Food fortification and decline in the prevalence of neural tube defects: does public intervention reduce the socioeconomic gap in prevalence?

OBJECTIVE

A significant decline in the prevalence of neural tube defects (NTD) through food fortification has been reported. Questions remain, however, about the effectiveness of this intervention in reducing the gap in prevalence across socioeconomic status (SES).

STUDY DESIGN

Using health number and through record linkage, children born in Ontario hospitals between 1994 and 2009 were followed for the diagnosis of congenital anomalies. SES quintiles were assigned to each child using census information at the time of birth. Adjusted rates and multivariate models were used to compare trends among children born in different SES groups.

RESULTS

Children born in low SES areas had significantly higher rates of NTDs (RR = 1.25, CI: 1.14-1.37). Prevalence of NTDs among children born in low and high SES areas declined since food fortification began in 1999 although has started rising again since 2006. While the crude decline was greater in low SES areas, after adjustment for maternal age, the slope of decline and SES gap in prevalence rates remained unchanged overtime.

CONCLUSIONS

While food fortification is successful in reducing the prevalence of NTDs, it was not associated with removing the gap between high and low SES groups.

Socioeconomic status and prevalence of congenital heart defects: does universal access to health care system eliminate the gap?

BACKGROUND

A twofold increase in the prevalence of congenital heart defects (CHDs) has been reported since the early 1970s with higher rates among children from low socioeconomic status (SES). This increase and the observed SES gap are postulated to be reflective of higher ascertainment, especially increased use of ultrasound and echography. The purpose of this study was to examine if trends over time in the prevalence of CHD were the same for high and low SES groups.

METHODS

Using the child's health number as a unique identifier and through record linkage, children born in Ontario between 1994 and 2007 were followed for the diagnosis of CHD. Using postal codes and census information, SES quintiles were assigned to each child. We used adjusted rates and used multivariate models to compare trends in the prevalence rate among children born in different SES groups.

RESULTS

Children born in low SES areas (23% of all births) had significantly higher rates of CHDs (rate ratio = 1.20; 95% confidence interval [CI] = 1.15-1.24). While prevalence of nonsevere CHDs declined in all SES groups since 2000, severe CHDs, especially atrial septal defects were on the rise during the study period.

DISCUSSION

It is assumed that increased ascertainment is responsible for observed increase in the prevalence of CHD, especially minor defects. While the trend and pattern over time changed for severe and nonsevere CHDs, the SES gap remained consistent during the study period. Our results indicate that even free and universal access to a health care system does not eliminate the SES gap observed in the prevalence of CHD.

Universal health insurance and equity in primary care and specialist office visits: a population-based study

PURPOSE

Universal coverage of physician services should serve to reduce socioeconomic disparities in care, but the degree to which a reduction occurs is unclear. We examined equity in use of physician services in Ontario, Canada, after controlling for health status using both self-reported and diagnosis-based measures.

METHODS

Ontario respondents to the 2000-2001 Canadian Community Health Survey (CCHS) were linked with physician claim files in 2002-2003 and 2003-2004. Educational attainment and income were based on self-report. The CCHS was used for self-reported health status and Johns Hopkins Adjusted Clinical Groups was used for diagnosis-based health status.

RESULTS

After adjustment, higher education was not associated with at least 1 primary care visit (odds ratio [OR] = 1.05; 95% confidence interval [CI], 0.87-1.24), but it was inversely associated with frequent visits (OR = 0.77; 95% CI, 0.65-0.88). Higher education was directly associated with at least 1 specialist visit (OR = 1.20; 95% CI, 1.07-1.34), with frequent specialist visits (OR = 1.21; 95% CI, 1.03-1.39), and with bypassing primary care to reach specialists (OR = 1.23, 95% CI 1.02-1.44). The largest inequities by education were found for dermatology and ophthalmology. Income was not independently associated with inequities in physician contact or frequency of visits.

CONCLUSIONS

After adjusting for health status, we found equity in contact with primary care for educational attainment but inequity in specialist contact, frequent visits, and bypassing primary care. In this setting, universal health insurance appears to be successful in achieving income equity in physician visits. This strategy alone does not eliminate education-related gradients in specialist care.

Social disadvantage, air pollution, and asthma physician visits in Toronto, Canada

BACKGROUND

Previous research demonstrates that ambient air pollution exacerbates asthma. Asthma morbidity also varies with socioeconomic position (SEP). Few studies have examined if ambient air pollution has a differential impact on income subgroups of the population. This paper investigates socioeconomic variation in ambulatory physician consultations for asthma and assesses possible effect modification of SEP on the association between physician visits and air pollution for children aged 1-17 and adults aged 18-64 in Toronto, Canada, between 1992 and 2001.

METHODS

Generalized additive models and generalized linear models were used to estimate the adjusted risk of asthma physician visits associated with an interquartile range increase in sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter (PM2.5), and ozone (O3).

RESULTS

A socioeconomic gradient in the number of physician visits was observed among children and adults and both sexes. SO2, NO2, and PM2.5 had positive associations with physician visits. The risk ratios for the low socioeconomic group were significantly greater than those for the high socioeconomic group in several of the models of SO2 and PM2.5.

