Data Gaps in Public Health Indicators in Ontario Introduction Data for local populations has become more readily available to public health epidemiologists in recent years due to initiatives such as the Canadian Community Health Survey (CCHS), the Rapid Risk Factor Surveillance System, the Provincial Health Planning Database (PHPDB), and the national Health Indicators project by Statistics Canada and the Canadian Institute for Health Information. As well, the number of public health unit epidemiologists has continued to increase, improving local capacity to use these data. In 1994, 31 epidemiologists (as determined by APHEO membership) covered 27 of 42 health units (75%). By 2005, 57 epidemiologists were employed in 86% of health units with 14 of 36 health units having two or more epidemiologists. Nevertheless, there are still important gaps in local public health data. Work continues to try to fill these gaps. Difficulties exist with making definitions specific enough that the indicator can be measured, reaching certain populations, and measuring complex aspects of health. Sometimes, it may not be feasible to obtain data at the local level because it is too expensive to collect. Many of the key data gaps are in the areas of child and adolescent health, reproductive health, and nutrition. These gaps are not easily filled. Some health units have undertaken special surveys and studies of children,1,2,3,4 often to better assess emerging issues such as child obesity. Filling data gaps will undoubtedly require more resources, working with new data or data not typically thought of in the public health field, and the development of new partnerships within the sphere of data collection and analysis (for example, school boards, Early Years Centres). Coordination of efforts across health units will be necessary to optimize resources. A particularly important initiative to fill data gaps is the Rapid Risk Factor Surveillance System (RRFSS). Indeed, its mission states that “Ontario’s RRFSS is a flexible, timely and responsive surveillance system designed to meet local Public Health intelligence needs and address information, geographic and time-related data gaps”. To be most effective, RRFSS needs to be available in all health units and to provide provincial estimates. Many of the data gaps listed below are based on objectives in the 1997 Mandatory Health Programs and Services Guidelines, or the draft Guidelines from 2003. For a complete list of the specific objectives that do not have a corresponding indicator, refer to Objective and Indicators for the Mandatory Health Programs and Services Guidelines. There are many other data gaps that could be identified. The list below is a starting point to identify some of the more important gaps in public health related to health status reporting. Data Gaps Listing Population Environment and Health: Social Environment Seniors in low income households
Source: Provincial Health Indicators Work Group
Comments: These indicators are described in the Core Indicators. The data source for these indicators is a special tabulation to Statistics Canada for Census data which the Public Health Division has requested on behalf of all public health units. Although low income in children was provided from the 2001 Census, data for seniors was not.
Environment and Health: Physical Environment Exposure to adverse physical environments
Example: Mould exposure Source: Provincial Health Indicators Work Group Comments: The Core Indicators currently describes only five physical environment indicators. PHIWG acknowledges that more work is needed in this area. 3.2 Awareness and behaviours that minimize exposure to an adverse physical environment Examples: Proportion of children and youth exposed to hazardous substances in their environment; Proportion of parents and caregivers aware of and adopting practices that minimize children’s and youth’s exposure to indoor air pollutants; Proportion of households, schools, and child care facilities that use Integrated Pest Management rather than conventional pest control measures; Proportion of parents and caregivers of children and youth, including those with respiratory problems, aware of and adopting strategies to reduce exposures to outdoor pollutants; Proportion of children and youth, as well as their parents and caregivers, aware of and adopting pollution prevention strategies (e.g. walking, cycling, energy conservation measures, and use of alternative sources of energy such as solar and wind energy); Proportion of children and youth involved in the development, implementation, and evaluation of policies and programs that reduce exposure to hazardous substances in their environment.
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: These indicators have not been developed. They are based on objectives in the Child Health section of the draft Mandatory Health Programs and Services Guidelines. The indicators are problematic because there are no data sources and operational definitions. Definitions are needed for concepts such as: hazardous substances in the environment; indoor air pollutants; practices that minimize exposure to indoor air pollutants; strategies to reduce indoor air pollutants; and energy conservation measures. Measuring these indicators may require special surveys. However, second-hand smoke is a specific indoor air pollutant for which there are existing indicators. As well, there is a pesticide module in RRFSS that can be used to assess use of and exposure to pesticides within a household. Schools and child care facilities would need to be surveyed separately. RRFSS could be used to ask about walking and cycling to school, work or for errands. If energy conservation measures were defined in specific terms, RRFSS may be a tool for collecting data. Because RRFSS’ respondents are aged 18+, questions relating to children and youth would need to be answered by parents and caregivers.
