Supplement to Statistics Canada's Generic Privacy Impact Assessment related to the Canadian Health Measures Survey, Cycle 7

Date: July 2022

Program manager: Director, Centre for Population Health Data
Director General, Health, Justice, Diversity and Inclusion

Reference to Personal Information Bank (PIB)

Personal information collected through the voluntary Canadian Health Measures Survey (CHMS) is described in Statistics Canada's "Health Surveys" Personal Information Bank. The Personal Information Bank refers to information collected through Statistics Canada's health surveys and includes a variety of topics and information such as: name, contact information, citizenship status, education, employment, financial, language, health and medical information (from blood, urine samples), place of birth, pregnancy, breastfeeding, sleep habits, sexual behavior, nutrition, alcohol, e-cigarette/cigarette use, medication/drug use, physical attributes, physical activity, neighborhood environment, health, COVID-19, and medical information using blood, saliva, and urine samples.

The "Health Surveys" PIB (Bank number: StatCan PPU 806) is published on the Statistics Canada website under the latest Information about Programs and Information Holdings chapter.

Description of statistical activity

Statistics Canada, under the authority of the Statistics ActFootnote 1, conducts the voluntary Canadian Health Measures Survey (CHMS). The CHMS aims to collect important health information through a household interview and direct physical measures at a mobile examination centre (MEC), sometimes referred to as a mobile clinic. The main objective of the survey is to gather information that helps improve the prevention, diagnosis and treatment of illnesses, as well as promote the health and wellness of Canadians. In addition, this survey helps shed light on illnesses and reveal the extent to which many diseases may be undiagnosed among Canadians, and enables health professionals and researchers to address public health challenges.

Fundamentally, the value of the data lies in analysis and interpretation. Demographic, socio-economic, and health characteristics such as age, sex and gender, marital status, ethnic origin, eating habits, physical activity and chronic diseases become especially meaningful when analyzed in relation to one another.

Aggregate survey results are published in the Daily (the Agency's official release bulletin) summarizing the survey findings in the form of profiles and cross-tabulations, anonymized public use microdata files (PUMFs)Footnote 2, and analytical reports. These data are fully anonymized and non-confidential, without any direct personal identifiers, which prevents the possibility of identifying individuals. Through a data sharing agreement, and as permitted by section 17(2) of the Statistics Act, Health Canada (HC) and the Public Health Agency of Canada (PHAC) have access to the data, with all personal identifiers removed, in the Research Data CentresFootnote 3 and are only permitted to release aggregate results, which are fully anonymized and non-confidential. They will use these data to: establish Canadian health reference ranges, identify the prevalence of health indicators (e.g., diabetes) and monitor trends, examine relationships between health indicators (e.g., blood pressure, cardiovascular disease), and provide insight on fitness and health.

To ensure the continued relevance of the CHMS, Statistics Canada conducts formal consultations at the start of each new survey cycle. Data users and stakeholders are invited to provide feedback on what information they use, for what purpose and what, if any, data gaps Statistics Canada should consider addressing in the next cycle. The most recent consultation has led to the following changes to the seventh cycle of data collection which is scheduled for 2022:

  1. Addition of a new age group (1 to 2 Year Old)

    The CHMS survey sample is being extended to include 1 to 2 year-olds. The legal parent or guardian responds to the CHMS household interview on behalf of the child, and must be present with the child at the MEC and provide written consent for the child to participate in the tests which include height and weight, bone health via DXA and blood collection.

  2. Addition of a new musculoskeletal health measures (DXA)

    Body composition and bone health will now be evaluated by anthropometry and dual energy X-ray absorptiometry (DXA) scans of the whole body, femur, and anterior-posterior (AP) lumbar spine.

  3. Re-introduction of the oral health component

    An oral health component was included in CHMS Cycle 1 (2007-2009); it was planned at that time to conduct the same oral health measurements every fifteen years. This component is essential in identifying oral health trends in Canada and provide evidence to support informed policy and program development at all levels of government.

