Stroke risk reassessment and oral anticoagulant initiation in primary care patients with atrial fibrillation: a ten-year follow-up

Aim: To examine the change in stroke risk over time and determine the proportion of patients with atrial fibrillation (AF) who were initiated on an oral anticoagulant (OAC) as their stroke risk increased from low/moderate to high, using the Australian general practice data set, MedicineInsight.

Methods: A total of 2296 patients diagnosed with AF between 1 January 2007 and 31 December 2008, aged 18 years or older and not initiated on an OAC before 2009, were included. We assessed the change in stroke risk and the proportion of patients who had a recorded prescription of an OAC, each year from 1 January 2009 to 31 December 2018.

Results: At baseline, 23.9%, 22.9% and 53.2% were categorised as being at low (score = 0), moderate (score = 1) and high stroke risk (score ≥ 2), respectively, using the sexless CHA2DS₂-VASc (CHA2DS₂-VA) score. Overall, the CHA₂DS₂-VA score increased by a mean of 1.34 (95% confidence interval, 1.29-1.39) points over the study period. Nearly two-thirds of patients (65%, 412/632) whose stroke risk changed from baseline low/moderate to high were subsequently prescribed an OAC. The median (interquartile range) lag time from becoming high stroke risk to having OAC initiation was 2 (5) years.

Conclusions: Nearly one-third of patients reclassified as being at high risk of stroke during the study period were not prescribed OAC therapy. Furthermore, the delay in OAC initiation following classification as being at high risk was a median of 2 years, suggesting that more frequent stroke reassessment is needed.