Effect of High Blood Pressure and Other Cardiovascular Risk Factors on All-causes Mortality in Elderly People: A Joined Survival Analysis from Brazil, Argentina and Italy

Non-Communicable Chronic Diseases (NCCDs) are the leading causes of ill health in elderly populations and are associated with increased risk of death. Then, the aim of this paper is to estimate the effect of High Blood Pressure on all-causes mortality among subjects aged ≥65 years old in three scenarios with different socio-economic backgrounds and urbanization processes by using flexible parametric survival models. Three cohorts coming from Brazil (n=365, 8 years of follow-up), Argentina (n=1800, 10 years of follow-up) and Italy (n=2472, 30 years of follow-up) were considered and only subjects older than 64 years included. Time to death (months) from enrolment and all-causes mortality were considered. Statistical analysis included Frailty Cox's Model and Flexible Parametric Survival Analysis. Due to the two-level structure of variability (subjects nested into cohorts), multilevel mixed-effect survival regression models were fitted. For modeling purposes, only the first twelve years of follow-up were considered. Frailty Cox model showed significant positive effects of age and an effect modification of High Blood Pressure and Non-communicable diseases, but not effects proportionality. Multilevel modeling evidenced a positive statistically significant effect of Age, Non-Communicable Chronic Diseases and Smoking. There was also an effect modification of Non-Communicable Chronic Diseases on High Blood Pressure. High Blood Pressure and Non-Communicable Chronic Diseases are important causal components and strong risk factors of cardiovascular mortality in these countries.