Population-Wide Trends in Aortic Stenosis Incidence and Outcomes
A number of registries and population-based cohort studies have shown a consistent and significant association between age and the prevalence of calcific aortic stenosis1-3. It is therefore generally assumed that the progressive aging of the population in developed countries will result in an increasing number of patients presenting with clinically significant aortic stenosis. Data from Medicare fee-for-service beneficiaries4 support this concept, in which the number of patients over the age of 65 hospitalized for aortic valve surgery increased from 24,568 in 1989 to 31,380 in 2011, a rate of increase greater than that of the general U.S. population over the age of 65 during the same period5. The rate of increase in surgical procedures was most striking in patients aged 85 or older in whom the adjusted rate rose from 48 to 91 per 100,000 person-years during that decade4. Data based on surgical procedures alone, of course, does not provide accurate insights into the true incidence of aortic stenosis, as surgical data pertain predominantly to symptomatic patients with severe aortic stenosis, excluding the larger number of patients with either asymptomatic disease or less severe stenosis, as well as those with extensive comorbidities considered too high risk for surgery. Increasing numbers of aortic valve replacements also reflect advances in surgical expertise and the greater comfort of referring physicians in referring elderly patients for surgery. In other words, the use of this type of data as a surrogate for true incidence is flawed because the referral patterns are not stable. This is a form of ascertainment bias.
- Received February 13, 2015.
- Accepted February 13, 2015.