Cost effectiveness of pregabalin in the treatment of fibromyalgia from a UK perspective

Abstract

Background:

Fibromyalgia is a chronic condition associated with widespread pain, sleep disturbance and disability. Disease related costs are high and effective treatment options few.

Objectives:

To evaluate the cost effectiveness of pregabalin in the treatment of fibromyalgia.

Methods:

A decision-analytic model was developed comparing pregabalin 300 mg or 450 mg against placebo, duloxetine 60 mg or 120 mg, gabapentin, tramadol and amitriptyline. After a 12 week treatment phase patients who responded to treatment entered an ongoing treatment phase using a Markov model in which patients maintained response, lost response or dropped out. The base case considered patients with severe fibromyalgia defined as a Fibromyalgia Impact Questionnaire score of ≥59 and a pain score of ≥6.5 at baseline. Response rates for pregabalin and placebo were taken from three randomised trials, and a 1 year open-label extension study was used for long-term parameters. Response was defined as a ≥30% improvement over baseline in pain score and a patient global impression of change rating of much improved or very much improved. Relative rates of response for other comparators over placebo were extracted from a systematic review of published randomised controlled studies. The primary effectiveness endpoint was Quality Adjusted Life Years (QALYs). Utilities gained over baseline were estimated by applying the SF-6D utility algorithm to SF-36 data collected in the pregabalin trials. Resource use associated with fibromyalgia management was estimated from published studies and costs were estimated from the UK NHS perspective at 2008 prices. Costs and QALYs were discounted at 3.5%. Non-parametric bootstrapping analysis was used to generate confidence intervals.

Results:

In the base case, pregabalin 300 mg and 450 mg increased cost per patient by £601 (95% CI: 532, 669) and £653 (587, 727) and improved QALYs per patient by 0.03 (−0.03, 0.06) and 0.03 (−0.04, 0.08) respectively compared to placebo. The cost per QALY gained (CQG) was £23,166 and £22,533. In the base case population CQG for pregabalin 450 mg against duloxetine 60 mg and 120 mg was £19,224 and £14,096, against gabapentin £35,737, against tramadol £98,072, and was dominated by amitriptyline. Sensitivity analysis found the cost effectiveness of pregabalin to be most sensitive to drug price and response rates. Limitations of the analysis include different definitions of response used and lack of subgroup data reported in the published studies synthesised, and limited data on long-term effect of therapies in fibromyalgia. Although the analysis was based on the best available evidence, the comparisons against amitriptyline and tramadol rely on old studies that were not designed to meet current quality criteria.

Conclusion:

This model found pregabalin 300 mg and 450 mg to be cost effective compared with placebo and, within the limits of available evidence, against duloxetine using standard UK criteria in patients with fibromyalgia experiencing severe pain.

Key words::

• Amitriptyline
• Duloxetine
• Fibromyalgia
• Gabapentin
• Pregabalin
• Tramadol

Transparency

Declaration of funding

The study was funded by Pfizer Inc.

Declaration of financial/other relationships

G.Z. and A.S. are employees of Pfizer Inc. K.B., A.L. and P.W. conducted this work as employees of IMS Health, which received research funding from Pfizer Inc. for this work; IMS Health also undertakes consultancy work for several other pharmaceutical and healthcare companies. E.C. and S.R. received a consultancy fee from Pfizer Inc. for contributing to this work.

Peer reviewers may receive honoraria from CMRO for their review work. Peer Reviewer 1 has disclosed that both he/she and his/her institution has received sponsorship study grants from Novartis, Abbott, Alcon, Takeda, Ortho-McNeil Janssen and sanofi-aventis; that he/she has consultancy agreements with Eli Lilly, sanofi-aventis, Novo Nordisk, Bristol Myers-Squibb and Bayer; and is on the speakers bureau for sanofi-aventis. Peer Reviewer 2 has disclosed that he/she has no relevant financial relationships.

Acknowledgements

The authors would like to thank Zahava Gabriel (Pfizer) for the systematic literature review of fibromyalgia treatments, as well as Steve Lister, Javier Rejas, Sophie Marbaix, Sally Thompson and Christin Prutz (all Pfizer) for their review, comments and suggestions on the model.

Notes

*Lyrica is a registered trade mark of the Pfizer group of companies.