Impact of cladribine tablets on PROs in patients with MS: insights from the 1st interim analysis of the CLADFIT-MS study

Background Cladribine tablets are an oral short-course disease-modifying therapy (DMT) approved for the treatment of highly active relapsing multiple sclerosis (MS). While their efficacy has been demonstrated in clinical trials, limited real-world evidence is available on their impact on patient-reported outcomes (PROs) and the potential added value of wearable devices for continuous functional monitoring. Objectives To evaluate the association between cladribine tablets use and PROs related to physical functioning and quality of life, and to explore the relationship between PROs and biometric data collected through wearable devices over 52 weeks in a real-world cohort of patients with highly active MS after therapeutic switch. Methods CLADFIT-MS is a prospective, multicenter, observational phase IV study conducted in Italy. This interim analysis includes 190 patients with highly active MS who initiated cladribine tablets and had data available up to Week 52. PROs included the Multiple Sclerosis Impact Scale (MSIS-29), EuroQoL-5D-5L, and PROMIS-29 physical function and fatigue scores. Biometric data (e.g., range of movement, walking distance, sleep time) were collected using Fitbit® devices. Associations between PROs and wearable-derived data were analyzed using univariate mixed models and correlation matrices. Results MSIS-29 physical scores and EQ-5D-5L remained stable over 52 weeks. PROMIS-29 fatigue scores showed slight improvement [from 54.6 (9.59) to 51.8 (10.30)], while PROMIS-29 physical function scores remained stable. An exploratory association was observed between baseline range of movement and changes in MSIS-29 scores ( p = 0.0425), and between walking distance and PROMIS-29 fatigue ( p = 0.0345). Biometric variables demonstrated moderate to strong inter-correlations, suggesting internal consistency of the wearable-derived data. Conclusion In this real-world cohort of patients with highly active MS, cladribine tablets treatment was associated with the maintenance of PROs over one year. The integration of wearable technology provided objective metrics that were consistent with patient perceptions, supporting the feasibility of combining digital tools with PROs to monitor functional outcomes in MS clinical practice.