The dynamic nature of frailty in metastatic spine disease patients.

Purpose: Frailty measures are critical for predicting outcomes in metastatic spine disease (MSD) patients. This study aimed to evaluate frailty measures throughout the disease process.

Methods: This retrospective analysis measured frailty in MSD patients at multiple time points using a modified Metastatic Spinal Tumor Frailty Index (MSTFI). Scores were 0: "not frail," 1: "mild", 2: "moderate, and ≥ 3: "severe." Measurements were taken at cancer diagnosis, spine metastasis (SM) diagnosis, and 4-month intervals up to 2-years. The change in frailty distribution was described at the general cohort and patient levels. Two-year survival was assessed from baseline frailty status at SM diagnosis.

Results: This study included 465 patients with an average age of 62.3 years (± 12.7), 33.8% female. Prostate cancer was most common (20.9%), followed by renal cell carcinoma (15.3%), non-small cell lung cancer (NSCLC, 13.5%), and others. Frailty changed dynamically, most significantly early in the disease. Initially, 79.4% were not frail; this dropped to 60.1% at SM diagnosis and to 42.7% at 4 months. Patients with short-term (4 month) data showed rapid frailty progression, with 57% becoming moderately to severely frail (p = 0.01), whereas 45% with long-term (24 months) data remained non-frail (p < 0.0001). Contributing factors included anemia (32.7%), electrolyte abnormalities (16.9%), and malnutrition (11.4%). Histological classification influenced frailty. Higher frailty scores at metastatic diagnosis correlated with worse 2-year survival outcomes (p: <0.001-0.04), underscoring frailty's prognostic significance.

Conclusion: Frailty is dynamic, with a potential early intervention point to maintain or reverse it. Further research is needed to assess which frailty measures are most dynamic and amenable to intervention.