New central acting drug use for treating patients with fibromyalgia has quadrupled during the last decade, but researchers were not convinced about the costly drugs’ clinical advantages, according to study results.
In a longitudinal study, researchers evaluated 3,123 patients (mean age, 54.1 years; 95.4% women) with fibromyalgia in the United States. Participants completed health questionnaires at 6-month intervals between 2000 and 2010. Severity-adjusted treatment prevalence was assessed. Health Assessment Questionnaire-Disability Index (HAQ-DI) measured the effect of the use of any new central acting drug (NCAD) on pain and fatigue, as well as functional status.
Researchers reported that opioids were used by 46.7% of patients in 2010, with 12.5% using strong opioids. Severity-adjusted strong opioid use increased from 6.3% to 11.7% during the study, while use of any opioid rose from 40% to 46.6%. At the same time, nonsteroidal anti-inflammatory drug and tricylic antidepressant use dropped from 74% to 44% and from 26.2% to 15.4%, respectively.
NCAD use increased from less than 10% to 39%, with drug discontinuation times estimated for the 25th and 50th percentiles at 1 and 2.5 years. Median daily doses for duloxetine, gabapentin and milnacipran were 60 mg, 900 mg, and 100 mg, respectively. Overall pain, fatigue and HAQ-DI scores were unchanged.
Following NCAD initiation, patients’ pain scores were reduced by 0.17 units, an improvement of 2.8%. Improvements up to 4.3% were shown by some sensitivity analyses, although fatigue or functional status did not show significant gains.
“In summary … switching to NCAD resulted in substantially increased drug costs, but not in clinically meaningful benefit,” the researchers reported. “Our results not only raise the question as to whether the new fibromyalgia therapies are truly effective, but also … whether expensive treatments with minimal benefit should be used.
“In the United States in 2011, pregabalin at 300 mg/day costs around $3,000 per year, duloxetine approximately $3,760 per year and milnacipran approximately $1,400 per year. By contrast, amitriptyline 75mg daily has an annual cost of $65.”