Biomedical subjects

Russell Wilkins

Publications and source records attributed to Russell Wilkins.

14 recordsLinked to original sources

PubMed2006

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 mother's 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.

Educational Status↗

PubMed2006

Socioeconomic status and childhood solid tumor and lymphoma incidence in Canada.

The authors examined the relation between neighborhood income, as a measure of socioeconomic status, and childhood cancer. Incident cases of childhood solid tumor and lymphoma in 1985-2001 were identified from provincial cancer registries in Canada. Residential postal codes at the time of diagnosis were used to assign cases to census neighborhoods. Person-years at risk were determined from quintiles of population by neighborhood income, sex, and 5-year age group, constructed using census population data. Poisson regression was used to calculate incidence rate ratios across neighborhood income quintiles. Compared with the incidence rate in the richest income quintile, moderately lower rate ratios of 0.73 (95% confidence interval: 0.63, 0.86) and 0.84 (95% confidence interval: 0.69, 1.04) were observed, respectively, for carcinomas and renal tumors in the poorest income quintile. No association was found for other types of cancer. Although a potential relation between socioeconomic status and childhood cancer cannot be excluded, the overall pattern seems compatible with random variation.

Adolescent↗

PubMed2005

Customized birth weight for gestational age standards: Perinatal mortality patterns are consistent with separate standards for males and females but not for blacks and whites.

BACKGROUND: Some currently available birth weight for gestational age standards are customized but others are not. We carried out a study to provide empirical justification for customizing such standards by sex and for whites and blacks in the United States. METHODS: We studied all male and female singleton live births and stillbirths (22 or more weeks of gestation; 500 g birth weight or over) in the United States in 1997 and 1998. White and black singleton live births and stillbirths were also examined. Qualitative congruence between gestational age-specific growth restriction and perinatal mortality rates was used as the criterion for identifying the preferred standard. RESULTS: The fetuses at risk approach showed that males had higher perinatal mortality rates at all gestational ages compared with females. Gestational age-specific growth restriction rates based on a sex-specific standard were qualitatively consistent with gestational age-specific perinatal mortality rates among males and females. However, growth restriction patterns among males and females based on a unisex standard could not be reconciled with perinatal mortality patterns. Use of a single standard for whites and blacks resulted in gestational age-specific growth restriction rates that were qualitatively congruent with patterns of perinatal mortality, while use of separate race-specific standards led to growth restriction patterns that were incompatible with patterns of perinatal mortality. CONCLUSION: Qualitative congruence between growth restriction and perinatal mortality patterns provides an outcome-based justification for sex-specific birth weight for gestational age standards but not for the available race-specific standards for blacks and whites in the United States.

Journal Article↗

PubMed2005

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.

Adolescent↗

PubMed2004

Infant mortality among First Nations versus non-First Nations in British Columbia: temporal trends in rural versus urban areas, 1981-2000.

BACKGROUND: Increasingly more First Nations (FN) people have moved from rural to urban areas. It is unknown how disparities in infant mortality among FN versus non-FN women have changed over time in urban versus rural areas. METHODS: We conducted a birth cohort-based study of all 877 925 live births (56 771 FN and 821 154 non-FN) registered in British Columbia, 1981-2000. Main outcomes included rates, risk differences, and relative risks of neonatal, postneonatal, and overall infant death. RESULTS: Both neonatal and postneonatal mortality rates for FN infants showed a steady decline in rural areas but a rise-and-fall pattern in urban areas. Relative risks for overall infant death among FN versus non-FN infants declined steadily from 2.75 (95% CI: 2.04, 3.72) to 1.87 (95% CI: 1.24, 2.81) in rural areas from 1981-1984 to 1997-2000, but rose from 1.59 (95% CI: 1.27, 1.99) (1981-1984) to 2.80 (2.33-3.37) (1989-92) and then fell to 1.89 (1.44-2.49) (1997-2000) in urban areas. Risk differences for neonatal death among FN versus non-FN infants declined substantially over time in rural but not urban areas. The disparities in neonatal death among FN versus non-FN were largely explained by differences in preterm birth, while the disparities in postneonatal death were not explained by observed maternal and pregnancy characteristics. CONCLUSIONS: Reductions in disparities in infant mortality among FN versus non-FN women have been less substantial and consistent over time in urban versus rural areas of British Columbia, suggesting the need for greater attention to FN maternal and infant health in urban areas.