  4. Change of device (physical activity)

    The current device (Actical) used to collect physical activity measures is not well-suited for the collection of sleep data, therefore a new device (Actigraph) will be used in this cycle. The collection of sleep data will establish 24-hour movement behaviours and their association with health conditions and risk factors.

  5. Change of device (blood pressure)

    The device used to measure blood pressure in Cycles 1 to 6 of the survey was provided by BPTru™ which has since ceased its operations. Therefore, a new device (OMRON) which is validated and highly recommended by experts will be used in this cycle.

  6. COVID-19 Screening Strategy

    In order to ensure a safe work environment for the MEC staff, protect the health of respondents, and mitigate the risk of SARS-CoV-2 transmission during collection, the CHMS will include a COVID-19 screening strategy for both MEC staff, respondents, and any other person who could be required to access the MEC (e.g., contractor, family member).

All other personal information collected through the survey remains the same as in previous cycles and is described in previous Canadian Health Measures Survey PIAsFootnote 4 as well as in the Generic PIA for Statistics Canada's Statistical Programs. Health Canada (HC) and the Public Health Agency of Canada's (PHAC) Research Ethics Board have reviewed Cycle 7 content.

Reason for supplement

While the Generic Privacy Impact Assessment (PIA) addresses most of the privacy and security risks related to statistical activities conducted by Statistics Canada, this supplement describes any potential new risks associated with the changes introduced in this survey cycle. This supplement also presents an analysis of the necessity and proportionality of these new elements. As is the case with all PIAs, Statistics Canada's privacy framework ensures that elements of privacy protection and privacy controls are documented and applied.

Necessity and proportionality

The changes in the collection and use of personal information for Cycle 7 of the Canadian Health Measures Survey can be justified against Statistics Canada's Necessity and Proportionality Framework:

1. Necessity

  1. Addition of a new age group (1 to 2 Year Old)

    The personal information collected for this age group will provide reliable information on the health and wellness of young Canadians. There is substantial interest for information on this age group as there is currently limited data available for this population in Canada. Dual Energy X-ray Absorptiometry (DXA) will be conducted in partnership with the Children's Hospital of Eastern Ontario (CHEO) and the environmental measures will be analyzed with the support of Health Canada. Exposure to environmental chemicals during these critical development years can have a lasting impact on the child's future health outcomesFootnote 5.

    The personal identifiers for the children included in the survey, as well as for all other respondents (full name, date of birth, and provincial or territorial health card number) are collected for linkage purposes. Personal identifiers are removed from the data file and stored separately and securely, once the linkage has been performed. Statistics Canada's microdata linkage and related statistical activities were assessed in Statistics Canada's Generic Privacy Impact AssessmentFootnote 6. All data linkage activities are subject to established governanceFootnote 7, and are assessed against the privacy principles of necessity and proportionalityFootnote 8. All approved linkages are published on Statistics Canada's websiteFootnote 9.

    The addition of this age group was submitted for review to the Public Health Agency of Canada-Health Canada Research Ethics Board to solicit their health and medical expertise in order to ensure ethical issues were considered, to ensure that internationally recognized ethical standards for human research were met and maintained, and to ensure minimal respondent burden while maximizing the data potential.

  2. Addition of a new instrument (DXA)

    The information collected with the dual energy X-ray absorptiometry (DXA) will fill a gap in quality national estimates of body composition and bone density. It will help address a wide range of priority policy questions pertaining to bone health which cannot currently be addressed with accuracy. The DXA will allow the investigation of health-related topics including osteoporosis, obesity and cardiovascular disease risk.

    Body composition and bone health will be evaluated using anthropometry and DXA scans of the whole body, femur, and anterior-posterior (AP) lumbar spine. The information provided by the scans will allow: nationally representative data on total and regional bone mineral content, lean mass, fat mass, and percent fat overall and for age, gender, and racial/ethnic groups; estimates of obesity, defined as an excess of body fat; data to study the association between body composition and other health conditions and risk factors, such as cardiovascular disease, diabetes, hypertension, physical activity, and dietary patterns; estimates of the prevalence of osteoporosis and low bone mass; and the first estimates of the prevalence of vertebral fractures and abdominal aortic calcification.