Chronic Diseases and Injury: Chronic Diseases Prevalence of diabetes in children
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Estimates for diabetes in adults are available from the CCHS; these are not ideal because many people are unaware that they have diabetes. No estimates are available for diabetes in children less than 12. Prevalence of osteoporosis
Source: Health Programs and Services Guidelines 1997, Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Osteoporosis could be added to the list of chronic diseases asked about in the CCHS or RRFSS; however, many people do not know that they have osteoporosis. The Institute for Evaluative Sciences (ICES) may be able to use physician billing data and hospitalizations to estimate prevalence, similar to what has been done for diabetes. Alternatively, an indicator such as hip fractures could be used as a proxy for osteoporosis. More research would be required to assess these options. Prevalence of asthma in children
Source: Health Programs and Services Guidelines 1997, Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Prevalence of asthma is available for ages 12+ from the CCHS; however, no data are available for children. Hospitalization rates may be used but provide a very incomplete picture of asthma. ICES completed an investigative report on the burden of childhood asthma in 2004.5
Chronic Diseases and Injury: Cancer Incidence and Early Detection of Cancer Incidence of non-malignant skin cancers
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Non-malignant skin cancer incidence is not available from the Ontario Cancer Registry because it is relatively common and treated in doctors’ offices (often dermatologists). Obtaining this data is problematic. Special surveys could be done. A system employing the physician billing database might be feasible. Mammography screening and pap smear rates of groups that are under screened
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Women facing significant barriers to screening, include: recent immigrants; women who have language and/or cultural barriers; socioeconomically disadvantaged women; aboriginal women; geographically isolated women; women without a family physician or other health care provider. The current “mammography” and “cervical cancer screening” indicators do not include sub-indicators to capture groups that are under screened. Indicators could be developed within the CCHS to capture some of these populations, but the definitions would need to be operationalized, particularly “socioeconomically disadvantaged women” and “geographically isolated women”. The definitions would likely use variables for household income, and rural communities respectively. Sample size would likely be small at the local level, even if all of these are grouped within one derived variable.
Chronic Diseases and Injury: Injury Prevention and Substance Abuse Prevention Rate of illicit substance use and the non-medical use of drugs and of other psychoactive substances
Source: Health Programs and Services Guidelines 1997
Comments: Some questions on illicit drug use are available from the CCHS 2.1 as optional content; however, a limited number of health units chose this module. Some data may be available from the Centre for Addition and Mental Health (CAMH) but would not be health unit specific. Proportion of older adults and their caregivers (formal and informal) who practise fall prevention behaviours
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Five modules have been developed in RRFSS, along with a module on restriction of activities. Because these modules focus on respondents aged 55 and older, obtaining sufficient sample size for analysis is an issue. Road Safety
Examples: Safety of the built (man-made) and other community environments; Road safety for pedestrians and vehicle occupants; Safety of built (man-made) and other external environments in which children and adolescents live and play.
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Operational definitions are needed. Information about playgrounds that meet CSA standards might be available for some health units but the definitions would likely vary by health unit and would need to be specified. This would be assessed using health unit-specific databases for playground inspection. Appropriate use of car seats for children could be assessed using the RRFSS module on car seats. Proportion of children, adolescents and their caregivers who practise injury prevention and risk management behaviours
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: No source of data. Operational definitions needed. RRFSS could be used to collect some of this information. Age of first experimentation with drugs
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Some data may be available from Centre for Addiction and Mental Health but would not be health unit specific.
Behaviour and Health: Smoking Proportion of children (<12 years) who reside in smoke-free homes
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Although the percentage of smoke-free homes is an indicator available through the CCHS, the percentage of children in smoke-free homes cannot be easily derived.
Behaviour and Health: Alcohol Age of first drinking
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Data are available from the CCHS; however, small sample sizes would make analysis difficult at the local level.
Behaviour and Health: Physical Activity Proportion of children who are active
Source: Mandatory Health Programs and Services Guidelines 1997, Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Operational definition of “active” needed. Data from the CCHS is only available for youth aged 12-19. For this group, energy expenditure in the “active” category could be used from the physical activity index. For children younger than 12, a special survey would be needed. Proportion of children/ adults/ older adults who are physically active at levels recommended in Canada's Physical Activity Guide to Healthy Active Living
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: This indicator would be difficult to assess. Health Canada's Physical Activity Guide recommends engaging in endurance activities 4-7 days a week, flexibility activities 4-7 days a week, and strength activities 2-4 days a week, accumulating 60 minutes of physical activity. Time needed depends on effort - as one progresses to moderately intensive activities, the time can be cut down to 30 minutes, 4 days per week. Experts in exercise science might be able to adapt data collected on physical activity from the CCHS to derive a variable on meeting the Guide’s recommendations. A variable that provides a range would be more useful than a simple “yes/no” variable, particularly since many assumptions would need to be made to derive the variable. Different criteria could be used for youth, adults and older adults. Physical activity data from the CCHS is available only for those aged 12 and older. No data are readily available for children at the health unit level.
