Understanding the Report on HIV/AIDS in Ontario

ACT Research Day --- 7 May 2009

Understanding the Report on Understanding the Report on HIV/AIDS in OntarioHIV/AIDS in Ontario

Greta Bauer, PhD, MPH

Epidemiology & BiostatisticsThe University of Western Ontario

John Maxwell

Director of Policy and Communications

AIDS Committee of Toronto


Report on HIV/AIDS in OntarioReport on HIV/AIDS in Ontario

Annual report produced since 1998

Funded by the AIDS Bureau

Produced by the Ontario HIV Epidemiologic Monitoring Unit at the University of Toronto

Authors (2008): Robert Remis, Carol Swantee, Lorraine Schiedel, Juan Liu

Tracks the HIV epidemic in Ontario

Available at: www.phs.utoronto.ca/ohemu


Jargon AlertJargon Alert


HIV/AIDS EpidemiologyHIV/AIDS Epidemiology

1.Not perfect2.Not meaningless


What is needed to have perfect versions What is needed to have perfect versions of current statistics?of current statistics?

1. Know HIV status of everyone

2. Identify new infections when acquired

3. Be able to determine exactly how each transmission occurred

4. Have accurate AIDS diagnoses for everyone

5. Know perfectly whether HIV/AIDS was a cause for each death

6. Know exact population sizes for exposure categories (e.g. MSM, IDU, people from endemic countries, high-risk heterosexual…)


STATISTICS = DATA + STATISTICS = DATA + ASSUMPTIONSASSUMPTIONS


Where do data used in the Ontario Where do data used in the Ontario Report come from?Report come from?

HIV test numbers and results HIV Laboratory – Central Public Health Laboratory, Ontario Ministry of Health and Long-Term Care (and five regional laboratories)

AIDS case diagnoses Public Health Division, Ontario Ministry of Health and Long-Term Care

Population size estimates by health region

Statistics Canada

Infant HIV infections Canadian Pediatric AIDS Research Group, Ontario Region

HIV-related deaths (ICD codes) Vital records - Registrar General


Understanding Exposure Understanding Exposure CategoriesCategories

Exposure categories (vs. transmissions)

Men who have sex with men (MSM)MSM-IDU Injection drug use (IDU)Mother-to-child transmission (MTC) Blood product recipient (pre Nov 1985) Transfusion recipient (pre Nov 1985)Origin/residence in HIV endemic countriesHigh-risk heterosexual Low-risk heterosexualNo identified risk (NIR)


Some assumptions…Some assumptions…

Continued…


Proportion of New HIV Diagnoses, Proportion of New HIV Diagnoses, Including Unknown Exposure GroupIncluding Unknown Exposure Group

0%

20%

40%

60%

80%

100%

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

MSM MSM-I DU I DU Clotting Factor

Transfusion HI V-endemic HR Hetero LR Hetero

MTC Other Unknown


Proportion of New HIV Diagnoses, Proportion of New HIV Diagnoses, Where Exposure Group KnownWhere Exposure Group Known

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006



MTC Other


Number and Proportion of Number and Proportion of New HIV DiagnosesNew HIV Diagnoses

0

500

1000

1500

2000

2500

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006



MTC Other Unknown


Raw vs. Modelled StatisticsRaw vs. Modelled Statistics

Modelling Adjust for duplicate HIV tests

Estimate proportion undiagnosed

Assume those with unknown exposure group distributed in accordance with known exposure groups

Estimate distribution by sex and geographic area

Adjust for different rates of testing

Estimate HIV infection numbers

Estimate AIDS cases, adjusting for reporting delays

Adjust estimates of HIV-related mortality for under ascertainment

Estimate population sizes


Some Statistics in the ReportSome Statistics in the Report

HIV Diagnoses (case counts)

Proportion of HIV Diagnoses by Exposure Category

HIV Prevalence

HIV Cumulative Incidence

HIV Incidence / Incidence Density

AIDS Diagnoses (case counts)

Proportions of AIDS Cases by Exposure Category

AIDS Cumulative Incidence

HIV-related Mortality


PREVALENCE vs INCIDENCEPREVALENCE vs INCIDENCE

Prevalence – How common is it for people to be living with HIV?

Incidence – At what rate do new infections occur amongst those at risk?