  3. Re-introduction of the Oral Health component

    The oral health component is Canada's only complete overview of the current oral health status of Canadians. The Canadian Health Measures Survey (CHMS) is the best survey to conduct data collection for these measures as it combines both clinical measurements and a household questionnaire.

    The objectives of the oral health component are to evaluate the association of oral health with major health concerns such as diabetes, respiratory and cardiovascular diseases. It will help determine relationships between oral health and certain risk factors such as poor nutrition, environmental factors such as levels of fluorides in water, and socioeconomic factors related to low income levels and education.

  4. Change of device (physical activity)

    In order to remain relevant and meet current and foreseeable future research needs, Statistics Canada will measure all respondent activities within a 24-hour period, including sleep, as opposed to only waking hours. The current device (Actical) is not well-suited for the collection of sleep data, therefore Statistics Canada will be using the Actigraph wGT3X-BT for use in future cycles of the survey.

    This new monitor captures and records high resolution, raw acceleration data, which is converted into a variety of objective activity and sleep measures using publicly available algorithms developed and validated by members of the academic research community. The high quality, timely and relevant data collected will determine the degree to which the Canadian Physical Activity GuidelinesFootnote 10 are being met and allow to measures the health benefits and potential risk of developing diseases. Available historical data will also allow for the monitoring of trends.

    The Canadian 24-hour Movement Guidelines, created by the Canadian Society for Exercise Physiology (CSEP), provide guidance on the optimal amount of physical activity, sedentary behavior, and sleep, and the best combination of these behaviours, for Canadians of all ages. Evidence suggests that people who follow these guidelines can improve their health. Benefits include lower risk of cardiovascular disease, obesity, and cancer, improved bone health, and enhanced psychosocial health.

    Currently, there is an information gap at the national level concerning the percentage of the Canadian population that meets these guidelines. In partnership with Health Canada and the Public Health Agency of Canada, Statistics Canada will use the information collected from the CHMS to evaluate the 24-hour movement behaviours and their association with health conditions and risk factors.

  5. Change of device (blood pressure)

    During Cycle 6 collection of the CHMS, the company BPTru™ which provided the device for the collection of blood pressure measures ceased its operations.

    To replace the device, Statistics Canada has opted for the OMRON HEM-907-XL which is highly recommended by experts, and is used for other national studies and major trials such as the National Health and Nutrition Examination Survey and Systolic Blood Pressure Intervention Trial (Center for Disease Control and Prevention, USA). It was also validated by the Association for the Advancement of Medical Instrumentation and the International Protocol of the European Society of HypertensionFootnote 11.

  6. COVID-19 Screening Strategy

    In order to ensure a safe work environment for the MEC staff, protect the health of respondents, and mitigate the risk of SARS-CoV-2 transmission during collection, Statistics Canada is planning on implementing a COVID-19 screening strategy for both MEC staff and respondents.

    During the MEC appointment reminder phone call (24-48 hours before the appointment), the Centre Coordinator will confirm verbally with the respondent that they are not symptomatic, and understands that they will have to undergo COVID-19 screening measures upon their arrival at the MEC to participate in the MEC visit. If the respondent is symptomatic or refuses to follow the protocols their appointment will be cancelled.

    Upon arrival, every individual entering the MEC will be required to follow the COVID-19 screening protocols established in collaboration with Statistics Canada Occupational Health and Safety group. They will be provided with a consent form (Appendix A) for the COVID-19 Screening Protocols, which will consist of a screening questionnaire (Appendix B) and temperature check (not recorded). The form and questionnaire will have the name of the individual, the date and the CLINIC ID of the respondent and will be stored in a secured drawer in the administrative room in the MEC. During the day, the secured drawer is accessible using a key by all deemed Statistics Canada MEC employees (approximately 20) for them to put the respondents file away after the appointment. The drawer is locked when the MEC is closed and the Site Manager, Team Leaders (2) and Clinic Coordinators (2) have access to the key. All respondent files are shipped to Head Office at the end of every MEC collection site (MEC changes site every 5-6 weeks) in a Versapack (same shipping procedure as previous cycles; the Versapack is the secure method used by Statistics Canada to ship confidential packages from the MEC to Statistics Canada's Head Office). At Head Office they are stored in a locked filing cabinet until they can be sent to Statistics Canada's Operations Integration team to be scanned and stored electronically. The documents will be stored and retained/destroyed as per Statistics Canada's retention standards. In this case, COVID-19 screening material is considered "work files in support of design and collection", making them transitory files with a retention requirement described as, "Delete as soon as they have served their use or purpose, within a year of the end of collection." with discretion also given to the responsible manager according to the following criteria:

