Research gaps on use of opioids for chronic noncancer pain: findings from a review of the evidence for an American Pain Society and American Academy of Pain Medicine clinical practice guideline.

UNLABELLED Chronic noncancer pain is common and use of opioids is increasing. Previously published guidelines on use of opioids for chronic noncancer pain have been based primarily on expert consensus due to lack of strong evidence. We conducted searches on Ovid MEDLINE and the Cochrane databases through July 2008 to identify studies that addressed one or more of 37 Key Questions that a multidisciplinary expert panel identified as important to be answered to generate evidence-based recommendations on the use of opioids for chronic noncancer pain. A total of 14 systematic reviews, 38 randomized trials not included in a previously published systematic review, and 13 other studies met inclusion criteria. Almost all of the randomized trials of opioids for chronic noncancer pain were short-term efficacy studies. Critical research gaps on use of opioids for chronic noncancer pain include: lack of effectiveness studies on long-term benefits and harms of opioids (including drug abuse, addiction, and diversion); insufficient evidence to draw strong conclusions about optimal approaches to risk stratification, monitoring, or initiation and titration of opioid therapy; and lack of evidence on the utility of informed consent and opioid management plans, the utility of opioid rotation, the benefits and harms specific to methadone or higher doses of opioids, and treatment of patients with chronic noncancer pain at higher risk for drug abuse or misuse. PERSPECTIVE Currently, clinical decisions regarding the use of opioids for chronic noncancer pain need to be made based on weak evidence. Research funding priorities need to be set to address these critical research needs if the care of patients with chronic noncancer pain is to improve.