Migraine Prophylaxis: preventing you a headache
Migraine headaches are common. They can be really disabling for patients and if they occur with any frequency they can make life miserable. Fortunately there are many options out there for the longer term management and prophylaxis of migraine and other primary headaches.
The only problem for us is that there are so many, seemingly effective remedies – it can be a real headache deciding which to try with your patient.
A dive into the literature reveals a broad range of medications and classes of medications that may be suitable – but the data is difficult to get one’s head around. There are many ways that headache prevention can be measured and weighed – making it hard to compare apples with apples. And to make things worse – a lot of newer agents come with a hefty price tag if you are prescribing off-schedule… so how to choose?
Well I have been diving into the literature and have tried to summarise the data around migraine prophylaxis as cleanly as I possible. How? The NNT and the NNH for these meds are a fair place to start – you can weigh the risks and benefit with your patient if you know the rough numbers. And then it is a matter of individualising care to your patient’s other needs and medical problems.
So here we go a whirlwind tour through Migraine Prophylaxis !
A quick explanation of the statistics is required! When researchers look into migraine prophylaxis interventions – they tend to use a slightly odd, but useful measure of “effect”. Clearly if you wanted you could measure the number of headaches per month / year etc and have a scale of effect – but that is a bit messy. So instead they use the arbitrary bar of “50% reduction in headache frequency”. So when I tell you that the NNT for drug X is 7 – that means that you would have to treat 7 patients with that drug for whatever time period in order to reduce their headaches from 12 to 6, or 8 to 4 – or whatever you like. Hope that makes sense.
Now usually when we look at drugs in medicine – they get NNTs of 10 or 20 – which most folk would regard as useful. [NB: aspirin has an NNT of 42 for mortality in acute STEMI. Its NN to harm is about 167.]
When we look at migraine prophylaxis we are talking about NNTs in the range of 3 – 10. Now that may sound like these drugs are really great! But recall we are using “50% reduction in headache frequency” as the end point. That is a reasonably low hurdle to jump over. If we were to ask for “complete prevention, absolute prophylaxis” then the NNT would be much higher- I am guessing in the 100s.
So who needs prophylaxis?
- Most Neurologists would consider 2 – 3 severe / disabling headaches per month a reasonable threshold for considering prophylaxis
- This may vary depending on the patient’s choice
- Some patient’s will feel strongly about preventing any headaches due to the severity; interference with life, work, family etc.
- This needs to be explored with each migraine sufferer on a case-by-case basis. That is what they pay us the big bucks to do!
- Remember that this is an “optional” intervention – so do not be too precious with particular drugs – it is a fine balance between potential harms and benefits – very much in the realm of “shared-decision making” and being pragmatic.
Most of the agents used for abortive therapy / acute management of migraine run the risk of causing rebound if used more than 10 – 15 times a month. So another way of looking at it would be to use prophylaxis as a means to limit the amount of “acute abortive care” required and therefore maintain its efficacy.
OK – so that is the boring biostats explained. Lets look at the candidates available to you and your patient to choose from. I have lifted this very useful table from the Med Journal of Australia 2008 – link is here – it is a really well written piece.
Migraine prophylaxis (Click for the summary table from the MJA 2008 paper)
OK – that is it for my quick review of the literature around migraine prophylaxis. Would love to hear your experience or views on the data. I stingily recommend reading the great MJA piece that is linked above.
“Grew up” with propranolol and Ca antagonists without too much success. Am more enamored of amitriptyline bedtime for prophylaxis at the moment. Just added steroid at time of D/C for acute migraine and haven’t done occipital injection, though I’m looking to get experience.