Abstract
Background Rheumatoid arthritis (RA) is a systemic inflammatory disease that frequently involves the cervical spine and often necessitates surgical intervention. Although the peripheral joint burden of RA has declined in the biological era, many patients still require cervical spine surgery, and whether RA status independently influences in-hospital outcomes remains poorly defined in contemporary, nationally representative data.
Methods We queried the National Inpatient Sample for all adult cervical spine surgery admissions from 2016 to 2021, identifying 164,837 unweighted cases (approximately 840,820 weighted). Patients with RA (ICD-10-CM M05–M06; n = 5082, 3.1%) were compared with non-RA controls (n = 159,755, 96.9%). Inverse probability of treatment weighting was applied to balance 27 preoperative covariates across 28 propensity model terms. Primary outcomes were in-hospital mortality, nonroutine discharge, length of stay, and total charges. Secondary outcomes included blood transfusion, blood loss anemia, pulmonary complications, sepsis/surgical site infection, venous thromboembolism, acute kidney injury, myocardial infarction/stroke, and additional cervical procedures during admission (proxy for unplanned intra-admission intervention).
Results After inverse probability of treatment weighting adjustment (propensity model area under the curve = 0.702; maximum standardized mean difference = 0.085; all 40 balance metrics standardized mean difference < 0.10), the most striking finding was among RA patients undergoing occipitocervical or cervicothoracic fusion, who faced 7-fold higher odds of blood transfusion (OR 7.41; 95% CI 3.88–14.2) and nearly 4-fold higher odds of nonroutine discharge (OR 3.84; 95% CI 3.17–4.64) compared with single-level fusion. Across the full cohort, RA was independently associated with higher odds of nonroutine discharge (OR 1.339; 95% CI 1.261–1.421; P < 0.001), longer length of stay (+0.28 days; 95% CI 0.11–0.45; P = 0.001), greater total charges (+9.1 %; P < 0.001), blood transfusion (OR 1.526; 95% CI 1.263–1.844; P < 0.001), blood loss anemia (OR 1.479; 95% CI 1.318–1.660; P < 0.001), pulmonary complications (OR 1.183; 95% CI 1.018–1.375; P = 0.028), and additional cervical procedures during the same admission (OR 1.331; 95% CI 1.073–1.651; P = 0.009). In-hospital mortality did not differ significantly (OR 0.856; 95% CI 0.500–1.464; P = 0.569).
Conclusions RA is independently associated with increased in-hospital morbidity and resource utilization following cervical spine surgery. These risks are graded by procedural complexity and are most pronounced among RA patients undergoing occipitocervical or cervicothoracic fusion, who demonstrate markedly increased transfusion requirements. The magnitude and procedure-specific gradient of these risks—quantified here in contemporary, biological-era data—provide an actionable basis for preoperative risk stratification, transfusion planning, and anticipatory discharge coordination in this population.
Clinical Relevance RA patients undergoing cervical spine surgery—particularly those requiring occipitocervical or cervicothoracic fusion—warrant proactive transfusion preparedness (type-and-screen and blood-product availability), preoperative anemia optimization, and discharge planning initiated at the time of surgical scheduling. These procedure-specific risk estimates allow surgeons to counsel patients and plan perioperative care in concrete rather than generic terms.
Level of Evidence 3.
- rheumatoid arthritis
- cervical spine
- spinal fusion
- decompression
- outcomes
- National Inpatient Sample
- inverse probability of treatment weighting
Introduction
Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease affecting approximately 0.5% to 1% of the global adult population, with a disproportionate burden on women and older adults.1 Beyond its well-recognized peripheral joint manifestations, RA frequently involves the cervical spine—most notably the atlantoaxial and subaxial segments—due to chronic synovitis that erodes stabilizing ligamentous and bony structures.2 Cervical spine involvement occurs in up to 50% to 80% of patients with long-standing RA and may result in atlantoaxial instability, basilar invagination, or subaxial subluxation, each carrying a risk of neurological compromise if untreated.
