A population-based study on chronic pain and the use of opioids in Portugal

Although increasing doubts exist regarding the long-term effectiveness and safety of opioids in patients with chronic pain (CP), most guidelines still recognize opioids as an option in effective management of CP. We aimed to describe the prevalence and factors associated with opioid use in subjects with CP in Portugal and to evaluate satisfaction and self-assessed treatment effectiveness. A nationwide study was conducted in a representative sample of the adult Portuguese population. The 5094 participants were selected using random digit dialing and estimates were adequately weighted for the population. The prevalence of opioid use by subjects with CP was 4.37% (95% confidence interval [CI] 3.4-5.5); and in subjects experiencing CP with and without cancer, it was 10.13% and 4.24%, respectively. Use of strong opioids was reported by only 0.17% of CP subjects. Sex, pain severity and symptoms of depression and anxiety were significantly associated with opioid use; however, in multivariate modeling, only pain-related disability remained significant. No significant differences among users and nonusers of opioids were observed regarding treatment satisfaction and self-assessed effectiveness. Although extremely high rates of use of opioids exist in a few countries, it should not be seen as a ubiquitous problem. Indeed, we showed that in Portugal, as in many other regions in the world, opioids are used much less frequently than in those few countries. Moreover, we did not find significant differences among users and nonusers of opioids regarding satisfaction and self-assessed effectiveness, eventually showing the results to be in line with reports that show doubt about opioids' effectiveness. Further research and particular attention to and continuous monitoring of the trends of use and abuse of opioids worldwide are recommended.