Page 11: HIV and AIDS in Canada: Surveillance Report to December 31, 2014 – Appendices
Appendix 1: Data contributors
BC Centre for Disease Control
655 West 12th Avenue
Vancouver, BC V5Z 4R4
Department of Health and Social Services
Whitehorse, YK Y1A 2C6
Alberta Health and Wellness
P.O. Box 1360, Station Main
Edmonton, AB T5J 2N3
Northwest Territories Health and Social Services
P.O. Box 1320
8th Floor, Centre Square Tower
Yellowknife, NWT X1A 2L9
Health and Social Services
Government of Nunavut
P.O. Box 1000, Station 1000
Iqaluit, NU X0A 0H0
3475 Albert Street
Regina, SK S4S 6X6
Communicable Disease Control (CDC) Unit
Public Health Branch - Manitoba Health
4th Floor - 300 Carlton Street
Winnipeg, MB R3B 3M9
Ministry of Health and Long-Term Care
Public Health Division
21st Floor, 393 University Avenue
Toronto ON M7A 2S1
Central Public Health Laboratory
Ontario Ministry of Health and Long-Term Care
81 Resources Road
Toronto, ON M9P 3T1
Institut national de santé publique du Québec
945, avenue Wolfe, 5e étage
Québec, QC G1V 5B3
Laboratoire de santé publique du Québec
20045, chemin Ste-Marie
Sainte-Anne-de-Bellevue, QC H9X 3R5
www.inspq.qc.ca/lspq (available only in French)
New Brunswick Department of Health and Wellness
520 King Street, HSBC Place
P.O. Box 5100
Fredericton, NB E3B 6G3
Department of Health and Social Services
P.O. Box 2000
16 Garfield Street
Charlottetown, PE C1A 7N8
Nova Scotia Health Promotion and Protection
Summit Place, 5th Floor
1601 Lower Water Street
P.O. Box 487
Halifax, NS B3J 2R7
Disease Control and Epidemiology
Newfoundland and Labrador Department of Health and Community Services
West Block, Confederation Building
P.O. Box 8700
St. John's, NL A1B 4J6
Other data contributors
Canadian Pediatric AIDS Research Group
Contact: Laura Sauve (email@example.com) or Lindy Samson (firstname.lastname@example.org)
Citizenship and Immigration Canada
Appendix 2: Exposure category hierarchy
HIV and AIDS cases are assigned to a single exposure category according to a hierarchy of risk factors. If more than one risk factor is reported, a case is classified according to the exposure category listed first (or highest) in the hierarchy. For example, people who inject drugs may also be at risk of HIV infection through heterosexual sexual activity. However, injection drug use (IDU) is accepted as the higher risk activity with greater likelihood of transmission of HIV. The only exception to this is men who have sex with men (MSM) and who have also injected drugs, as there is a fairly equivalent level of risk in some circumstances (e.g., in the case of risky sex, lack of condom adherence and condom failure). Such cases are classified in the combined exposure category MSM/IDU.
Classifying cases in a single exposure category according to a hierarchy has inherent limitations. For example, the categories do not distinguish between at-risk populations and risk behaviours which combine the individual with the activity. Furthermore, assignment of these categories is subject to the questions asked by a health care provider as well as the information that an individual chooses to disclose. Nonetheless, it is recognized that there is much evidence on HIV risk and exposure, although the current hierarchy of exposure category would benefit from a review. PHAC intends to work with provincial and territorial partners and experts on this review.
MSM: Men who have sex with men. This category includes men who report either homosexual or bisexual sexual contact.
MSM/IDU: Men who have sex with men and use injection drugs.
IDU: Injection drug use.
Recipient of blood/clotting factor: Before 1998, it was not possible to separate this exposure category. However, where possible, it has been separated into subcategories b and c.
Recipient of blood: Received transfusion of whole blood or blood components, such as packed red cells, plasma, platelets, or cryoprecipitate.
Recipient of clotting factor: Received pooled concentrates of clotting factor VIII or IX for treatment of hemophilia/coagulation disorder.
