Across all categories observed, unadjusted reimbursements have remained stable to slightly increased. However, there is a trend of decreasing real value in medical service payments when adjusted relative to CPI inflation statistics over the 21-year period. Applying this adjustment to the Medicare Part B payment schedule reveals the following two concerns: first, real generalized inflation appears to have outpaced physician reimbursement inflation. Secondly, the decreasing real value of reimbursement rates has not kept pace with the rising costs of tumor resections, creating a significant cost discrepancy. Interestingly, data released by the BLS indicate the CPI medical care index approximately doubled from 2000–2021 [14]. Meanwhile, this acceleration exceeds the general CPI data suggesting the U.S. dollar has lost approximately 33% of its purchasing power throughout the same timeframe [15]. Despite these figures, the data presently furnished suggest reimbursements for surgeons performing spinal tumor resections has suffered. To better contextualize this discussion, note that a 2016 study by Lau et. al which found that the mean direct cost of hospital admission for the surgical management of spinal tumors was $52,083 [16].

The data highlighted a decline in reimbursement rates for procedures with the most allowed services by Medicare. Within the subcategory of extradural resections, CPT 63276 (thoracic laminectomy; extradural) remained the most in-demand service while also accumulating the greatest relative increase in allowed services. The second most utilized service in this subcategory, CPT 63277 (lumbar laminectomy; extradural), showed a stable number of services allowed. However, both of these extradural surgeries saw decreases in inflation-adjusted reimbursement of 2.35% and 3.24% respectively. Moreover, CPT 63277 received the lowest absolute inflation-adjusted payment rate in this subcategory despite its relative frequency.

The subcategory of intradural, extramedullary tumor resection displays stable trends in allowed services across the twenty-one-year span and decreasing inflation-adjusted payments for all procedures. This data elicits two noteworthy observations regarding the influence of demand on reimbursement for CPT codes 63280 and 63283 (“cervical laminectomy; intradural, extramedullary” and “sacral laminectomy; intradural”). The year 2004 saw an impressive spike in allowed services for CPT 63280, which precipitated an antithetical nadir in real value payments for that procedure. Both allowed services and inflation-adjusted payments for this surgery returned to their prior trajectories immediately following 2004 with no apparent propagating effects within its subcategory. Here, it simply appears Medicare did not accomplish price adjustments reflective of real-time market dynamics. For CPT 63283, the studied time-frame saw stable, low-level utilization of this billing code. Despite its relatively low employment, CPT 63283 saw a sudden rise in inflation-adjusted payments from 2009–2012. Between 2011–2012, despite no concomitant rise in utilization, CPT 63283 offered the greatest real-value payment within this subcategory and a relatively high yielding service until 2014. Again, this data suggests a misalignment of the pricing mechanism, which if further exacerbated, may have potential consequences on innovation and advancements in quality of patient care within this subset of spinal procedures.

The subcategory representing partial excision of posterior vertebral elements offers findings tangential to this point. Allowed services for CPT 22102 (lumbar partial posterior excision; bony) saw a significant rise in 2006, which then tapered down towards its baseline employment by around 2011, while the two other CPTs within this subcategory- 22100 (cervical partial posterior excision; bony) and 22101 (thoracic partial posterior excision; bony)- also display employment spikes around this time. However, the rise in allowed services for CPT 22101 had no obvious correlation to payments. Interestingly, the steep rise in utilization of CPT 22102 seems to have provoked a subsequent rise in real-value reimbursements, which peaked in 2010–2012, several years after the dramatic 2006 utilization spike and during a time when its employment was reverting back to baseline. This procedure is also noteworthy due to its large service volume. It may be the case that this extent of service volume enabled a larger number of surgeons to unify into a more perceptible entity better capable of appealing to policymakers responsible for drafting Medicare payment schedules.

