Background

Mortality and morbidity have been shown to follow a ‘social gradient’ in Canada and many other countries around the world. Comparatively little, however, is known about whether ageing amplifies, diminishes or sustains socio-economic inequalities in health.

Methods

Growth curve analysis of seven cycles of the Canadian National Population Health Survey (n=13 682) for adults aged 20 and older at baseline (1994/95). The outcome of interest is the Health Utilities Index Mark 3, a measure of health-related quality of life (HRQL). Models include the deceased so as not to present overly optimistic HRQL values. Socio-economic position is measured separately by household-size-adjusted income and highest level of education attained.

Results

HRQL is consistently highest for the most affluent and the most highly educated men and women, and is lower, in turn, for middle and lower income and education groups. HRQL declines with age for both men and women. The rate of the decline in HRQL, however, was related neither to income nor to education for men, suggesting stability in the social gradient in HRQL over time for men. There was a sharper decline in HRQL for upper-middle and highest-income groups for women than for the poorest women.

Conclusion

HRQL is graded by both income and education in Canadian men and women. The grading of HRQL by social position appears to be ‘set’ in early adulthood and is stable through mid- and later life.

Background

Interest in the determinants of “successful aging” is growing. Nonetheless, successful aging remains ill defined, and its appropriate measurement is hotly contested. Most studies have focused on the absence of disability or deficits in physical performance as outcomes. The present study extends this research by using the Health Utilities Index Mark 3 (HUI3), a multidimensional measure of health status, to examine the maintenance of exceptionally good health among older participants in the Canadian National Population Health Survey (1994–2004).

Methods

The maintenance of exceptionally good health in old age was examined prospectively among 2432 individuals (65–85 years old at baseline) who met the inclusion criteria. The participants were classified into one of four health trajectories: thrivers (who maintained exceptional health with no or only mild disability), nonthrivers (who experienced a moderate or severe disability), the deceased, and the institutionalized.

Results

In 10 years of follow-up, 190 (8%) were thrivers (HUI3 score ≥ 0.89 at all interviews), 1076 (47%) were nonthrivers, 893 (36%) died, and 273 (9%) were institutionalized. The maintenance of exceptionally good health among the elderly participants was related to younger age at baseline, socioeconomic status (higher income), psychosocial factors (including lower psychological distress), and behavioral factors (never smoked and moderate alcohol use).

Conclusions

The maintenance of exceptionally good health in old age is related, at least in part, to modifiable lifestyle factors. However, elevated socioeconomic status also distinguishes those who are able to maintain exceptionally good health.

Imported malaria cases in adults are strongly patterned by neighborhood economic and immigration levels.

Malaria, once endemic in Canada, is now restricted to imported cases. Imported malaria in Canada has not been examined recently in the context of increased international mobility, which may influence incidence of imported and autochthonous cases. Surveillance of imported cases can highlight high-risk populations and help target prevention and control measures. To identify geographic and individual determinants of malaria incidence in Ontario, Canada, we conducted a descriptive spatial analysis. We then compared characteristics of case-patients and controls. Case-patients were significantly more likely to be male and live in low-income neighborhoods that had a higher proportion of residents who had emigrated from malaria-endemic regions. This method’s usefulness in clarifying the local patterns of imported malaria in Ontario shows its potential to help identify areas and populations at highest risk for imported and emerging infectious disease.

Background

Only about 30% of cases of breast cancer can be explained by accepted risk factors. Occupational studies have shown associations between the incidence of breast cancer and exposure to contaminants that are found in ambient air.

Objectives

We sought to determine whether the incidence of postmenopausal breast cancer is associated with exposure to urban air pollution.

Methods

We used data from a case–control study conducted in Montreal, Quebec, in 1996–1997. Cases were 383 women with incident invasive breast cancer, and controls were 416 women with other incident, malignant cancers, excluding those potentially associated with selected occupational exposures. Concentrations of nitrogen dioxide (NO2) were measured across Montreal in 2005–2006. We developed a land-use regression model to predict concentrations of NO2 across Montreal for 2006, and developed two methods to extrapolate the estimates to 1985 and 1996. We linked these estimates to addresses of residences of subjects at time of interview. We used unconditional logistic regression to adjust for accepted and suspected risk factors and occupational exposures.

Results

For each increase of 5 ppb NO2 estimated in 1996, the adjusted odds ratio was 1.31 (95% confidence interval, 1.00–1.71). Although the size of effect varied somewhat across periods, we found an increased risk of approximately 25% for every increase of 5 ppb in exposure.

