Epidemiological characterization of ischemic heart disease at different altitudes: a nationwide population-based analysis from 2011 to 2021 in Ecuador

Abstract

Background Cardiovascular diseases, including ischemic heart disease, are the leading cause of prema- ture death and disability worldwide. While traditional risk factors such as smoking, obesity, and diabetes have been thoroughly investigated, non-traditional risk factors like high-alti- tude exposure remain underexplored. This study aims to examine the incidence and mortal- ity rates of ischemic heart disease over the past decade in Ecuador, a country with a diverse altitude profile spanning from 0 to 4,300 meters. Methods We conducted a geographic distribution analysis of ischemic heart disease in Ecuador, uti- lizing hospital discharge and mortality data from the National Institute of Census and Statis- tics for the years 2011–2021. Altitude exposure was categorized according to two distinct classifications: the traditional division into low (< 2,500 m) and high (> 2,500 m) altitudes, as well as the classification proposed by the International Society of Mountain Medicine, which delineates low (< 1,500 m), moderate (1,500–2,500 m), high (2,500–3,500 m), and very high (3,500–5,800 m) altitudes. Findings From 2011–2021, we analyzed 49,765 IHD-related hospital admissions and 62,620 deaths. Men had an age-adjusted incidence rate of 55.08/100,000 and a mortality rate of 47.2/ 100,000, compared to 20.77/100,000 and 34.8/100,000 in women. Incidence and mortality surged in 2020 by 83% in men and 75% in women. Altitudinal stratification revealed higher IHD rates at lower altitudes (<2500 m), averaging 61.65 and 121.8 per 100,000 for incidence and mortality, which declined to 25.9 and 38.5 at elevations >2500 m. Men had more pronounced rates across altitudes, exhibiting 138.7% and 150.0% higher incidence at low and high altitudes respectively, and mortality rates increased by 48.3% at low altitudes and 23.2% at high altitudes relative to women. Conclusion Ecuador bears a significant burden of ischemic heart disease (IHD), with men being more affected than women in terms of incidence. However, women have a higher percentage of mortality post-hospital admission. Regarding elevation, our analysis, using two different alti- tude cutoff points, reveals higher mortality rates in low-altitude regions compared to high- altitude areas, suggesting a potential protective effect of high elevation on IHD risk. Never- theless, a definitive dose-response relationship between high altitude and reduced IHD risk could not be conclusively established.