The score is a reasonable prediction of one's risk, whether due to a comorbidity or simply due to aging, since those are strong co-factors in those who historically have more strokes. The decision to actually take a prophylactic against strokes is a decision shared between the patient and the physician assigning the risk. At some point, though, if I were a physician some of whose patients, well aged, were still taking a DOAC, I would counsel them to consider the risk of bleeding to death from something like a hip fracture, which a DOAC will exacerbate. Hip factors and heart attacks are also common among the aged, as are cancers.