Surgical management of RA-related cervical pathology—ranging from posterior cervical decompression and fusion to complex occipitocervical constructs—remains a high-stakes undertaking.3 The systemic manifestations of RA, including chronic inflammation, immunosuppressive and corticosteroid therapy, and associated comorbidities such as osteoporosis and cardiopulmonary disease, create a perioperative environment that may amplify the risk of complications seen in the general spine surgery population.4 Disease-modifying antirheumatic drugs (DMARDs) and biological agents, while central to disease control, have well-documented implications for wound healing and infection susceptibility.5 Indeed, U.S. data show that 12.3% of RA patients are readmitted within 90 days after cervical spine surgery, most commonly due to postoperative infections.6
Importantly, the epidemiology of RA cervical spine surgery is itself changing. The widespread adoption of treat-to-target strategies and biological therapy has improved control of synovial disease and reduced the incidence of destructive cervical instability, such that fewer patients now progress to surgery than in previous decades.7,8 This declining and increasingly selected surgical population makes contemporary characterization of perioperative risk more, rather than less, important; the patients who still reach the operating room may represent a residual cohort with more refractory disease, greater deformity, or higher comorbidity burden, for whom accurate risk estimates cannot be extrapolated from older literature.
Nationwide administrative databases offer a powerful platform for characterizing surgical outcomes across large, real-world patient populations.9 The National Inpatient Sample (NIS), the largest all-payer inpatient database in the United States, has been used extensively to study population-level trends and outcomes in spine surgery.10 Prior work using the NIS or Medicare data has described secular trends in the rate of cervical surgery among patients with RA, as well as complication patterns in inflammatory arthritis cohorts.7,11 However, these studies were limited by older datasets predating widespread biological use, restriction to Medicare beneficiaries, or comparison of RA against noncervical surgical populations.
The epidemiology and management of RA have evolved substantially over the past decade.12 Treat-to-target strategies and biological therapies have altered the comorbidity profile of patients reaching surgical candidacy. Simultaneously, advances in spinal implant technology and surgical techniques—including the expansion of posterior cervical fixation constructs—have changed the operative landscape.13 Contemporary, nationally representative data comparing RA to non-RA patients across the full spectrum of cervical spine procedures are therefore needed.
Unadjusted comparisons between RA and non-RA surgical patients are confounded by substantial baseline differences, including age, sex, payer status, comorbidity burden, and surgical complexity. Inverse probability of treatment weighting (IPTW)—a propensity score-based method that creates a pseudopopulation with balanced covariates—provides a robust framework for causal inference in observational data.14
The purpose of this study was to characterize in-hospital outcomes of cervical spine surgery in patients with RA compared with non-RA controls using contemporary NIS data from 2016 to 2021 and rigorous IPTW adjustment. To our knowledge, this is the first propensity score-weighted analysis comparing RA and non-RA patients across the full spectrum of cervical spine procedures in a contemporary, all-payer nationally representative database. Rather than simply reconfirming that RA patients experience greater perioperative morbidity—a direction that is biologically expected—our aim was to quantify the independent magnitude of that excess after rigorous confounding control and to determine whether it is uniform or concentrated within specific, identifiable procedural subgroups that could guide clinical decision-making. We hypothesized that RA would be independently associated with increased complication rates, longer hospitalization, and higher resource utilization, even after accounting for measurable confounders, and these risks would be graded by construct complexity.15
Methods
Data Source
This retrospective cohort study used the NIS (Health Care Cost and Utilization Project, Agency for Health Care Research and Quality), which samples approximately 20% of all US inpatient admissions and provides national estimates through discharge-level weighting. Annual NIS data from 2016 to 2021 were combined into a single analytic file.
Study Population
We included all adult admissions (age ≥18 years) with a coded cervical spine surgical procedure and without any exclusion diagnosis. RA was identified using ICD-10-CM codes M05 (seropositive RA) and M06 (other RA) in any diagnosis position. Cervical surgery was defined by the presence of cervical fusion (ICD-10-PCS 0RG0–0RG2, 0RG4), cervical decompression (00NW, 01N1, 0RN1, 0RN3, and 0RN4), or cervical discectomy (0RB3 and 0RB5), assigned hierarchically so that each admission was classified once.
Admissions were excluded for cervical spine trauma (S12 and S13), spinal malignancy, spinal infection, congenital deformity (Q76), or ankylosing spondylitis (M45). To ensure control group purity, admissions with other inflammatory arthropathies (M07 and M08) were also excluded. Complete ICD-10 code lists are provided in Appendix A in the Supplementary Material.
