Thursday, November 19, 2009

Depressed Patients Receive More Opioids for Pain

Patients with chronic noncancer pain and a history of depression are 3 times more likely to receive long-term prescriptions for opioid medications than similar patients who do not suffer from depression, according to new research. However, the association of depression with chronic pain and the proper role of opioid therapy in these patients need further consideration.

An extensive retrospective study, published in the November-December issue of the journal General Hospital Psychiatry, analyzed the medical records between 1997 and 2005 of tens of thousands of patients enrolled in two large Northern California health plans; together, the plans cover about 1% of the U.S. population. Long-term opioid use was defined as a patient with chronic noncancer pain receiving a prescription for 90 days or longer. The incidence rates of long-term opioid use were 3 times higher in patients with a history of depression than in those without diagnosed depression. During the 9-year study period, the overall prevalence of long-term opioid prescriptions for noncancer pain in patients with depression increased from roughly 70 to 126 per 1000 patients at Group Health and from 84 to 118 per 1000 at Kaiser Permanente. Furthermore, those with a history of depression were more likely to receive higher average daily opioid doses, greater amounts (more days supply), and more Schedule II opioids than nondepressed persons.

Clinical Comments: The researchers conclude that persons with a history of depression appear more likely to receive long-term opioid therapy for chronic noncancer pain than those without depression. According to Mark Sullivan, MD, a study coauthor and professor of psychiatry at the University of Washington, depression is a common finding in patients with chronic noncancer pain: 46% of patients seeing primary care doctors for ongoing pain have a history of depression and the vast majority of those seeing pain specialists have suffered both disorders. Previously, we noted research indicating that patients with depression are highly prone to “somatoform pain” — pain without medical explanation — which might account for up to 80% of pain symptoms reported in general medical practices [see blogpost of 7/30/09]. Other research found that the prevalence of chronic pain due to any cause in typical samples of persons in the U.S. may be 22%, with more than a third (35%) of those persons also suffering depression [see blogpost 7/19/09].

Sullivan expresses concern that patients with depression are generally excluded from controlled clinical trials testing the efficacy of opioids for noncancer pain. So, whether or not opioids are adequate and/or appropriate therapy for these patients has not been evaluated by the research. “If you study depressed people, they tend to have lot of pain complaints that are poorly responsive to a lot of things so it’s not surprising that they end up on opioids,” he says. Pain perception and depression are mediated in significant ways by the same limbic structures and opioid receptor systems in the brain. Therefore, it can be difficult to assess whether pain is causing or exacerbating the depression — or vice versa. Sullivan and colleagues recommend that opioid treatment for chronic noncancer pain should not replace or distract from screening for and treating concurrent mental disorders like depression.

Reference: Braden JB, Sullivan MD, Ray GT, et al. Trends in long-term opioid therapy for noncancer pain among persons with a history of depression. Gen Hosp Psychiatry. 2009(Nov);31(6):564-570 [see abstract].