Are Stroke Risk Scores Transportable to Newly Diagnosed Atrial Fibrillation?: A Model-Based Evaluation.

BACKGROUND: Stroke risk scores for atrial fibrillation (AF) were developed from established AF cohorts conditioned on pre-entry stroke-free status, potentially underestimating risk in newly diagnosed AF. METHODS AND RESULTS: To evaluate the transportability of these scores, we calibrated frailty survival models to score-deriving cohorts and mapped stroke risks at cohort entry back to AF diagnosis. Under model assumptions, risks near 1%/year remained stable; higher risks were mapped to substantial, scenario-dependent initial levels. CONCLUSIONS: Our conceptual modeling provides theoretical reassurance for score-guided decision-making in patients with newly diagnosed AF, while suggesting a potential urgency for those at high risk.