Outcomes
Primary outcomes were in-hospital mortality, nonroutine discharge (discharge to a skilled nursing facility, inpatient rehabilitation, long-term acute care, or other nonhome destination as defined by the NIS DISPUNIFORM variable), length of stay (LOS), and total charges. Secondary outcomes included blood transfusion (ICD-10-PCS codes 302*), blood loss anemia (D62), pulmonary complications (J18, J96, and J951), surgical site infection (SSI)/sepsis (T81, A41, and R6521), venous thromboembolism (I82 and I26), acute kidney injury (N17), MI/stroke (I21 and I63), and additional cervical procedures performed on a later hospitalization day. This last variable serves as a proxy for unplanned intra-admission cervical intervention; it does not reliably distinguish planned staged procedures from unplanned returns to the operating room, and results should be interpreted accordingly. Neurological deficit (G82 and G83) was recorded as a descriptive variable only, as NIS coding does not allow reliable distinction of pre-existing from new deficit. The primary and secondary outcomes are listed in Appendix B in the Supplemental Material.
Statistical Analysis
To account for systematic baseline differences between RA and non-RA patients, we applied IPTW targeting the average treatment effect. A propensity score was estimated using multivariable logistic regression with 27 preoperative covariates, including patient demographics, hospital characteristics, admission year, elective status, and comorbidities relevant to RA (full list in Appendix C in the Supplemental Material). Surgery type (fusion, decompression, or discectomy) was included as a covariate in the propensity model, so that the primary and secondary RA vs non-RA comparisons are made across cohorts balanced not only on demographic and comorbidity profiles but also on the distribution of procedure categories. Two variables were deliberately excluded from the propensity model: the Elixhauser autoimmune flag, which is collinear with the RA exposure and would cause near-perfect separation; and fusion extent (single-level, multilevel, or occipitocervical/cervicothoracic), which is undefined for nonfusion cases and therefore could not be entered as a whole-cohort covariate. Fusion extent was instead examined within the fusion subgroup, as described below.
IPTW weights were stabilized and winsorized at the 1st and 99th percentiles to reduce the influence of extreme values. Balance was assessed using standardized mean differences (SMDs), with values below 0.10 prespecified as acceptable; model discrimination was quantified by the area under the curve. The full balance profile before and after weighting—including surgery type—is reported in Table 1 and displayed graphically in the Figure. Binary outcomes were modeled using survey-weighted logistic regression and continuous outcomes using survey-weighted linear regression, both incorporating the NIS complex sampling design (technical details in Appendix D in the Supplemental Material). Total charges were log-transformed; results are expressed as percent differences.
Covariate balance before and after IPTW.
Baseline characteristics of the study cohort (unweighted counts; nationally representative percentages).
Primary outcomes: RA vs non-RA after IPTW adjustment.
Secondary outcomes: RA vs non-RA after IPTW adjustment.
Love plot of absolute standardized mean differences (SMD) for all 40 balance metrics before (unadjusted) and after inverse probability of treatment weighting (IPTW; targeting the average treatment effect) in patients with rheumatoid arthritis (RA) versus without rheumatoid arthritis. The dashed vertical line denotes the conventional balance threshold of |SMD| = 0.10. All covariates achieved |SMD| < 0.10 after weighting (maximum 0.085, for age). Variables shown in gray were not tabulated per group in Table 2 and are displayed with their post-IPTW SMD only. National Inpatient Sample, 2016–2021; N = 164,837 (RA = 5,082; non-RA = 159,755); effective sample size after weighting 159,519 (control) and 3,417 (treated); propensity-model C-statistic (area under the curve) = 0.702. Generated with the cobalt package in R version 4.4.1.
Two sets of stratified analyses were performed. First, to confirm that the overall association was not driven by the mix of procedures, the RA vs non-RA comparison was reestimated within each surgery-type stratum (fusion, n = 150,199; decompression only, n = 13,324; discectomy only, n = 1314), applying the same combined IPTW × discharge weights within each stratum. Second, to characterize the effect of construct complexity, fusion extent was examined within RA fusion patients (n = 4741) using survey (discharge) weighting, with single-level fusion as the reference category; because this comparison is internal to the RA group, it isolates the incremental risk attributable to more extensive constructs rather than to RA status per se. A sensitivity analysis restricted to elective admissions (n = 135,347) assessed robustness of primary outcome estimates. All analyses were performed in R version 4.4.1; statistical significance was set at P < 0.05.