CONCLUSIONS

These findings suggest increased ambulatory physician visits represent another component of the public health impact of urban air pollution. The burden of this impact may be borne disproportionately by those with lower SEP. Clarifying the role of SEP in altering susceptibility to the effects of air pollution is essential not only to inform revisions of ambient air quality standards, but also to design public health interventions to reduce health impacts on sensitive subgroups of the population.

Relationship between social inequalities and ambulatory care-sensitive hospitalizations persists for up to 9 years among children born in a major Canadian urban center

OBJECTIVE

Hospitalizations for ambulatory care-sensitive (ACS) conditions have been considered a marker for access to timely and effective primary care, but there are few pediatric studies. Our purpose was to examine socioeconomic disparities in ACS and non-ACS admissions among birth cohorts in a universal health insurance setting.

METHODS

We examined ACS and all hospitalizations of children born from 1993 to 2000 in Toronto, Canada, by birth year, calendar year, and socioeconomic status (SES). SES was evaluated by using quintiles of mean neighborhood income from the 1996 Canadian census. Cohort, age, and temporal effects were described for all admissions, ACS admissions, and specific ACS conditions. Attributable risk by SES was calculated by using rates for the highest and lowest SES quintiles.

RESULTS

Among 255,284 children born in Toronto during 1993-2001, ACS conditions were responsible for 28% of hospitalizations during the first 2 years of life and close to half of admissions during the third year. Low income was associated with 50% higher rates of ACS hospitalizations (relative risk [RR] = 1.50, 95% confidence interval [95% CI] 1.43-1.58), including asthma (RR = 1.69, 95% CI 1.54-1.86) and bacterial pneumonia (RR = 1.59, 95% CI 1.40-1.81), the leading causes of admission. Socioeconomic disparities in ACS and all admissions occurred in every cohort, every calendar year, and every age group.

CONCLUSIONS

The relationship between socioeconomic disadvantage and both ACS and all-cause hospitalization in children was large, consistent across many conditions, remained stable over time, and persisted up to 9 years of age. These effects occurred in a universal health insurance setting without direct financial barriers to physician or hospital care. The effect of SES on hospitalizations in children in our setting appears to be mediated by factors other than financial access to care.

Inadequacy of cervical cancer screening among urban recent immigrants: a population-based study of physician and laboratory claims in Toronto, Canada

OBJECTIVE

In Canada, Pap smears are recommended from 18 to 69. Self-reported socioeconomic gradients in screening have been documented in North America but there have been few direct measures of Pap smear use among immigrants or socially disadvantaged groups. Our purpose was to investigate whether socioedemographic factors are related to cervical cancer screening in Toronto, Canada.

METHOD

Pap smears were identified using fee and laboratory codes in Ontario physician service claims for 3 years (2000-2002 inclusive) for women aged 18-66. Area-level socioeconomic factors were derived from the 2001 census. At the individual level, recent registrants for health coverage, over 80% of whom are expected to be recent immigrants, were identified as women first registering after January 1, 1993.

RESULTS

Among 724,584 women, 55.4% had Pap smears within 3 years. Recent immigration, visible minority, foreign language, low income and low education were all associated with significantly lower area rates. Recent registrants had much lower rates than non-recent registrants (36.9% versus 60.9%).

CONCLUSION

Pap smear rates in Toronto fall below those dictated by evidence-based practice. Recent registrants, a largely immigrant group, have particularly low rates. Efforts to improve coverage need to emphasize women who recently immigrated and those with socioeconomic disadvantage.

Determinants of survival in children with congenital abnormalities: a long-term population-based cohort study

BACKGROUND

Today more children with birth defects survive early childhood because of improved medical care; however, little information is available about patterns of long-term mortality and survival in this population. In particular, it is not clear whether other birth characteristics, apart from birth defects, have any role in their mortality.

METHODS

Two large cohorts of children with and without birth defects were followed for up to 17 years. More than 45,000 children with birth defects, and 45,000 matched children without birth defects born in Ontario between 1979 and 1986 were followed. Throughout the study period long-term survival rates and the risk of death were compared between the 2 cohorts. Birth characteristics were also examined to determine their effect on the risk of death.

RESULTS

During the study the deaths of 3620 and 301 children with and without birth defects, respectively, were recorded, indicating that those with birth defects had a 13 times higher rate of mortality (relative risk [RR], 12.9, 95% confidence interval [CI], 12.1-13.7). Mortality rates in the birth-defects cohort remained higher even after 10-15 years. In both groups children of low gestational age and low birth weight had a higher risk of death. There was a strong dose-response relationship between the number of defects and the risk of death.

CONCLUSIONS

Children born with abnormalities face many challenges throughout their lifetimes. If they survive the high mortality risk of the first year of life, they still have to face the considerably higher risk of death in the years to come. In addition to birth defects, other birth characteristics play an independent role in their mortality. These indicators could be used to identify high-risk children.

Age- and sex-specific income gradients in alcohol-related hospitalization rates in an urban area

PURPOSE

This study examines the effects of age and sex on the relationship between neighborhood income and alcohol-related hospitalization rates in a large urban area.