    Respondents who do not consent to COVID-19 screening will be informed that they are ineligible to participate in the direct measures component of the survey.

    The COVID-19 Screening Strategy will be subject to change depending on the evolution of the pandemic, recommendations from the Occupational Health and Safety group (that will be consulted regularly through collection) and provincial public health guidelines. Should any of those changes have a privacy impact, an amendment to this Sought PIA will be created.

    • "In determining the appropriate level of additional documentation required, the responsible manager's decision should be based on the use of statistical microdata files and their expected retention. The following are suggested criteria that could be considered in making this determination:

      Use:

      Retention:

      • intended use or purpose
      • types of uses (one specific use versus multiple widespread usage)
      • number of users
      • type of users (e.g., IT professionals only, internal project staff only, researchers external to the project or to Statistics Canada)
      • a one-time event or part of an ongoing repeated process
      • length of time the information is retained"

2. Effectiveness - Working assumptions

The CHMS is carefully designed to produce relevant, high priority, statistically meaningful information. Although a great deal of health knowledge can be obtained through survey interviews and administrative databases, the most accurate information that is relevant to the present and future health of the population can only be obtained through direct measures of physical characteristics.

  1. Addition of a new age group (1 to 2-Year-Old)

    A sample size of 670 1-2-year-olds has been assessed as necessary by methodologists to produce statistics of sufficient quality for that age group. The total sample size for the survey is therefore consequentially increasing from 5700 to 6370. Data analysis and reporting will not be modified and will follow approved guidelines used in previous cycles.

  2. Addition of a new instrument (DXA)

    Dual-energy X-ray absorptiometry (DXA) is a clinically proven, accurate, and reproducible method of measuring bone mineral density in the lumbar spine, proximal femur, and whole body. Body composition and bone health will be evaluated starting in Cycle 7 of the CHMS by anthropometry and DXA scans of the whole body, femur, and anterior-posterior (AP) lumbar spine.

    All respondents will be asked to undergo scans. The final report will only summarize group results, and no individual, personal or confidential information will be shared.

  3. Re-introduction of the Oral Health component

    The oral health component is Canada's only complete overview of the current oral health status of Canadians. The Canadian Health Measures Survey (CHMS) is the best survey to conduct data collection for these measures as it combines both clinical measurements and a household questionnaire.

  4. Change of device (physical activity)

    The Actigraph will measure raw acceleration, activity counts, energy expenditure, MET rates, steps taken, physical activity intensity, activity bouts, sedentary bouts, body position, sleep latency, total sleep time, wake after sleep onset, sleep efficiency, and ambient light. Raw data will be stored using participant numbers as identifiers.

    The final report will only summarize group results, and no individual, personal or confidential information will be shared.

  5. Change of device (blood pressure)

    The decision was made to use the OMRON HEM-907-XL because it was highly recommended by experts and it is used in other national studies and major trials such as the National Health and Nutrition Examination Survey and Systolic Blood Pressure Intervention Trial (Center for Disease Control and Prevention, USA). It has also been validated by the Association for the Advancement of Medical Instrumentation and the International Protocol of the European Society of HypertensionFootnote 12.

    The final report will only summarize group results, and no individual, personal or confidential information will be shared.

  6. COVID-19 Screening Strategy

    COVID-19 screening strategies will evolve through survey collection to ensure they are following the provincial and federal health & safety guidelines at the minimum. They will also be reviewed by Statistics Canada's Occupational Health and Safety group to ensure that all necessary precautions to protect employees and survey respondents are taken. COVID-19 screening results will not be retained nor shared.

