In Chronic Noncancer Pain—but Choose Patients Carefully
Long-term opioid treatment can produce positive outcomes in chronic noncancer pain when physicians prescribe it carefully to individuals who have low risks for addiction and overdose, according to the results of a systematic review.
Andrea Furlan, MD, PhD, and her colleagues searched Medline, EMBASE, CINAHI, PsycINFO, Central and Business Source Premier for studies published since 2000 on function and quality of life (QOL) in patients taking long-term opioids for chronic noncancer pain.
The studies included in the analysis involved chronic noncancer pain that lasted longer than three months, opioid use for longer than three months, and outcomes that included measures of function and QOL. Most of the studies excluded patients who had comorbidities and psychiatric diagnoses. The majority of the patients were monitored closely by health care professionals, and were on doses of opioids that were less than approximately 200 mg per day.
The initial literature search by Dr. Furlan, a scientist at the Institute for Work & Health, and pain physician at University Health Network, Toronto, Canada, and her colleagues yielded 16,288 references. The studies focused on function and QOL, as well as outcomes of misuse, abuse, addiction, and falls and fractures. They then excluded all papers that lacked sufficient detail for a careful analysis.
Ultimately, the researchers performed a meta-analysis of pre–post results on eight randomized controlled trials, eight open-label extension studies from randomized controlled trials and nine observational controlled studies. These 25 studies included 4,719 patients, 3,160 of whom (67%) completed the studies. The analysis focused on these latter patients.
The investigators found that long-term opioid use resulted in significantly improved function, and physical and mental QOL.
Mark Sullivan, MD, PhD, professor, Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, said that although Dr. Furlan and her collaborators do “careful work,” he had queries about the study, which was presented at the Canadian Pain Society’s 2014 annual meeting (poster 56).
“First, in pre–post studies without a control group, estimates of efficacy are strongly related to who drops out. Since almost all patients who drop out are not doing well on the drug, the mean pre–post differences can grossly overstate efficacy. We are told 67% were completers. How did this 67% compare with those who did drop out?” Dr. Sullivan noted in an email. He also pointed out that the populations in the studies included in the systematic review were not typical.
Dr. Furlan said she and her team discussed at great length these points, and other potential critiques, while they were completing the systematic review.
She said that, for publication, the paper will include an uncertainty analysis that takes into account the worst-case scenario of a high dropout rate and the resulting underestimates of complications and overestimates of opioid effectiveness. Dr. Furlan also conceded that the patients in the systematic review represented a minority of typical chronic pain patients, because they did not have risk factors and were monitored carefully.
“It is true that most of these conditions are not followed in real-life opioid prescribing. In clinical practice I see a lot of careless prescribing, which can be characterized as ‘high-risk patients’ or ‘high-risk prescriptions.’ When you mix both, it is dangerous,” Dr. Furlan said in an interview. “But when physicians and their teams take the time to carefully screen patients, keep them on as low a dose as possible and monitor them very regularly, our results show that the outcomes can be very satisfactory.”