Conclusions

We found evidence of an association between the incidence of postmenopausal breast cancer and exposure to ambient concentrations of NO2. Further studies are needed to confirm whether NO2 or other components of traffic-related pollution are indeed associated with increased risks.

Background

The high glucose levels typically occurring among adults with type 2 diabetes contribute to blood vessel injury and complications such as blindness, kidney failure, heart disease, and stroke. Higher physical activity levels are associated with improved glycemic control, as measured by hemoglobin A1C. A 1% absolute increase in A1C is associated with an 18% increased risk for heart disease or stroke. Among Canadians with type 2 diabetes, we postulate that declines in walking associated with colder temperatures and inclement weather may contribute to annual post-winter increases in A1C levels.

Methods

During this prospective cohort study being conducted in Montreal, Quebec, Canada, 100 men and 100 women with type 2 diabetes will undergo four assessments (once per season) over a one-year period of observation. These assessments include (1) use of a pedometer with a concealed viewing window for a two-week period to measure walking (2) a study centre visit during which venous blood is sampled for A1C, anthropometrics are assessed, and questionnaires are completed for measurement of other factors that may influence walking and/or A1C (e.g. food frequency, depressive symptomology, medications). The relationship between spring-fall A1C difference and winter-summer difference in steps/day will be examined through multivariate linear regression models adjusted for possible confounding. Interpretation of findings by researchers in conjunction with potential knowledge "users" (e.g. health professionals, patient groups) will guide knowledge translation efforts.

Discussion

Although we cannot alter weather patterns to favour active lifestyles, we can design treatment strategies that take seasonal and weather-related variations into account. For example, demonstration of seasonal variation of A1C levels among Canadian men and women with T2D and greater understanding of its determinants could lead to (1) targeting physical activity levels to remain at or exceed peak values achieved during more favourable weather conditions. Strategies may include shifting to indoor activities or adapting to less favourable conditions (e.g. appropriate outdoor garments, more frequent but shorter duration periods of activity) (2) increasing dose/number of glucose-lowering medications during the winter and reducing these during the summer, in anticipation of seasonal variations (3) examining the impact of bright light therapy on activity and A1C among T2D patients with an increase in depressive symptomology when sunlight hours decline.

In this study, we identify the significant factors associated with having difficulties accessing first-contact healthcare services. Population-based data from two national health surveys, the Health Services Access Survey and the Canadian Community Health Survey, were used to identify respondents who required first-contact services for themselves or for a family member during 2003. Fifteen percent of Canadians reported difficulty accessing routine care, and 23% reported difficulties with immediate care. Physician/service availability was the chief reason cited for difficulties accessing routine care, while for urgent care, it was long wait times. Women, younger respondents and residents of eastern Canada and Quebec were consistently more likely to report difficulties accessing both types of these first-contact services, whereas less educated Canadians were less likely to report problems. Canadians without a regular family doctor were more than twice as likely to report difficulties accessing routine care compared to those who had a regular doctor. New immigrants were almost two and a half times more likely to report difficulties accessing immediate care than were Canadian-born respondents. Household income was not associated with difficulties accessing either type of care. The relatively low level of reporting of difficulties by older and less educated Canadians may be related, in part, to more modest expectations about the healthcare system.

The relationship between income inequality and mortality has come into question as of late from many within-country studies. This article examines the relationship between income inequality and working-age mortality for metropolitan areas (MAs) in Australia, Canada, Great Britain, Sweden, and the United States to provide a fuller understanding of national contexts that produce associations between inequality and mortality. An ecological cross-sectional analysis of income inequality (as measured by median share of income) and working-age (25–64) mortality by using census and vital statistics data for 528 MAs (population >50,000) from five countries in 1990–1991 was used. When data from all countries were pooled, there was a significant relationship between income inequality and mortality in the 528 MAs studied. A hypothetical increase in the share of income to the poorest half of households of 1% was associated with a decline in working-age mortality of over 21 deaths per 100,000. Within each country, however, a significant relationship between inequality and mortality was evident only for MAs in the United States and Great Britain. These two countries had the highest average levels of income inequality and the largest populations of the five countries studied. Although a strong ecological association was found between income inequality and mortality across the 528 MAs, an association between income inequality and mortality was evident only in within-country analyses for the two most unequal countries: the United States and Great Britain. The absence of an effect of metropolitan-scale income inequality on mortality in the more egalitarian countries of Canada. Australia, and Sweden is suggestive of national-scale policies in these countries that buffer hypothetical effects of income inequality as a determinant of population health in industrialized economies.