Our analysis revealed a paradox wherein patient out-of-pocket expenses, encapsulated by the CPI-MEDSL, notably doubled within the study period. In contrast, Medicare reimbursements for spinal tumor resection procedures, when adjusted for inflation, declined over this period. This discrepancy highlights a growing financial burden on patients, which is not mirrored in the reimbursement patterns for these procedures. Despite escalating costs borne by patients, indicative of heightened medical care valuations from a consumer standpoint, procedural reimbursement rates do not reflect adjustments for inflation, suggesting a devaluation of spinal tumor surgeries over time. The factors contributing to this divergence are complex and warrant further exploration.

A limitation of this study is the reliance solely on reimbursement rate Medicare part B data, which may introduce bias as this dataset is limited to patients 65 years or older. This may not fully represent the entire spectrum of the spinal surgery market which could include patients younger than 65 years old, thus it is unclear if payments are reflective of the incidence of procedures in the younger population. Additionally, this data does not account for reimbursement of coupled/associated procedures, for example, the common occurrence of fusion procedures alongside neoplasm excisions. Because a similar phenomenon has been shown to affect these concomitant procedures [4, 5], complex cases involving both tumor resection and fusion are subject to compounded devaluations such that our current results likely underestimate inflationary erosion in certain circumstances. However, in some instances it may be possible that increases in associated procedures could impact perceived reimbursement rates for excisions performed within complex cases if excision codes have been artificially lowered to account for expensive predicted associated instrumentation coding. The absence of comparative data from private or third-party insurers also limits the generalizability of the findings, as reimbursement dynamics can significantly vary across different payers. Additionally, the study did not account for geographic factors accounted for by the geographic practice cost index (GPCI), which can play a crucial role in influencing reimbursement rates and patient access to specialized care. Careful evaluation of geographic reimbursement trends may be of value in the future. Furthermore, the study's timeframe, concluding in 2021, may not capture the complete ramifications of the Coronavirus pandemic and the subsequent shifts in the economic landscape, necessitating cautious interpretation of the findings in the context of a rapidly changing healthcare environment. However, we would expect the pandemic’s impact on the trends of spinal tumor reimbursements to be self-limited to several years rather than permanent.

To this point, economic downturns, such as the 2008 financial crisis and subsequent recessions, may have influenced health care spending, reimbursement structures, and patient access to specialized procedures. These fluctuations could introduce confounding variables that are not explicitly addressed in the analysis. The study's focus on reimbursement rates may not fully capture the complex interplay between economic downturns and the financial dynamics of subspecialty spinal procedures.

Another factor that can aid in explaining the decreasing adjusted reimbursement in neurosurgery demonstrated in this study is through underlying congressional policy during this time period. From 1997 to 2015, CMS determined Medicare and Medicaid reimbursement utilizing the sustainable growth rate (SGR) under the Balanced Budget Act of 1997. This legislation was originally proposed to control Medicare spending on physician reimbursement in an effort to balance the United States federal budget by 2002 [4]. The SGR was set annually and determined changes to Medicare reimbursement for procedures based on the prior year's data. This reactive approach led to a lag in adjusting reimbursement rates to keep up with rising healthcare costs, contributing to the decreasing trends observed in reimbursement rates. Additionally, a bipartisan congress vote to implement the Medicare Access and CHIP Reauthorization Act (MACRA), has significantly impacted physician reimbursement rates within our study. The introduction of MACRA in 2015 replaced the sustainable growth rate (SGR) formula with two new payment tracks: the Merit-based Incentive Payment System (MIPS) and Advanced Alternative Payment Models (APMs). While MACRA aimed to reward value and quality of care, the shift to these new models brought unintentional strain and complexity. The combined effect of reduced Medicare reimbursements and the transition to MACRA's value-based payment models has pressured physicians to adapt to new financial realities, often focusing changes in practice management and patient care strategies. These changes have created a challenging environment for many providers, impacting total reimbursement rates.

Therefore, it is crucial to recognize that the observed trends may be influenced by broader economic factors and policy changes and the study's conclusions should be interpreted within the context of the specific economic conditions during the analyzed period. These limitations underscore the importance of interpreting the study results within the specified scope and acknowledging the need for future research endeavors to address these constraints.