Wearable devices may aid the recognition of fluctuation-related pain in Parkinson’s disease—An exploratory, cross-sectional analysis of two prospective observational studies - Katarina Rukavina; Juliet Staunton; Pavlos Zinzalias; Magdalena Krbot Skoric; Kit Wu; Kirsty Bannister; Alexandra Rizos; K. Ray Chaudhuri (PLoS ONE)