considering current bench marks [14, 15]. In order to consider the full range of potential OR costs of care (in United State Dollars, USD, $), lower ($14.5/min), mid ($37.45/min), and upper mean costs ($131.65/min) per minute were applied for calculation of OR expenses of the investigated surgeries. Further, the effective Swiss DRG reimbursement for each included patient case was obtained in collaboration with our in-hospital coding staff. For standard cases, the Swiss DRG (version 13.0) codes B61D (case weight [CW] 1.604) and B61C (CW 2.979) while for complex cases the codes A46G (CW 3.295) and A46F (CW 4.041) were applied. A base rate of confoederatio helvetica franc (CHF) of CHF9,758.33 was chosen for all calculations of reimbursement (rate retrieved from current reimbursement valid in the canton of Lucerne, Switzerland). An exchange rate of $1.00 equaling CHF0.90 was applied for currency conversion.

Statistical analysis

Mean ± standard deviation (SD) was used for quantitative variables and frequencies or percentages were applied for categorical parameters. The Shapiro-Wilk test was used as test for normality. Depending on the type of variable either the Chi-Square or the t-test were applied to identify differences among the investigated data. Either box plots or bars were used for visualization of the analyzed data. There were no missing data sets concerning data analysis. A power analysis aiming at a statistical power of 0.8 and considering a type I error rate of 0.05 resulted in a minimal study population of 60 patients. Effect sizes were calculated to estimate the importance of our findings (< 0.1 trivial effect, 0.1–0.3 small effect, 0.3–0.5 moderate effect, > 0.5 large effect). As the nature of this study should be perceived as explorative, no prespecified level of significance was determined. Consequently, the level of evidence was provided on a continuous scale as previously recommended [16], and p-values were quantified according to their level of evidence. All the performed analysis was done using SPSS 28 (SPSS, Chicago, IL, USA).

Results

The mean age of the investigated 60 patients (49 men and 11 women) at the time of SCI was 29.0 ± 10.9 years while the mean age at the time of spinal cord untethering was 46.3 ± 11.8 years. 68.3% of patients (n = 41) were classified as ASIA Impairment Scale (AIS) type A. The mean level of SCI was 11.5 ± 5.6 which equals thoracic vertebra 4 (Th4). The mean number of tethered segments was 7.8 ± 5.6 and the mean amount of surgically untethered segments was 2.8 ± 1.4. The mean duration of surgeries was 251.0 ± 93.5 min. After surgery all patients went to the intensive care unit for at least 1 night. The rate of complications was 5% (n = 3) including cerebrospinal fluid (CSF) fistula and postoperative hematoma. Each of these patients underwent early surgical revision during the same hospital stay. After conclusion of acute care, all patients went for rehabilitation at our center. During the follow-up period, the surgical reintervention rate due to symptomatic retethering was 33.3% (n = 20). The indication to perform a surgical revision was based on both on failure to preserve the neurological level (i.e. function of the patient) and on magnetic resonance (MR) evaluation. An overview of patient baseline characteristics is provided in Table 1.

Table 1 Patient baseline characteristics

According to the US benchmarks for estimation of OR cost of care and by application of one the lowest costs (equaling $14.5/minute), the lower mean OR cost per untethering was $3,640.0±$1,355.2 (ranging from $1,595.0 to $7,830.0). Using an estimated mid-situated mean rate of OR cost of care of $37.45/minute resulted in average OR cost per spinal untethering of $9,401.2±$3,500.2 (ranging from $4,119.5 to $20,223.0). Finally, by application of one of the highest rates of OR cost of care of $131.65/minute led to an upper mean OR cost of care of $33,049.0±$12,304.6 (ranging from $14,481.5 to $71,091.0). The estimated lower, mid-situated, and upper OR cost of care for surgical treatment were different from each other (p < 0.001; effect sizes: 21.7, 6.8, and 4.3, respectively).

The mean rate of reimbursement according to Swiss DRG for a standard case was $24,122.5±$7,409.3 (ranging from $17,249.8 to $31,977.1) while the mean rate of reimbursement for a complex case was calculated as $39,106.0±$4,028.6 (ranging from $35,369.1 to $43,376.8, Fig. 1). All the estimated OR costs of care were different from the DRG reimbursements (p = 0.005; effect sizes for comparison to standard DRG reimbursement: 15.1, 4.2, and 0.7, and for complex DRG reimbursement: 26.2, 8.5, and 0.5, respectively).