Results
Study Cohort
After applying inclusion and exclusion criteria, the final cohort comprised 164,837 unweighted admissions (approximately 840,820 nationally weighted) from 2016 to 2021. Of these, 5082 (3.1%) had RA and 159,755 (96.9%) served as non-RA controls. Baseline characteristics are presented in Table 2.
RA patients were older (mean age 62.65 vs 59.04 years) and more frequently women (70.0% vs 48.2%). RA patients more often had Medicare as their primary payer (56.6% vs 40.7%) and had higher rates of osteoporosis (10.6% vs 2.8%), chronic lung disease (30.5% vs 20.4%), depression (26.8% vs 17.8%), and chronic steroid use (8.3% vs 0.9%). Cervical fusion was the most common procedure in both groups (RA: 93.3%; non-RA: 91.1%), with RA patients more frequently undergoing occipitocervical or cervicothoracic constructs (19.4% vs 12.8%). Isolated decompression accounted for 6.4% of RA and 8.1% of non-RA admissions; discectomy for 0.3% and 0.8%, respectively. Among fusion cases, multilevel fusion was most common in both groups (RA: 57.6%; non-RA: 61.5%), followed by single-level (RA: 22.9%; non-RA: 25.7%). The elective admission rate was similar (RA: 82.7%; non-RA: 82.3%).
Propensity Score Weighting and Balance
The propensity model demonstrated acceptable discriminative ability (area under the curve = 0.702). After stabilization and winsorization at the first and 99th percentiles (postwinsorization weight range: 0.62–1.29), all 40 balance metrics—covariates and missing-value indicators—achieved SMD < 0.10, with a maximum post-IPTW SMD of 0.085 for age. The effective sample size after weighting was 159,519 (control) and 3417 (treated). Covariate balance before and after weighting is reported in full in Table 1 and displayed graphically in the Love plot (Figure). Notably, several covariates with substantial preweighting imbalance—female sex (unadjusted SMD 0.454), chronic steroid use (0.357), age (0.317), and osteoporosis (0.316)—were all brought below the 0.10 threshold after IPTW. Surgery type, which differed modestly between groups before weighting (unadjusted SMD 0.094), was well balanced after weighting (SMD 0.014), confirming that the primary and secondary comparisons reflect RA status rather than differences in the mix of cervical procedures.
Primary Outcomes
After IPTW adjustment, RA was not associated with in-hospital mortality (OR 0.856; 95% CI 0.500–1.464; P = 0.569). The nonsignificant and slightly protective point estimate likely reflects the low overall mortality rate (0.3%), limited statistical power for this outcome, and the high proportion of elective admissions (82.7% in RA), rather than a true protective effect of RA. In contrast, RA was independently associated with higher odds of nonroutine discharge (OR 1.339; 95% CI 1.261–1.421; P < 0.001), a longer LOS (+0.28 days; 95% CI 0.111–0.448; P = 0.001), and higher total charges (+9.1 %; P < 0.001). In absolute terms within the balanced pseudopopulation, nonroutine discharge occurred in a survey-weighted 35.5% of RA admissions vs 29.1% of non-RA admissions, and weighted mean LOS was 3.8 vs 3.5 days. These findings were robust in the elective-only sensitivity analysis (nonroutine discharge OR 1.407; 95% CI 1.313–1.507; P < 0.001; mortality OR 1.701; 95% CI 0.809–3.579; P = 0.161). Primary outcome results, including weighted group values, are presented in Table 3.
Secondary Outcomes
RA was independently associated with significantly higher odds of blood transfusion (OR 1.526; 95% CI 1.263–1.844; P < 0.001; weighted rate 2.4 % in RA vs 1.6 % in non-RA), blood loss anemia (OR 1.479; 95% CI 1.318–1.660; P < 0.001; 6.2 % vs 4.3%), and pulmonary complications (OR 1.183; 95% CI 1.018–1.375; P = 0.028; 3.9 % vs 3.3%). RA patients also had significantly higher odds of additional cervical procedures on a later admission day (OR 1.331; 95% CI 1.073–1.651; P = 0.009); this variable is a proxy for intra-admission cervical intervention and should be interpreted with caution, as it may reflect planned multistage procedures rather than unplanned revisions. SSI/sepsis (OR 1.184; P = 0.179), venous thromboembolism (OR 1.069; P = 0.648), acute kidney injury (OR 1.059; P = 0.537), and MI/stroke (OR 0.869; P = 0.510) did not differ significantly between groups. Neurological deficit was present in 5735 admissions (3.5%) overall; because NIS coding does not reliably distinguish pre-existing from new deficit, this variable was not included as a comparative outcome. Secondary outcome results are presented in Table 4.
