Russell Wilkins

Effect of neighbourhood income and maternal education on birth outcomes: a population-based study

Background: Maternal socioeconomic status (SES) is an important determinant of inequity in maternal and fetal health. We sought to determine the extent to which associations between adverse birth outcomes and SES can be identified using individual-level measures (maternal level of education) and community-level measures (neighbourhood income). Methods: In Quebec, the birth registration form includes a field for the mothers years of education. Using data from birth registration certificates, we identified all births from 1991 to 2000. Using maternal postal codes that can be linked to census enumeration areas, we determined neighbourhood income levels that reflect SES. Results: Lower levels of both maternal education and neighbourhood income were associated with elevated crude risks of preterm birth, small-for-gestational-age (SGA) birth, stillbirth and neonatal and postneonatal death. The effects of maternal education were stronger than, and independent of, those of neighbourhood income. Compared with women in the highest neighbourhood income quintile, women in the lowest quintile were significantly more likely to have a preterm birth (adjusted odds ratio [OR] 1.14, 95% confidence interval [CI] 1.10–1.17), SGA birth (OR 1.18, 95% CI 1.15–1.21) or stillbirth (OR 1.30, 95% CI 1.13–1.48); compared with mothers who had completed community college or at least some university, mothers who had not completed high school were significantly more likely to have a preterm birth (adjusted OR 1.48, 95% CI 1.44–1.52), SGA birth (OR 1.86, 95% CI 1.82–1.91) or stillbirth (OR 1.54, 95% CI 1.36–1.74). Interpretation: Individual and, to a lesser extent, neighbourhood-level SES measures are independent indicators for subpopulations at risk of adverse birth outcomes. Women with lower education levels and those living in poorer neighbourhoods are more vulnerable to adverse birth outcomes and may benefit from heightened clinical vigilance and counselling.

Mortality among residents of shelters, rooming houses, and hotels in Canada: 11 year follow-up study

Objective To examine mortality in a representative nationwide sample of homeless and marginally housed people living in shelters, rooming houses, and hotels. Design Follow-up study. Setting Canada 1991-2001. Participants 15 100 homeless and marginally housed people enumerated in 1991 census. Main outcome measures Age specific and age standardised mortality rates, remaining life expectancies at age 25, and probabilities of survival from age 25 to 75. Data were compared with data from the poorest and richest income fifths as well as with data for the entire cohort Results Of the homeless and marginally housed people, 3280 died. Mortality rates among these people were substantially higher than rates in the poorest income fifth, with the highest rate ratios seen at younger ages. Among those who were homeless or marginally housed, the probability of survival to age 75 was 32% (95% confidence interval 30% to 34%) in men and 60% (56% to 63%) in women. Remaining life expectancy at age 25 was 42 years (42 to 43) and 52 years (50 to 53), respectively. Compared with the entire cohort, mortality rate ratios for men and women, respectively, were 11.5 (8.8 to 15.0) and 9.2 (5.5 to 15.2) for drug related deaths, 6.4 (5.3 to 7.7) and 8.2 (5.0 to 13.4) for alcohol related deaths, 4.8 (3.9 to 5.9) and 3.8 (2.7 to 5.4) for mental disorders, and 2.3 (1.8 to 3.1) and 5.6 (3.2 to 9.6) for suicide. For both sexes, the largest differences in mortality rates were for smoking related diseases, ischaemic heart disease, and respiratory diseases. Conclusions Living in shelters, rooming houses, and hotels is associated with much higher mortality than expected on the basis of low income alone. Reducing the excessively high rates of premature mortality in this population would require interventions to address deaths related to smoking, alcohol, and drugs, and mental disorders and suicide, among other causes.

Disparities in Birth Outcomes by Neighborhood Income: Temporal Trends in Rural and Urban Areas, British Columbia

Background: Knowledge of socioeconomic disparities in health is of interest to both the general public and public health policymakers. It is unclear how disparities in birth outcomes by socioeconomic status have changed over time, particularly in settings with universal health insurance and favorable socioeconomic conditions. Methods: We identified a cohort of all births (n = 713,950) registered in British Columbia, 1985–2000. We compared rates and relative risks (RRs) of preterm birth, small-for-gestational-age (SGA), stillbirth, and neonatal and postneonatal death across neighborhood-income quintiles from Q1 (richest, the reference) to Q5 (poorest) by 4-year intervals in rural and urban areas. Logistic regression was used to control for maternal and pregnancy characteristics. Results: Maternal characteristics varied widely across neighborhood-income quintiles in both rural and urban areas. There were moderate and persistent disparities in birth outcomes across neighborhood-income quintiles in urban but not rural areas. The relative disparities in urban areas did not diminish over time for all birth outcomes and actually rose for postneonatal mortality. For example, crude RRs (95% confidence intervals) for Q5 versus Q1 in urban areas for SGA were 1.44 (1.37–1.52) in 1985–1988 and 1.41 (1.33–1.49) in 1997–2000; for postneonatal death, the corresponding results were 1.61 (1.17–2.20) and 2.20 (1.24–3.92), respectively. Most of the observed disparities could not be explained by observed maternal and pregnancy characteristics. Conclusion: Moderate disparities in birth outcomes by neighborhood income persist in urban areas (although not rural areas) of British Columbia, despite a universal health insurance system and generally favorable socioeconomic conditions.

