Many older adults hesitate to take opioids for fear of addiction despite having to cope with chronic non-cancer pain.
However, a new review finds that taking opioids long term is associated with clinically significant pain relief in some patients with a very small risk of addition.
"Not every patient has adequate pain relief, though, and side effects are intolerable for others," said lead review author Meredith Noble.
"There is a lack of consensus that opioids are safe and effective for people with chronic severe non-cancer pain," Noble said. "We wanted to look at studies that treated people for six months or longer, given that chronic pain can go on for years. This review includes studies of individuals on opioids for as long as 48 months."
Noble is a senior research analyst at ECRI Institute, one of 14 evidence-based Practice Centers in the country under the U.S. Agency for Healthcare Research and Quality.
The review appears in the latest issue of The Cochrane Library
, a publication of the Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Noble and her colleagues reviewed the findings of 26 clinical studies comprising 4,893 participants. This review updates a review published in the Journal of Pain and Symptom Management in 2008.
Patients previously had tried other treatments like non-opioid medications and physical therapy, but still had considerable pain. Clinicians prescribed opioids including oxycodone, morphine and methadone by pill, transdermal (skin) patch or intrathecal pump. Only people who could find relief in no other way received medication by an intrathecal pump, which is a surgically implanted device that delivers drugs directly to the fluid around the spinal cord.
Among studies reporting abuse or addiction, only seven of 2,613 participants reportedly were addicted or took their medicine inappropriately.
Of all participants, 22.9 percent of those taking opioids orally left the clinical studies because of adverse effects. Almost 9 percent of those using an intrathecal pump, and 12.1 percent of those using a patch, discontinued for the same reason. These participants most commonly reported nausea and other gastrointestinal problems, along with headache, fatigue and urinary disturbances.
Insufficient pain relief caused 10.3 percent of patients on opioid pills, 7.6 percent using a pump and 5.8 percent on a patch to drop out of clinical studies.
Most of the patients in this review had chronic back pain following failed surgery, severe osteoarthritis, or pain related to nerve damage, Noble said, and study findings might not necessarily be applicable to other kinds of pain.
"Opioids work by binding pain receptors in the spinal cord and the brain, so they change the way pain is perceived," Noble said. "The long-term use of opioids to relieve pain is controversial, however." Some patients who have chronic non-cancer pain that has not responded to other treatments will not consider opioid therapy, because they worry about addiction. Severe chronic pain decreases quality of life and it might elevate suicide risk.
The findings suggest, however, that carefully selected patients with no history of addiction and abuse, who are compliant with their medication usage, might experience good amounts of pain relief with a very small risk of addition.
"The most important message about this review is that we still don''t have an answer for many people living with chronic pain," Noble said. "We also don''t have a good way to tell who will benefit and who will not, or who would be at risk for getting addicted without a prior history. People doing pain research are working to try to design studies to answer some of these questions."
Alex DeLuca, M.D., an independent consultant specializing in addiction and pain medicine, praised the thoroughness of this review and pointed out the very low rate of signs of addiction in treated pain patients. He said he was not surprised that many people discontinued meds due to insufficient pain relief, as study dosages were often quite low.
A take-home message for physicians reading this review is that all relevant studies find that long-term opioid therapy improves the life of non-cancer patients experiencing chronic pain and is both safe and effective, DeLuca said, and there is zero evidence to the contrary.
"I find, however, that the ethical implications of screening for 'well -selected'' patients potentially problematic," DeLuca said. "Current or historical substance abuse is not a contraindication for opioid therapy, but rather a call for physicians and patients to exercise extra vigilance. It is important pain patients be screened in - not screened out and abandoned."