In a large dataset of primary care patients, use of CHA2DS2-VA score leads to almost universal recommendation for anticoagulation in those aged 65 years and over with atrial fibrillation
Bibliographic record
Abstract
Abstract Background Treatment with oral anticoagulants (OAC) for high-risk atrial fibrillation (AF) patients can reduce stroke risk by two-thirds. From 2012–14, the OAC treatment recommendation threshold in international guidelines moved from CHADS2 ≥2 to CHA2DS2-VASc ≥2 (men) or ≥3 (women), equivalent to a “sexless” CHA2DS2-VA≥2. This move aimed to identify truly low risk patients who did not need OAC treatment. General practitioners (GPs) report barriers about assessing patient suitability for OAC. Objectives To compare the proportion of AF patients for whom OAC treatment is recommended under CHADS2 ≥2 and CHA2DS2-VA ≥2, and to look at the drivers of any differences, using an existing dataset. Methods Analyses were conducted on a large Australian general practice dataset collated during previous studies (2011–2019), with deidentified data extracted from the clinical records system at a single timepoint for regularly-attending adult patients from 164 practices. CHADS2 and CHA2DS2-VA scores were calculated for AF patients with sufficient data available and the proportion with CHADS2 and CHA2DS2-VA ≥2 was compared using chi-square tests. Results There were records for 340,463 patients, of which 285,635 (8,294 with AF) had sufficient data to calculate CHADS2 and CHA2DS2-VA scores. Among AF patients of all ages, the CHA2DS2-VA ≥2 threshold captured a significantly higher proportion than CHADS2≥2 (85% vs 68%, p<0.0001). In AF patients aged ≥65 years, the CHA2DS2-VA ≥2 threshold also captured a significantly higher proportion than CHADS2 ≥2 (96% vs 76%, p<0.0001). Almost all older patients (≥65 years) who were captured by CHA2DS2-VA ≥2 but not CHADS2 ≥2 (n=1395) qualified on the basis of age, with only 1.4% eligible because of age 65–74 years and vascular disease history. Conclusions The change from CHAD2 to CHA2DS2-VA has resulted in a significantly higher proportion of patients with AF being recommended OAC treatment under the guidelines, driven almost entirely by the revised scoring for age. Among AF patients aged ≥65 years, almost all (96%) were recommended OAC treatment under CHA2DS2-VA, demonstrating that AF is strongly associated with other vascular pathology. These findings support the Canadian guidelines, which recommend OAC treatment for all AF cases aged ≥65 years. The findings also reinforce the argument that AF screening in those aged ≥65 years is justified, as almost all patients with prevalent AF in that age group are eligible for OAC treatment. These results suggest could be an argument for simplifying the treatment message for GPs, which may reduce barriers and further improve treatment rates. High rates of associated vascular pathology in AF patients suggest that additional management strategies are also justified, including promotion of exercise, smoking cessation, and treatment of associated conditions such as hypertension and diabetes. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): RACGP Foundation / HCF Research Foundation GrantUniversity of Notre Dame Australia Research Grant
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.028 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".