Childhood leukemia and socioeconomic status in Canada.

Background: Leukemia is one of the most common potentially fatal illnesses in children, and its causes are not well understood. Although socioeconomic status (SES) has been related to leukemia in some studies, this apparent association may be attributable to ascertainment or participation bias. This study was undertaken to determine whether there is a difference in incidence of childhood leukemia for different levels of SES, as measured by neighborhood income, in an unselected population case group. Methods: All cases of childhood leukemia diagnosed in the years 1985–2001 were identified from population-based cancer registries in Canada. Postal codes for the place of residence at diagnosis were used to ascertain the census neighborhoods for cases. We constructed neighborhood-based income quintiles from census population data, and stratified the population at risk by sex and 5-year age groupings. Age-standardized incidence rates and 95% confidence intervals (CIs) were calculated. We used Poisson regression to compare incidence rate ratios (RRs) across income quintiles. Results: A slightly lower relative risk of childhood leukemia was observed in the poorest quintile compared with the richest (RR = 0.87; 95% CI = 0.80–0.95). The lower risk in the poorest quintile was restricted to acute lymphoid leukemia (0.86; 0.78–0.95) and was strengthened slightly by restriction to urban areas (0.83; 0.74–0.93). Conclusions: This analysis suggests that high SES is a true risk factor for childhood leukemia and that inconsistent results from other studies may be related to differences in case ascertainment or study participation.

Disparities in pregnancy outcomes according to marital and cohabitation status.

OBJECTIVE: To assess the risks and trends of adverse pregnancy outcomes among mothers in common-law unions versus traditional marriage relationships. METHODS: We conducted a birth cohort-based study of all 720,586 births registered in Quebec for the years 1990 to 1997. RESULTS: The proportion of births to common-law mothers more than doubled from 20% in 1990 to 44% in 1997. Preterm birth, low birth weight, small for gestational age, and neonatal and postneonatal mortality rates increased progressively from mothers legally married, to common-law unions, to lone mothers with father information, to lone mothers without father information on birth registrations. Adjusted odd ratios with 95% confidence intervals (CIs) for common-law versus legally married mothers were 1.14 (95% CI 1.11, 1.17) for preterm birth, 1.21 (95% CI 1.18, 1.25) for low birth weight, 1.18 (95% CI 1.16, 1.20) for small for gestational age, 1.07 (95% 0.97, 1.19) for neonatal death, and 1.23 (95% CI 1.04, 1.44) for postneonatal death after controlled for observed individual- and community-level characteristics. The crude and adjusted odds ratios were virtually unchanged over time. CONCLUSION: Pregnancy outcomes are worse among mothers in common-law unions versus traditional marriage relationships but better than among mothers living alone. Modest disparities in pregnancy outcomes in common-law versus traditional marriage relationships have persisted despite the striking rise in common-law unions. LEVEL OF EVIDENCE: II-2

Expectations of life and health among spinal cord injured adults

While our understanding of aging and mortality in spinal cord injury is evolving, precise estimates are still not available for expectations of life and health following a spinal cord injury. In order to derive these estimates, information about mortality and health must be combined into a single estimate. Health expectancy estimates have been widely used in the literature of the last decade to try to understand the relationship between population health and survival, both in the general population and in special populations. This study brought the benefit of this methodology to the question of long-term survival following spinal cord injury. Specifically, the study aimed to calculate life and health expectancy in a population of spinal cord injured individuals; and, to estimate the effect of factors associated with survival and health. The study involved a retrospective cohort, all of whom sustained a spinal cord injury between the ages of 25 and 34 years, and between 1945 and 1990. The study predicted a median survival time of 38 years post-injury, with 43% surviving at least 40 years. These findings suggest an increase in life expectancy of about 5 years over previous research on the same cohort.1 Factors affecting survival were age at injury, level and completeness of lesion. Expectations of health found in the present study are similar to those found in studies of the general population.2 This study showed seven remaining years of poor health expected at injury, and five remaining years expected at 40 years post injury, presumably occurring at the end of life.

