The researchers say doctors should provide information about acupuncture as an option when discussing preventive treatment strategies with patients.

More than one billion people worldwide are affected by migraine. It has considerable impact on quality of life and imposes a substantial burden on society.

For people with frequent migraines, preventive treatments to reduce headache frequency are available, but not all patients respond well to drug therapy and many prefer to avoid it. Evidence for the benefit of acupuncture on migraine prevention has been mixed.

So a team of researchers based in China set out to compare the effectiveness of manual (real) acupuncture with sham (placebo) acupuncture or usual care.

Their findings are based on 147 patients (average age 37) with a history of migraine without aura who were recruited from seven hospitals in China from June 2016 to November 2018.

None of the patients had received acupuncture before, and all were instructed not to take any painkillers or start any other treatments during the trial.

After 4 weeks of baseline assessment, patients were randomly allocated to receive either 20 sessions of manual acupuncture at true acupuncture points, 20 sessions of non-penetrating sham acupuncture at non-acupuncture points, or usual care (including advice on lifestyle and self-management) over eight weeks.

Over the next 12 weeks, the researchers compared changes in migraine days and migraine attacks per four-week period from baseline.

Compared with sham acupuncture, manual acupuncture resulted in a greater reduction in migraine days (3.9 vs 2.2) at weeks 13 to 20 and migraine attacks (2.3 vs 1.6) at weeks 17 to 20, with an apparent increasing trend.

The adjusted difference between manual and sham acupuncture was 1.4 fewer migraine days at weeks 13 to 16, and 2.1 fewer migraine days and at weeks 17 to 20.

Sham acupuncture resulted in a minor reduction in migraine attacks compared with usual care (1.6 vs 0.4) during weeks 17 to 20, with a slightly decreasing trend over this period.

No severe adverse events were reported.

The researchers point to some limitations, such as the relatively short (20 week) study period. Strengths include use of a non-penetrating needle for sham acupuncture, and successful blinding to increase the reliability of the results.

These results show that treatment with manual acupuncture compared to sham acupuncture or usual care, "resulted in a significantly higher reduction in the frequency of migraine days and migraine attacks," write the authors.

They say acupuncture "can be recommended as a prophylactic treatment" and clinicians "should provide patients with information about acupuncture as an option when discussing prophylactic treatment strategies."

And they call for longer term studies to assess how long the effects of acupuncture would last.

"We now have good evidence that acupuncture is an effective treatment for episodic migraine," writes Heather Angus-Leppan, a consultant neurologist at the Royal Free London NHS Foundation Trust, in a linked editorial.

She acknowledges that the effects of acupuncture (and other preventive treatments) are a modest reduction in migraine days each month, and it is difficult for clinicians to know whether this level of benefit would be noticeable to patients until we have long-term data.

But she says, given that almost 90% of people with frequent migraine have no effective preventive treatment, "acupuncture provides a useful additional tool in our therapeutic armoury."

This study "helps to move acupuncture from having an unproven status in complementary medicine to an acceptable evidence based treatment," she concludes.