Translation of clinical practice to research: the VETS and ETHOS epidemiologic prospective cohorts

Abstract

For >30 years, the Exercise Testing and Health Outcomes Study (ETHOS) and the Veterans Exercise Testing Study (VETS) cohorts have contributed significantly to the understanding of the association between cardiorespiratory fitness (CRF), health outcomes, and the prevention of chronic disease. Multiple reports from these studies have consistently shown an inverse and graded association between higher CRF and the incidence of chronic conditions including cardiovascular disease, site-specific cancers, chronic kidney disease, rhythm disturbances, and neurological conditions. In addition, higher CRF is inversely related to health care costs. Among individuals whose CRF level improves over periods of time ranging from 5 to 7 years, improvements in health outcomes have been observed, and the converse is true among those who decrease CRF over time. The Veterans Administration Health Care System (VAHCS) has pioneered electronic medical records that have facilitated epidemiologic research and have provided the foundation for the ETHOS and VETS cohorts. The VAHCS is particularly suited for epidemiologic studies because patients can be accurately traced through VAHCS benefits services. These studies have helped formulate guidelines on exercise testing as well as recommendations from national and international health organizations on physical activity. In addition, they have provided strong support for efforts to reduce sedentary behavior, promote physical activity, and enhance CRF by public health organizations and healthcare systems in order to reduce the risk of chronic disease. This paper outlines the development of the ETHOS and VETS cohorts and highlights key studies contributing to our understanding of CRF as a critical health determinant.

Keywords: cardiorespiratory fitness; cardiovascular disease; epidemiology; exercise testing; exercise testing (CPET).

Figure 1

Exercise test reporting aide (EXTRA) released by Mosby publishers in 1996. Reproduced with permission from “Extra: Exercise Testing and Reporting Aide” by Victor Froleicher, 1996.

Figure 2

Bars from left to right within each age group represent the cardiorespiratory fitness (CRF) categories on the basis of the percentile of age-specific peak METs achieved (≤20%, 21%–40%, 41%–60%, 61%–80%, 81%–97%, and ≥98%). The mortality risk associated with CRF within each age category is depicted by the HRs (numbers) above each bar. Red bars represent the CRF category for each age group and the peak METs required for approximately 50% lower mortality risk. Reproduced with permission from “Relative Risk According to Cardiorespiratory Fitness Categories Across the Age Spectrum” by Peter Kokkinos, Charles Faselis, Immanuel Babu Henry Samuel, Andreas Pittaras, Michael Doumas, Rayelynn Murphy, Michael S. Heimall, Xuemei Sui, Jiajia Zhang, and Jonathan Myers.

Figure 3

Relative mortality risk by fitness category among patients taking and not taking statins. Adapted with permission from “Relative mortality risk by fitness category among patients taking and not taking statins” by Prof Peter F Kokkinos, Charles Faselis, Prof Jonathan Myers, Demosthenes Panagiotakos and Michael Doumas, licensed under CC BY-NC-ND.

Figure 4

The association between costs per patient per year (USD) and exercise capacity (% age-predicted). USD, US dollars. Reproduced with permission from “The association between costs per patient per year (USD) and exercise capacity (% age-predicted)” by Jonathan Myers, Rachelle Doom, Robert King, Holly Fonda, Khin Chan, Peter Kokkinos and David H. Rehkopf, licensed under CC BY-NC-ND.