Opioid therapy for chronic noncancer pain (CNCP) is controversial due to concerns regarding long-term effectiveness and safety, particularly the risk of tolerance, dependence, or abuse.
OBJECTIVES: To assess safety, efficacy, and effectiveness of opioids taken long-term for CNCP.
SEARCH STRATEGY: We searched 10 bibliographic databases up to May 2009.
MAIN RESULTS: We reviewed 26 studies with 27 treatment groups that enrolled a total of 4893 participants. Twenty five of the studies were case series or uncontrolled long-term trial continuations, the other was an RCT comparing two opioids.
Signs of opioid addiction were reported in 0.27% of participants in the studies that reported that outcome.
All three modes of administration were associated with clinically significant reductions in pain, but the amount of pain relief varied among studies.
Many patients discontinue long-term opioid therapy (especially oral opioids) due to adverse events or insufficient pain relief;
however, weak evidence suggests that patients who are able to continue opioids long-term experience clinically significant pain relief.
Whether quality of life or functioning improves is inconclusive.
Many minor adverse events (like nausea and headache) occurred, but serious adverse events, including iatrogenic opioid addiction, were rare.