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 as many as 24 per cent of women worldwide, including up to one million in the UK.
In 55 per cent 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 per cent of GPs and 90 per cent 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, which is published in the Lancet, 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.
These results are important because an increased risk of suicidal behaviour, as a potential side effect of gabapentin, and possible misuse of the drug have been of concern with the rise in the prescribing of gabapentin, although the latter is more of an issue in the USA. Fundamentally, there was little evidence for the use of gabapentin in CPP before GaPP2, although the drug appeared to be of benefit for other types of chronic pain. Our rigorous trial enables the results to be interpreted with confidence, and we can conclude that gabapentin is not effective for chronic pelvic pain.
This work was funded through the National Institute for Health Research and Medical Research Council's joint Efficacy and Mechanism Evaluation programme.
