ABSTRACT
STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To externally validate the Spinal Orthopaedic Research Group (SORG) index for predicting 90-day mortality from Spinal Epidural Abscess (SEA) and compare its utility to the 11-item modified frailty index (mFI-11) and Charlson Comorbidity Index (CCI). SUMMARY OF BACKGROUND DATA: Providing a mortality estimate may guide informed patient and clinician decision-making. A number of prognostic tools and calculators are available to help predict the risk of mortality from SEA, including the SORG index, which estimates ninety-day post discharge mortality. External validation is essential before wider use of any clinical prediction tool. METHODS: Patients were identified using hospital coding. Medical and radiological records were used to confirm the diagnosis. Mortality data, and data to calculate the SORG index, mFI-11 and CCI was collected. Area under the curve (AUC) and calibration plots were used to analyse. RESULTS: 150 patients were included: 58 female (39%), with median age 63 years. Fifteen deaths (10%) at 90-days post discharge and 20 (13%) at one-year. The mean SORG index was 13.6%, mean CCI 2.75, and mean mFI-11 was 1.34. The SORG index (P=0.0006) and mFI-11 (P<0.0001) were associated with 90-day mortality. AUC for SORG, mFI-11, and CCI were 0.81, 0.84, and 0.49, respectively. The calibration slope for the SORG index showed slight overestimation in the middle ranges of the predicted probability, more so than mFI-11, and was not well-calibrated over the higher ranges of predicted probability. CONCLUSIONS: This study externally validated the SORG index, demonstrating its utility in our population at predicting 90-day mortality, however, it was less well calibrated than the mFI-11. Variations in algorithm performance may be a result of difference in socioethnic composition and health resource between development and validation centres. Continued multicentre data input may help improve such algorithms and improve their generalisability.
ABSTRACT
STUDY DESIGN: A retrospective study. OBJECTIVE: To develop a prognostic score for mortality and treatment failure in Spinal epidural abscess (SEA), based on simplicity and multidimensional assessment principles. METHODS: One-hundred-fifty patients were reviewed. Variables assessed included comorbidities, functional status, clinical presentation, Frankel classification, and biochemical and radiological parameters. The main outcomes were the 90-day mortality and treatment failure, corresponding to any intensification of the initial treatment plan. Variables were sorted out with a factorial analysis. Logistic regressions were performed, and the new score was derived from the coefficients. ROC curves with Area Under Curve, calibration plots, and cross-validation were performed. RESULTS: Forty-three patients (29%) had treatment failure, and 15 died (10%) by 90 days. Factorization created 3 groups: Comorbidities (C), Severity (S), and Function (F). For 90-day mortality, Odds ratios were 1.20 (P = .0002), 1.15, (P = .03), 1.36, (P < 10-4) for C, S, F, respectively. The new score 'CSF' had 1 point per item, ranging from zero to 3. OR increased by 1.2/point for 90-day mortality (P < 10-4), AUC was .86. For failures OR increased by 1.15/point (P = .014), AUC was .58, and increased to .64 for patients who survived after 90 days, probably due to competing risks. CONCLUSIONS: Comorbidities, Severity, and Function is a new simplistic tool, easy to use in daily practice; its performances were excellent for 90-day mortality, and acceptable for failures. Simple tools are more likely to be adopted into practice. External validation of this technique is desirable.
