“…An exemplar study reported that patients fell into three groups of pain types and locations (back pain, head pain and other) and a mean chronicity of pain of 8.6 years (SD 7.8) [ 92 ]. While most studies examined patients who had persistent pain despite continuous opioid use, some [ 47 , 52 , 56 , 57 , 69 , 73 , 76 , 93 , 103 , 112 ] attempted to examine specifically patients who had evidence of opioid use disorder in the context of chronic pain. Other terms used in the studies included opioid dependence, drug dependence/addiction, and narcotic addiction, but for the purposes of this paper we grouped these under opioid use disorder.…”