Background and Purpose Arterial stiffening is associated with hypertension, stroke, and cognitive decline; however, the effects of aging and cardiovascular disease risk factors on carotid artery stiffening have not been assessed prospectively in a large multi-ethnic, longitudinal study. Methods Distensibility coefficient and Young’s elastic modulus of the right common carotid artery were calculated at baseline and after a mean (standard deviation) of 9.4 (0.5) years in 2,650 participants. Effects of age and cardiovascular disease risk factors were evaluated by multivariable mixed regression and analysis of covariance models. Results At baseline, participants were 59.9 (9.4) years old (53% female; 25% Black, 22% Hispanic, 14% Chinese). Young’s elastic modulus increased from 1,581 (927) to 1,749 (1,306) mmHg (p<0.0001) and distensibility coefficient decreased from 3.1 (1.3) to 2.7 (1.1) x 10−3 mmHg−1 (p<0.001), indicating progressive arterial stiffening. Young’s elastic modulus increased more among participants who were >75 years old at baseline (p<0.0001). In multivariable analyses, older age and less education independently predicted worsening Young’s elastic modulus and distensibility coefficient. Stopping antihypertensive medication during the study period predicted more severe worsening of Young’s elastic modulus (β=360.2 mmHg, p=0.008). Starting antihypertensive medication after exam 1 was predictive of improvements in distensibility coefficient (β =1.1 x 10−4, mmHg−1; p=0.024). Conclusions Arterial stiffening accelerates with advanced age. Older individuals experience greater increases in Young’s elastic modulus than do younger adults, even after considering the effects of traditional risk factors. Treating hypertension may slow the progressive decline in carotid artery distensibility observed with aging and improve cerebrovascular health.

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AbstractIncreased morbidity and mortality have been associated with extreme heat events, particularly in temperate climates. Few epidemiologic studies have considered the impact of extreme heat events on hospitalization rates in the Pacific Northwest region. This study quantifies the historic (May to September 1990–2010) heat-morbidity relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the association between heat and all non-traumatic hospitalizations on 99th percentile heat days, whereas a time series analysis using a piecewise linear model approximation was used to estimate the effect of heat intensity on hospitalizations, adjusted for temporal trends and day of the week. A non-statistically significant 2% [95% CI: 1.02 (0.98, 1.05)] increase in hospitalization risk, on a heat day vs. a non-heat day, was noted for all-ages and all non-traumatic causes. When considering the effect of heat intensity on admissions, we found a statistically significant 1.59% (95% CI: 0.9%, 2.29%) increase in admissions per degree increase in humidex above 37.4°C. Admissions stratified by cause and age produced statistically significant results with both relative risk and time series analyses for nephritis and nephrotic syndromes, acute renal failure, and natural heat exposure hospitalizations. This study demonstrates that heat, expressed as humidex, is associated with increased hospital admissions. When stratified by age and cause of admission, the non-elderly age groups (<85 years) experience significant risk for nephritis and nephrotic syndromes, acute renal failure, natural heat exposure, chronic obstructive pulmonary disease, and asthma hospitalizations.

Extreme heat has been associated with increased mortality, particularly in temperate climates. Few epidemiologic studies have considered the Pacific Northwest region in their analyses. This study quantified the historical (May to September, 1980–2010) heat-mortality relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the relationship between heat and all-cause mortality on 99th percentile heat days, while a time series analysis, using a piece-wise linear model fit, was used to estimate the effect of heat intensity on mortality, adjusted for temporal trends. For all ages, all causes, we found a 10 % (1.10 (95 % confidence interval (CI), 1.06, 1.14)) increase in the risk of death on a heat day versus non-heat day. When considering the intensity effect of heat on all-cause mortality, we found a 1.69 % (95 % CI, 0.69, 2.70) increase in the risk of death per unit of humidex above 36.0 °C. Mortality stratified by cause and age produced statistically significant results using both types of analyses for: all-cause, non-traumatic, circulatory, cardiovascular, cerebrovascular, and diabetes causes of death. All-cause mortality was statistically significantly modified by the type of synoptic weather type. These results demonstrate that heat, expressed as humidex, is associated with increased mortality on heat days, and that risk increases with heat’s intensity. While age was the only individual-level characteristic found to modify mortality risks, statistically significant increases in diabetes-related mortality for the 45–64 age group suggests that underlying health status may contribute to these risks.