Reporting of the included studies – RECORD (Figure 3):
The median completeness score was 87% (interquartile range 82–92%) and only one study scored 100%. A large proportion of studies did not describe/outline the study design, either in the abstract (56 studies, 45% - Item 1A) or in the methods 4 (37 studies, 29% - Item 4). Despite the fact LTOT definition was stated, 14 studies (11% - Item 7) did not provide enough detail to allow the replication of results or provided inconsistent definitions in the abstract/methods. In addition, 37 studies did not specify which opioids were considered in the analysis (29% - Item 7.1). Other methodological areas of underreporting included how missing data and loss to follow-up were addressed (77 studies and 48 studies, Items 12C and 12D, respectively).