Study identification
We searched MEDLINE and EMBASE online databases using a combination of
keywords, MeSH headings, and words commonly used to describe LTOT, such
as persistent or chronic use of opioids. The search strategy was
undertaken after consultation with the information specialist of UNSW
Sydney library in July 2018 and updated in August 2019 (see
Supplementary Appendix A). We also conducted a manual search of the
references of included studies and published systematic reviews for any
additional articles not captured by our search strategy.