A study protocol for a European, mixed methods, prospective, cohort study of the effectiveness of naloxone administration by community members, in reversing opioid overdose: NalPORS. - Metrebian N; Carter B; Eide D; McDonald R; Neale J; Parkin S; Dascal T; Mackie C; Day E; Guterstam J; Horsburgh K; Kåberg M; et al. (BMC public health, 2023)