Origin from an HIV-endemic country (Het-Endemic): People who were born in a country where HIV is endemic. An HIV-endemic country is defined as having an adult (ages 15-49) prevalence of HIV that is 1.0% or greater and one of the following:
- 50% or more of HIV cases attributed to heterosexual transmission.
- A male to female ratio of 2:1 or less.
- HIV prevalence greater than or equal to 2% among women receiving prenatal care.
Before 1998, it was not always possible to separate origin from an HIV-endemic country and sexual contact with a person at risk. However, where possible, it has been separated into subcategories a and b.
Sexual contact with a person at risk (Het-Risk): People who report heterosexual contact with someone who is either HIV-infected or who is at increased risk of HIV infection (e.g., a person who injects drugs, a bisexual male, or a person from an HIV-endemic country).
No identified risk-heterosexual (NIR-Het): If heterosexual contact is the only risk factor reported and nothing is known about the HIV-related factors associated with the partner, the case is classified as NIR-Het.
Occupational exposure: Exposure to HIV-contaminated blood or body fluids, or concentrated virus in an occupational setting. This applies only to reported AIDS cases and not to HIV cases where the occupational exposure category is captured under "other". The Canada Communicable Disease Report (CCDR) contains more information about occupational exposureFootnote 14 Footnote 15.
Perinatal transmission: The transmission of HIV from a woman infected with HIV to her infant, either in utero, during childbirth, or through breastfeeding.
Other: Used to classify cases where the mode of HIV transmission is known but cannot be classified into any of the major exposure categories listed here; for example, a recipient of semen from an HIV-positive donor.
No identified risk (NIR): Used when the history of exposure to HIV through any of the other modes listed is unknown, or there is no reported history (e.g., because of death, or loss to follow-up).
Not reported: In certain provinces and territories, exposure categories are not reported to PHAC and are classified as "not reported".
Appendix 3: HIV/AIDS Case Report Form
Appendix 4. List of HIV-endemic countriesFootnote 16
- Caribbean and Central/South America
- Antigua and Barbuda
- British Virgin Islands
- Cayman Islands
- Dominican Republic
- French Guiana
- Netherlands Antilles
- St. Lucia
- St. Kitts and Nevis
- St. Vincent and the Grenadines
- Trinidad and Tobago
- Turks and Caicos Islands
- U.S. Virgin Islands
- Myanmar (Burma)
- Burkina Faso
- Cape Verde
- Central African Republic
- Democratic Republic of the Congo (formerly Zaïre)
- Equatorial Guinea
- Ivory Coast
- Republic of the Congo
- Sierra Leone
- South Africa
Appendix 5: Data limitations
Reporting delays and under-reporting
The number of reported HIV and AIDS cases at any point in time is not necessarily a true reflection of the total number of people with a new diagnosis of HIV infection or AIDS during that time period. This may happen for several reasons:
- There may be a delay between the time when a person tests positive for HIV or is given a diagnosis of AIDS and the time when the report is received by PHAC. The effects of such reporting delays are typically rectified in the surveillance report for the subsequent year because data for past years are routinely adjusted to correct for reporting delays.
- Some individuals with a diagnosis of HIV infection or AIDS are never reported to the provincial or territorial public health authority. This results in under-reporting of HIV or AIDS cases in the province or territory, and ultimately also at the national level. Under-reporting is particularly an issue with AIDS surveillance. Before the widespread use of antiretroviral medications, the occurrence of an AIDS-defining illness was significant and usually an indicator of severe disease progression. In 1996, the profile of the disease changed dramatically with the introduction of antiretroviral medications. The onset of an AIDS-defining illness has become less likely except in particular circumstances. For many, HIV is now a complex chronic disease that can be managed over time. Given these changes, not all physicians continue to report AIDS-defining illnesses in patients already living with HIV. Furthermore, not all jurisdictions collect and submit data on AIDS cases to PHAC. As a result, AIDS cases are under-reported at the national level, making it difficult to present a national picture of the AIDS epidemic in Canada.
