A population-based cohort study on chronic pain: the role of opioids.

OBJECTIVES: The aims of this study were 2-fold: (1) to investigate the consequences of opioid use in individuals with chronic pain in the Danish population, and (2) to investigate the development of and recovery from chronic pain from 2000 to 2005.
METHODS: Data derived from the Danish Health Interview Survey in 2000, which were linked on the individual level with register-based follow-up data. The survey was based on a county-stratified random sample of 16,684 individuals, out of which 10,434 individuals (62.5%) completed a face-to-face interview and returned a self-administered questionnaire. In addition, a subsample of the sample in 2000 was reinvited to a follow-up survey in 2005. In total, 3649 individuals (61.7%) of this subsample completed the interview and returned the questionnaire at baseline in 2000. At follow-up, 2354 of these participants completed the interview and returned the self-administered questionnaire. Respondents with cancer diagnosis were excluded from all analyses. Respondents with chronic pain were identified as having chronic/long-lasting pain more than 6 months. RESULTS AND DISCUSSION: The annual incidence for the development of and the recovery from chronic pain was 2.7% and 9.4%, respectively. Increasing age up to 64 years, short education, poor self-rated health, high body mass index, and physical strain at work were predictors of chronic pain. The odds of recovery from chronic pain were almost 4 times higher among individuals not using opioids compared with individuals using opioids. In addition, use of strong opioids was associated with poor health-related quality of life. Furthermore, the results indicated that individuals with chronic pain using strong opioids pain had a higher risk of death than individuals without chronic pain (HR: 1.67; 95% CI: 1.03-2.70). However, this study cannot exclude disease severity as the primary cause of increased mortality.