Smartphone Video Hand Gesture Analysis for Psoriatic Arthritis Assessment

Psoriatic Arthritis (PsA) is a heterogeneous chronic inflammatory disease that affects the peripheral and axial skeleton, significantly impacting patients' quality of life. Diagnosis and monitoring of PsA can be challenging, as it relies on subjective assessments by experienced healthcare professionals (HCPs). Here, we introduce a video-based approach for assessing the mobility of hand joints in patients with PsA, developing suitable digital biomarkers (dBMs) that process data acquired via a dedicated smartphone app, HD4PsA. Co-created with HCPs and PsA patients, the HD4PsA app consists of three hand motion tests, each targeting specific hand gesture - hook, full fist, and wrist flexion/extension. During each motor test, the coordinates of the hand joints are tracked, and the extracted joint landmarks are processed to generate a set of hand joint mobility dBMs. The clinical relevance of these measures was validated using data acquired from a cohort of 16 clinically verified PsA patients and nine healthy subjects. A Mann-Whitney U test revealed statistically significant difference between HC and PsA patients for a subset of the proposed dBMs. Additionally, the latter performed sufficiently as binary classifiers. Finally, a statistically significant fair correlation was found between the estimated number of fingers with limited ROM and inflammation grade. Overall, the results highlight the potential of the hand joint mobility dBMs calculated via the HD4PsA app for clinical applicationClinical relevance-This work demonstrates the potential of hand range of motion measures, derived from smartphone videos recorded during specific hand gestures, as reliable indicators of PsA.