EU RO PEAN SOCIETY O F CARDIOLOGY ®Original scientific paper Performance of the CHARGE-AF risk model for incident atrial fibrillation in the EPIC Norfolk cohort

Background: Identification of individuals at risk for developing atrial fibrillation (AF) will help to target screening and preventive interventions. We aimed to validate the CHARGE-AF model (including variables age, race, height, weight, blood pressure, smoking, antihypertensive medication, diabetes, myocardial infarction and heart failure) for prediction of five-year incident AF in a representative European population with a wide age range. Methods and results: The CHARGE-AF model was calculated in 24,020 participants of the population-based EPIC Norfolk study with 236 cases of hospitalization with diagnosis of AF within five years. The model showed good dis-crimination (c-statistic 0.81, 95 % confidence interval (CI) 0.75–0.85), but weak calibration (Chi2-statistic 142) with an almost two-fold overestimation of AF incidence. A recalibration to characteristics of the European Prospective Investigation into Cancer and Nutrition (EPIC) Norfolk cohort improved calibration considerably (Chi2-statistic 13.3), with acceptable discrimination in participants both>65 and 65 years of age (c-statistics 0.70, 95 % CI 0.61–0.77 and 0.83, 95 % CI 0.74–0.88). The recalibrated model also showed good discrimination in participants free of cardiovascular disease (c-statistics 0.80, 95 % CI 0.75–0.84). Categories of predicted risk (<2.5%, 2.5–5 % or>5%) showed good concordance with observed five-year AF incidence of 0.62%, 3.49 % and 8.74 % (log rank test p< 0.001), respectively. Conclusion: A recalibration of the CHARGE-AF model is necessary for accurate predictions of five-year risk of AF in the EPIC Norfolk population. The recalibrated model showed good discrimination across a wide age range and in individuals free of cardiovascular disease, and hence is broadly applicable in primary care to identify people at risk for development of AF