Cost effectiveness of duloxetine in the treatment of fibromyalgia in the United States
Objective: To evaluate the cost effectiveness of duloxetine when considered as an alternative treatment for patients in the United States (US) being treated for fibromyalgia pain. Research design and methods: A Markov model was used to evaluate the economic and clinical advantages of duloxetine in controlling fibromyalgia pain symptoms over a 2-year time horizon. A base-case treatment sequence was adopted from clinical guidelines, based on tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, anticonvulsants, and opioids. Treatment response was modeled using changes from baseline in pain severity, and response thresholds: full response (at least a 50% change), response (30-49% change), and no response (less than a 30% change). Clinical efficacy and discontinuation data were taken from placebo- and active-controlled trials identified in a systematic literature review and mixed-treatment comparison. Utility data were based on EQ-5D data. Main outcome measures: Additional symptom-control months (SCMs), defined as the amount of time at a response level of 30% or less, and quality-adjusted life-years (QALYs) over a 2-year time horizon. Results: For every 1000 patients, first-line duloxetine resulted in an additional 665 SCMs and 12.3 QALYs, at a cost of $582,911 (equivalent to incremental cost-effectiveness ratios [ICERs] of $877 per SCM and $47,560 per QALY). Second-line duloxetine resulted in an additional 460 SCMs and 8.7 QALYs, at a cost of $143,752 (equivalent to ICERs of $312 per SMC and $16,565 per QALY). Limitations: Response data for TCAs are limited to 30% improvement levels, reported trials are small, and have low placebo response rates. The model necessarily assumes that response rates are independent of placement in the treatment sequence. Conclusions: The results suggest that the introduction of duloxetine into the standard treatment sequence for fibromyalgia not only provides additional patient benefits, reflected by time spent in pain control, but also is cost effective when compared with commonly adopted thresholds.