3. Proportionality

The data collected will contain only the variables required to achieve the statistical goals of the CHMS. Statistics Canada directives and policies with respect to data collection and publication will be followed to ensure the confidentiality of the data. Individual responses will be grouped with those of others when reporting results. Individual responses and results for very small groups will never be shared with government departments or agencies.

The benefits of the findings, which are expected to support services aimed at improving the prevention, diagnosis and treatment of illnesses and to promote the health and wellness of Canadians, are believed to be proportional to the potential risks to privacy.

4. Alternatives

The CHMS is one of the only sources of information for small geographic areas, based on the same statistical concepts for the entire country, and the only source of information for many health characteristics.

Data linkages are used between CHMS data and other sources of information for statistical analyses; to evaluate data quality, to assist with data processing, and for direct replacement of data when the quality is deemed appropriate.

Mitigation factors

Some questions and measurements contained in the CHMS are considered sensitive as they relate to an individual's health and wellness; however, the overall risk of harm to the survey respondents has been deemed manageable with existing Statistics Canada safeguards that are described in Statistics Canada's Generic Privacy Impact Assessment, including, but not limited to the following:

Consent

For the household interview portion of the CHMS, participants will be informed in the invitation letter that their participation is voluntary and before being asked any questions. For the direct physical measures element, participants will also be informed of the voluntary nature of the CHMS and the topic of each component before participating. Finally, prior to entering the MEC, participants will be informed that the COVID-19 screening is voluntary, yet is necessary to proceed with the clinical component of the survey.

Confidentiality

Variables that directly identify respondents will be separated from the data files in the first stage of data processing and placed in a secure location with controlled access. Variables that might indirectly identify respondents are examined and modified as necessary in order to protect the privacy and confidentiality of respondents. Individual responses will be grouped with those of others when reporting results. Individual responses and results for very small groups will never be published or shared with government departments or agencies. Careful analysis of the data will be performed prior to the publication and sharing of aggregate data to ensure that marginalized and vulnerable communities are not disproportionally impacted.

Data linkage

The linkage of CHMS data with other sources of information will be used in statistical studies to evaluate data quality and the impact of non-response, to improve and assist with data editing and imputation, and for direct replacement of data in presence of partial non-response when the quality is deemed appropriate. The linkage files will be used only within Statistics Canada for methodological research, development and processing.

Security measures for linkage keys and administrative files respect the policies, directives and guidelines for information technology security at Statistics Canada. When linkage is required, it is done using anonymized statistical identifiers ("linkage keys") and, as a result, no linked file contains personal identifiers such as name, phone number and address (excluding postal code). These anonymized statistical identifiers are used to link to other sources of information for statistical purposes only. The personal identifiers obtained are removed from the rest of the information and securely stored with restricted access with an approved operational requirement to access them, and whose access is removed when no longer required.

Transparency

It is the policy of Statistics Canada to provide all respondents with information about: the purpose of a survey (including the expected uses and users of the statistics to be produced from the survey), the authority under which the survey is taken, the mandatory or voluntary nature of the survey, confidentiality protection, the record linkage plans and the identity of the parties to any agreements for sharing of the information provided by those respondents, where applicable.

For Cycle 7 of the CHMS, this information is provided in the letter of invitation, in the survey's consent form, and in Frequently Asked Questions (FAQs) accessible through the CHMS websiteFootnote 13.

Conclusion

This assessment concludes that, with the existing Statistics Canada safeguards, any remaining risks are such that Statistics Canada is prepared to accept and manage the risk.

Formal approval

This Supplementary Privacy Impact Assessment has been reviewed and recommended for approval by Statistics Canada's Chief Privacy Officer, Director General for Modern Statistical Methods and Data Science, and Assistant Chief Statistician for the Enterprise Statistics Field.

The Chief Statistician of Canada has the authority for section 10 of the Privacy Act for Statistics Canada and is responsible for the Agency's operations, including the program area mentioned in this Supplementary Privacy Impact Assessment.

This Privacy Impact Assessment has been approved by the Chief Statistician of Canada.

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