When we ran every combination of inputs through the atrial fibrillation (AF) stroke score, dropping the point for female sex moved none of the 192 into another guideline band, while counting age from 50 instead of 65, as a version built on data from Taiwan does, moved 10 of the 64 combinations aged 50 to 64 into a higher one. The European Society of Cardiology (ESC) dropped that point on 30 August 2024, replacing CHA2DS2-VASc with CHA2DS2-VA, and said as much: its earlier rules already asked women for one more point, so the sex-free score "has effectively been in place".
The change lowered women's scores and left their risk where it was, because the cut-point a woman's total meets fell by one too. What varies widely is the stroke rate printed beside a score, which depends on whose cohort supplied it.
Unchanged guideline classes stem from women's cut-points sitting a point higher
- C: heart failure, 1 point
- H: high blood pressure, 1
- A2: age 75 or over, 2
- D: diabetes, 1
- S2: previous stroke, transient ischaemic attack (often called a mini-stroke) or arterial clot, 2
- V: coronary or peripheral artery disease, 1
- A: age 65 to 74, 1
- Sc: female sex, 1, dropped in CHA2DS2-VA
Under ESC's 2020 rule, anticoagulants (blood-thinning medicines) were "recommended" (class I) at a CHA2DS2-VASc of 2 or more in men and 3 or more in women, and "should be considered" (class IIa) at 1 in men and 2 in women. The 2024 rule applies 2 and 1 to everyone. A woman under 65 with no other condition scored 1, below the women's band at 2; she now scores 0, below the band at 1. Across all 192 combinations of age band, sex and condition, the 96 female ones fell by one point and none changed class, matching a UK records study by Yoshimura and colleagues.
ESC also widened its heart failure and vascular definitions, which can move a real person's total. Its 2024 guideline gives its reasons: female sex is "an age-dependent stroke risk modifier rather than a risk factor per se", it "complicates clinical practice", and it "omits individuals who identify as non-binary, transgender, or are undergoing sex hormone therapy".
An extra point for women goes back to a 1.6-fold estimate from an older review
A 2012 BMJ paper by Friberg and colleagues credits the Stroke in Atrial Fibrillation Working Group with finding that female sex "multiplied the risk of stroke by 1.6-fold". In Friberg's untreated Swedish cohort, diagnosed in 2005 to 2008, women had 6.2% a year of ischaemic stroke (from a blocked artery) against 4.2% for men; the adjusted hazard ratio was 1.18.
In Taiwan's insurance records for 2001 to 2013, Wu and colleagues found women's hazard lower than men's up to 65 and higher only above 75. A 2018 Danish study called female sex "a risk modifier", and in Finland its link with stroke had lost statistical significance by 2018.
Singapore's sex-free score traces back to November 2017
Singapore's Agency for Care Effectiveness guideline, first published on 20 November 2017, already used a "modified" score "where gender does not contribute", according to an archived copy; its web edition was last updated on 7 July 2026. It reads "Start anticoagulation therapy" at 2 or more and "Consider anticoagulation" at 1. Singapore was not first: its 2017 text noted that "recent guidelines have also disregarded gender".
The edition dated 28 November 2023 gives 1.1 strokes per 100 patients per year at Singapore's sex-free score of 1, citing a 2022 paper in the Journal of Clinical Medicine that the journal retracted on 26 October 2023, concluding that its overall findings "could not be relied upon". The 1.1 matches a rate in that paper's table; we could not tell whether the figure came from it. Singapore's sex-free score predates the paper, and its threshold of 2 or more is the one ESC 2024 and Thailand's 2025 guideline use.
| Guideline | Date | Sex point counted |
|---|---|---|
| Singapore | Nov 2017 | No |
| Asia Pacific Heart Rhythm Society | Nov 2021 | Yes |
| US, ACC/AHA/ACCP/HRS | Nov 2023 | Yes |
| European Society of Cardiology | Aug 2024 | No |
| Heart Association of Thailand | Oct 2025 | No |
The Asia-Pacific society warned that ignoring sex "may underestimate the stroke risks in female patients" with other factors. The UK's NICE NG196 (2021) applies "offer" at a CHA2DS2-VASc of 2 or more for both sexes, so on our arithmetic five female combinations fall under its "offer" and ESC 2024's "should be considered". As for Malaysia, we could not open its guideline.
Every percentage printed beside a score derives from a single cohort
A 2019 German study by Wicke and colleagues set other cohorts beside its own. Ischaemic stroke per year without anticoagulation, with study years where we have them:
| Cohort | Score 2 | Score 6 |
|---|---|---|
| Germany, 2015–16 | 1.1% | 3.3% |
| United Kingdom | 1.4% | 12.1% |
| Netherlands | 1.9% | 7.1% |
| South Korea | 1.9% | 8.4% |
| Sweden, 2005–08 | 2.2% | 9.7% |
On our arithmetic the highest is twice the lowest at score 2 and nearly four times at score 6. A CHA2DS2-VASc of 0 can only be a man's: Sweden reported 0.2% a year there, while an insurance-claims cohort in Taiwan studied by Chao and colleagues reported 1.15% a year of ischaemic stroke for untreated men scoring 0, and 1.95% for those aged 50 to 64. Two cohorts disagree about one profile; neither corrects the other. The same group's age-50 version, which the US guideline lists as "Validated in Asian cohort", moved our 10.
Until 12 October 2026 our CHA2DS2-VASc calculator printed the Swedish series with no cohort named, used the 2019 US wording "may be considered", said a woman could "fall on different sides of the two guidelines", and scored a blank age as 60. The revision made that day uses the 2023 wording, names the cohort and the spread, and refuses a blank age.
US guidelines' middle band grows out of an annual-risk range rather than points
The 2023 ACC/AHA/ACCP/HRS guideline sets its bands by estimated risk: at 2% a year or more anticoagulation "is recommended", and from 1% to under 2%, which it equates with a score of 1 in men and 2 in women, it "is reasonable". Friberg's table of ischaemic stroke without anticoagulation falls outside that range on both sides, 0.6% a year at a score of 1 and 2.2% at 2; one reason is that it pools men and women by total. The guideline says "any score should be viewed as only an estimate of true risk".
SINGLE-AF, a randomised trial in this band in South Korea, reported in 2026. Over 24 months, 4 of 902 people given a direct oral anticoagulant (DOAC) and 13 of 901 given none had a primary event, a composite of stroke, embolism, major bleeding or cardiovascular death. The open-label trial's participants averaged 60.4 years, and 23.7% were women.
The score came out of people without mechanical valves or moderate-to-severe mitral stenosis
Episodes picked up by a pacemaker or implanted monitor in people with no prior AF diagnosis carry their own duration-based thresholds in the US guideline. Singapore's and NICE's guidelines assess bleeding risk separately. Singapore's guideline states the score's boundary: it "was developed to estimate stroke risk in patients with AF without mechanical heart valves or moderate-to-severe mitral stenosis".
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