1 Introduction

Cervical disc arthroplasty (CDA) is a safe and effective procedure that has garnered a significant amount of interest among both patients and physicians due to its ability to maintain segmental motion.¹ Moreover, CDA has demonstrated decreased rates of adjacent segment disease, leading to improved long-term outcomes and reduced need for revision procedures.² Despite contraindications like osteopenic bone, pre-operative deformities (e.g. scoliosis), or facet joint arthrosis, CDA remains a viable option for many patients when appropriately selected.³ As CDA continues to be utilized for treating degenerative cervical spine conditions, understanding the role that hospital size plays in patient outcomes is essential.

Hospital size has been implicated as a key indicator of access to resources, operational efficiencies, research capabilities, and the capacity to offer advanced care.^4,5 Thus, it serves as a valuable metric for analyzing outcomes in spine surgery. An in-depth exploration of these institution-based predictors of patient outcomes can provide insights into the factors influencing postoperative recovery and overall patient care quality across different hospital settings. A study conducted by Shah et al. highlighted the risk factors of 90-day readmission rates for single-level anterior cervical discectomy and fusion (ACDF) among small, medium, and large hospitals.⁵ The authors found that hospital size had a significant effect on charges and length of stay (LOS), suggesting that hospital economics, including provisions of care, may play a role in outcomes for these patients.

While previous studies have aimed to assess the role that hospital size has on readmission rates following ACDF, no study has specifically investigated this relationship in CDA– a procedure that has witnessed a dramatic increase in utilization over the past decade.⁶ Therefore, the aims of this study are to evaluate the demographic and geographic differences across hospital sizes, and assess the impact of hospital size on postoperative outcomes, including LOS, hospital costs, discharge disposition, and complications, as well as their role in predicting non-routine discharge, in patients undergoing single-level CDA. We hypothesize that larger hospitals will be associated with longer hospital stays, higher rates of non-routine discharge, and an increased incidence of complications in patients undergoing single-level CDA, compared to smaller hospitals.

2 Methods

3 Results

4 Discussion

As the landscape of spine surgery evolves to incorporate more motion-preserving procedures, prioritizing functional outcomes in patients, CDA has witnessed an impressive 654.24 % increase in utilization over the past decade.⁶ This rise is particularly notable alongside a simultaneous plateau in ACDF utilization, suggesting that CDA is being the preferred option for treating cervical spine pathologies. Given the well-documented effect of hospital size on patient outcomes in various spine surgeries, it is essential to examine whether hospital size similarly influences outcomes in this increasingly utilized procedure. This study aimed to address the impact of hospital size on postoperative outcomes, including complications, LOS, costs, and non-routine discharge rates in patients undergoing CDA. The findings displayed differences across hospital sizes in terms of patient demographics, payer distribution, geographic region, complications, LOS, and discharge disposition. These results highlight the impact of hospital size on both patient characteristics and outcomes following CDA, providing insights into healthcare economics and operational inefficiencies.

Hospital size significantly influenced the demographic profile and geographic distribution of patients undergoing CDA. Medium and large hospitals treated slightly older patients, reflecting a well-established trend in the literature concerning the resource availability of larger hospitals. Studies have highlighted the complex needs of geriatric patients, emphasizing the importance of integrated multidisciplinary encounters.^10–12 For instance, Shahrokni et al. found that geriatric co-management significantly lowered 90-day postoperative mortality in older cancer patients, underscoring the value of multidisciplinary care.¹⁰ Small hospitals were more likely to accept private insurance, whereas large public hospitals, often in the western U.S., treated more Medicaid beneficiaries as safety-net providers serving low-income populations.¹³ Medicaid reimbursements often fail to cover care costs, leaving public hospitals reliant on federal subsidies like tax exemptions to offset deficits.^14,15 In contrast, private hospitals lack such benefits, leading to disparities in patient populations and healthcare access. Policymakers must address these challenges by ensuring public hospitals receive adequate reimbursement and staffing resources. Reforming Medicaid funding to align with actual care costs — through higher reimbursement rates for high-volume public hospitals or incentives for treating Medicaid patients — could mitigate these disparities, relieve financial pressure on safety-net institutions, and support equitable care delivery.

Hospital size was a key determinant of postoperative outcomes, particularly LOS and discharge disposition. Although costs were similar across all hospital sizes, medium hospitals had the highest rate of non-routine discharge, and LOS was notably longer for medium and large hospitals. The increased rate of non-routine discharge in medium hospitals is likely explained by their longer LOS, as LOS is widely recognized as an independent predictor of non-routine discharge.¹⁶ However, large hospitals did not exhibit increased non-routine discharge rates despite similarly prolonged LOS. This may be due to larger hospitals treating more Medicaid-insured patients, as Medicaid status has been shown to prolong hospital stays due to insurance-related delays rather than clinical need.¹⁷ Prior research indicates non-routine discharge is a significant risk factor for 30-day readmissions, and studies have linked higher staffing levels of doctors and registered nurses to lower readmission risks.¹⁸ Lasater et al. demonstrated that improving nurse-to-patient ratios could significantly reduce LOS, in-hospital mortality, and readmission rates, potentially saving lives and healthcare costs.¹⁹ While staffing relationships between medium and large hospitals were not directly assessed, inadequate staffing likely contributes to the higher rates of non-routine discharge observed in medium hospitals. Ensuring adequate staffing resources, particularly nurses and specialized care teams, in medium hospitals may mitigate these complications and improve discharge outcomes. Investments in multidisciplinary care and addressing Medicaid-related delays could further reduce prolonged stays and readmissions.