Subgroup Analyses
By Surgery Type
To confirm that the overall RA association was not an artifact of the procedure mix, the RA vs non-RA comparison was re-estimated within each surgery-type stratum using the same combined weights (Table 5, upper panel). Within the fusion subgroup (n = 150,199)—the largest and most clinically relevant stratum—results were consistent with the primary analysis: RA was associated with nonroutine discharge (OR 1.354; 95% CI 1.272–1.441; P < 0.001), blood transfusion (OR 1.619; 95% CI 1.334–1.965; P < 0.001), and SSI/sepsis (OR 1.336; 95% CI 1.028–1.736; P = 0.031), with no significant mortality difference (OR 0.722; P = 0.308). Within the decompression-only subgroup (n = 13,324), RA remained associated with nonroutine discharge (OR 1.271; 95% CI 1.010–1.598; P = 0.041), while transfusion and SSI/sepsis did not differ significantly, consistent with the lower hemostatic burden of decompression without instrumentation. The discectomy-only subgroup (n = 1314; RA n = 17) could not support stable estimation—mortality and transfusion models exhibited complete separation owing to insufficient events—and its results are not interpreted.
Subgroup analyses: (upper panel) RA vs non-RA within each surgery-type stratum; (lower panel) fusion extent within RA fusion patients.
By Fusion Extent Within RA
Among RA patients undergoing fusion (n = 4741), fusion extent had a pronounced effect on outcomes (Table 5, lower panel). Compared with single-level fusion, occipitocervical or cervicothoracic constructs were associated with 3.84-fold higher odds of nonroutine discharge (95% CI 3.17–4.64; P < 0.001) and 7.41-fold higher odds of blood transfusion (95% CI 3.88–14.2; P < 0.001). Multilevel fusion was associated with modestly higher odds of nonroutine discharge (OR 1.28; 95% CI 1.10–1.49; P = 0.002). The apparent protective association of multilevel fusion vs single-level on mortality (OR 0.238; 95% CI 0.057–0.997; P = 0.050) is borderline significant and should be interpreted with caution given the small number of deaths.
Discussion
The central finding of this study is that RA is independently associated with increased in-hospital morbidity following cervical spine surgery. In this contemporary, nationally representative analysis of 164,837 adult admissions, RA patients experienced higher rates of nonroutine discharge, longer hospitalization, greater resource utilization, and increased hemorrhagic and pulmonary complications, even after rigorous adjustment for baseline differences using IPTW. Within the RA population, fusion extent emerged as an important modifier of risk, with patients undergoing occipitocervical or cervicothoracic constructs demonstrating markedly higher transfusion requirements and discharge complexity compared with those undergoing single-level fusion.
We acknowledge that the direction of several of these associations—a greater burden of transfusion, prolonged hospitalization, and nonroutine discharge in patients with a chronic systemic inflammatory disease—is clinically anticipated, given the established links between RA and anemia of chronic disease, osteoporosis, cardiopulmonary comorbidity, and immunosuppressive exposure. The contribution of this study lies not in reversing that expectation but in 3 quantitative and clinically translatable insights that were not previously available. First, we isolate the independent magnitude of the RA-attributable excess after balancing 27 confounders, including the procedure mix itself; the persistence of elevated transfusion (OR 1.53), blood loss anemia (OR 1.48), and discharge (OR 1.34) risk after this adjustment establishes RA as a risk modifier in its own right rather than a marker of an older, sicker, more comorbid population. Second, we demonstrate that this excess risk is not uniform but is steeply graded by construct complexity, culminating in a 7-fold transfusion risk for occipitocervical/cervicothoracic fusion—a gradient that converts a general statement of “higher risk” into a specific, operative-level prediction. Third, these estimates derive from a contemporary (2016–2021), all-payer, biological-era cohort, and therefore describe the residual surgical population that persists despite modern medical control of RA, rather than the historical populations captured in older Medicare-restricted series.7,8,11
These findings are consistent with, and extend, a broader literature demonstrating that systemic inflammatory disease independently worsens perioperative outcomes across surgical disciplines. In elective total joint arthroplasty, systemic lupus erythematosus and inflammatory arthritides have been shown to independently increase transfusion requirements and perioperative complications, mirroring the hemorrhagic and resource signals we observe in the cervical spine.16 Contemporary perioperative guidelines for patients with inflammatory rheumatic disease emphasize proactive anemia evaluation, structured management of DMARD and biological therapy around the operative window, and multidisciplinary rheumatology-surgery coordination.12,17 Our data place cervical spine surgery firmly within this paradigm and argue that RA should be treated, like other systemic inflammatory conditions, as a whole-patient modifier of operative risk rather than a localized structural problem to be addressed by fixation alone.
