by University of Edinburgh

Credit: CC0 Public Domain

A drug that is regularly used to treat chronic pelvic pain in women has been found to be no more effective than a placebo, a new study has found.

As a result, researchers recommend against routinely prescribing the drug gabapentin for women with the condition.

Chronic pelvic pain affects up to 24 percent of women worldwide to varying degrees. It is estimated that as many as one million in the UK are affected by the condition.

In 55 percent of women there is no known cause. If no underlying cause is found, the pain is much more difficult to treat.

Gabapentin is used to manage many forms of chronic pain. In two separate surveys, 74 percent of GPs and 92 percent of gynaecologists said that they would consider prescribing the drug for chronic pelvic pain.

Researchers from the Universities of Edinburgh, Birmingham, Oxford and Nottingham tested the drug's effectiveness in treating chronic pelvic pain through a randomised clinical trial involving 306 women with the condition and no known underlying cause.

As part of the study, 153 women received gabapentin and 153 received placebo for 16 weeks. Neither group nor the prescribing clinicians knew what they were receiving.

The women were asked to rate their average pain and worst pain, using a scale from zero to ten, on a weekly basis. The scores were then averaged for the drug and placebo groups.

The team found that there was very little difference between the reported pain in both groups.

However, the group that received gabapentin reported experiencing more side-effects—including dizziness, drowsiness and changes of mood—than the placebo group.

The researchers say that gabapentin should no longer be considered in the treatment of chronic pelvic pain where no cause has been identified, and other avenues of treatment should be explored, such as different drugs, physiotherapy and cognitive behavioural therapy.

The research findings have been published in The Lancet. This work was funded through the Efficacy and Mechanism Evaluation Programme—a Medical Research Council (MRC) and the National Institute for Health Research (NIHR) partnership.

Professor Andrew Horne, lead researcher from the University of Edinburgh's MRC Centre for Reproductive Health, said: "We have been prescribing this drug for many years with little evidence of its effectiveness. As a result of our study, we can confidently conclude that gabapentin is not effective for chronic pelvic pain in women where no cause has been identified. More research is needed to explore if other therapies can help instead."

Professor Andy Shennan, Professor of Obstetrics, and Clinical Director NIHR Clinical Research Network South London, said: "This important study was delivered in the UK across 39 sites in the NIHR Clinical Research Network (CRN). It is vital that large studies like this help answer these important health questions to guide management of these debilitating and common conditions. Another success from the CRN."

Journal information: The Lancet 

Provided by University of Edinburgh