Chronic pain and use of opioids: a population-based pharmacoepidemiological study from the Norwegian prescription database and the Nord-Trøndelag health study.

In previous studies on prescription patterns of opioids, accurate data on pain are missing, and previous epidemiological studies of pain lack accurate data on opioid use. The present linkage study, which investigates the relationship between pain and opioid use, is based on accurate individual data from the complete national Norwegian prescription database and the Nord-Trøndelag health study 3, which includes about 46,000 people. Baseline data were collected in 2006 to 2008, and the cohort was followed up for 3 years. Of 14,477 people who reported chronic nonmalignant pain, 85% did not use opioids at all, 3% used opioids persistently, and 12% used opioids occasionally. Even in the group reporting severe or very severe chronic pain, the number not using opioids (2680) was far higher than the number who used opioids persistently (304). However, three quarters of people using opioids persistently reported strong or very strong pain in spite of the medication. Risk factors for the people with chronic pain who were not persistent opioid users at baseline to use opioids persistently 3 years later were occasional use of opioids, prescription of >100 defined daily doses per year of benzodiazepines, physical inactivity, reports of strong pain intensity, and prescription of drugs from 8 or more Anatomical Therapeutic Chemical groups. The study showed that most people having chronic nonmalignant pain are not using opioids, even if the pain is strong or very strong. However, the vast majority of patients with persistent opioid use report strong or very strong pain in spite of opioid treatment.