Saturday, February 13, 2010

Followup: Safety of Long-Term Opioid Therapy

The prescribing of opioid analgesics for chronic noncancer pain is still shrouded by some controversy; particularly, when patients are continued on these medications for many years. However, evidence is growing in support of long-term opioid therapy for providing less pain, better function, and improved quality of life in select patients. Benefits clearly may outweigh risks.

Last August, we reported on a study by Forest Tennant, MD, of 24 patients administered strong opioid analgesics for from 10 to 35 years [see blogpost 10+ Years on Opioid Analgesics! What Happens?]. Overall, he observed that patients experienced significant pain relief and ongoing quality of life and physical functioning enhancements. At the same time, there were relatively few complications of the therapy, which were easily managed. However, this was a quite limited cases series of patients.

Now, writing in the January/February 2010 edition of the journal Practical Pain Management, Tennant has expanded his study four-fold to include 100 patients [Tennant 2010]. Patients ranged in age from 30 to 83 years, were 61% male, and had been administered opioids for 10 to 35 years. Significant causes of chronic pain being treated with opioids included spine disease (51%), arthritis (16%), peripheral neuropathy (14%), and headache (10%). A majority were administered a single opioid (62%), with those most commonly prescribed being hydrocodone (56%), oxycodone (25%), fentanyl (15%), and morphine (13%) [exact formulations are not specified in the report]. Far from becoming debilitated by ongoing opioid therapy most patients were able to read newspapers and other literature (97%), attend social events (89%), dress themselves (82%), walk unassisted (85%), and even drive a car (74%). Almost half of patients (45%) had been on a stable opioid dose without significant escalation for at least 3 years (range 3 months – 31 years).

CAVEATS: It is of interest that significant numbers of patients were benefitting from long-term opioid therapy for headaches and peripheral neuropathy, since some guidelines and clinical literature argue against the value of opioid analgesia in aiding these conditions. Therefore, further research in much larger patient populations appears warranted to explore these applications of opioids before indisputably accepting perspectives in the literature.

Unfortunately, Tennant’s updated and expanded report does not comment on the full range of risk factors that might be of concern. In his original report on only 24 patients, he noted that some developed other conditions during long-term opioid therapy, including tachycardia, hypertension, hyperlipidemia, diabetes, tooth decay, and weight gain. These could be medically managed and whether the conditions were pain related, opioid induced, or simply inherent in the patients and/or a result of aging was unclear. No neurologic complications such as hyperalgesia, dementia, tremor, or seizures were noted; nor were hepatic, renal, or gastrointestinal complications, except for minor constipation.

Tennant rightly concedes that even his expanded study of 100 patients does not incorporate sophisticated epidemiological techniques or the prospective randomization of patients to long-term opioid therapy. It is more of a preliminary “proof of concept” than a clinical trial. He writes that this study, or survey, was merely intended to answer a fundamental question: “Are there chronic pain patients in the United States who have taken opioids over 10 years and report less pain, better function, and have a better quality of life?” The answer clearly is “Yes.” Might some of the patients have done just as well if treated by other pain management modalities? Possibly so. Are there some patients who would not respond or thrive as well on long-term opioid therapy as those in Tennant’s cohort? Probably so. At the same time, however, when patients appear to be doing well on opioid therapy for chronic noncancer pain, Tennant believes, “there is no obvious reason to discourage opioid use or encourage pain patients to cease opioids.”

Reference: Tennant F. Opioid treatment 10-year longevity survey. Final report. Prac Pain Manage. 2010;10(1):47-48.