Chronic pain, opioid prescriptions, and mortality in Denmark: A population-based cohort study

This study aimed to investigate the risk of death, development of cancer, and hospital inpatient admissions resulting from injuries and toxicity/poisoning among opioid users with chronic noncancer pain. A population-based cohort of 13,127 adults, who have participated in the Danish Health Interview Surveys in 2000 or 2005 and have been followed up prospectively by registers until the end of 2011, were classified according to the absence or presence of chronic pain (ie, pain lasting ⩾ 6 months) and long-term or short-term opioid use (individuals using at least 1 prescription per month for 6 months in the previous year and at least 1 prescription in the previous year, respectively). The risk of all-cause mortality was 1.72 (95% confidence interval [CI]=1.23-2.41) times higher among long-term opioid users than among individuals without chronic pain. The risk of death was lower, but still significantly higher in short-term (1.36, 95% CI=1.07-1.72) and non-opioid users with chronic pain (1.39, 95% CI=1.22-1.59) than in the background population. There was no statistically significant association between long-term opioid use and cardiovascular and cancer mortality. No deaths among opioid users were caused by accidents or suicides, although opioid users had higher risks of injuries and toxicity/poisoning resulting in hospital inpatient admissions than individuals without chronic pain. The risk of all-cause mortality was significantly higher among long-term opioid users, but no obvious associations between long-term opioid use and cause-specific mortality were observed. However, opioid use increased the risk of injuries and toxicity/poisoning resulting in hospital inpatient admissions.