Physical activity and arterial stiffness in older adults of the SAPALDIA 3 cohort study

Background: This PhD thesis presents the research work of the Swiss National Science Foundation (SNSF) funded project (#147022) entitled “Physical activity as a life style component of aggressive decrease of atherosclerotic modifiers (ADAM) in elderly subjects: the SAPALDIA Cohort Study.” The study has been performed against the background that a physically active lifestyle is linked with decreased risk of cardiovascular disease (CVD) and CVD events, such as myocardial infarction or stroke, at all ages among others through improvements in arterial stiffness reflecting arterial remodeling. Arterial stiffness proved to be an independent predictor of all-cause and cardiovascular mortality. However, arterial stiffness in association with physical activity of different intensities has insufficiently been studied in Caucasian cohorts of older adults and not at all concerning the change of physical activity over time in older Caucasian adults.
Aims: The research program realized the following aims: (1) evaluation of the measuring characteristics of the novel cardio-ankle vascular index (CAVI) and the brachial-ankle pulse wave velocity (baPWV) as marker of arterial stiffness for the first time in a Caucasian cohort of older adults and analyses of the (2) cross-sectional and (3) longitudinal association between physical activity as a preventive life style component of aggressive decrease of atherosclerotic modifiers and CVD assessed as arterial stiffness in this ageing Caucasian clientele.
Methods: The PhD thesis comprised a large nested study of the second follow-up of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA 3) including 3026 participants aged 50-81 years. SAPALDIA is a multi-center cohort study in eight distinct areas representative of the environmental diversity of Switzerland geared to the investigation of respiratory and cardiovascular health (including morbidity and mortality) in its ageing cohort. Mixed central and peripheral arterial stiffness was measured oscillometrically and simultaneously by CAVI and baPWV using a non-invasive VaSera VS-1500N vascular screening system (Fukuda Denshi, Tokyo, Japan). The self-reported International Physical Activity Questionnaire (IPAQ) long version was administered to classify the physical activity level in 3072 individuals for the cross-sectional analyses. The IPAQ long form asks for the frequency and duration of moderate and vigorous physical activity in different domains performed during the last seven days (leisure time, domestic and gardening activities, work-related, transport-related). Furthermore, we assessed physical activity in SAPALDIA 2 (2001-2003) and SAPALDIA 3 (2010-2011) using a short questionnaire with a cut-off of at least 150 minutes of moderate-to-vigorous physical activity per week for sufficient activity for the longitudinal analyses. We used multivariable mixed linear and logistic regression models adjusted for several potential confounders to analyze associations between physical activity and arterial stiffness.
Results: Measuring characteristics of arterial stiffness indices (CAVI, baPWV)
The first aim was to determine the measuring characteristics in terms of the reproducibility of the novel arterial stiffness measure CAVI together with baPWV in a Caucasian clientele within the SAPALDIA cohort. These two arterial stiffness indices are derived from an oscillometric measurement with the VaSera VS-1500N vascular screening system. This work resulted in one publication showing the high reproducibility of these indices (Milestone 1). This could be done for the first time in a Caucasian cohort, since both of these newly emerging arterial stiffness indices reflecting early CVD risk have so far mainly been studied in Asian populations or only in small studies with Caucasians. Valid markers of CVD are essential and highly important for CVD risk stratification on the population level. The analyses of the association of CAVI with blood pressure in comparison with baPWV has been conducted but could not been integrated in a publication so far. The association between CAVI and carotid intima media thickness as a traditional and well established marker of cardiovascular risk is pending. However, we have analyzed associations of CAVI and baPWV with age and sex as the main determinants of arterial stiffness in the SAPALDIA cohort proving the high quality of these indices.
Cross-sectional association of physical activity and arterial stiffness
In the next step, we have focused on the second aim targeting the analyses of the cross-sectional association between physical activity and arterial stiffness reflecting CVD risk in multilevel models including several confounding factors. Physical activity is regarded as an important health promotion measure with protective impact on the cardiovascular system and, thus, as one component of aggressive decrease of atherosclerotic modifiers. The main focus of the second aim was the question how a physically active lifestyle is cross-sectionally associated with arterial stiffness in the SAPALDIA cohort. Up-to-date this question has been insufficiently studied in older adults in population based studies. Furthermore, there is no comparable cohort in which a measure of arterial stiffness could be analyzed in association with a detailed questionnaire of physical activity like the IPAQ. During the data collection of SAPALDIA 3 the IPAQ has been consulted to classify the subjects’ physical activity level. We hypothesized that a sedentary lifestyle is associated with increased arterial stiffness assessed by CAVI and baPWV. We found that in this general Caucasian population of older adults higher levels especially of vigorous physical activity were associated with lower arterial stiffness reflecting lower cardiovascular risk. These data support the importance of physical activity for improving cardiovascular health in older adults. These results are included in a manuscript published in the European Journal of Epidemiology (Milestone 2).
Longitudinal association of physical activity and arterial stiffness
To add on this from a longitudinal point of view we have extensively worked on the third aim analyzing the association between change in physical activity between the first and second follow-up of SAPALDIA (SAPALDIA 2 to 3) and CVD risk using CAVI and baPWV as marker in multilevel models including several confounding factors. We hypothesized that an increase in physical activity between SAPALDIA 2 and 3 is associated with lower cardiovascular risk assessed by arterial stiffness. This is the first longitudinal population based cohort study showing that keeping up or adopting a physically active lifestyle was associated with lower arterial stiffness in older adults after a follow-up of almost a decade. Increasing the proportion of older adults adhering to physical activity recommendations incorporating also vigorous physical activity may have a considerable impact on vascular health at older age and may contribute to healthy ageing in general. These findings will strengthen physical activity recommendations within CVD prevention guidelines in older adults with respect to the prevention of manifest CVD and related health outcomes. A manuscript presenting these findings have been published in the journal Age and Ageing (Milestone 3).
Conclusions:
Consequently, the aims of the PhD research plan could be fulfilled within the proposed timeline, except the pending analyses of the association between CAVI and baPWV with carotid-intima media thickness. We could show that CAVI and baPWV are non-invasive arterial stiffness indices that are easy-to-apply and reproducible for population wide CVD risk stratification in Caucasians. Because arterial stiffness receives growing significance for examinations of asymptomatic subjects in research our cohort study results will lead to improvements of early stage diagnosis and treatment of CVD. Risk stratification is essential for goal-oriented and area-wide primary and secondary care. Early detection of CVD and cardiovascular risk factors is crucial besides promotion of prevention and early treatment for diminishing the increasing health and economic impact of CVD. CAVI and baPWV could be implemented in this epidemiological cohort study to assess the cardiovascular risk related to increased arterial stiffness and associated with insufficient physical activity. Besides, a long-term physically active lifestyle was shown to be beneficially associated with vascular ageing and therefore decreased CVD risk on the population level in the long-term. Since there are few population based studies in Caucasians concerning this topic and the growing acknowledgement of physical activity in population health interventions this study presents highly relevant and unique results in line with current epidemiological, medical and sports science research trends. In conclusion, physical activity may play a major role in long-term healthy cardiovascular ageing at the population level and should be emphasized in CVD management and prevention guidelines. Increasing the proportion of older adults adhering to physical activity recommendations incorporating also vigorous physical activity may have a considerable impact on vascular health at older age and may contribute to healthy ageing in general.