Davies M, Wise L and Shakir S.

Background

Since its incorporation in the European Society of Cardiology guidelines in 2010, the CHA2DS2-VASc score is widely used to characterise the risk of stroke in patients (pts) with atrial fibrillation (AF). It is frequently calculated in pharmacoepidemiological studies through retrospective application of the component criteria included in the risk score. CHA2DS2-VASc Scores of 0, 1, or ≥2 indicate low, moderate, or high stroke risk, respectively.

Objectives

To describe the distribution of CHA2DS2-VASc scores and individual stroke risk components in two cohorts of pts prescribed rivaroxaban for AF in primary (1 o) vs. secondary (2 o) care.

Methods

Two PASS were conducted to investigate the safety of rivaroxaban in pts with AF in 1o care (Modified-Prescription Event Monitoring) and 2 o care (Specialist Cohort Event Monitoring) (2012-2016). Baseline characteristics were provided by general practitioners (1o care) and specialist prescribers (2 o care) using customised questionnaires. An algorithm was used to compute a CHA2DS2-VASc score (0 – 9) for each pt from fixed response options or open questions, according to published guidelines.

Results

The response rate for baseline questionnaires was lower in 1o care vs. 2 o care (22.3% vs. 99.7%). The 1o care cohort consisted of 10225 pts with a primary indication of AF (median age 78 yrs [IQR 70-84]; 5253 [51.4%] male). The median CHA2DS2-VASc score was 4 (IQR 3-5) reflecting a high risk of stroke. The 2 o care cohort consisted of 965 pts with a primary indication of AF (median age 76 yrs [IQR 69-83]; 517 [53.6%] male), with a median CHA2DS2-VASc score of 4 (IQR 3-6). There were a higher proportion of pts with a score of 6 – 9 in 2 o care vs. 1 o care. The proportions of pts in 1o care vs. 2 o care with each criterion were:

• Age 65-74 yrs (25.7% vs. 25.8%)
• ≥75 yrs (61.8% vs. 58.0%)
• Female (48.6% vs. 46.5%)
• Congestive Heart Failure/Left ventricular Dysfunction (14.3% vs. 14.6%)
• History Hypertension (82.6% vs. 73.2%)
• History Stroke, Transient Ischaemic Attack (TIA) or Thromboembolism (TE) (19.8% vs. 46.9%)
• Vascular disease (11.3% vs. 26.9%)
• Diabetes Mellitus (17.2% vs. 18.8%)

Conclusion

These results suggest that pts initiated rivaroxaban for AF in 2 o care are more likely to have a history of stroke, TIA, TE or vascular disease than pts treated in 1o care. This may mean that pts considered to be at ‘higher risk’ with greater co-morbidities are more likely to be managed in 2 o care, or that co-morbidities may be less well recorded in 1o care.

Ref: Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest. 2010;137(2):263-72.