Birth outcomes in the Inuit-inhabited areas of Canada

Background: Information on health disparities between Aboriginal and non-Aboriginal populations is essential for developing public health programs aimed at reducing such disparities. The lack of data on disparities in birth outcomes between Inuit and non-Inuit populations in Canada prompted us to compare birth outcomes in Inuit-inhabited areas with those in the rest of the country and in other rural and northern areas of Canada. Methods: We conducted a cohort study of all births in Canada during 1990–2000 using linked vital data. We identified 13 642 births to residents of Inuit-inhabited areas and 4 054 489 births to residents of all other areas. The primary outcome measures were preterm birth, stillbirth and infant death. Results: Compared with the rest of Canada, Inuit-inhabited areas had substantially higher rates of preterm birth (risk ratio [RR] 1.45, 95% confidence interval [CI] 1.38–1.52), stillbirth (RR 1.68, 95% CI 1.38–2.04) and infant death (RR 3.61, 95% CI 3.17–4.12). The risk ratios and absolute differences in risk for these outcomes changed little over time. Excess mortality was observed for all major causes of infant death, including congenital anomalies (RR 1.64), immaturity-related conditions (RR 2.96), asphyxia (RR 2.43), sudden infant death syndrome (RR 7.15), infection (RR 8.32) and external causes (RR 7.30). Maternal characteristics accounted for only a small part of the risk disparities. Substantial risk ratios for preterm birth, stillbirth and infant death remained when the comparisons were restricted to other rural or northern areas of Canada. Interpretation: The Inuit-inhabited areas had much higher rates of preterm birth, stillbirth and infant death compared with the rest of Canada and with other rural and northern areas. There is an urgent need for more effective interventions to improve maternal and infant health in Inuit-inhabited areas.

Cervical cancer mortality by neighbourhood income in urban Canada from 1971 to 1996.

Background: The reduction of socioeconomic inequalities in health is an explicit objective of health policy in Canada, yet rates of death from cervical cancer are known to be higher among women of low socioeconomic status than among those of higher socioeconomic status. To evaluate progress toward the World Health Organizations goal of “Health for All,” we examined whether income-related differentials in cervical cancer mortality diminished from 1971 to 1996. Methods: Death registration data for Canadas census metropolitan areas in 1971, 1986, 1991 and 1996 were assigned to census tracts through postal code, and the tracts were in turn assigned to income quintiles based on their proportion of the population below the Statistics Canada low-income cutoff values. We compared age-standardized death rates (using the 1966 world population standard) in the female population (excluding those in institutions) across the 5 income quintiles and calculated interquintile rate ratios (poorest over richest) and interquintile rate differences (poorest minus richest). Results: From 1971 to 1996, the overall age-standardized cervical cancer death rate per 100 000 women (and 95% confidence interval) declined from 5.0 (4.5–5.6) to 1.9 (1.7–2.1), the interquintile rate ratio diminished from 2.7 (1.8–4.2) to 1.7 (1.1– 2.6), and the interquintile rate difference decreased from 4.6 (2.8– 6.4) to 1.1 (0.2–1.9). Interpretation: The income-related disparity in rates of death from cervical cancer as measured by rate ratios and rate differences diminished markedly in urban Canada from 1971 to 1996. Among the numerous factors that may have contributed to the decline (including decline in fertility and improvement in diet), one important factor was probably the implementation of effective screening programs.

Expectations of independence and life satisfaction among ageing spinal cord injured adults

PURPOSE The present study offers information about independence and life satisfaction over the lifespan for individuals with traumatic spinal cord injuries. METHODS The study uses the health expectancy methodology to estimate expectations of the remaining years of life that may be spent in states of independence and satisfaction with life. SUBJECTS The cohort studied had all incurred a spinal cord injury between the ages of 25 and 34, between the years 1945 and 1990 in central and south-eastern Ontario. RESULTS AND CONCLUSIONS The study found that levels of independence and quality of life in the sample conformed closely to those found in other similar studies with the spinal cord injured population: 22% reported their own functional status as dependent, and 22% reported fair to poor life satisfaction. Expectations of independence appeared to decline steadily over the five decades studied, while expectations of modified independence increased proportionally. Estimates varied significantly for those with paraplegia vs. quadriplegia, and those with complete vs. incomplete lesions. Expectations of life satisfaction appeared to change after the 30 year mark; at that point, the balance changed so that expectations of dissatisfaction outweighed expectations of satisfaction. Multiple regression showed that independence was related to lesion level, completeness and recency of injury, and both independence and satisfaction were related to marriage and employment.

Gender differences in disability-free life expectancy for selected risk factors and chronic conditions in Canada.

SUMMARY This article shows how mortality and morbidity patterns differ for women and men 45 years of age and older. The impact on disability-free life expectancy was calculated for selected risk factors and chronic conditions: low income, low education, abnormal body mass index, lack of physical activity, smoking, cancer, diabetes, and arthritis. For each factor, the expected number of years free of disability was calculated for men and women using multi-state life tables. In terms of disability-free life expectancy, the greatest impacts on affected women were for diabetes (14.1 years), arthritis (8.8 years), and physical inactivity (6.0 years), while for affected men, the greatest impacts were for diabetes (10.5 years), smoking (6.9 years), arthritis (6.5 years), and cancer (6.4 years). The implications of these results are discussed from the perspective of developing programs designed to improve population health status.