Background 

Racial health disparities across orthopaedic surgery subspecialties, including spine surgery, are well established. However, the underlying causes of these disparities, particularly relating to social determinants of health, are not fully understood.

Questions/purposes 

(1) Is there a racial difference in 90-day mortality, readmission, and complication rates (“safety outcomes”) among Medicare beneficiaries after spine surgery? (2) To what degree does the Centers for Disease Control and Prevention Social Vulnerability Index (SVI), a community-level marker of social determinants of health, account for racial disparities in safety outcomes?

Methods 

To examine racial differences in 90-day mortality, readmission, and complications after spine surgery, we retrospectively identified all 419,533 Medicare beneficiaries aged 65 or older who underwent inpatient spine surgery from 2015 to 2019; we excluded 181,588 patients with endstage renal disease or Social Security disability insurance entitlements, who were on Medicare HMO, or who had missing SVI data. Because of the nearly universal coverage of those age 65 or older, Medicare data offer a large cohort that is broadly generalizable, provides improved precision for relatively rare safety outcomes, and is free of confounding from differential insurance access across races. The Master Beneficiary Summary File includes enrollees’ self-reported race based on a restrictive list of mutually exclusive options. Even though this does not fully capture the entirety of racial diversity, it is self-reported by patients. Identification of spine surgery was based on five Diagnosis Related Groups labeled “cervical fusion,” “fusion, except cervical,” “anterior-posterior combined fusion,” “complex fusion,” and “back or neck, except fusion.” Although heterogeneous, these cohorts do not reflect inherently different biology that would lead us to expect differences in safety outcomes by race. We report specific types of complications that did and did not involve readmission. Although complications vary in severity, we report them as composite measures while being cognizant of the inherent limitations of making inferences based on aggregate measures. The SVI was chosen as the mediating variable because it aggregates important social determinants of health and has been shown to be a marker of high risk of poor public health response to external stressors. Patients were categorized into three groups based on a ranking of the four SVI themes: socioeconomic status, household composition, minority status and language, and housing and transportation. We report the “average race effects” among Black patients compared with White patients using nearest-neighbor Mahalanobis matching by age, gender, comorbidities, and spine surgery type. Mahalanobis matching provided the best balance among propensity-type matching methods. Before matching, Black patients in Medicare undergoing spine surgery were disproportionately younger with more comorbidities and were less likely to undergo cervical fusion. To estimate the contribution of the SVI on racial disparities in safety outcomes, we report the average race effect between models with and without the addition of the four SVI themes.

Results 

After matching on age, gender, comorbidities, and spine surgery type, Black patients were on average more likely than White patients to be readmitted (difference of 1.5% [95% CI 0.9% to 2.1%]; p < 0.001) and have complications with (difference of 1.2% [95% CI 0.5% to 1.9%]; p = 0.002) or without readmission (difference of 3.6% [95% CI 2.9% to 4.3%]; p < 0.001). Adding the SVI to the model attenuated these differences, explaining 17% to 49% of the racial differences in safety, depending on the outcome. An observed higher rate of 90-day mortality among Black patients was explained entirely by matching using non-SVI patient demographics (difference of 0.00% [95% CI -0.3% to 0.3%]; p = 0.99). However, even after adjusting for the SVI, Black patients had more readmissions and complications.

Conclusion 

Social disadvantage explains up to nearly 50% of the disparities in safety outcomes between Black and White Medicare patients after spine surgery. This argument highlights an important contribution of socioeconomic circumstances and societal barriers to achieving equal outcomes. But even after accounting for the SVI, there remained persistently unequal safety outcomes among Black patients compared with White patients, suggesting that other unmeasured factors contribute to the disparities. This is consistent with evidence documenting Black patients’ disadvantages within a system of seemingly equal access and resources. Research on racial health disparities in orthopaedics should account for the SVI to avoid suggesting that race causes any observed differences in complications among patients when other factors related to social deprivation are more likely to be determinative. Focused social policies aiming to rectify structural disadvantages faced by disadvantaged communities may lead to a meaningful reduction in racial health disparities.

Level of Evidence 

Level III, therapeutic study.