From a health-system perspective, the morbidity-related differences translate into a disproportionately high rate of nonroutine discharge—particularly among RA patients undergoing occipitocervical or cervicothoracic fusion (OR 3.84)—which represents an important driver of health care utilization that extends beyond the index hospitalization. These findings suggest that RA patients, especially those requiring complex stabilization, are more likely to require postacute institutional care and consume greater inpatient resources. This interpretation is supported by prior literature demonstrating that RA patients incur higher total hospitalization costs ($17,622 vs $12,489) and have longer hospital stays (3.13 vs 2.08 days) compared with controls.15 Together, these data underscore the disproportionate system-level impact of this population and highlight the potential value of proactive discharge planning and early multidisciplinary involvement to anticipate postacute care needs.
The elevated risk of blood transfusion (OR 1.53) and blood loss anemia (OR 1.48) observed among RA patients is biologically plausible and mechanistically coherent. Chronic systemic inflammation in RA is a well-established driver of anemia of chronic disease through hepcidin-mediated iron sequestration and suppression of erythropoiesis.4 In addition, a substantially higher proportion of RA patients in this cohort had documented chronic corticosteroid use (8.3% vs 0.9% in non-RA patients), which is known to contribute to osteoporosis, tissue friability, and impaired surgical hemostasis.5 Together, these systemic factors create a permissive milieu for perioperative bleeding. The hemorrhagic risk is further amplified in the setting of occipitocervical or cervicothoracic fusion, where long-segment posterior dissection, multilevel instrumentation, and prolonged operative time impose a substantial local hemostatic burden on an already compromised host. This is consistent with institutional series reporting significantly higher estimated blood loss in RA patients undergoing extended posterior cervical constructs.3
Pulmonary complications were significantly more common in RA patients (OR 1.18; 95% CI 1.02–1.38; P = 0.028). This is consistent with the documented association between RA and interstitial lung disease, restrictive physiology, and perioperative pneumonia risk.5 Although the confidence interval is relatively wide—reflecting the modest absolute frequency of this outcome (3.3% overall)—the direction and magnitude are consistent with the well-established association between RA, interstitial lung disease, and perioperative respiratory vulnerability. These findings support consideration of formal pulmonary risk assessment in the preoperative evaluation of RA patients, including spirometry, baseline chest imaging review, and rheumatology input on the timing of biological therapy.
The 33% higher odds of additional cervical procedures performed later during the same admission among RA patients (OR 1.331; P = 0.009) represent an important secondary finding with meaningful operational implications. Although this variable—derived from procedure day coding in the NIS—cannot reliably distinguish planned staged procedures from unplanned intraoperative conversions or early complication-driven returns, it consistently reflects increased procedural complexity and resource utilization in this population. This interpretation aligns with prior evidence demonstrating that cervical spine surgery in patients with RA, particularly involving the craniocervical junction, often requires more complex instrumentation strategies and is associated with a higher rate of intraoperative technical challenges compared with surgery for degenerative disease alone.13
In contrast, the absence of a statistically significant difference in SSI/sepsis (OR 1.184; P = 0.179) should be interpreted cautiously rather than as reassuring. Patients with RA receiving immunosuppressive therapy are known to carry elevated infectious risk following major orthopedic procedures, and the NIS captures only in-hospital events, likely missing a substantial proportion of SSIs that manifest after discharge—a period during which up to 12.3% of RA patients are readmitted, most commonly for infection.6,18 The significant SSI/sepsis signal that did emerge within the fusion subgroup (OR 1.34; P = 0.031) reinforces that this risk is real but concentrated in instrumented procedures and likely underestimated by an index-admission database.
