Cumulative toll of exposure to stressors in Canadians: An allostatic load profile.

BACKGROUND: The cumulative toll of exposure to stressors (psychosocial, chemical, physical) can contribute to disease processes. The concept of allostatic load, essentially the cost of maintaining physiological stability in response to environmental demands, may be useful in assessing broad population health impacts of stressors beyond morbidity and mortality. In the present study, allostatic load scores were generated for Canadians and associations with age, sex, education and household income were examined. DATA AND METHODS: Data from cycles 1, 2, and 3 (2007 to 2013) of the Canadian Health Measures Survey (CHMS) were used to generate a composite index of cumulative health burden (allostatic load score) for adults aged 20 to 79 (n=8,678) based on risk thresholds for nine biological measures: diastolic blood pressure, systolic blood pressure, heart rate, high-density lipoprotein (HDL), total cholesterol, glycated hemoglobin (HBA1c), waist-to-hip ratio, C-reactive protein (CRP), and albumin. Logistic regression models that included age (continuous), sex, education and household income were fit to generate model-adjusted predicted allostatic load scores. RESULTS: The most prevalent individual risk factors were elevated waist-to-hip ratio, elevated CRP, total cholesterol, and low HDL. Allostatic load scores increased with age. Males generally exhibited higher scores than females. Lower educational attainment and lower household income were found to be significantly associated with higher allostatic load scores after taking account of the effects of age and sex. DISCUSSION: Age and socioeconomic gradients are associated with differences in allostatic load scores in the Canadian population. This composite measure of multisystem dysfunction, generated from a nationally representative survey that includes measurement of numerous health-relevant behaviours, biomarkers, and chemical levels, can be used in future to quantify sub-clinical impacts on health.

Air Health Trend Indicator: Association between Short-Term Exposure to Ground Ozone and Circulatory Hospitalizations in Canada for 17 Years, 1996⁻2012.

The Air Health Trend Indicator is designed to estimate the public health risk related to short-term exposure to air pollution and to detect trends in the annual health risks. Daily ozone, circulatory hospitalizations and weather data for 24 cities (about 54% of Canadians) for 17 years (1996⁻2012) were used. This study examined three circulatory causes: ischemic heart disease (IHD, 40% of cases), other heart disease (OHD, 31%) and cerebrovascular disease (CEV, 14%). A Bayesian hierarchical model using a 7-year estimator was employed to find trends in the annual national associations by season, lag of effect, sex and age group (≤65 vs. >65). Warm season 1-day lagged ozone returned higher national risk per 10 ppb: 0.4% (95% credible interval, -0.3⁻1.1%) for IHD, 0.4% (-0.2⁻1.0%) for OHD, and 0.2% (-0.8⁻1.2%) for CEV. Overall mixed trends in annual associations were observed for IHD and CEV, but a decreasing trend for OHD. While little age effect was identified, some sex-specific difference was detected, with males seemingly more vulnerable to ozone for CEV, although this finding needs further investigation. The study findings could reduce a knowledge gap by identifying trends in risk over time as well as sub-populations susceptible to ozone by age and sex.