Interesting analysis from Annals of Internal Medicine. The decision to start anticoagulation in atrial fibrillation, using CHADSVASC score is not so clear cut. See tables below.
Shah, S., Eckman, M., Aspberg, S., Go, A. and Singer, D. (2018). Effect of Variation in Published Stroke Rates on the Net Clinical Benefit of Anticoagulation for Atrial Fibrillation. Annals of Internal Medicine.