Opioids for Chronic Noncancer Pain: A Systematic Review and Meta-analysis

Area of Science:

• Pain Management
• Pharmacology
• Clinical Trials

Background:

• The efficacy and safety of opioid analgesics for chronic noncancer pain are not well-established.
• Understanding the comparative effectiveness of opioids versus nonopioid alternatives is crucial for clinical decision-making.

Purpose of the Study:

• To systematically review randomized clinical trials (RCTs) evaluating the effectiveness and harms of opioids for chronic noncancer pain.
• To compare the effects of opioids against placebo and various nonopioid pain medications.

Main Methods:

• A comprehensive search of multiple databases (CENTRAL, CINAHL, EMBASE, MEDLINE, AMED, PsycINFO) was conducted for RCTs.
• Data were independently extracted by paired reviewers, and analyses employed random-effects models.
• The Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework was used to assess evidence quality.

Main Results:

• Ninety-six RCTs involving 26,169 participants were included, covering neuropathic pain, nociceptive pain, and central sensitization.
• Opioids demonstrated statistically significant, albeit small, improvements in pain intensity (WMD: -0.69 cm) and physical functioning (WMD: 2.04 points) compared to placebo.
• Opioid use was associated with a higher incidence of vomiting (5.9% vs. 2.3%) compared to placebo.

Conclusions:

• High-quality evidence indicates that opioids provide modest benefits for pain and physical function in chronic noncancer pain but increase the risk of vomiting.
• Low- to moderate-quality evidence suggests that the benefits of opioids for pain and functioning may be comparable to nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, and anticonvulsants.
• Further high-quality research is needed to clarify the long-term comparative effectiveness and safety of opioids in this patient population.