Thursday April 15 2010
Aspirin was not compared to other migraine treatments
“Migraine sufferers could find relief in three aspirin tablets,” reported The Times. It said that researchers have suggested that one in four migraine sufferers could be pain-free within two hours if they take up to 1,000mg of aspirin in one go.
This well-conducted Cochrane review combined the results of 13 trials, which compared aspirin to placebo or another migraine drug. It found that 24% of people given aspirin were pain-free at two hours compared to 11% of those given placebo. Nausea and vomiting associated with migraines were improved with the addition of an anti-sickness drug.
The studies in this review used 900–1,000mg of aspirin. This is a high dose and aspirin is not without adverse effects, nor is it a suitable treatment for everyone. Regular use can increase the risk of stomach irritation and ulceration.
Also, the review found no evidence that aspirin was any more effective than sumatriptan, the most common migraine treatment, or other migraine treatments. Individuals should refer any questions about their treatment to their GP.
Where did the story come from?
The research was carried out by Varo Kirthi and colleagues from the Pain Research and Nuffield Department of Anaesthetics. The work was funded by Pain Research Funds, the NHS Cochrane Collaboration Programme Grant Scheme and the NIHR Biomedical Research Centre Programme. The research was published in the Cochrane Library, an online database of systematic reviews by the Cochrane Collaboration.
The review found no evidence that aspirin is more effective than other migraine treatments, and the Mail’s headline, “Why aspirin could be the best remedy for a migraine”, is incorrect.
What kind of research was this?
This systematic review searched multiple medical databases to find all randomised controlled trials to date on aspirin for treating migraine episodes. Systematic reviews are the best way to reliably collect evidence to assess the overall effectiveness and safety of a particular treatment. Combining the results of different trials can make the effects of a treatment more apparent, but the different methods of the individual trials need to be considered when deciding whether the trials are similar enough for their results to be pooled.
What did the research involve?
The researchers reviewed medical databases for relevant studies published up to March 2010. To be eligible for inclusion, studies had to have included at least 10 adults with migraines. Migraines had to have been diagnosed according to specific diagnostic criteria, and included people with and without visual aura (the visual changes that some people experience with migraines). Studies also had to compare aspirin to either placebo or to an active drug treatment. Aspirin could have been used either alone or with an antiemetic (anti-sickness medicine).
The researchers assessed the quality of each study. The main outcomes of interest of the review were based on the outcomes considered in the available studies, those that the researchers thought were important outcomes for migraine sufferers, and those suggested by International Headache Society guidance. Based on these considerations, the researchers looked at:
- being pain-free at two hours
- having reduced pain (relief from pain) at one to two hours
- remaining pain-free or with reduced pain during the following 24 hours
Pain intensity and pain relief were subjective measures rated by the migraine sufferers themselves on a visual scale. Study results were combined using standard statistical methods. The researchers also looked at the rate of adverse effects experienced with aspirin, placebo or the other active treatment tested.
What were the basic results?
The review included 13 studies with a total 4,222 participants and 5,261 treated migraine attacks. All participants had a history of migraines over the past 12 months, with between one and six attacks of moderate to severe intensity each month. The studies varied in whether they included people taking migraine preventative medicines (prophylaxis) and whether they included people whose migraines were associated with vomiting.
Five studies compared aspirin with placebo, four compared aspirin with active treatment and four compared aspirin with both placebo and active treatment. The amount of aspirin used varied between studies:
- In five studies, 1,000mg of aspirin was given as either a single tablet or in soluble form (dissolved in water).
- One study used 900mg of aspirin (soluble).
- Five studies used 900mg of aspirin (soluble) in combination with metoclopramide (an antiemetic).
Active comparators included sumatriptan, zolmitriptan, paracetamol plus codeine, ibuprofen, and ergotamine plus caffeine. The researchers considered the 900mg and 1,000mg doses of aspirin to be similar enough for the results of these studies to be combined.
The main results for being pain-free at two hours were:
- Aspirin was more effective at treating headache than placebo (in six studies with 2,027 participants): 24% of people treated with aspirin were pain-free at two hours compared to 11% using placebo. This meant that 8.1 people needed to be treated (number needed to treat or NNT) with aspirin for one extra person to be pain-free after two hours.
