Puzzled by CHADS, response to djroute66

"I still can't get my head around CHADS scoring which I am zero on. As surely AF is AF how can I be at lesser risk of blood clots than someone with a score of 1,2 or 3 ? and indeed if there's no difference what is the point of even mentioning chad score?"

This is a link to the original posting so please go back there if it's still active to continue the discussion... healthunlocked.com/afassoci...

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Well I'm afraid you're quite right to be puzzled - the answer is we don't know why. It's just what has been found by looking at the statistical occurrence of strokes in people with AF.

For young people with no other cardiovascular disease it hardly ever happens. This means that over a year or more the very small risk of life-threatening bleeding from taking anticoagulants is actually worse than the risk of having a stroke if you don't take them. So obviously it's not worth taking anticoagulants long term.

Older people and those with high blood and heart disease who are in AF have a higher risk of stroke if they don't take anticoagulants so if you add up the risk factors (the CHADS score) and it's more than 1 they probably have a higher risk from clots / stroke than they do from the bleeding risk of anticoagulation – so then it IS worth taking anticoagulation.

Just one risk factor (CHADS score=1) is borderline and there is no solid evidence of benefit though most "expert groups" recommend starting anticoagulation unless there is some problem with it. Unfortunately, with large profits being made from the new oral anticoagulants (NOACs) there is a lot of pressure on the "expert groups" NOT to do the obvious trial comparing anticoagulation with placebo for CHADS=1 AF patients. So we may never get evidence either way.

The important thing to understand is that there is no zero-risk option but the risks are very low indeed if your CHADS score is zero.

32 Replies

  • This is a most interesting topic for me. I'm 66 and have a history of high blood pressure, so I have a CHADS score of 2, which translates to a 2.2% risk of stroke. My BP has been well-managed for years but I still get that extra point. My cardiologist/EP told me that for every 5mg/day of Eliquis (apixaban), the risk is reduced by 0.7 percentage points. So 5mg/day cuts the risk to 1.5%, and 10mg/day cuts it further to 0.8%. I have a hard time seeing how a very small risk is significantly worse than a vanishingly small risk.

    Anyway, I've quite taking Eliquis because I don't have a problem with a 2.2% likelihood of anything. Considering the risk of a bleedout, the lack of an antidote, and the high cost ($5,000/year in the US), it seems more hazardous to take the stuff.

    I'm interested in your take on this, if you care to comment.


  • These have been posted before, they are both very good and worth a watch in themselves, but pertinently one of them describes in detail the ins and outs of the CHADS score.

    $5000 - crikey, and I complain about prescription charges!

  • I read it's £800 a year in the UK, with few tests required seems quite good.

  • Its currently about £8/item but you can buy a 'season ticket' for a year at £100-ish

  • I think everybody has trouble translating statistics into real life but a 2.2% risk is far worse than the risk of driving with no seat belts or taking a parachute jump with no reserve 'chute - so you have to ask yourself if you would feel comfortable with these. Plus the risk is cumulative, so over the next 10 years the risk of having a stroke is over 20% (before you get to 76).

    Like I said, there is no zero-risk option but the risks from bleeding, even without an available antidote, are far less – and slightly less than the risk with warfarin (even WITH an antidote).

    But cost is a significant issue and warfarin IS a helluva lot cheaper.

    It's an old saying that you should never gamble what you can't afford to lose.

  • I respect your opinion and respectfully prefer to differ.

    First of all, if it weren't for AF, I wouldn't know anything about the CHADS scale and wouldn't be taking an anticoagulant. My doc put me on low-dose aspirin years ago but I had bleeding issues so he agreed it was best to stop it. So I wonder, how does knowing about AF change the issue? (I have no heart issues at all - completely clear of any deposits, no arrhythmias any more, and in the superior range of cardio fitness for my age group.)

    My bottom line is this: I love wilderness canoeing and other outdoor activities, and the only way I'll stop them is to become physically incapable. If I were on an anticoagulant and got a cut or a serious bruise several days away from civilization, I could have a serious problem. I'll take the 2.2% risk over that. I suppose I could just stop the drug before going on a trip, but there are also the other issues.

    If we should never gamble what we can't afford to lose - and I see the wisdom in that - we should not drive cars, or especially motorcycles or bicycles, fly in airplanes, or cross the street. I don't mean to take this to extremes, but there are a lot of nasty things in everyday life with >2% probability.

    That said, I'll consider your arguments and who knows, maybe change my mind. It's been known to happen, though according to some, with <2% probability. :-)

  • Whilst I understand fully what you are saying and you have made your decision on QoL to you there are actually very few things indeed that are significantly detrimental in day to day life and most are actually small fractions of a percentage. For instance being killed in a train accident is I believe is less than in the order of magnitude of 1 in a million (ie 0.000001%) even 1 in 100,000 would only be 0.00001%). 2.2% is actually quite a high number.

  • I think of it this way:

    Line up 50 people. At 2% risk, one of them will have a stroke. Does it bother me to be one of the 50?

    Line up 100 people. At 1% risk, one of them will have a stroke. Do I feel significantly safer as one of the 100?

    I answer "no" to both questions.

  • BTW: $5,000 a year is a bit steep - it shouldn't cost more than ½ that - see


  • Wow, some of those prices are amazing - less than 1/3 the cost here. But since my cost is (only) $50/month, and my insurance wouldn't cover the ones on the list, I wouldn't be able to buy from any of those suppliers.