Beyond differences in LOS and staffing, the types of postoperative complications also played a crucial role in discharge outcomes across hospital sizes. Previous literature clearly shows that postoperative complications increase non-routine discharge rates in spine surgery.²⁰ In this study, cardiovascular complications were linked to higher odds of non-routine discharge in large hospitals, while surgical complications were significant predictors in medium hospitals. This distinction highlights how hospital resources influence the management of specific issues. For instance, surgical complications like dysphagia often require intensive recovery and individualized therapies by speech-language pathologists to reduce LOS and non-routine discharges.^6,21,22 Medium hospitals, lacking specialized care teams, may struggle to detect and manage these complications promptly, leading to more discharges to rehabilitation centers.^23,24 Conversely, cardiovascular complications are more manageable in larger hospitals equipped with resources like dedicated Cardiac Intensive Care Units (CICUs), which improve outcomes.²⁵ High-volume centers with multidisciplinary teams, as highlighted by Kirigaya et al., demonstrate better patient outcomes through experienced staff and specialized care protocols.²⁵ This differentiation explains why medium hospitals, despite longer LOS, had higher non-routine discharge rates.

Additionally, the higher rate of surgical complications observed in medium-sized hospitals may reflect resource limitations and staffing gaps relative to larger academic centers. Medium hospitals may have less access to specialized care teams such as speech-language pathologists, wound care specialists, or dedicated neurologic consultants, which are often essential in identifying and managing complications like postoperative dysphagia or wound issues. Delayed recognition or suboptimal management of these complications may contribute to worse outcomes. To mitigate these risks, medium hospitals could benefit from standardized enhanced recovery protocols, improved perioperative complication screening, and partnerships with larger centers for subspecialty consultation. Investment in staff training and multidisciplinary infrastructure could also play a key role in reducing surgical complications and improving patient outcomes.

This study is limited by the retrospective nature of the analysis and the reliance on administrative data from the NIS, which may contain inaccuracies in ICD-10 coding and potential misclassification of procedures and complications. Discharge disposition was used as a key outcome, but it does not fully capture patient recovery or functional status following surgery. Additionally, the classification of hospital size, based on HCUP definitions, may not reflect the full spectrum of hospital resources, staffing levels, or patient volumes, all of which can impact postoperative outcomes. The exclusion of patients with missing data may have introduced selection bias, affecting the overall generalizability of the findings. While cost data were adjusted for inflation, regional differences in healthcare costs and reimbursement rates were not considered, which could influence cost-related outcomes. The cross-sectional design also limits any conclusions about causality between hospital size and differences in perioperative complications, length of stay, and discharge outcomes. Further research incorporating prospective data and patient-reported outcomes could offer a more comprehensive perspective on how hospital characteristics influence recovery after CDA.

5 Conclusions

The results of this study suggest that medium-sized hospitals may face challenges related to resource limitations and staffing inefficiencies, which could impact postoperative outcomes such as length of stay and non-routine discharge. The increased rate of non-routine discharge in medium hospitals may reflect potential healthcare inefficiencies that could be mitigated through targeted interventions. To address these potential inefficiencies, strategies such as enhancing early detection of complications, improving care coordination via multidisciplinary teams, and ensuring adequate staffing in specialized care should be considered. Policymakers and hospital administrators should consider these strategies, including developing partnerships with larger hospitals and providing financial support for staffing, to ensure that medium-sized hospitals are better equipped to manage postoperative care. By addressing these disparities, healthcare systems can move towards more equitable and efficient recovery processes for patients undergoing CDA. Future research should explore this relationship more explicitly by examining hospital-level variables such as nurse-to-patient ratios and access to specialized care teams.

CRediT authorship contribution statement

Paul G. Mastrokostas: Conceptualization, Methodology, Data curation, Software, Formal analysis, Visualization, Writing – original draft, Writing – review & editing. Leonidas E. Mastrokostas: Conceptualization, Methodology, Data curation, Software, Formal analysis, Visualization, Writing – original draft, Writing – review & editing. Jason M. Dayan: Writing – original draft, Writing – review & editing. Luke B. Schwartz: Writing – original draft, Writing – review & editing. Joseph Razi: Writing – original draft, Writing – review & editing. Ahmed K. Emara: Writing – original draft, Writing – review & editing. Ahmed Saleh: Conceptualization, Supervision, Project administration, Writing – review & editing. Jad Bou Monsef: Conceptualization, Supervision, Project administration, Writing – review & editing. Afshin E. Razi: Conceptualization, Supervision, Project administration, Writing – review & editing. Mitchell K. Ng: Conceptualization, Supervision, Project administration, Writing – review & editing.

Guardian/patient's consent

The National Inpatient Sample (NIS) is a publicly available, de-identified database. As such, this study was exempt from institutional review board approval, and the requirement for informed patient or guardian consent was waived.

Ethical statement

The authors affirm that this study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki. All methods adhered to relevant guidelines and regulations. As the study utilized publicly available, de-identified data from the National Inpatient Sample, no direct patient involvement occurred, and institutional review board approval was not required.

Funding statement

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.