Date of Award

January 2024

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Aladine A. Elsamadicy

Second Advisor

Michael DiLuna

Abstract

As hospital costs associated with spine surgeries continue to climb, length of stay(LOS) and discharge disposition have been utilized as proxies through which these increasing costs can be assessed. Cervical spondylotic myelopathy (CSM) is the most common spinal pathology among older adults. As a result, studies assessing drivers of increased costs, LOS, and discharge disposition following surgery for CSM are needed. Two factors of interest are psychiatric comorbidities and safety net hospital (SNH) status. Psychiatric disorders are common and can have a profound impact on health, while SNHs serve a large proportion of patients with Medicaid or without insurance. However, the relationships between PD and SNH statuses and outcomes following anterior cervical discectomy and fusion (ACDF) or posterior cervical decompression and fusion (PCDF) for CSM have been previously understudied. The aim of this study was to assess the association between psychiatric comorbidities and SNH status and LOS, non-routine discharge disposition, and costs of hospital admission following ACDF or PCDF for CSM. A retrospective cohort study was performed using the 2016–2019 National Inpatient Sample (NIS) database. All adult patients (≥18 years old) undergoing ACDF or PCDF for CSM were identified using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) coding. Two cohorts were generated. One comprised patients stratified by whether they presented with comorbid psychiatric conditions, while the other comprised patients stratified by SNH status of the treating hospital. Hospitals in the top quartile of Medicaid/uninsured patient admissions were defined as SNHs while all other hospitals were defined as Non-SNHs (N-SNHs). Patient demographics, hospital characteristics, comorbidities, operative variables, adverse events (AEs), LOS, discharge disposition, and admission costs were assessed. Multivariate analyses were performed to identify associations between preoperative psychiatric diagnoses or SNH status and LOS, non-routine discharge disposition, and costs. The psychiatric comorbidity cohort consisted of 49,950 study patients. Of these patients, 34,195 (68.5%) underwent ACDF and 15,755 (31.5%) underwent PCDF. Within the ACDF and PCDF cohorts, 9,485 (27.7%) and 4,085 (25.9%) patients presented with comorbid psychiatric diagnoses, respectively. Mean LOS was significantly greater in the psychiatric comorbidity cohorts among patients undergoing both procedures (ACDF: No PD: 2.47 ± 3.42 days vs PD: 2.76 ± 3.32 days, p=0.002; PCDF: No PD: 4.46 ± 5.81 days vs PD: 5.14 ± 5.65 days, p=0.003). Patients with psychiatric comorbidities undergoing PCDF incurred greater mean costs (No PD: $26,079 ± $21,652 vs PD: $28,275 ± $18,147, p=0.004), and a significantly greater proportion of patients in the PCDF psychiatric comorbidity cohort had non-routine discharges (No PD: 32.0% vs PD: 39.2%, p=0.001). Within the ACDF cohort, mean admission costs (p=0.153) and discharge disposition (p=0.548) were similar. On multivariate analysis for ACDF, having a comorbid psychiatric condition was significantly associated with extended LOS [aOR: 1.52, CI (1.28, 1.79), p<0.001] and with non-routine discharge [aOR: 1.21, CI (1.01, 1.46), p=0.043], but not with increased costs [p=0.563]. On multivariate analysis for PCDF, having a comorbid psychiatric condition was significantly associated with extended LOS [aOR: 1.32, CI (1.06, 1.64), p=0.012] and with non-routine discharge [aOR: 1.54, CI (1.27, 1.88), p<0.001], but not with increased costs [p=0.347]. The SNH cohort comprised 49,945 patients. Of these patients, 34,195 (68.5%) underwent ACDF and 15,750 (31.5%) underwent PCDF. Within the ACDF cohort, 8,025 patients (23.5%) were treated at SNHs. Among patients undergoing PCDF, 4,120 (26.2%) were treated at SNHs. Patients treated at SNHs were more likely to be Black- or Hispanicidentifying and have incomes in the bottom quartile in both cohorts. Number of comorbidities, operative variables, and number of complications were each similar between SNH and N-SNH cohorts for patients undergoing ACDF and PCDF. Mean LOS was significantly greater in the SNH cohorts for both procedures (ACDF: N-SNH: 2.43 ± 3.12 days vs SNH: 2.94 ± 4.13 days, p<0.001; PCDF: N-SNH: 4.36 ± 4.28 days vs SNH: 5.41 ± 8.67 days, p=0.002), as were mean costs (ACDF: N-SNH: $20,991 ± $12,126 vs SNH: $22,412 ± $15,302, p=0.010; PCDF: N-SNH: $25,835 ± $16,812 vs SNH: $28,945 ± $29,166, p=0.010). A significantly greater proportion of patients in the ACDF cohort treated at SNHs experienced non-routine discharges (N-SNH: 10.9% vs SNH: 13.9%, p=0.006). On multivariate analysis for both procedures, SNH status was not significantly associated with extended LOS [ACDF: p=0.097; PCDF: p=0.158], with non-routine discharge [ACDF: p=0.288; PCDF: p=0.246], or with increased costs [ACDF: p=0.664; PCDF: p=0.593]. Our study found that preoperative psychiatric diagnoses were significantly associated with increased odds of prolonged LOS and non-routine discharge but not with increased costs on multivariate analysis for ACDF and PCDF. Additionally, our results demonstrated that SNH status may not significantly impact postoperative outcomes following ACDF or PCDF for CSM. Further studies assessing interventions to mitigate these outcome disparities in patients with psychiatric comorbidities are needed.

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This is an Open Access Thesis.

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