1.5 million atrial fibrillation cases may be undiagnosed in US
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Key takeaways:
- Data from 2015 suggest an overall undiagnosed atrial fibrillation prevalence estimate of 11%.
- Undiagnosed patients were more likely to be women, to be older and to have more comorbidities.
An analysis of five U.S. medical claims databases suggests as many as 23% of 5.6 million to 6.6 million presumptive atrial fibrillation cases are undiagnosed, with many undiagnosed patients likely eligible for oral anticoagulant treatment.
“[A] barrier to determining AF prevalence is the presence of undiagnosed AF,” Mintu P. Turakhia, MD, MAS, associate professor of cardiovascular medicine at the Stanford School of Medicine, and colleagues wrote in in Clinical Cardiology. “Undiagnosed AF cases are especially challenging, as it is estimated that about a third of the AF population is asymptomatic. As such, it is often hospitalization for acute symptoms such as ischemic stroke that brings them to light. There is mounting evidence of considerable proportions of undiagnosed AF cases in the United States and Europe.”
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In a retrospective study, Turakhia and colleagues analyzed patient information from five U.S. medical claims data sets from 2012 to 2017. Researchers estimated undiagnosed AF based on the observed incidence of ischemic stroke, systemic embolism and AF incidence after a stroke or systemic embolism.
The diagnosed AF cohort included patients with AF documented between the first quarter of 2014 and the third quarter of 2015. The undiagnosed AF cohort were patients with assumed undiagnosed AF in the year before a stroke or systemic embolism and who were newly diagnosed with AF in the 3 months after stroke or systemic embolism. Researchers calculated the incidence of stroke and systemic embolism among all patients with AF and the ratio of number of undiagnosed AF patients to stroke rate. Age‐ and sex‐adjusted estimates were stratified by a period of assumed undiagnosed AF before an AF diagnosis (1 or 2 years).
The estimated U.S. prevalence of AF (diagnosed and undiagnosed) in the third quarter of 2015 was 5,628,000 cases, of which 11% were undiagnosed.
The assumed 2‐year undiagnosed AF prevalence was 23% of the total prevalent patients with AF. Compared with diagnosed patients, those who remained undiagnosed tended to be women, to be older, to have more comorbidities and to have higher CHA2DS2‐VASc scores.
“The data we generated from back‐calculation suggest considerable proportions of undiagnosed patients, in the context of growing overall prevalence, with diagnosed cases increasing from 3.7 to 5 million within 2 years and as many as 1.5 million presumptive undiagnosed cases at the end of that period,” the researchers wrote. “Together with the known burden of AF, this expanding unmet need underscores the critical importance of early detection. Our data can support both disease surveillance and future research and policy initiatives aimed at addressing this diagnostic gap.”
Perspective
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This retrospective study using a back-calculation method highlights the silent but potentially deadly burden of undiagnosed atrial fibrillation. I would not be surprised if this is actually an underestimation of the true burden, especially if we begin to factor in the large proportion of patients with subclinical AF. This arrhythmia is silent in a substantial proportion of these patients and can often manifest for the first time with either a stroke or a cardiovascular event.
This paper highlights the need for better digital surveillance strategies via wearables or smartphones that can put into play preventative approaches to reduce the downstream burden of undiagnosed AF on the health care system.
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