HIV PREVALENCEHIV PREVALENCE

# People Living with HIV # People Living with HIV

== x 100x 100

# in Population# in Population

presented as a percentagepresented as a percentage


Modelled MSM number and HIV prevalence by Modelled MSM number and HIV prevalence by health region, Ontario, 2006health region, Ontario, 2006

Health Region

Number MSM

Number HIV

Prevalence HIV

Toronto 48,100 11,140 23.2%

Ottawa 10,400 1,240 11.9%

Rest of Ontario

32,300 3,280 10.2%

Ontario, Total

90,800 15,660 17.2%

R. Remis, 2008


What influences changes in HIV What influences changes in HIV prevalence statistics over time?prevalence statistics over time?

Changes in number of new cases of HIV Changes in duration of illness

Longer survival = higher prevalence of HIV

Changes in HIV testing Overall changes in rates of testing Different rates of testing between groups

(adjusted statistically) Policies (immigration testing, prenatal testing)

Improvements in HIV testing Changes in estimates of (sub)population

size


What influences changes in proportion What influences changes in proportion of prevalent cases over time?of prevalent cases over time?

Changes in prevalence for the group you’re interested in

Changes in prevalence for all other groups


PREVALENCE vs INCIDENCEPREVALENCE vs INCIDENCE

Prevalence – How common is it for people to be living with HIV?

Incidence – At what rate do new infections occur amongst those at risk?


HIV CUMULATIVE INCIDENCEHIV CUMULATIVE INCIDENCE

# cumulative HIV diagnoses# cumulative HIV diagnoses

==

1996 population (midpoint)1996 population (midpoint)


HIV INCIDENCE DENSITYHIV INCIDENCE DENSITY

# new HIV diagnoses# new HIV diagnoses

= x = x 100100

Person-years at riskPerson-years at risk

presented per 100 person-yearspresented per 100 person-years


Example: 1 per 50 person-yearsExample: 1 per 50 person-years


Modelled MSM number, HIV prevalence andModelled MSM number, HIV prevalence andincidence by health region, Ontario, 2006incidence by health region, Ontario, 2006

Health Region

Number MSM

Number HIV

Prevalence HIV

Annual HIV Incidence (no.)

Annual HIV Incidence (%)

Toronto 48,100 11,140 23.2% 620 1.7%

Ottawa 10,400 1,240 11.9% 100 1.1%

Rest of Ontario

32,300 3,280 10.2% 170 0.59%

Ontario, Total

90,800 15,660 17.2% 890 1.2%

R. Remis, 2008


What influences changes in HIV What influences changes in HIV incidence statistics over time?incidence statistics over time?

Changes in number of new cases of HIV Changes in estimates of prevalence Changes in HIV testing

Overall changes in rates Different rates of testing between groups

(adjusted statistically) Policies (immigration testing, prenatal testing)

Improvements in HIV testing Changes in estimates of (sub)population

size


AIDS Diagnoses and AIDS Diagnoses and Cumulative IncidenceCumulative Incidence

HIV vs. AIDS


What influences changes in AIDS What influences changes in AIDS statistics over time?statistics over time?

Changes in treatment and duration of illness Healthier survival = lower prevalence of

AIDS

Different rates of AIDS diagnosis between groups

Changes in definition of AIDS Changes in estimates of

(sub)population size


HIV-RELATED MORTALITYHIV-RELATED MORTALITY

# HIV-related deaths# HIV-related deaths

= x = x 100,000100,000

PopulationPopulation

presented per 100,000 populationpresented per 100,000 population


What influences changes in HIV-related What influences changes in HIV-related mortality statistics over time?mortality statistics over time?

Changes in incidence of HIV Changes in treatment and duration of

illness Healthier survival = lower mortality

Changes in HIV testing – number of people who are known to have HIV Overall changes in rates Different rates of testing between groups Policies (immigration testing, prenatal testing)

Changes in ICD codes


Major changes to be aware ofMajor changes to be aware of

1985 – Testing of the blood supply 1993 – Change in AIDS definition

Increased classification of women with AIDS 1996 – Introduction of protease inhibitors

Decreased AIDS cases, increased survival (and prevalence) 2000 – Change in ICD definitions from ICD-9 to ICD-10

10% increase in HIV-related deaths 2002 – Required testing of all immigrants

Ontario tests for visa purposes: 1294 in 2001, 28,712 in 2006 54% increase in testing for the HIV-endemic exposure

classification Prenatal HIV testing

41% in 1999, 89% in 2006 62% increase in testing and 41% increase in new diagnoses in

the low-risk heterosexual exposure classification from 2001 to 2006


Thank you!Thank you!

Contact: [email protected]

Understanding the Report on HIV/AIDS in Ontario

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