Conclusion
Continued reliance only on outpatient and inpatient claims greatly underestimates AF prevalence and incidence in the general population by over 100%. Multimorbidity is common amongst AF patients (affecting approximately 1 in 10 patients). AF patients with 4 or more co-morbidities captured 20 to 40% of the AF cohorts depending on age groups and prevalent or incident cases. Our proposed methodology can guide future analysis of the quality/cost of care for progressive medical conditions at the population level.