Fig. 1

Absolute expenses and reimbursement for surgically treated spinal cord tethering and syringomyelia. Lower mean operating room cost (OR cost min), mid-situated mean OR cost (OR cost mid), and upper mean OR cost (OR cost max) including reimbursement of standard diagnosis related group (standard DRG) and complex DRG are displayed as bar graphs with respective error bars. All the estimated OR costs of care were different from DRG reimbursements (p = 0.005). Operating room, OR; diagnosis related groups, DRG; United States Dollar, USD

Using the OR cost of care to calculate the coverage of costs while receiving a standard DRG reimbursement for the treated cases resulted in ratios of OR expenses to total reimbursement of 0.16 ± 0.06, 0.41 ± 0.15, and 1.45 ± 0.52 (Fig. 2A), respectively. This demonstrates a coverage of OR cost of care for lower and mid-situated OR costs, however, not for maximal OR cost of care. Using the OR cost of care to calculate the coverage of expenses while receiving a complex DRG reimbursement for the treated cases resulted in ratios of OR expenses to total reimbursement of 0.09 ± 0.03, 0.24 ± 0.08, and 0.84 ± 0.28 (Fig. 2B), respectively. This resulted in full coverage of at least OR cost of care irrespective of estimated OR cost per minute and consequently applied infrastructure. The estimated ratios for lower, mid-situated, and upper OR cost of care to standard or complex DRG reimbursements were different (p < 0.001; effect sizes for comparison to standard DRG reimbursement: 12.9, 6.9 and 2.5, and for complex DRG reimbursement: 27.7, 7.5, and 7.7).

Fig. 2

Ratio of operating room (OR) cost of care to DRG reimbursement for the surgical treatment of spinal cord tethering and syringomyelia. Ratio of lower (min), mid-range (mid), an upper (max) OR cost of care to standard DRG reimbursement (A) and complex DRG reimbursement (B). There was a difference between the estimated ratios versus standard and complex DRG reimbursement (p < 0.001). Operating room, OR; diagnosis related groups, DRG

Discussion

Posttraumatic spinal cord tethering and syringomyelia are rare diseases in SCI patients with an approximate incidence of < 1–7% [17]. Thus, the need to perform surgical untethering and shunt placement (if indicated) in symptomatic cases is even less frequent. Therefore, the establishment of a solid and evidence-based remuneration rate of surgically treated cases is a challenge as posttraumatic spinal cord tethering and syringomyelia are considered rare and complex diseases which consequently provide only limited information to calculate an optimal DRG reimbursement. In this investigation, we show that using both a DRG for standard or complex cases leads basically to coverage of costs of care resulting from the OR. The mean ratio for cost-coverage receiving a standard DRG was 0.41 ± 0.15 while the mean ratio for cost-coverage using a complex DRG was 0.24 ± 0.08. However, these cost-coverage ratios should not only reimburse OR costs but also allow a breakeven of total hospital expenses during inpatient care with total revenues. Thus, when integrating overall hospital cost structures, it remains questionable whether the current Swiss DRG reimbursement for surgical treatment of posttraumatic spinal cord tethering and syringomyelia is sufficient to cover total hospital expenses resulting from a surgical treatment of spinal cord tethering and syringomyelia.

Although the estimation of total expenses for the treatment of rare and complex diseases is demanding, it is critical to value-based care [18]. Here, the change from fee-for-service models to bundled payments like DRG, shifts cost-control away from insurers and on to the care centers. Consequently, hospitals are focusing on optimizing costs ideally without losing quality of care. In surgical disciplines, one of the major expenses of medical treatment are the expenses resulting from the OR [19]. If partitioning hospital costs, expenses in the OR account for approx. 8.4% of all operating costs while ranking second of all care services directly after inpatient care (9.1% of total hospital expenses) [20]. Therefore, calculating cost of care in the OR resulting from a surgical treatment provides a solid tool to estimate total expense of a hospital stay and assess revenue or loss by application of the DRG reimbursement system. Looking at Swiss DRG reimbursement of standard surgical cases in posttraumatic spinal cord tethering and syringomyelia, the ratio of OR expenses to total reimbursement varies from 0.16 to 1.45 while for complex surgical cases this ratio ranges from 0.09 to 0.84, respectively. Taking into consideration the approx. share of the OR in overall operating costs of a care center, the current DRG reimbursement insufficiently covers total expenses of a surgical treatment of posttraumatic spinal cord tethering and syringomyelia. Therefore, cost-effectiveness of these pathologies is currently, and in most cases not provided, and generating net losses despite the need to provide this kind of surgical treatments for the affected patients. On the one hand, this may force hospitals into ethically delicate situations when tailoring decision-making regarding personalized patient care towards economic profit or loss [21, 22]. On the other hand, this contrasts with recent investigations focusing on the economic value of surgery particularly in resource-poor countries and supporting the expansion of surgery in global health care [23]. Compared to conservative therapies like vaccination, surgery requires more infrastructure and particularly initial investment with recurring costs for maintenance and depreciation. Therefore, we integrated both lower and upper including mid-situated mean OR cost per minute in order to optimally depict the whole range (starting from $14.5/min up to $131.65/min [15]) of potential cost of care in the OR concerning surgical treatment of posttraumatic spinal cord tethering and syringomyelia. While lower mean costs of care in the OR are most likely reflecting smaller surgical units in primary care centers, higher costs are predominantly resulting from tertiary care centers with modern and usually expensive infrastructures [14]. Taking into consideration both the level of surgical experience and complexity of the performed surgeries [2, 7, 24], it is justified to assume that centers which perform surgical procedures for posttraumatic spinal cord tethering and syringomyelia need both experienced neurosurgical staff specialized within the field of this rare pathology and also high-end surgical equipment like microscopes with microsurgical instruments to successfully and safely perform these interventions and achieve acceptable surgical outcomes. As a consequence, the mean expenses resulting from surgical treatment of spinal cord tethering and syringomyelia are located most likely in upper range concerning mean OR cost of care. Here, the current Swiss DRG reimbursement for a standard case (ratio of OR expenses to total reimbursement of 1.45) is insufficient and currently results in loss of revenue for the care center. In complex cases, the DRG reimbursement covers at least the upper mean costs resulting from the OR (ratio of OR expenses to total reimbursement of 0.84). However, it is comprehensible that the residual 16% of revenue are not sufficient to cover the total expenses when integrating also the costs of inpatient care and/or administrative/overhead costs. Although the DRG reimbursement system is internationally established and continuously adapting and improving [25], it is questionable whether it is able to improve quality of care by bundled payments [13, 26]. Further, in rare and complex diseases with difficult decision-making concerning adequate medical treatment due to variable patient outcome, the DRG system confronts care centers with great challenges. Particularly, in SCI patients with symptomatic spinal cord tethering and syringomyelia treatment strategies are continuously debated with a critical view regarding surgical management of the pathology [7]. This could additionally be fueled by the current and apparently insufficient reimbursement system which raises economic barriers to provide surgical treatment of these patients, and such requires higher levels of evidence to convince centers of care to still perform surgery despite the knowledge that it will frequently result in a net loss but not in a revenue. Here, both care givers as well as authorities and insurance providers are confronted with the opposing interests of the optimal and personalized medical care for the patient and the overwhelming pressure of the economic system with the continuously raising costs in health care.

