Assessing combined effects of risk analysis index-revised (RAI-rev), malnutrition, and anemia on morbidity and mortality after spine surgery for metastatic spinal tumors.

Purpose: This study evaluates the combined effects of frailty, anemia, and malnutrition on outcomes in spinal metastases patients.

Methods: We conducted a retrospective cohort study using the 2011-2022 NSQIP database. Adult patients undergoing spinal surgery for spinal metastases were identified using CPT and ICD codes and stratified based on Risk Analysis Index-revised (RAI-rev) frailty status; frail patients were subdivided based on anemia and malnutrition status. Our primary outcomes were extended hospital length of stay (LOS), 30-day adverse events (AEs), non-routine discharge (NRD), and 30-day mortality. For each outcome, we fitted four nested multivariable logistic regression models (RAI-rev + anemia + malnutrition, RAI-rev + anemia, RAI-rev + malnutrition, and RAI-rev alone) and compared the incremental discrimination of each model using receiver operating characteristic (ROC) analysis.

Results: 1530 patients were stratified accordingly: 355 Frail Alone, 540 Frail + Anemic, 85 Frail + Malnourished, 407 Frail + Anemic + Malnourished, and 143 Not Frail. RAI-rev and malnourishment were risk factors for extended LOS ((RAI-rev: aOR 1.04, 95% CI 1.01-1.08; malnourishment: aOR 1.98, 95% CI 1.44-2.73)) and mortality (RAI-rev: aOR: 1.07, 95% CI 1.03-1.11; malnourishment: aOR: 2.37, 95% CI 1.50-3.75). RAI-rev (aOR 1.02, 95% CI 1.00-1.03) and anemia (aOR 2.06, 95% CI 1.50-2.84) independently predicted AEs and malnourishment predicted NRD (aOR 1.56, 95% CI 1.15-2.13). On ROC analysis, RAI-rev + anemic + malnourished superiorly predicted extended LOS (p = 0.021), AEs (p = 0.035), and mortality (p = 0.023) compared to RAI-rev. RAI-rev + malnourished outperformed RAI-rev in predicting extended LOS (p = 0.035) and mortality (p = 0.020). RAI-rev + anemic outperformed RAI-rev in predicting AEs (p = 0.032).

Conclusion: Our study suggests that RAI-rev-defined frailty combined with anemia and malnutrition is a superior predictor of outcomes in spinal metastases patients.