  • The principal you state is certainly a significantly increasing risk over a 10 year period but using statistics, probabilities and extrapolation it is not actually over 20% unless specific studies have been undertaken to determine that. However in all probability it will be in the teens of % chance.

    This assumes that the medical world doesn't have some special statistical adjustment factors.

  • OK, i'm no expert in statistics, just using the probably simplistic calculation 0.978¹⁰ = 0.8 approx. and taking into account that the risk rises as you get older gives the "over 20%" estimate. I was trying to express the idea that what might sound like a small(ish) annual risk gets to be a pretty big risk when taken over a reasonably expected healthy period of life.

  • I just had another look at the CHADSVASC page at MDCalc:


    I see at the top it says "CHADS2 Score for Atrial Fibrillation Stroke Risk." Since I don't have AF any more, I wonder if I even fit under that rubric.

    Sorry to muck up a perfectly good conversation with my irrelevancies! :-)

  • That obviously makes a big difference - the question of post (successful) ablation anticoagulation is quite different and you need to discuss this with your EP doc. I misunderstood your situation.

  • I am in a similar boat to Kodaska in that my CHADS2VASC score is 1.

    I had a PVI ablation 18 months ago for PAF which my EP deemed to be successful with no episodes of AF since. Ectopics only recorded on the monitors at 3 months and 6 months.

    My EP agreed that I stop Apixiban at the 12 month review of all aspects of my case.

    Although this seems to be a minefield of sometimes contrary information I have put my trust in my EP as he is the one who knows all the aspects of my case.

    I do wonder if the CHADS2VASC scoring, whilst a useful guidance is just the starting point in the decision process used by our EP's

    AF is not a "one size fits all" condition.

  • At my 6-month followup, my cardio/EP was alarmed that I cut my apixaban dose in half. He was firm that it should be taken according to the manufacturer's recommendations. (You can imagine what that did to his credibility.)

    Anyway, he said that we can't be sure the ablation was a success until I've been free of arrhythmias for 12 months. I haven't told him that I stopped the drug completely after only 9 months.

    He's never mentioned the CHADS approach.

  • To be fair, CHADS doesn't apply in the post-ablation situation – it's more about scar tissue in the left atrium and endothelialisation (the smooth "teflon" lining re-growing after the thermal injury)

  • Thank you for your informed feedback and patient responses. :-)

  • I have a score of 1 and I am on warfarin (no NOACs in North Wales!). I chose to go on it because my cousin also has AF and he had a series of TIAs at my age - looking at the family history I decided better to be anticoagulated than not...

  • I have just turned 65 and being female my score is now two. I have no other risk factors and my GP has said he does not see the need for anticoagulant at this point.

    I really don't know what to do as nearly everyone here says you should be on anticoagulant. what I don't understand is how they can tell when you have a stroke that it is AF related. If you have been a lifelong smoker or heavy drinker maybe obese and have CHF/ HIGH BP/ DIABETES/ among other things then how do you know what caused the stroke. also in the US they say 75 is the age when you start anticoagulant.

    Not so long ago Aspirin was given for protection for AF. we are now told it is useless Has there been any research into people who have taken A/C and the stopped taking them are you then you more as risk from stroke, or bleeds, so many questions not enough data for sold answers. it is all so very confusing.

  • The statistics tell us that whatever the risk of stroke from smoking, diabetes etc. if you ALSO have AF the risk jumps up – and it's that increase in risk that's "attributable to AF" and dramatically reduced by anticoagulation.

    So for an individual case you can't say it was the AF that caused a stroke but for a group of 100 people having a stroke you CAN say that AF was probably responsible for x% of them and that most of these could have been prevented by anticoagulation.

    There never was any evidence that aspirin reduces the risk in AF but it does reduce the risk from TCIAs and atheroma-related stroke.

  • Thank you for making that clear I think I need to go back to my GP.

  • At the end of the day statistics is not a science!!!! The old saying the exception proves the rule is very true in medical scenarios. Someone could be in persistent AF that IS symptomatic for 30 years and not suffer a stroke. Someone else with unsymptomatic AF could have a stroke within weeks.

    I have known a few people who have had severe strokes aged from early 40s to 70s. I certainly don't want to go there and will insist on remaining on anticoagulants for life. One was paralysed from the neck down and could only grunt and move eyes. Brain was fully there (his sister said it was 120% sharper). He lived like that for 17 years.

  • I have been anti-coagulated for years on the advice of my EP, despite having a CHADS score of zero (until I recently hit 65, so now my score is 1). I don't have any history, or family history of strokes or high blood pressure.



  • You're now in the borderline group I mentioned - but if you have nad no problems with anticoagulation so far you may as well carry on IMHO.

  • It is confusing Souljacs but I think the general rule is,naïf you've got AF, get anticoagulation!

  • See my new response.

  • I read on internet recently that in America, 90 % of AF related strokes that arrived at hospital were people who were either not anticoagulated or were on warfarin and out of range.

    Being on apixaban I found this quite reassuring.

  • Yes I would much rather take Apixaban one tablet every 12hrs than risk a stroke!I was an SRN and saw many people suffering,also their relatives who have to cope!

  • Just my feeling, having seen the disastrous effects of severe strokes.

  • Further to NooNoo's comment re Anticoagulation (which I agree with 100%) you don't know how much AF you actually have unless you are in persistent AF. I am in persistent AF. I understand that even those with paroxsymal AF who get symptomatic attacks can also have non symptomatic AF episodes. Also people can have episodes at night that they are unaware of.

  • Absolutely - that is very important.

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