Dynamic frailty trajectories identify thymoma patients at high risk of postoperative muscle weakness

Thymoma is the most common anterior mediastinal tumor and poses significant postoperative challenges, including muscle weakness. Frailty is a multidimensional syndrome linked to poor surgical outcomes and remains understudied in thymoma. This study investigates the impact of preoperative frailty and its dynamic trajectories on postoperative muscle weakness.

A retrospective cohort of 531 thymoma patients (2015-2025) was recruited. Frailty was assessed pre- and postoperatively using the Rockwood Frailty Index (FI), categorized as robust (FI ≤ 0.10), pre-frail (0.10 < FI < 0.25), or frail (FI ≥ 0.25). Postoperative muscle weakness was defined as ≥1 MRC grade decline. Cox regression models adjusted for demographics, comorbidities, and laboratory parameters evaluated associations between frailty status, ΔFI (change in FI), and outcomes.

Among 405 analyzed patients, pre-frail (HR = 1.70, 95%CI: 1.38-2.02) and frail (HR = 1.83, 95%CI: 1.51-2.15) individuals had significantly higher muscle weakness risks versus robust. Frailty progression (ΔFI increase) raised risk by 41% (HR = 1.41, 95%CI: 1.22-1.60), while recovery reduced it by 31% (HR = 0.69, 95%CI: 0.58-0.81). Cumulative FI (upper tertile HR = 2.85, 95%CI: 2.64-3.03) and ΔFI (upper tertile HR = 1.83, 95%CI: 1.69-1.97) exhibited dose-dependent associations with adverse outcomes (trend P < 0.01).

Preoperative frailty and its dynamic changes independently are associated with postoperative muscle weakness in thymoma patients. The Rockwood FI provides prognostic value for risk stratification, highlighting the pre-frail state as a modifiable target for prehabilitation. Integrating longitudinal frailty assessments into perioperative care may optimize recovery and survival, urging future trials to validate disease-specific thresholds and interventions.