Study Population: Adults with fibromyalgia
Efficacy End Points: Moderate to substantial symptom relief
Harm End Points: Withdrawal from trials due to adverse effects
Fibromyalgia is a debilitating condition marked by widespread pain, fatigue, and sleep disturbances. In its most severe form, it can significantly impair daily functioning. A Cochrane review of high-quality studies has consistently shown that Lyrica 75 and Lyrica 150 (pregabalin) can help reduce pain in about 9% of patients with fibromyalgia. The number needed to treat (NNT) to achieve a moderate to substantial symptom benefit is 11. In these studies, 36% of the 932 patients receiving pregabalin experienced moderate to substantial symptom improvement, compared to 27% of the 937 patients receiving a placebo. This improvement in symptoms can notably enhance a patient’s quality of life.
However, pregabalin use is associated with some adverse effects. The most common side effects reported were dizziness and drowsiness. Adverse effects led 17% of patients in the pregabalin group to withdraw from the trials, compared to 9% in the placebo group. This results in a number needed to harm (NNH) of 11, indicating that patients are just as likely to experience intolerable adverse effects as they are to benefit significantly from the drug.
Caveats:
While the trials included in the Cochrane review were methodologically rigorous, they did not assess the long-term tolerability of pregabalin. Most studies followed participants for 12 to 13 weeks, with a maximum follow-up of six months. Long-term effectiveness and tolerability are important considerations and may vary over time.
Another important factor is the potential for functional unblinding in the pregabalin group. Although 9% of patients withdrew due to adverse effects, others may have experienced side effects that were not severe enough to warrant withdrawal but still affected their experience of the treatment. For example, data from the U.S. Food and Drug Administration indicates that 20% of patients on pregabalin experienced somnolence, compared to 4% in the placebo group. Similarly, 38% of pregabalin users experienced dizziness, compared to 9% of placebo users. Such side effects may contribute to unblinding, where patients may become aware of their treatment assignment due to their adverse experiences.
Pregabalin can provide significant pain relief for some fibromyalgia patients, but it is not effective for everyone. Physicians should consider alternative treatments if the desired effect is not achieved after a trial of pregabalin.