The following limitations apply to this investigation: As the design of this study is retrospective and was conducted at only one clinical center it is subject to any bias associated with this kind of investigations. Thus, caution must be applied when generalizing our findings. Next, the approach to take mean OR costs for the conducted surgeries to estimate cost-coverage by DRG reimbursement remains only an estimation and does not reflect the true overall expenses per surgical case. Moreover, both OR costs as well as DRG reimbursement are continuously optimized and are from an international perspective, subject to large variations amongst different countries. Unfortunately, this makes it very difficult to draw conclusions with long-term validity. Additionally, the calculation of OR costs of care demonstrate significant variations even when comparing centers with similar infrastructure. Finally, we applied OR cost of care established from US health care providers to estimate surgical cost. However, as far as the expertise of health care providers and the extent of infrastructure are comparable between the US and Switzerland, OR costs are most likely similar in the two countries. Importantly, in our study we did not differ between private and public hospital expenses and reimbursement systems. Thus, attention has to be paid when our conclusions are applied to health care systems with different reimbursements and structures of cost. Further, a differentiation of the economic burden between SCI at higher vs. lower levels was not feasible as true costs of care and particularly, additional expenses resulting from for example complications were not available. However, it might be assumed that the financial burden is probably greater in those patients with higher injuries and thus higher rates of complications. Last but not least, a conclusive investigation of the financial impact of revision cases was also not feasible due to the limited number of patients and the variability of the applied surgical techniques in case of a revision. However, it is obvious that any surgical revision is associated with increased expenses and thus financial pressure on both hospitals as well as on health care insurances. Finally, our calculations are based on an extrapolation from surgical care and not on a true cost analysis resulting from the ICU length-of-stay, the hospital length-of-stay, or investigations of entire costs structures (e.g. lab tests, radiology, nursing, etc.). For such an investigation, the available data is insufficient. Nevertheless, an integration of true costs could be of significant value in a further investigation.

Conclusion

The surgical treatment of SCI patients with symptomatic spinal cord tethering and syringomyelia is an accepted and effective therapeutic strategy. However, as these disorders are rather rare and complex to treat, patients usually gravitate to tertiary care centers with high OR operating costs. Although the cost of surgery appears to be generally covered by Swiss DRG reimbursement, it remains questionable if total expenses of the additional costs resulting from the in-hospital stay are sufficiently counterbalanced by the current reimbursement model. This could confront hospitals with ethically delicate situations when decision making regarding patient care is not only oriented by what is best for the patient but also by economic considerations. Conclusively, the economic pressure might not only jeopardize the quality of health care but could also limit the availability of optimal and personalized medical treatment. However, as the nature of this study is explorative and calculated costs are based on estimates, our conclusions have to be regarded with caution and need to be confirmed by a true cost analysis integrating both costs of the entire stay as well as total hospital operating expenses.