Behaviour and Health: Nutrition and Healthy Weights Nutrient Intake
Examples: Dietary fat intake by adults (18 years and over); Proportion of children (4-11 years) consuming five or more servings of vegetables and fruit daily; Proportion of youth (10-16 years) consuming three or more servings of milk products daily; Proportion of adults consuming two or more servings of milk products daily; Proportion of the population age four and older consuming five or more servings of grain products daily
Source: Mandatory Health Programs and Services Guidelines 1997, Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Collecting nutrition data is difficult. The 1990 Ontario Health Survey had a large food frequency questionnaire for ages 12+ that was able to assess fat intake, servings of fruits and vegetables, milk products, and grain products. CCHS 2.2 focused on nutrition and may be able to provide some of this information at a national and provincial level. A general data source on nutrition that may serve some data needs is Canada Food Stats (CFS). Statistics Canada produces CFS, an electronic compendium of food statistics compiled from a wide variety of sources, both survey and administrative, from within Statistics Canada as well as other provincial and federal government departments, growers' associations and marketing boards. The data are updated twice each year (June and November). Although generally only at the national level, some data are available at the provincial level. Data are reported per capita, with the new food consumption data adjusted for retail, household, cooking and plate loss. The main disadvantages of the CFS is that data are not provided by age or public health unit; however, they are useful for seeing overall trends, e.g. caloric consumption in Canada has been rising between 1 and 3 percent year-over-year since 1993. (URL: http://www.statcan.ca/english/ads/23F0001XCB/index.htm) Nutrition data for children particularly problematic and would require special surveys. Proportion of people in their reproductive years following “Canada’s Food Guide to Healthy Eating”
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: The proportion meeting Canada’s Food Guide has the same issues as indicators related to nutrient intake discussed above. In addition, a derived variable would be needed to consider the number of servings of each of the food groups. In terms of the proportion following Canada’s Food Guide, a subjective question could be asked on the CCHS or RRFSS; however, this information may be difficult to interpret. A validation study may be required to ask a series of questions that would indicate whether the respondent’s eating patterns follow the Food Guide. Proportion of the population who has a waist circumference that is a risk factor for certain chronic diseases
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. This information could be asked in the CCHS or RRFSS but since many people do not know their waist circumference, they would need some way to measure it. A special survey may be needed to collect this information. Proportion of youth and adults (12 years and over) who accept their current body weights
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: There is currently no indicator. Need operational definition for “accept current body weight”. The following question in the Height and Weight section of the CCHS could be used for this indicator: “Do you consider yourself: 1) overweight, 2) underweight, 3) just about right”. The question would need to be analyzed in conjunction with respondent’s body mass index.
Behaviour and Health: Sun Safety Proportion of the population of all ages who avoid artificial sources of ultraviolet light (i.e., sun lamps, tanning booths)
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: Many of the components of sun safety are covered under the Sun Safety indicator, as collected in RRFSS. The exception is the piece “avoid artificial sources of ultraviolet light (i.e., sun lamps, tanning booths)”. The RRSS module “artificial tanning equipment” does collect this information.
Family Health: Sexual Health Access to contraception for individuals in need to decrease unplanned pregnancy
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: Currently no systematic source of data. Some health units may have databases related to client access to contraception in their sexual health clinics, but these data would not be consistent across all health units and would only capture clinic clients, not all individuals at risk for unplanned pregnancy. Awareness and knowledge about personal responsibility and life skills required to deal with sexual relationships
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: Currently no source of data. Need operational definitions. Some Information may be available through health units’ sexual health clinics.
Family Health: Reproductive Health Intentions and health behaviours among pregnant women and people planning pregnancies
Examples: Proportion of both pregnant women and people planning pregnancies who intend to breastfeed; Proportion of pregnant women who quit and remain smoke-free throughout their pregnancy; Proportion of people planning pregnancies and pregnant women who avoid alcohol; Proportion of pregnant women living in smoke-free environments, including homes, cars, workplaces and public places.
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Special surveys may be needed to capture intention to breastfeed among people planning pregnancies. Suggestions:
· The Niday Perinatal Database includes the field “intention to breastfeed (on admission)” that could be used to capture the proportion of pregnant women who intend to breastfeed.
