Opioids for chronic noncancer pain: still no evidence for superiority of sustained-release opioids.

Opioids are controversial in the treatment of chronic pain due to the risk of addiction, misuse, and death. Long-acting formulations of opioids have been hypothesized to improve pain relief, sleep quality, and lower the risk of side effects and addiction compared to short-acting formulations of opioids. Thus, several guidelines have recommended the use of long-acting opioid formulations over short-acting ones in the treatment of chronic noncancer pain. However, is there really evidence of their superiority?