Assessing the predictive value of the Risk Analysis Index for short-term outcomes in acute spinal cord injury surgery.

Background: Acute traumatic spinal cord injury (tSCI) requires rapid surgical intervention to maximize neurological function. Older patients comprise an increasingly larger proportion of SCI patients annually, necessitating accurate preoperative risk stratification tools. This study utilized a frailty-based preoperative risk stratification score to predict adverse events following non-elective neurosurgical intervention for acute tSCI patients.

Methods: The National Inpatient Sample (NIS) was queried for acute tSCI patients aged ≥18 who underwent spine surgery in 2019-2020. The Risk Analysis Index (RAI) was implemented with crosstabulation, to analyze frailty scores with the following binary outcome measures: overall complications, non-home discharge (NHD), extended length of stay (eLOS) (>75^th percentile), and mortality. Area Under the Receiver Operating Characteristic (AUROC) analysis assessed the discriminative threshold of RAI compared to the modified 5-item Frailty Index (mFI-5) for NHD and 30-day mortality.

Results: A total of 9995 SCI patients underwent non-elective spine surgery. There were 1525 perioperative complications (15.3%) and 510 (5.1%) mortalities. An increasing RAI score was significantly associated with increasing postoperative mortality rates: RAI 0-20 (1.5%, N.=45), RAI 21-30 (3.4%, N.=110), RAI 31-40 (6.8%, N.=115), and RAI>41 (11.8%, N.=240) (P<0.001). RAI demonstrated superior discrimination compared to the mFI-5 for mortality and NHD with a C-statistic >0.72.

Conclusions: Increasing frailty, as measured by RAI, was a reliable predictor of non-home discharge and 30-day mortality for SCI patients who underwent non-elective spinal surgery and RAI demonstrated superior discrimination compared to the mFI-5 for NHD and mortality.