Correlation of Clinical Frailty Scale and Outcomes in Patients Treated With Non-invasive Ventilation: A Retrospective Cohort Study.

Background Frailty is defined as a state of vulnerability to stressors due to physiological decline. While frailty is an increasingly recognized determinant of outcomes in acute illness, its specific role in patients receiving non-invasive ventilation (NIV) for acute type 2 respiratory failure (T2RF) remains poorly defined. Methods We conducted a retrospective cohort study of 112 patients treated with NIV at a district general hospital in the United Kingdom between December 2024 and April 2025. Frailty was assessed using the Clinical Frailty Scale (CFS) and categorised as CFS 1-3 (very fit to managing well), CFS 4-6 (mild to moderate frailty), and CFS 7-9 (severe frailty to terminally ill). Outcomes included inpatient mortality and readmissions within four months. Associations were analysed using the Chi-square test. Results Frailty was highly prevalent, affecting 90 (80.4%) patients in this cohort. Mortality rose significantly with frailty: one (4.5%) patient in CFS 1-3 group, 12 (21.4%) in CFS 4-6 group, and 14 (41.2%) in CFS 7-9 group (p = 0.006). Among survivors, 35 (41.2%) patients were re-admitted within four months, and did not differ significantly across frailty groups (p=0.400). Conclusion Frailty, as measured by the CFS, was a strong predictor of short-term mortality in patients receiving NIV for acute type 2 respiratory failure, independent of age. Routine frailty assessment could improve risk stratification and guide clinical decision-making in this patient group.