The overarching aim of this thesis was to improve the understandings of opioid therapy for chronic non-cancer pain (CNCP) by examining the feasibility of different assessment methods of substance use, and opioid use disorder (OUD), and exploring the sense-making of opioid therapy in CNCP.  

Methods: In study I, the reliability of the Addiction Severity Index Self-Report form (ASI-SR) was assessed by the agreement (intraclass correlation (ICC)) between the composite scores (CS) of the ASI interview and the ASI-SR, internal consistency of the CS subscales measured with Cronbach’s α, and sensitivity and specificity of the alcohol and drug CS’s, using Receiver Operating Characteristics analyses. Study II was a feasibility study of the U-PAIN cohort. Cohen’s к, PABAK, and ICC were used to assess the agreement between self-reported data on opioid use and data from medical records. In study III, interpretative phenomenological analysis was used to explore the lived experience of managing CNCP with opioids. In Study IV, phenomenography was used to explore physicians’ understandings of prolonged opioid prescribing practices.

Results: In study I, 6/7 domains the ICC for the ASI interview and ASI-SR were good to excellent. Internal consistency was acceptable for 5/7 of the domains. Alcohol- and drug CS’s predicted clinical substance dependence diagnoses. In study II, the agreement between self-reported opioid use and prescribed dose, and the agreement between OUD according to DSM-5 and clinical ICD-10 opioid dependence diagnoses, were almost perfect. In study III, opioids were used to regain control over the pain, but opioid use could also be experienced as a downward spiral of pain, dependence, and stigmatization. In study IV, specifics of a patient could justify opioid therapy. Insufficient follow-up, ignorance about pain management and opioids, an obligation to treat patients’ pain, and lack of alternative treatments, were understood to drive continued opioid prescribing practices. 

Conclusion: The studies suggest that the examined assessment methods of self-reported opioid use were feasible for assessing patterns of opioid use. To manage CNCP pain with opioids was experienced and conceptualized as a balancing act between pain control and quality of life, and aversive effects of opioids, e.g., OUD and stigmatization.