Adult↗

PubMed2004

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 Organization's 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 Canada's 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.

Adult↗

PubMed2004

Risks of stillbirth and early neonatal death by day of week.

BACKGROUND: Higher risks of stillbirth or early neonatal death, or both, have been reported from several countries for births on weekend days. It is unclear whether such higher risks have persisted in recent years. We investigated weekend-associated risks of stillbirth and early neonatal death in most Canadian provinces. METHODS: We studied all 3 239 972 births recorded in Canada, excluding Ontario, between 1985 and 1998. The main outcome measures were the relative risks (RRs) of stillbirth and early neonatal death for infants born on weekends versus weekdays. RESULTS: The proportion of births on weekend days was 24% lower than the proportion on weekdays. Infants born on weekend days had slightly but significantly elevated risks of stillbirth (RR 1.06, 95% confidence interval [CI] 1.02-1.09) and early neonatal death (RR 1.11, 95% CI 1.07-1.16). However, the higher risks disappeared after adjustment for gestational age. INTERPRETATION: The crude risks of stillbirth and early neonatal death remained slightly higher for births on weekend days, but the excesses were much smaller than those reported from other countries.

Asphyxia Neonatorum↗

PubMed2004

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

Birth Weight↗

PubMed2004

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.

British Columbia↗

PubMed2004

Risks of adverse pregnancy outcomes among Inuit and North American Indian women in Quebec, 1985-97.

We used Statistics Canada's linked stillbirth, live birth and infant death files to assess the risks of adverse pregnancy outcomes among Inuit and North American Indian vs. other ethnic women in Quebec, 1985-97 (1 125 462 singleton births). Mother tongue was used to define ethnicity, with the largest French language group as the reference. Main outcome measures are adjusted odds ratios (AOR) for preterm birth, small-for-gestational-age (SGA), stillbirth, neonatal and postneonatal death controlled for maternal age, education, marital status, parity, infant sex, community size, and community-level random effects using multilevel logit models. Inuit women had higher risks of preterm birth (AOR = 1.49, 95% CI [1.25, 1.78]) and immaturity-related infant mortality (AOR = 3.03 [1.36, 6.74]), while Indian women did not. Infants of Inuit (AOR = 0.39 [0.31, 0.49]) and Indian (AOR = 0.27 [0.24, 0.31]) women had substantially lower risks of SGA. Elevated risks of stillbirth were observed among Indian women [AOR = 1.53 (1.09, 2.15)], and of postneonatal death among both Inuit (AOR = 4.45 [2.74, 7.22]) and Indian (AOR = 1.86 [1.28, 2.70]) infants. Both Inuit and Indian infants had much higher risks of sudden infant death syndrome (SIDS) and infection-related mortality. Although the absolute risks of adverse outcomes declined from 1985-87 to 1995-97, the relative disparities between aboriginal and non-aboriginal women changed little over this period. We conclude that Inuit and Indian women have different risk profiles for adverse pregnancy outcomes, and that prevention of preterm birth among Inuit women, and of SIDS and infection-related infant mortality in both aboriginal groups, are important targets for future research and intervention.

Adult↗

PubMed2004

Premature mortality in health regions with high aboriginal populations.