- Similar to the under-reporting of AIDS cases, the number of reported AIDS-related deaths is an underestimate of the actual number of deaths among people with a diagnosis of AIDS. This is influenced by the under-reporting of AIDS cases (that is, cases themselves are under-reported, therefore deaths in unreported AIDS cases cannot be recorded) and because death is not a mandatory reportable variable in the National HIV/AIDS surveillance system.
- Deaths due to causes other than AIDS are less likely to be reported to PHAC than deaths due to AIDS. For example, if a person living with AIDS is killed in a motor vehicle collision, PHAC may be less likely to receive that update than if the person died directly as a result of AIDS. For these reasons, the number of reported AIDS deaths is a minimum estimate of all deaths among AIDS cases. Therefore, caution must be exercised when interpreting the data. The difference between the total reported AIDS cases and total reported deaths should not be used to calculate the number of people living with AIDS.
The identification and removal of duplicates (for example, repeat positive HIV tests for the same individual) is difficult because of the non-nominal (or non-identifying) nature of HIV reporting in some jurisdictions. Where possible, provinces and territories periodically review and assess the inclusion of duplicate reports in order to provide as accurate a picture as possible of the number of new individuals who have tested positive for HIV. Duplicates result in an overestimate of HIV cases.
Some provinces (e.g., Quebec), take a conservative approach to remove potential duplicates, including the exclusion of results from anonymous tests. For jurisdictions that use such an approach, the data presented in this report reflects the minimum number of HIV-positive individuals in that jurisdiction.
HIV reporting for children
Reporting of HIV diagnoses for children under two years of age differs among the provinces and territories due to varying approaches used for testing children who have been perinatally exposed to HIV infection. For example, data from Quebec and Newfoundland and Labrador exclude positive serology results for HIV cases under two years of age. Most of the remaining provinces and territories, where HIV infection in children under 18 months of age is confirmed using other testing modalities, report HIV cases under two years of age in the surveillance data.
Exposure category and race/ethnicity data
Several limitations are associated with reported race/ethnicity, therefore caution is recommended in interpreting these data. Specifically, Quebec does not submit exposure category or race/ethnicity information for HIV cases to PHAC because this information is not available within the data source used for reporting to PHAC. For Ontario, limited exposure category information was available for reported HIV cases before 2009 and no race/ethnicity data was available for reported HIV cases before 2009. Since the inclusion of supplementary information collected for HIV cases (for 2009 and onwards) through the Laboratory Enhancement Program, data completeness for exposure category and race/ethnicity data has improved substantially. However, for Ontario AIDS cases, exposure category and race/ethnicity data are not available after 2004.
An additional limitation related to race/ethnicity information is the possibility of misclassification, which may occur due to:
- Challenges or errors in determining the race/ethnicity of cases.
- Constraints in the defined list of racial/ethnic groups used for reporting, which may not be appropriate for some individuals.
- Reluctance or refusal of individuals who do not want to identify their racial/ethnic background.
These limitations in exposure category and race/ethnicity data have implications for the representativeness of data at the national level and for the identification and interpretation of trends. In particular, race/ethnicity analyses presented for HIV and AIDS cases should not be viewed as representative of all of Canada, particularly as data are missing from jurisdictions with large racially and ethnically diverse populations.
Canadian Perinatal HIV Surveillance Program
The perinatal data presented are based on infants born to women known to be HIV-positive during their pregnancy. The numbers presented reflect all infants perinatally exposed to HIV infection currently receiving care in Canada. However, not all pregnant women were aware of their HIV status and able to benefit from antiretroviral therapy in pregnancy. Therefore, it would not be valid to calculate vertical transmission rates directly from these data.
Vital Statistics - Death Database (Statistics Canada)
Data on HIV-related mortality obtained from the Death Database are more complete and accurate than the surveillance-related mortality data. Mortality attributed to HIV infection has been coded only since 1987. In addition, release of data are normally delayed by several years. Limitations associated with Vital Statistics - Death Database include:
- Deaths attributed to HIV infection include some HIV-related deaths of patients who did not meet the Canadian AIDS case definition, although their death certificates indicate that they died as a result of HIV infection. This may occur if there has been no AIDS-defining illness, or if there is no record of an AIDS-defining illness even though one may have been present.