Objective

To compare the relation between mortality and income inequality in Canada with that in the United States.

Design

The degree of income inequality, defined as the percentage of total household income received by the less well off 50% of households, was calculated and these measures were examined in relation to all cause mortality, grouped by and adjusted for age.

Setting

The 10 Canadian provinces, the 50 US states, and 53 Canadian and 282 US metropolitan areas.

Results

Canadian provinces and metropolitan areas generally had both lower income inequality and lower mortality than US states and metropolitan areas. In age grouped regression models that combined Canadian and US metropolitan areas, income inequality was a significant explanatory variable for all age groupings except for elderly people. The effect was largest for working age populations, in which a hypothetical 1% increase in the share of income to the poorer half of households would reduce mortality by 21 deaths per 100 000. Within Canada, however, income inequality was not significantly associated with mortality.

Conclusions

Canada seems to counter the increasingly noted association at the societal level between income inequality and mortality. The lack of a significant association between income inequality and mortality in Canada may indicate that the effects of income inequality on health are not automatic and may be blunted by the different ways in which social and economic resources are distributed in Canada and in the United States.

Objective To assess the extent to which observed associations between income inequality and mortality at population level are statistical artifacts. Design Indirect “what if” simulation using observed risks of mortality at individual level as a function of income to construct hypothetical state-level mortality specific for age and sex as if the statistical artifact argument were 100% correct. Method Data from the 1990 census for the 50 US states plus Washington, DC, were used for population distributions by age, sex, state, and income range; data disaggregated by age, sex, and state from the Centers for Disease Control and Prevention were used for mortality; and regressions from the national longitudinal mortality study were used for the individual-level relation between income and risk of mortality. Results Hypothetical mortality, although correlated with inequality (as implied by the logic of the statistical artifact argument), showed a weaker association with the level of income inequality in each state than the observed mortality. Conclusions The observed associations in the United States at the state level between income inequality and mortality cannot be entirely or substantially explained as statistical artifacts of an underlying individual-level relation between income and mortality. There remains an important association between income inequality and mortality at state level above anything that could be accounted for by any statistical artifact. This result reinforces the need to consider a broad range of factors, including the social milieu, as fundamental determinants of health.

Objective

To assess the extent to which observed associations at population level between income inequality and mortality are statistical artefacts.

Design

Indirect “what if” simulation by using observed risks of mortality at individual level as a function of income to construct hypothetical state level mortality specific for age and sex as if the statistical artefact argument were 100% correct.

Setting

Data from the 1990 census for the 50 US states plus Washington, DC, were used for population distributions by age, sex, state, and income range; data disaggregated by age, sex, and state from the Centers for Disease Control and Prevention were used for mortality; and regressions from the national longitudinal mortality study were used for the individual level relation between income and risk of mortality.

Results

Hypothetical mortality, while correlated with inequality (as implied by the logic of the statistical artefact argument), showed a weaker association with states’ levels of income inequality than the observed mortality.

Conclusions

The observed associations in the United States at the state level between income inequality and mortality cannot be entirely or substantially explained as statistical artefacts of an underlying individual level relation between income and mortality. There remains an important association between income inequality and mortality at state level over and above anything that could be accounted for by any statistical artefact. This result reinforces the need to consider a broad range of factors, including the social milieu, as fundamental determinants of health.

Key messagesEvidence is accumulating that living in a society with higher inequality in income predisposes its members to higher mortality; at the same time, there is widespread evidence that, for individuals, higher income is protectiveThis individual level relation could “explain” the former societal level relationThe strength of observed levels of association between income inequality and mortality, however, may go well beyond what can be explained as a statistical artefact of an individual level relation between income and mortalityThe empirical analysis reported here, based on 1990 data for US states, suggests that the association between income inequality and mortality is considerably stronger than can be accounted for by any statistical artefactResearch underpinning public health policy should therefore take a broad view of the importance of the social milieu as a fundamental determinant of health

Abnormal thromboscintigrams were observed in patients with lymphatic obstruction. This syndrome was reproduced by surgically ligating the lymphatic drainage of the lower extremity of a dog prior to thromboscintigraphy.

Images