Trends in Age at Diagnosis in Individuals with Aortic Stenosis

Abstract

To the Editor: Aortic stenosis (AS) is the most common valvular disease in elderly adults,1 and its prevalence is expected to grow with the aging of the population.2-5 In the last decade, new therapies have become available for the treatment of symptomatic severe AS in elderly adults in whom the condition is deemed to be inoperable or who are at high risk for surgery,6 which poses significant implications for healthcare systems.7 Data regarding long-term trends in age at diagnosis of AS are scarce, so this study was designed to evaluate these temporal trends, with particular emphasis on individuals with severe AS. Between January 1, 1991, and December 31, 2015, 107,880 individuals aged 18 and older who underwent a first transthoracic echocardiogram within the public health care system of the Area Sanitaria de A Coruña in Spain (2,754 km2, 2013 census: 553,490 residents) and in whom comprehensive data regarding demographic characteristics and AS severity assessment were available were identified. The 25-year period was divided into five quinquennia (1991–1995, 1996–2000, 2001–2005, 2006–2010, 2011–2015), and trends across these epochs were assessed. For the purposes of this study, AS was defined on the basis of a maximal jet velocity of 2 m/s or greater through a native aortic valve and was further classified as mild (maximal jet velocity 2.0–2.9 m/s or mean gradient <20 mmHg), moderate (maximal jet velocity 3.0–3.9 m/s or mean gradient 20–39 mmHg), or severe (maximal jet velocity ≥4 m/s or mean gradient ≥40 mmHg) according to current guidelines.8 Trends over time were tested using the Cuzick nonparametric test for continuous variables and the Cochran–Armitage test for binary categorical variables. The local research ethics committee approved the study. Overall, 18,731 (17.4%) individuals met criteria for AS, including 12,590 (67.2%) with mild, 3,330 (17.8%) with moderate, and 2,811 (15%) with severe AS. Mean age upon referral of individuals with any degree of AS increased gradually and significantly over time (64.9 ± 13.3 in 1991–1995, 69.8 ± 12.0 in 1996–2000, 71.2 ± 11.8 in 2001–2005, 72.6 ± 11.6 in 2006–2010, 74.5 ± 11.8 in 2011–2015; P for trend <.001). These results were consistent in the subset of individuals with severe AS, in whom mean age ranged from 67.3 ± 12.9 in the first quinquennium to 76.8 ± 10.7 in the last (P for trend <.001). The proportion of individuals aged 80 and older also increased gradually from 8.5% to 36.2% in those with any degree of AS and from 12.8% to 45.9% in those with severe AS (P for trend <.001 for both comparisons) (Figure 1). No significant trends in sex were observed; the proportion of male subjects with any degree of AS ranged from 49.9% in 1991–1995 to 50.1% in 2011–2015 (P for trend = .09). In this study, mean age at the time of diagnosis of AS increased gradually by almost 10 years over a period of 25 years, and this finding was consistent in the subset of individuals with severe AS. In particular, the proportion of individuals aged 80 years and older with any degree of AS at the time of diagnosis quadrupled, and the proportion of those aged 80 and older with severe AS tripled. These findings occurred despite greater availability of echocardiography, which would be expected to lead to earlier detection of the disease. The results of this study agree with those recently reported in a study9 that found that, not only age, but also predicted surgical risk of individuals with severe AS referred for echocardiography increased over time. It is likely that progressive aging of the population explains these trends in the burden of AS in elderly adults because degenerative etiology (which correlates with increasing age) remains the most frequent cause of AS.10 Other possible explanations include a progressive decline in the incidence of rheumatic heart disease in industrialized countries in recent decades, and a lower threshold for referring elderly adults with suspected valvular heart disease for echocardiography. In individuals with severe symptomatic AS, older age is associated with greater operative risks and more comorbidities. Given the significant changes in the management of elderly adults with severe AS over the past few years, including the advent of transcatheter aortic valve implantation,6 these results may have substantial implications for healthcare planning. Author Contributions: Bouzas-Mosquera: study concept and design, acquisition of subjects and data, analysis and interpretation of data, preparation of manuscript. Broullón, Álvarez-García, Vázquez-Rodríguez: acquisition of subjects and data, review of manuscript. Sponsor's Role: The study had no external funding.