- Data from the Death Database do not include people with HIV who died from causes unrelated to their HIV infection (such as a motor vehicle collision), because the unrelated cause is recorded on the death certificate.
Therefore, it is not valid to calculate HIV prevalence rates (i.e., the number of people living with HIV) by direct use of HIV surveillance data in conjunction with these data on HIV-related deaths.
Appendix 6: Terminology
For a more extensive list of terms, please see A Guide to HIV/AIDS Epidemiological and Surveillance Terms, which contains more than 65 terms and more than 20 frequently asked questions (available at: at http://library.catie.ca/PDF/P6/19782.pdf).
AIDS - Acquired immunodeficiency syndrome.
HIV - Human immunodeficiency virus.
Incidence - The number of new occurrences of a given disease during a specified period of time.
Non-nominal reporting - A reporting system in which no identifying information or names are provided to public health officials when HIV and AIDS data are reported.
Prevalence - The number of people with the disease who are alive during a specified period of time.
Deaths Due to HIV Infection (ICD-9 codes 042 to 044 and ICD-10 codes B20 to B24) - The provincial and territorial registrars of vital statistics maintain records of deaths in Canada. The provinces and territories or Statistics Canada code the records using the 9th and 10th revisions of the International Classification of Disease (ICD-9 and ICD-10). The number of reported HIV deaths in Canada, coded to ICD-9 042-044, is available from 1987 to 1999. HIV deaths from 2000 onward are coded to ICD-10 B20 to B24.
HIV incidence - The number of new HIV infections in the population during a specific period of time.
HIV incidence versus positive HIV test reports/HIV cases - This report presents data on reported positive HIV tests or on people (cases) diagnosed with HIV, not on the actual incidence of HIV in Canada (as not all HIV-infected individuals have been tested or diagnosed in a given reporting year). It is important to note as well that neither HIV incidence nor HIV test reporting provide information about when a case of HIV infection occurred, only about when it is diagnosed.
HIV prevalence - The number of people living with HIV during a specific period of time.
Canadian surveillance definition of AIDS - This definition is used as the standard inclusion/exclusion criterion to decide whether a case report qualifies to be entered into the AIDS surveillance database. It requires a positive HIV test result and the onset of one or more defined clinical diseases that characterize a weakened immune system. Further details can be found in the CCDRFootnote 17.
Cumulative AIDS cases - The total number of AIDS cases that have occurred in Canada since the beginning of the epidemic. The true number of cumulative AIDS cases is not the same as the total number in this report as a result of reporting delay and under-reporting.
Cumulative reported AIDS cases - The total number of AIDS cases that have occurred in Canada since the beginning of the epidemic and that are documented in the AIDS surveillance database from 1979 to the end of the current reporting period. The cumulative number of reported AIDS cases is only a proportion of the cumulative AIDS cases.
Date of AIDS diagnosis - The date of the earliest onset of at least one of the clinical diseases listed in the Canadian surveillance definition of AIDS according to the physician's report of an HIV-infected patient. If multiple diseases have been diagnosed at different times, the earliest date will be used as the date of AIDS diagnosis in this report.
Date of AIDS reporting - The date when a diagnosed AIDS case is entered into the AIDS surveillance database.
Reported AIDS cases by year of diagnosis - The breakdown of the cumulative number of reported AIDS cases according to year of AIDS diagnosis. The number of AIDS cases diagnosed but not yet reported is higher for more recent years because of reporting delays.
Reported AIDS cases by year of report - The breakdown of the cumulative reported AIDS cases according to the year of report. In the absence of reporting delays, this figure would be the same as the reported cases by year of diagnosis. The greater the discrepancy between the two, the greater the problem with reporting delays.
Reported death among reported AIDS cases - An update to the record of an AIDS case previously reported to PHAC that results in a change in vital status.
Reporting delay of AIDS cases - Refers to the difference in time between AIDS diagnosis and AIDS reporting.
Unreported AIDS cases - The number of AIDS cases diagnosed but not reported. Some of the cases are delayed and will eventually be reported and some may never be reported.
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