Evaluating Subgroups of Patients with Spinal Epidural Abscess

Panayiota Siskos ’23

Figure 1: Spinal epidural abscess is a condition that may be fatal, especially if left undiagnosed.

Spinal epidural abscess (pus that has built up in tissue, organs, or spaces in the body) is a rare infection that has rising incidence, as well as high morbidity and mortality due to delayed diagnosis. These abscesses are in the epidural region (located between the outermost layer of tissue and the inside surface of bone containing the spine that runs down its entire length) and may lead to nerve compression and damage to vascular structures. Prior literature has shown that a primary risk factor is intravenous drug use, but other risk factors for spinal epidural abscesses include diabetes, chronic kidney disease, malignancy, and old age. The primary objective of this paper included identifying characteristics of subgroups with spinal epidural abscesses, and secondary analysis delved into associationing subgroups with new paralysis, in-hospital mortality, as well as 180-day readmissions. The hypothesis was that the subgroups would have common risk factors that include drug use and immunocompromised states.

         To find subgroups of patients in a larger set, latent class analysis was used. A statistical analysis tool, latent class analysis makes it possible to test hypotheses between subgroup assignments and variables of interest. The variables included in the latent class analysis were Alcohol Use Disorder, Opioid Use Disorder, Stimulant Use Disorder, Diabetes Mellitus, Homelessness, Active Malignancy, Medicaid, and Age. Exploratory analysis was planned for comparison of assigned classes through demographics and key outcomes, as well as chi-squared tests and Fisher’s exact tests using an alpha 0.05 to analyze differences.

         With latent class analysis, two subgroups were identified, with Group 1 having major medical comorbidities that lead to immunosuppression and demanded vascular access (having access to the bloodstream). Meanwhile, Group 2 had substance use disorder. There were no major differences in new paralysis or mortality, however Group 2 was more likely to become readmitted in 6 months. In the future such clusters may be validated in national datasets by using additional patient sets that are more diverse. In addition to this, patients with drug use require further research to understand how to offer the best support during first and future readmissions, as well as to understand why they have a higher readmission risk. This research holds great significance as it reflects two populations with this condition, and these groups may have differences in microbiological etiology (the cause of the disease) of spinal epidural abscesses that include differences for Pseudomonas infection (a genus of bacteria that may cause infection, allowing possible differences between the two groups in the specific type of pseudomonas or mechanism by which they contribute to spinal epidural abscess) which may inform antibiotic choices. In addition to this, separate consideration of the identified groups may have better outcome predictions, risk factor identification, and treatment needs. 

Works Cited:

[1] P. Brown, et al., Evaluating new paralysis, mortality, and readmission among subgroups of patients with spinal epidural abscess: A latent class analysis. PLoS ONE 15 (2020). doi: 10.1371/journal.pone.0238853

[2] Image retrieved from: https://unsplash.com/photos/Nk7hHi3I__0 

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