METHODS

Adults in Toronto, Canada, who were hospitalized with an alcohol-related condition between 1995 and 1998 were identified using discharge diagnoses. Income quintiles were determined based on area of residence. Annual rates of hospitalization for alcohol-related conditions per 10,000 individuals were calculated.

RESULTS

Rates of hospitalization with a primary diagnosis of an alcohol-related condition were similar among men age 20 to 39 in all incomes quintiles, but were inversely associated with income among men age 40 to 64 (28.8 and 13.3 per 10,000 in the lowest and highest income quintiles). Among women age 40 to 64, the lowest income quintile had the highest hospitalization rate (12.1 per 10,000), but women in all other income quintiles had relatively low hospitalization rates (5.9 to 7.7 per 10,000). As age increased above 65 years, rates of hospitalization with a primary diagnosis of an alcohol-related condition decreased or stabilized in both men and women.

CONCLUSIONS

The inverse association between income level and alcohol-related hospitalization rates becomes apparent after age 40. A gradient in hospitalization rates is seen in men across all income levels, but in women a prominent effect is seen only in those with the lowest income.

Congenital abnormalities and childhood cancer

BACKGROUND

The examination of specific characteristics of neoplasms diagnosed in children have suggested that a significant proportion can be attributed to a genetic mutation or genetic predisposition. Although the study of a genetic predisposition to cancer in children remains in the early stages, congenital abnormalities could provide essential information for mapping predisposing lesions in children with cancer.

METHODS

In the current study, 2 large cohorts of children with and without congenital abnormalities were followed for the occurrence of cancer and death up to 18 years. Through this study, the risk of developing cancer by age at diagnosis, effects of birth characteristics on cancer risk, and possible associations between specific anomalies and tumor types were examined.

RESULTS

Based on the follow-up of 90,400 children, the risk of developing cancer during the first year of life was found to be nearly 6 times higher in children with anomalies (rate ratio [RR] of 5.8; 95% confidence interval [95% CI], 3.7-9.1). Children with birth defects were found to be at a higher risk for developing leukemia (RR of 2.7; 95% CI, 2.1-3.6), tumors of the central nervous system (RR of 2.5; 95% CI, 1.8-3.4), sympathetic nervous system tumors (RR of 2.2; 95% CI, 1.4-3.4), and soft tissue sarcomas (RR of 1.9; 95% CI, 1.0-3.5). Among children with birth defects, children with Down syndrome, nervous system anomalies, and anomalies of the urinary system had the highest incidence rates of cancer. In the presence of birth defects, other factors such as birth weight, gestational age, age of the mother, and birth order were not found to be associated significantly with the risk of cancer.

CONCLUSIONS

The significant relative risks found in the current study provided evidence of links between the presence of abnormalities and the development of cancer. Some "cancer-prone" abnormalities were identified in the current study. Such anomalies may be markers of other exposures or processes that increase the risk of developing cancer.

Neighbourhood recent immigration and hospitalization in Toronto, Canada

Recent immigrants to Canada tend to initially settle in low-income urban core areas. The relationships among immigration, neighbourhood effects and health are poorly understood. This study explored the risk of hospitalization in high recent-immigration areas in Toronto compared to other Toronto neighbourhoods. The study used 1996 hospitalization and census data. Regression was used to examine the effects of recent immigration on neighbourhood hospitalization rates. Most hospitalization categories showed significantly higher rates of admission as the proportion of recent immigrants increased. Income was also significantly associated with all categories of hospitalization except surgical admissions. Average household income was almost 60% lower (dollar 36,122) in the highest versus the lowest immigration areas (dollar 82,641) suggesting that, at the neighbourhood level, the effects of immigration and income may be difficult to disentangle. These findings have important implications for health care planning, delivery, and policy.

Socioeconomic misclassification in Ontario's Health Care Registry

BACKGROUND

Addresses in some provincial health care registries are not systematically updated. If individuals are attributed to the wrong location, this can lead to errors in health care planning and research. Our purpose was to investigate the accuracy of socioeconomic classification based on addresses in Ontario's provincial health care registry.

METHODS

The study setting was Toronto's inner city, an area with a population of 799,595 in 1996. We ordered enumeration areas by 1996 mean household income and divided them into five roughly equal income groups by population. We then assigned an income quintile to each individual using both the address from Ontario's provincial heath care registry and that from hospital discharge abstracts. We compared these two sets of income quintiles and also used them to generate quintile-specific rates of medical hospital admissions in the year 2000.

RESULTS

Provincial registry and hospital-based addresses agreed on the exact enumeration area for 78.1% of individuals and for income quintile for 84.8% of individuals. Disagreement by more than one income quintile occurred for 7.4% of individuals. The two methods of assigning income quintiles yielded income-specific medical hospitalization rates and rate ratios that agreed within 1%.

INTERPRETATION

Although address inaccuracy was found in Ontario's health care registry, serious socioeconomic misclassification occurred at a relatively low rate and did not appear to introduce significant bias in the calculation of hospital rates by socioeconomic group. Updating of addresses at regular intervals is highly desirable and would result in improved accuracy of provincial health care registries.