Skip navigation
Link to Back issues listing | Back Issue Listing with content Index | Subject Index

Prevalence of Atrial Fibrillation (AF)

Study
Results
Comment

Bandolier is interested in common conditions, and in good evidence on prevalence and natural history of disease. Atrial fibrillation (AF) is just one of the common conditions that seems to creep up on us as we get older, and the number of people on warfarin is huge. So a report on the prevalence of the condition [1] is welcome, both because it gives us good information, but it also informs on how to get it.

Study


This was a cross-sectional study of adults older than 20 years enrolled in a large (1.9 million) health maintenance organisation in California. The enrolled population was examined to discover the number who had AF diagnosed in the 18 months between mid 1996 and end 1997.

Searching several automated clinical databases for a diagnosis of AF identified patients with atrial fibrillation. One database of electrocardiograms included all diagnoses for inpatient and outpatient electrocardiograms. Exclusion criteria were applied to identify only those with nontransient AF, and who were also health plan members in the source population. So transient AF after cardiac surgery was not included, nor AF relating to recent-onset hyperthyroidism.

The same databases were searched for five years beforehand for diagnoses of valvular heart disease, stroke, AF, coronary heart disease, hypertension and diabetes. Patient demographics were available, including ethnicity, for 89% of patients.

The denominator for the prevalence calculation was the adult population of plan members, and the results were presented both for the total population and by different age ranges.

Results


There were 17,974 adults with diagnosed, nontransient atrial fibrillation, and it was estimated by testing that 87% had AF confirmed by electrocardiogram. The overall prevalence in the 1.9 million members was 0.95% (95% confidence interval 0.94% to 0.96%). This increased with age from low levels in the under 55s to about 10% in the over-80s (Figure 1).

Figure 1: Prevalence of AF in California



Prevalence was greater in men than in women (1.1% vs 0.8%), and among patients aged over 55 was more common in white (2.2%) than black (1.5%) patients.

The paper also projected these figures to the whole population of the USA, both now and for the next 50 years. Based on the growth in older people expected over this period the number of people with AF in the USA was expected to grow from a current 2.3 million to 5.6 million by 2050.

Comment


One interesting feature of this paper is that it exemplified how the use of electronic databases, together with coding of disease, testing of data to ensure its quality, and a bit of thought can give interesting information on the amount of disease that we have to deal with. It is worth reading alongside two other recent reviews of AF [2,3] that give a wider perspective on the clinical implications of this disease burden.

References:

  1. AS Go et al. Prevalence of diagnosed atrial fibrillation in adults. JAMA 2001 285:2370-2375.
  2. SS Chugh et al. Epidemiology and natural history of atrial fibrillation: clinical implications. Journal of the American College of Cardiology 2001 37: 371-378.
  3. WB Kannel et al. Prevalence, incidence, prognosis, and predisposing conditions for atrial fibrillation: population-based estimates. American Journal of Cardiology 1998 82: 2N-9N.
previous or next story in this issue