McMahon, S.B. Dargan, P. Lanas, A. Wiffen, P. The burden of musculoskeletal pain and the role of topical non-steroidal anti-inflammatory drugs (NSAIDs) in its treatment. Ten underpinning statements from a global pain faculty Curr. med. res. opin. 10.1080/03007995.2020.1847718 2021 2021