· The CCHS could add a question about whether the respondent is currently planning a pregnancy. Questions about smoking, alcohol and nutrition could then be analyzed for this sub-group, although sample size would be a problem. Alternatively, analysis could be done for ages 20-44, the prime reproductive age group.
· The CCHS does ask about whether the respondent is currently pregnant. The sample size is too small to be useful at the local level but may provide meaningful data at the provincial and national levels.
· Some health units may be able to use data collected in the Integrated Services for Children Information System (ISCIS) through the Healthy Babies Healthy Children Program for some of these indicators (refer to Resource for information). For these data to be representative of the population, referrals to the HBHC program should be high. Health behaviours among pregnant women
Examples: Proportion of pregnant women who access appropriate prenatal health care beginning in the first trimester by 2010 (link to HBHC); Proportion of pregnant women and their families identified, referred to services, and/or directly supported in the prenatal period, who are experiencing psychosocial and/or other health risk factors that are likely to affect birth outcomes (HBHC objective); Proportion of all pregnant women and their families who are linked to prenatal information sources, informal supports and/or existing programs and services in their community (HBHC objective); Proportion of pregnant women and their families who are aware of the signs and symptoms of preterm labour by 2010.
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Some health units may be able to use data collected in the Integrated Services for Children Information System (ISCIS) through the Healthy Babies Healthy Children Program for some of these indicators (refer to Resource for information). For these data to be representative of the population, referrals to the HBHC program should be high. Proportion of families experiencing abuse during pregnancy
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Some health units may be able to use data collected in the Integrated Services for Children Information System (ISCIS) through the Healthy Babies Healthy Children Program for some of these indicators (refer to Resource for information). For these data to be representative of the population, referrals to the HBHC program should be high. The Family Violence module in RRFSS asks about attitudes towards family violence including one question on abuse during pregnancy. Proportion of planned pregnancies
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. The CCHS does not ask women if their last pregnancy was planned.
Family Health: Child and Adolescent Health Percentage of children and youth who meet physical, cognitive, communicative and psychosocial developmental milestones
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: Currently no source of data. Operational definitions needed. Possible sources of data include ISCIS, data from school boards, and the Data Analysis Coordinators (DACs) part of the Ontario Early Years Initiative. Percentage of infants breast-fed up to six months
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: Although there is a “breastfeeding initiation and duration” indicator using CCHS data, sample size will likely not be large enough at the health unit level to present breastfeeding prevalence at six months. Special studies or surveillance systems would be required. Dental health in youth
Examples: Prevalence of dental diseases in youth; Proportion of children and youth with good oral health.
Source: Mandatory Health Programs and Services Guidelines 1997, Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Although various dental indicators are available for children as defined in the Core Indicators, data are not currently available for youth. Special studies or surveillance systems would be required. Access to and the use of needs-based services and supports for children who are at risk of poor physical, cognitive, communicative, and psychosocial development, and their families
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: Currently no source of data. Operational definitions needed. Some health units may be able to use data collected in the Integrated Services for Children Information System (ISCIS) through the Healthy Babies Healthy Children Program for some of these indicators (refer to Resource for information). For these data to be representative of the population, referrals to the HBHC program should be high. The Data Analysis Coordinators (DACs) part of the Ontario Early Years Initiative may have relevant data. Effective parenting ability in high-risk families
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: Currently no source of data. Operational definitions needed. Some health units may be able to use data collected in the Integrated Services for Children Information System (ISCIS) through the Healthy Babies Healthy Children Program for some of these indicators (refer to Resource for information). For these data to be representative of the population, referrals to the HBHC program should be high. The Data Analysis Coordinators (DACs) part of the Ontario Early Years Initiative may have relevant data. Proportion of children will reach developmental milestones at 18 months
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Health units are using the Nipissing screen and other similar instruments to assess children at 18 months as part of the Healthy Babies Healthy Children Program. However, this is generally used on an individual level and is not a population measure, thus there is no systematic sampling and data collection. The Data Analysis Coordinators (DACs) part of the Ontario Early Years Initiative may have relevant data. Proportion of children will be ready to learn at school entry
