Comparative Assessment of Frailty on Lumbosacral Fusion Post-operative Outcomes

Introduction: Lumbosacral fusions are typically used to stabilize the lower spine, which may help with chronic pain, correct spinal deformities, and treat traumatic fractures. We sought to determine which frailty scores are most predictive of lumbosacral fusion outcomes.

Methods: This study used the National Inpatient Sample (NIS) database. Patients of all ages undergoing specific lumbosacral fusion procedures were included while those undergoing sacral only procedures were excluded. Frailty was computed using the modified Frailty Index-5 (mFI-5), modified Frailty Index-11 (mFI-11), Charlson Comorbidity Index (CCI), and Risk Analysis Index (RAI). Mortality, complications, length of stay (LOS), discharge disposition, and cost of care were the outcomes analyzed.

Results: 1,422,315 admissions were analyzed. Multivariable regression showed revised RAI was most predictive of in-hospital mortality (OR 3.366, 95% CI 2.780 – 4.075, p < 0.001); administrative RAI had comparable predictive value (OR 3.329, 95% CI 2.958 – 3.746, p < 0.001). Administrative RAI was most predictive of non-home discharge (OR 1.995, 95% CI 1.932 – 2.059, p < 0.001); revised RAI had similar predictive value (OR 1.899, 95% CI 1.866 – 1.932, p < 0.001). Administrative RAI was most predictive of complications (OR 2.091, 95% CI 2.027 – 2.157, p < 0.001) and an extended LOS (OR 2.338, 95% CI 2.270 – 2.408, p < 0.001) (top quartile of LOS). Finally, CCI was most predictive of cost of care (p < 0.001).

Conclusion : Frailty assessment using the administrative RAI is a practical predictor of complications, extended LOS, discharge disposition, and in-hospital mortality. Revised RAI is a comparable predictor of discharge disposition and in-hospital mortality. CCI is the most effective predictor of cost of care. While administrative and revised RAI can be trickier to calculate, their robust, broad predictive utility motivates the need for widespread automation of its calculation in clinical settings.