WASHINGTON – Many fibromyalgia patients could benefit from the care and expertise provided by psychiatrists, Dr. Lesley M. Arnold said at the annual meeting of the American Academy of Clinical Psychiatrists.
Psychiatrists are in a position to evaluate fibromyalgia patients for psychiatric comorbidities and consider prescribing antidepressants as part of a treatment plan, said Dr. Arnold, associate professor of psychiatry at the University of Cincinnati.
Tricyclics have been shown to reduce chronic pain independent of any effects on the patient's mood, which suggests a common neurochemical channel for persistent pain and psychiatric conditions that remains unexplored, she said.
Consequently, fibromyalgia patients might benefit from a multidisciplinary approach, said Dr. Arnold, who has received grants and research support from several pharmaceutical companies, including Eli Lilly, Pfizer, and Cypress Bioscience. She also has served as a consultant for these and other pharmaceutical companies.
The American College of Rheumatology criteria for fibromyalgia include chronic widespread pain of more than 3 months' duration and pain in at least 11 of 18 pressure point areas of the body. Patients must report pain with about 4 kg of pressure (enough to blanch your thumb when you press on the area).
But the muscular criteria are only part of the disorder. Patients with fibromyalgia may have hyperalgesia throughout the body rather than at specific points, and patients who do not report pressure on at least 11 of the 18 tender points will often report other symptoms of fibromyalgia, including debilitating fatigue, Dr. Arnold said.
“Fatigue really knocks people out, and that impairs their function more than the pain,” she commented. Fibromyalgia patients also report difficulty falling asleep, difficulty staying asleep, and unrefreshing sleep.
Patients with fibromyalgia report depression and anxiety symptoms, too. The fibromyalgia literature suggests that about one-third of patients with a fibromyalgia diagnosis have a comorbid psychiatric condition, which contributes to the rationale for treating fibromyalgia patients with antidepressants, Dr. Arnold said.
To further assess the relationship between psychiatric comorbidity and fibromyalgia, Dr. Arnold and colleagues conducted a family study. They recruited 78 patients with fibromyalgia and 533 of their relatives, and compared the prevalence of mood disorders between this population and 40 patients with rheumatoid arthritis and 272 of their relatives (Arthritis Rheum. 2004;50;944–52).
“Mood disorders were much more common in the relatives of the fibromyalgia patients than the RA patients,” she said. Overall, 32% of relatives of fibromyalgia patients had any mood disorder versus 19% of relatives of rheumatoid arthritis patients. On further analysis, the odds ratio for bipolar disorder was much higher in patients with fibromyalgia, compared with those who didn't have fibromyalgia, she added.
When prescribing antidepressants off label to fibromyalgia patients with comorbid mood disorders, be sure to titrate the medication to a high enough dose for a long enough time to allow a response, Dr. Arnold said.
“There is a tendency to use low doses when treating chronic pain, but I encourage people to use the full standard dose,” she said. Also consider combining a tricyclic antidepressant with a selective serotonin reuptake inhibitor, but be aware of drug interactions. “Sometimes you need to do two treatments–one for mood and one for pain,” she added.
Dr. Arnold and her colleagues conducted two randomized trials to assess the effectiveness of duloxetine (Cymbalta) on reducing pain in fibromyalgia patients with and without major depressive disorder. Overall, duloxetine was associated with significantly less pain than a placebo, whether or not the patients had major depressive disorder (Arthritis Rheum. 2004;50:2974–84).
Similarly, pregabalin and gabapentin are approved by the Food and Drug Administration for treating some types of neuropathic pain and neuralgia, and they are being studied as treatments for anxiety disorders and fibromyalgia.