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: The Offord Centre for Child Studies has developed a teacher-completed instrument called the Early Development Instrument: A Population-based Measure for Communities (EDI) to assess children’s readiness to learn at the time of school entry. The EDI measures five domains: physical health and well-being; social knowledge and competence; emotional health/maturity; language and cognitive development; and general knowledge and communication. The EDI has been implemented in many sites across Ontario and Canada, with the Offord Centre for Child Studies at McMaster University being the national repository.6 Partnerships between health units, school boards and the Offord Centre may allow school readiness to be a feasible Core Indicator. Proportion of infants and preschool children aged 0-4 who are well nourished
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Operational definitions needed. School food programs may provide information relating to school-aged children. Knowledge and skills related to parenting, and health in children and youth among parents/caregivers/others Examples:
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Operational definitions needed. RRFSS does provide a number of modules related to parenting, including one on parenting style (positive parenting) and sexual health education. The Data Analysis Coordinators (DACs) part of the Ontario Early Years Initiative may have relevant data. Proportion of parents/caregivers with knowledge of and adopting practices to minimize risk of SIDS; Proportion of parents/caregivers/others with knowledge of Shaken Baby Syndrome and adopting behaviours to minimize its risks
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Operational definitions needed. In terms of SIDS, sleeping position and breastfeeding are perhaps most relevant. In terms of Shaken Baby Syndrome, risk factors related to child abuse are important. Some health units may be able to collect relevant data through the Healthy Babies Healthy Children Program. Access to services
Examples: Proportion of children will have access to a range of coordinated and integrated prevention, early intervention, and treatment services; Proportion of children identified as being at risk for poor developmental outcomes will receive intervention prior to school age; Proportion of youth and new/expectant mothers will have access to urgent dental care; Proportion of children and youth will have access to affordable regulated, flexible, developmental child care, including before and after school care, which meets provincial standards; Proportion of children and youth will have access to and be involved in recreational and other skill building programs.
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Operational definitions needed. Some health units may be able to use data collected in the Integrated Services for Children Information System (ISCIS) through the Healthy Babies Healthy Children Program for some of these indicators that focus on children aged 0-6 (refer to Resource for information). For these data to be representative of the population, referrals to the HBHC program should be high. Data related to child care and youth programs may be available through various government organizations but would be difficult to coordinate and analyze. The Data Analysis Coordinators (DACs) part of the Ontario Early Years Initiative may have relevant data. Attitudes towards youth
Examples: Proportion of community members will have positive attitudes towards youth; Proportion of youth friendly public places will be increased; Proportion of programs and/or policy initiatives, which have public health involvement and which are targeted towards youth, will have active youth participation.
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Operational definitions needed. Access to information
Example: Proportion of parents/caregivers of infants and preschool children aged 0-4 will have access to accurate, consistent information and advice regarding healthy eating.
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: Currently no source of data. Operational definitions needed. Some health units may be able to use data through the Healthy Babies Healthy Children.
Mental Health Community capacity to address suicide
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: No source of data. Need operational definition. Special survey likely needed. Incidence of violence directed toward children, youth and the elderly, violence in pregnancy, and family/relationship violence
Source: Draft Mandatory Health Programs and Services Guidelines Jan 2003
Comments: There is currently an indicator on Crime Rate, but it does not address specific targets of violence. The Family Violence module in RRFSS asks about attitudes towards family violence, but is not useful for assessing incidence of violence. Emergency room data may provide information about more extreme cases of violence.
Infectious Diseases Morbidity and mortality associated with infectious diseases in institutions, day care centres and personal service settings.
Source: Mandatory Health Programs and Services Guidelines 1997
Comments: While reportable diseases, hospitalizations, deaths and other data can capture morbidity and mortality associated with infectious diseases, it can be difficult to determine the settings from which the diseases originated. Data for reportable diseases occurring as part of an outbreak within these settings can be assessed through the Integrated Public Health Information System (iPHIS).
References - Region of Peel Health Department. Student Health 2005 - Gauging the health of Peel’s youth, 2005. URL: http://www.peelregion.ca .
- Simcoe Muskoka District Health Unit. Child Health Survey, 2004. URL: http://www.simcoehealth.org/Surveys/hs_intro2.asp#child
- Northern Ontario Perinatal and Child Health Survey Consortium. Various child health reports. URL: http://www.sdhu.com/content/resources/folder.asp?folder=4109&parent=11&lang=0
- Middlesex-London Health Unit. The Health Index: Breastfeeding Practices, Awareness & Attitudes in Middlesex-London; Issue 13, January 2005. URL: http://www.healthunit.com/articlesPDF/11184.pdf
- To T, Dell S, Dick P, Cicutto L, Harris J, Tassoudji M, Duong-Hua M. Burden of childhood asthma. ICES, Toronto, Ontario, 2004. URL: http://www.ices.on.ca/file/ACF77.pdf
- Offord Centre for Child Studies. School Readiness to Learn (SRL) Project. URL: http://www.offordcentre.com/readiness/project.html
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