Spinal Epidural Abscess Patients Have Higher Modified Frailty Indexes Than Back Pain Patients on Emergency Room Presentation: A Single-Center Retrospective Case-Control Study.

Objective: Spinal epidural abscess (SEA) patients have increased medical comorbidities and risk factors for infection compared with those without SEA. However, the association between frailty and SEA patients has not been documented.

Methods: A total of 46 SEA patients were randomly paired and matched by age and sex with a control group of patients with back pain who had presented to our emergency department from 2012 to 2017. Statistical analysis identified the risk factors associated with SEA and frailty using the modified frailty index (mFI), and the patients were stratified into robust, prefrail, and frail groups. We examined the value of the mFI as a prognostic predictor and evaluated the classic risk factors (CRFs).

Results: The SEA patients had higher mFIs and CRFs (P = 0.023 and P < 0.001, respectively) and a longer length of stay (22.89 days vs. 1.72 days; P < 0.001). Of the mFI variables, only diabetes had a significant association with SEA (odds ratio [OR], 3.60; P = 0.012). Among the stratified mFI subgroups, a frail ranking (mFI >2) was the strongest risk factor for SEA (OR, 5.18; P = 0.003). A robust ranking (mFI, 0-1) was a weak negative predictor for SEA (OR, 0.41; P = 0.058). The robust patients were also more likely to be discharged to home (OR, 7.58; P = 0.002). Of the CRF variables, only intravenous drug use had a statistically significant association with SEA (OR, 10.72; P = 0.015).

Conclusions: Patients with SEA were more frail compared with the control back pain patients. Frailty was determined to be an independent risk factor for SEA, outside of the CRFs. The use of the mFI could be potentially useful in predicting the diagnosis, prognosticating, and guiding SEA treatment.