Lower mortality rates in those living at moderate altitude

(up to about 2000 m) were shown to have lower mortality from coronary artery disease (CAD) and stroke (-22% and-12% per 1000 m) [1] and an about 50% lower risk of dying from Alzheimer's disease compared with their counterparts living at lower altitudes [2]. In contrast, reported altitude effects on cancer mortality are still conflicting [3]. However, due to shared risk factors, e.g. obesity and diabetes, in cardiovascular disease and cancer a shared biology for both disease entities may be assumed [4]. Therefore, it is hypothesized that mortality from certain cancers will decline with increasing altitude as demonstrated for CAD. Altitude-dependent mortality from CAD, male colorectal cancer and female breast cancer from 2003 to 2012 in Austria has been evaluated based on data from the Austrian Mortality Registries (Statistik Austria) [5]. Since the phenomenon of migration was most pronounced towards larger communities (>20,000 population) [5] only communities with a population below 20,000 were included to avoid important confounding from migration. Effects of more rural conditions have at least partly been evaluated by considering agriculture employment (<3%, 3-7%, and >7%). The total numbers of deaths amounted to 87,127 from CAD (ICD-10: 120-125), 7,640 from male colorectal cancer (ICD-10: C18-C21), and 8,953 from female breast cancer (ICD-10: C50). Age-standardized mortality rates (ASMR) per 100,000 population and 95% confidence intervals (CI), based on the assumption that the data follow a Poisson distribution, are reported (provided by Statistik Austria) [5]. The general life expectancy, e.g. in 2009, increased from low altitude (<251 m) to higher altitudes (1001 to about 2000 m) by about 2 years, in males from 76. ASMR from male colorectal cancer and female breast cancer decreased almost linearly from low to higher altitude by 45% and 38% (Figure 1). Independent of altitude, increasing agriculture employment was associated with a diminished ASMR from ischemic Letter to the Editors heart disease by about 15% for males and females [5]. In contrast, solely increasing altitude was related to the reduction in cancer mortality. The lower mortality from CAD at moderate altitudes is in close agreement with that reported from Switzerland [1]. Reduced oxygenation at higher altitudes and altitude-related climate changes, e.g. temperature, UV-radiation, and/or air-pollution but also differences in dietary behaviour were considered as potentially protective factors [1]. Similarly, a set of altitude-dependent environmental and lifestyle factors have been suggested to contribute to lower mortality from Alzheimer's disease at higher altitudes [2]. The present …