Clinical Implications
Taken together, these findings support several concrete changes to perioperative practice. The fusion extent analysis identifies occipitocervical and cervicothoracic constructs as the highest-risk surgical subset in this cohort and is, in our view, the most clinically actionable result of the study. These extended constructs—performed in 19.4% of RA fusion patients compared with 12.8% of non-RA fusion patients—were associated with nearly 4-fold higher odds of nonroutine discharge and 7-fold higher odds of blood transfusion compared with single-level fusion within the RA group. For the surgeon planning an occiput-to-subaxial construct in an RA patient, these effect sizes justify treating type-and-screen and active blood-product availability as the default rather than the exception, anticipating a high probability of postacute institutional care during preoperative counseling, and initiating discharge planning at the time of surgical scheduling rather than postoperatively. For the perioperative physician, they support preoperative anemia optimization (iron studies and correction where indicated), structured review of corticosteroid and biological timing in coordination with rheumatology as recommended by current perioperative guidelines,17 and formal pulmonary assessment in patients with known or suspected interstitial lung disease. For patient counseling, the data allow risk to be communicated in procedure-specific rather than generic terms. The biomechanical basis for the elevated risk of extended constructs is well established: atlantoaxial and craniocervical instability in RA often necessitate long-segment posterior instrumentation with multilevel decortication and bone grafting, resulting in greater blood loss, longer operative times, and a more demanding postoperative course than single-level anterior or posterior procedures.2,3
Several limitations warrant acknowledgment. First, as an administrative database, the NIS relies on billing diagnoses and procedure codes and lacks granular clinical information on disease severity, functional status, implant selection, surgeon volume, and perioperative medication management beyond proxy variables. Although the IPTW approach mitigates confounding from measured covariates, residual confounding from unmeasured factors—such as RA disease activity at the time of surgery, specific DMARD or biologic regimens, preoperative laboratory values, and institutional experience with complex RA spine surgery—cannot be excluded. Notably, chronic steroid use (Z79.52) was coded in only 1.1 % of the overall cohort, substantially lower than clinical expectations, reflecting well-described under-coding of this variable in administrative datasets and suggesting that residual confounding related to steroid exposure is likely.15 In addition, the later-cervical-procedure variable serves only as a procedural proxy and cannot reliably distinguish planned staged procedures from unplanned operative returns, limiting causal inference for this outcome. The fusion-extent subgroup analysis was internal to the RA group and used survey weighting rather than propensity weighting, and the discectomy-only stratum was too small for stable estimation. Finally, because the NIS captures only the index hospitalization, longer-term outcomes—including readmission, implant failure, neurological recovery, and reoperation—are beyond the scope of this analysis.
RA is not merely a comorbidity in cervical spine surgery but a system-level modifier of operative risk, particularly when long-segment posterior instrumentation is required. The markedly increased risks of blood transfusion and nonroutine discharge observed in occipitocervical and cervicothoracic constructs underscore the need to move beyond general risk awareness toward more tailored perioperative planning for this population. More broadly, these findings support further investigation into whether targeted perioperative optimization strategies—including medication management, preoperative anemia optimization, and coordinated postoperative care—can mitigate the excess morbidity observed among RA patients undergoing complex cervical reconstruction.
Conclusions
RA is independently associated with increased in-hospital morbidity following cervical spine surgery, manifesting as higher rates of nonroutine discharge, longer hospitalization, greater resource utilization, and elevated hemorrhagic and pulmonary complications. These associations persist after rigorous adjustment for baseline differences, underscoring RA as a meaningful modifier of perioperative risk rather than a neutral comorbidity in this surgical population.
Importantly, fusion extent substantially modifies risk within the RA population. Patients undergoing occipitocervical or cervicothoracic fusion represent a particularly high-risk subgroup, with markedly increased transfusion requirements and discharge complexity compared with those undergoing single-level fusion. These findings highlight the need to incorporate both disease status and procedure-specific complexity into preoperative risk stratification, patient counseling, and anticipatory discharge planning.
Although in-hospital mortality did not differ between RA and non-RA patients, the excess morbidity observed in RA—particularly in the setting of long-segment posterior constructs—has important clinical and system-level implications. Future studies should evaluate whether targeted perioperative optimization strategies, including anemia management, medication optimization, and coordinated multidisciplinary care, can mitigate the disproportionate morbidity associated with complex cervical reconstruction in patients with RA.
Supplementary material
Supplementary data
Supplemental material: Appendices A through F and Appendix Figure 1.Footnotes
Funding The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests The authors report no conflicts of interest in this work.
- This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2026 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.
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