Long-term opioid therapy is one of the methods of treating long-term pain that, in many cases, leads to problematic use, development of addiction, and complications. Effective screening and risk assessment are important both before treatment begins and continuously during treatment. At the moment, there are no relevant or sufficiently sensitive questionnaires in Swedish for assessing risk development for opioid addiction in pain patients treated with opioids for long-term pain. Many instruments have been evaluated abroad, and the ones with the greatest relevance are the "Current opioid misuse measure" (COMM) for control of ongoing treatment and the Addiction Severity Index (ASI), a standardized assessment instrument validated for the assessment of general addiction problems. A shorter version, the ASI-SR, has been validated for assessment in a Swedish population and reflects more on ongoing problems. We, therefore, plan to translate the COMM form and validate it using the ASI-SR in a Swedish population of pain patients treated with opioids. This includes both quantitative and qualitative approaches according to the COSMIN guidelines. The qualitative part includes semi-structured interviews of respondents. At the same time, the prevalence of illicit substance use will be investigated in this population and compared with patients who are not treated with opioids. Inflammatory markers will be collected in Uppsala Biobank for future analyses of neurobiological processes during long-term pain treatment.