OBJECTIVES: Potential years of life lost (PYLL) before age 75 in health regions with a relatively high proportion of Aboriginal residents is compared, by cause of death, with all other health regions. DATA SOURCES: The findings are based on mortality data for 1995 through 1997 from the Canadian Vital Statistics Database, and on population estimates for 1995, 1996 and 1997 at the health region level. ANALYTICAL TECHNIQUES: PYLL was calculated by age and sex for two groups of health regions: the 18 with a high proportion (19% or more) of Aboriginal residents and the remaining 120, which had smaller proportions of Aboriginal residents. PYLL rate differences and rate ratios were used to compare the two groups. MAIN RESULTS: The PYLL rate per 1,000 person-years at risk for all causes of death was about 50% greater in the high-Aboriginal health regions than in the other group. Almost 40% of total PYLL in high-Aboriginal health regions was attributable to injuries, notably, suicide and motor vehicles accidents.

Accidents, Traffic↗

PubMed2002

How does early ultrasound scan estimation of gestational age lead to higher rates of preterm birth?

OBJECTIVE: Early ultrasound scanning estimation of gestational age is known to increase the reported preterm delivery rate (<37 completed weeks) compared with estimation by date of the last normal menstrual period, but it is unclear how this systematic difference arises. STUDY DESIGN: This study was a hospital-based study of 44,623 women who delivered a live-born or stillborn infant between January 1, 1978, and March 31, 1996, and who had both last normal menstrual period-based and early (usually at 16-18 weeks) ultrasound scan-based gestational age estimates. Cross-classification of the 2 estimates by completed weeks was used to examine the direction and magnitude of the differences between them and to compare the resulting classifications of preterm birth. RESULTS: The early ultrasound scan-based gestational age distribution was shifted uniformly to the left (ie, lower gestational age) relative to the last normal menstrual period gestational age distribution; the early ultrasound scan-based preterm delivery rate was 9.1%, which was 19.5% (n = 659 births) higher than the 7.6% rate by last normal menstrual period (P <.0001). The last normal menstrual period estimate exceeded the early ultrasound scan estimate far more often than the reverse, up to and including early ultrasound scan estimates of 40 weeks. No concentration of 4-week discrepancies was observed in either direction, as would be expected with random or systematic errors in recall of the last normal menstrual period. The absolute number of births at 37 to 39 weeks of gestation (by last normal menstrual period) that were reclassified as preterm (n = 1206 births) was much higher than the number of preterm births at 34 to 36 weeks of gestation that were reclassified as term (n = 581 births). The net increase of 625 preterm births (from 581 to 1206 births) that resulted from reclassification of births at 37 to 39 last normal menstrual period weeks accounted for 95% of the total 659-birth increase in early ultrasound scan-based preterm births at all last normal menstrual period gestational ages. CONCLUSION: Early ultrasound scanning reduces the gestational age estimate across the entire gestational age range; early ultrasound scan-based reclassification of gestational age results in a substantial increase in the prevalence of preterm births. Small downward reclassifications exceed upward reclassifications of similar magnitude, which is consistent with previous reports that delayed (>14 days) ovulation is more frequent than early (<14 days) ovulation.

Adult↗

PubMed2002

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

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.

Activities of Daily Living↗

PubMed2002

Disability-free life expectancy by health region.

OBJECTIVES: This article presents a profile of variations in disability-free life expectancy (DFLE) by health region. DATA SOURCES: Mortality data for 1995 through 1997 are from the Canadian Vital Statistics Database. Estimates of disability (major activity limitations) and sociodemographic characteristics are based on data from the 1996 Census. Supplementary information was provided by the Demography and Geography divisions at Statistics Canada. ANALYTICAL TECHNIQUES: DFLE was calculated using a modified version of Sullivan's method. Linear regression using 4 factors representing socio-demographic profiles was used to explain the variation of DFLE by health region. These 4 synthetic variables were determined using principal component analysis. MAIN RESULTS: In 1996, DFLE for both sexes was estimated to be 68.6 years. Estimates by health region varied considerably. Socio-economic status explains a high proportion of the variation of DFLE by health region.

Aged↗