An extensive literature review of studies evaluating the effectiveness of long-term opioid therapy in chronic noncancer pain (CNCP) concludes that the drugs continue to provide reliable and safe analgesia for six months or more.
"We see both in our own internal data and in the data that are in the published literature from multiple studies that there is a large drop in pain score in the first three months or so of pain treatment, then it levels off, and the pain efficacy is maintained over time in those patients who stay on opioid treatment," Laura Wallace, MPH, from Purdue Pharma, LP, Stamford, Connecticut, told Medscape Medical News.
The suitability of opioid analgesic therapy for the long-term management of moderate to severe CNCP has been the subject of ongoing debate, Wallace said at the American Academy of Pain Management (AAPM) 24th Annual Clinical Meeting.
"Due to FDA regulatory guidelines, most contemporary phase three randomized controlled trials of opioid analgesics for CNCP are three months long or less. Also, doing placebo-controlled trials for longer than three months presents an ethical dilemma, because some patients have to go without analgesia, and also difficulties retaining patients," Wallace said.
"There is great value in open-label studies, many of which are six months or more in duration and reflect actual patient experience before and after long-term opioid therapy, and in addition to those studies, we were able to look at RCTs [randomized controlled trials], open-label extension studies, and epidemiology studies, and in all of these, we see that improvements in pain scores are maintained," she said.
In this report, funded by Purdue Pharma, Wallace and her group searched for studies in MEDLINE, EMBASE, BIOSIS Previews, and PubMed through February 2013. They also identified more articles through consensus statements, clinical guidelines, literature reviews, and meta-analyses.
All literature evaluated the efficacy of opioids in CNCP when given for at least six months.
The researchers identified 60 studies: eight RCTs, 26 open-label trials, and 12 open-label extension studies, which represented 10,131 patients and 8463 person-years of opioid treatment experience, and 14 epidemiology studies (10 cohort studies and 4 cross-sectional studies), which represented 5415 patients and 4441 person-years of opioid treatment experience.
Forty-six studies had data for the percentage change in pain scores from baseline to end of study.
Of these, 18 were six to less than 12 months in duration and 28 were 12 months or longer in duration.
Among studies six to less than 12 months long, 15 (83%) reported an improvement in pain of at least 25% from baseline. Of the studies that lasted for 12 months or more, 223 (82%) reported an improvement in pain of greater than 25% from baseline.
Six RCTs, 14 open-label studies, and eight open-label extension studies reported pain scores over three-month intervals. All of these reported that pain decreased substantially from baseline to three months and that this decrease was maintained through six and 12 months. A few studies demonstrated a maintenance of pain scores out to 36 months.
Insurance Companies, Take Note
"One of the biggest problems we have as pain management practitioners is that medical directors of insurance companies will call up and say 'you need to take this person off the opioid-based medication because there is no evidence to support the use of chronic opioids in patients who are not cancer patients'," commented Gerard J. Hevern, MD, a family physician and medical director of the chronic pain program at the Elliot Pain Management Center in Manchester, New Hampshire.
"This is the first time that I've ever seen presented accumulated data that really speaks to the efficacy over a long period of time of using chronic opioids," Dr. Hevern told Medscape Medical News.
"It is what people in the pain management group see, but we haven't been able to effectively document it. This is the first time we've seen this efficacy documented in this manner," he said.
This study was funded by Purdue Pharma. Ms. Wallace is an employee of Purdue Pharma. Dr. Hevern has disclosed no relevant financial relationships.
American Academy of Pain Management (AAPM) 24th Annual Clinical Meeting. Abstract #13. Presented September 27, 2013.
Fran Lowry • Medscape Medical News © 2013 WebMD, LLC