- Aspirin plus antiemetic was more effective than placebo (two studies, 519 participants): 18% of people treated with aspirin were pain-free after two hours compared to 7% using placebo (NNT 8.8).
- The effectiveness of aspirin was not significantly different from 50mg of sumatriptan, the most frequently used active treatment (two studies, 726 participants): 26% were pain-free at two hours compared to 32% using sumatriptan.
- Aspirin plus antiemetic was less effective than 100mg of sumatriptan (two studies, 528 participants): 18% were pain-free at two hours compared to 28% using sumatriptan. For every 10 people treated with sumatriptan, one person would be pain-free who would not have been if they had received aspirin.
Summary of other outcomes:
- Aspirin was more effective than placebo for giving pain relief at two hours (NNT 4.9) and for giving sustained pain relief at 24 hours (NNT 6.6).
- Aspirin plus antiemetic was more effective than placebo for giving pain relief at two hours (NNT 3.3) and for giving sustained pain relief at 24 hours (NNT 6.2).
- Aspirin (alone or with antiemetic) was not significantly different from 50mg or 100mg of sumatriptan at providing pain relief at two hours (24-hour data not available).
- Associated symptoms of nausea and vomiting and dislike of light or sound were reduced with aspirin compared to placebo, but the addition of an antiemetic significantly reduced these symptoms compared to aspirin alone.
- Fewer people needed rescue medication when they took aspirin compared to when they took placebo.
- Adverse events occurred more often with aspirin than placebo, but were mostly mild and self-limiting, and occurred less frequently than with the higher dose of sumatriptan.
How did the researchers interpret the results?
The reviewers concluded that 1,000mg of aspirin is an effective treatment for acute migraine headaches with effects similar to sumatriptan. Addition of the antiemetic (10mg of metoclopramide) gave better relief from nausea and vomiting.
This well-conducted review has identified and combined the results of 13 trials that compared the use of aspirin with inactive placebo or another medicine to treat a migraine attack in diagnosed sufferers. It combined studies of different populations of migraine sufferers and several different treatments. Some important points to note are:
- As the researchers specified, they were primarily interested in the effectiveness of aspirin compared to placebo, rather than active treatment. Only a quarter of the people in these studies who were treated with aspirin were pain-free after two hours. Also, nine people would have to be treated with aspirin for one extra person to be pain-free who would not have been pain-free with placebo. This means that many people would not be pain-free two hours after taking aspirin.
- In the main, the newspapers have accurately reported the findings of this review. However although the papers report that relief could be found through three aspirin tablets, only 24% of those studied gained relief from 900-1000mg aspirin. Also, the review found no evidence that aspirin is more effective than other migraine treatments, and the Mail headline 'Why aspirin could be the best remedy for a migraine' is incorrect.'
- There was only a limited amount of trial data comparing aspirin to other active comparators, and aspirin was mostly compared with sumatriptan. This review does not provide evidence that aspirin is more effective than other active treatments used for migraines.
- Pain intensity and pain relief are subjective experiences, and when measuring all study outcomes, a particular pain is likely to be rated quite differently by different individuals.
- These trials all included people who were able to self-administer their medications at home. As such, these findings cannot be applied to people who have severe migraines and have to seek medical or hospital attention.
- The review did not investigate prophylactic use of aspirin to prevent migraine. In other words, the findings do not show whether aspirin can prevent migraine.
- Aspirin is not without adverse effects. Regular use can increase the risk of stomach irritation and ulceration, particularly in elderly people. It is also not a suitable treatment for everyone and should be used with caution by people with asthma and those who have a history of bleeding conditions. Taking three high-dose tablets at once may increase the risk of side effects in people who are susceptible to them.
Migraines can be extremely debilitating, particularly when associated with their typical symptoms of nausea, vomiting and intolerance to light and sound. Different people have different symptoms and severity of migraines, and some may find relief from aspirin while others may not.
Anyone who has an extremely severe headache and is not known to have migraines or is experiencing a migraine that is more severe than usual should immediately seek medical attention.
Revised: April 23, 2010