Clinical Question: Is duloxetine (Cymbalta) effective in controlling symptoms in women with fibromyalgia?
Setting: Outpatient (specialty)
Study Design: Randomized controlled trial (double-blinded)
Synopsis: The researchers conducting this study enrolled 354 female patients throughout the United States with primary fibromyalgia, with or without a diagnosis of major depression. All women in the study met the American College of Radiology criteria for primary fibromyalgia and had a score of at least 4 out of a possible 10 on the Brief Pain Inventory (average score = 6.5).
Most of the women were white, and the average age was 50 years. Only 26 percent of enrollees were depressed, and none were taking analgesics other than acetaminophen. The women were randomly assigned (concealed allocation unknown) to receive placebo or duloxetine once or twice daily for three months. Dropouts were common in all groups, but more women in the treatment groups dropped out because of adverse effects. Nausea was reported by approximately 40 percent of patients, and dry mouth occurred in 20 percent of patients.
The average (adjusted) response to placebo was a decrease of 1.16 on the Brief Pain Inventory. Patients receiving either dose of duloxetine had an additional drop in pain scores of between 1.31 and 1.44 beyond that achieved by placebo. There was no difference in response among the patients in the two duloxetine arms.
Significantly more patients receiving duloxetine experienced a 50 percent drop in their Brief Pain Inventory scores: 41 percent in each treatment group compared with 23 percent in the placebo group ( P = .0003). Although the average treatment response is not large, one out of six patients treated with duloxetine instead of placebo will have at least a 50 percent decrease in pain (number needed to treat = 5.6). There was no difference between women who were depressed and those who were not.
Bottom Line: Duloxetine is effective in some women with fibromyalgia, whether or not they are depressed. (Level of Evidence: 1b–)