“…There was a large range of treatment settings, with OST clinics accounting for the largest proportion of treatment settings at 53.7% (n = 36) [31, 33-39, 42, 45, 46, 48-51, 53, 55, 57, 60, 62, 64, 66, 67, 75-81, 83, 92, 94-97]. Other treatment settings included office based or primary care OST (n = 9) [32,40,47,58,82,84,87,88,93], hospital setting (n = 5) [61,63,65,85,91], outpatient treatment programmes (n = 4) [54,56,71,72] and mixed treatment settings (n = 3) [41,44,73]. The remaining studies reported on national or regional registries, including health insurance databases (n = 10) [43,52,59,69,74,86,89,90] or Veteran Health Administration records in the US [68,70].…”