Els, Charl and Jackson, Tanya T and Kunyk, Diane and Lappi, Vernon G and Sonnenberg, Barend and Hagtvedt, Reidar and Sharma, Sangita and Kolahdooz, Fariba and Stroube, Sebastian (2017) Adverse events associated with medium- and long-term use of opioids for chronic non-cancer pain: an overview of Cochrane reviews. Cochrane Database of Systematic Reviews , (10) .