Association of baseline frailty status with clinical outcome following aneurysmal subarachnoid hemorrhage

Objectives: Aneurysmal subarachnoid hemorrhage (aSAH) is an emergent neurosurgical condition associated with high morbidity and mortality. The prognostic significance of baseline frailty status in aSAH patients has not been previously evaluated in a large, nationally representative sample. Materials and Methods: Clinical outcomes data from the National Inpatient Sample from 2010-2018 were compared among sub-cohorts stratifying admissions by increasing frailty thresholds [(assessed using the 11-point modified frailty index (mFI-11)]. The previously validated NIS-SAH Severity Score (NIS-SSS) and NIS-SAH Outcome Measure (NIS-SOM) were utilized. Complex samples multivariable logistic regression and receiver operating characteristic (ROC) curve analyses were performed to assess adjusted associations and discrimination of frailty for endpoints. Results: Among 64,102 aSAH hospitalizations (mean age 55.4 years), 20.4% of admissions were classified as robust (mFI=0), 43.4% as pre-frail (mFI = 1), 24.9% as frail (mFI = 2), and 11.2% as severely frail (mFI ≥ 3). Following multivariable analysis adjusting for age and aSAH severity, increasing frailty was independently associated with NIS-SOM (OR = 1.15, 95% CI 1.09-1.21; p < 0.001), extended length of hospital stay (eLOS) (OR = 1.08, 1.02-1.13; p = 0.008), neurological complications (OR = 1.08, 1.03-1.13; p < 0.001), and medical complications (OR = 1.14, 1.08-1.21; p < 0.001). Based on ROC curve analysis, frailty achieved an AUC of 0.59 (0.58-0.60) and 0.54 (0.53-0.55) for NIS-SOM and eLOS, respectively. Age and NIS-SSS demonstrated significantly greater discrimination for NIS-SOM [AUC 0.69 (0.68-0.70) and 0.79 (0.78-0.80), respectively), while NIS-SSS achieved significantly greater discrimination for eLOS [(AUC 0.74 (0.73-0.75)] in comparison to both age and frailty. Conclusions: This national database evaluation of frailty in aSAH patients demonstrates an independent association between increasing frailty and poor functional outcome. Age and aSAH severity, however, may be more robust prognostic factors.