中文翻译：

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社区层面的劣势是否会导致脊柱手术安全性方面的种族差异？基于医疗保险索赔的大型数据库研究

背景 

骨科手术亚专业（包括脊柱手术）之间的种族健康差异已经确立。然而，这些差异的根本原因，特别是与健康的社会决定因素有关的原因，尚未完全了解。

问题/目的 

(1) Medicare 受益人在脊柱手术后的 90 天死亡率、再入院率和并发症发生率（“安全结果”）是否存在种族差异？(2) 疾病控制和预防中心社会脆弱性指数 (SVI)（健康社会决定因素的社区级标记）在多大程度上解释了安全结果中的种族差异？

方法 

为了检查脊柱手术后 90 天死亡率、再入院率和并发症的种族差异，我们回顾性地确定了 2015 年至 2019 年接受住院脊柱手术的所有 419,533 名 65 岁或以上的医疗保险受益人；我们排除了 181,588 名患有终末期肾病或享有社会保障伤残保险权利、使用 Medicare HMO 或缺少 SVI 数据的患者。由于几乎覆盖了 65 岁或 65 岁以上的人群，Medicare 数据提供了一个可广泛推广的大型队列，为相对罕见的安全结果提供了更高的精确度，并且没有因不同种族的不同保险获取而造成的混淆。主受益人摘要文件包括登记者根据互斥选项的限制性列表自行报告的种族。尽管这并不能完全体现种族多样性，但这是患者自我报告的。脊柱手术的识别基于标记为“颈椎融合”、“融合，颈椎除外”、“前后联合融合”、“复杂融合”和“背部或颈部，融合除外”的五个诊断相关组。尽管存在异质性，但这些队列并没有反映出内在不同的生物学特性，这将导致我们预期不同种族的安全结果存在差异。我们报告涉及和不涉及再入院的特定类型的并发症。尽管并发症的严重程度各不相同，但我们将它们报告为综合指标，同时认识到基于综合指标进行推论的固有局限性。选择 SVI 作为中介变量是因为它汇总了重要的健康社会决定因素，并且已被证明是公共卫生对外部压力源反应不佳的高风险标志。根据四个 SVI 主题的排名将患者分为三组：社会经济地位、家庭构成、少数民族地位和语言以及住房和交通。我们根据年龄、性别、合并症和脊柱手术类型使用最近邻马氏匹配报告了黑人患者与白人患者的“平均种族效应”。马氏匹配提供了倾向型匹配方法之间的最佳平衡。在匹配之前，接受脊柱手术的 Medicare 中的黑人患者不成比例地年轻，合并症更多，并且不太可能接受颈椎融合术。

结果 

在对年龄、性别、合并症和脊柱手术类型进行匹配后，黑人患者平均比白人患者更有可能再次入院（差异为 1.5% [95% CI 0.9% 至 2.1%]；p < 0.001）并且有并发症有（差异为 1.2% [95% CI 0.5% 至 1.9%]；p = 0.002）或没有再入院（差异为 3.6% [95% CI 2.9% 至 4.3%]；p < 0.001）。将 SVI 添加到模型中可以减弱这些差异，根据结果可以解释 17% 到 49% 的种族安全差异。黑人患者观察到的较高 90 天死亡率完全可以通过使用非 SVI 患者人口统计数据进行匹配来解释（差异为 0.00% [95% CI -0.3% 至 0.3%]；p = 0.99）。然而，即使在调整 SVI 后，黑人患者的再入院率和并发症也更多。

结论 

社会劣势解释了近 50% 的黑人和白人 Medicare 患者在脊柱手术后的安全结果差异。这一论点强调了社会经济环境和社会障碍对实现平等结果的重要贡献。但即使在考虑 SVI 后，与白人患者相比，黑人患者的安全结果仍然存在持续不平等，这表明其他未测量的因素导致了差异。这与记录黑人患者在看似平等的机会和资源系统中的劣势的证据是一致的。当与社会剥夺相关的其他因素更有可能起决定作用时，骨科种族健康差异的研究应考虑 SVI，以避免暗示种族会导致患者并发症的任何观察到的差异。旨在纠正弱势社区面临的结构性劣势的有针对性的社会政策可能会导致种族健康差异的显着减少。

证据等级 

III 级，治疗研究。