1

Population Health Model (POHEM)

AMI

Acknowledgements: CCORT for collaboration and funding.

2

2001

……..……..……..……..……..……..……..……..……..……..……..

POHEM exampleStarting Population: Canadian Community Health Survey 2001 (CCHS)

cross-sectional representation of the Canadian population aged 18+

VARIABLEage sex provincehealth regionimmigration statuseducation levelincome quartilebody mass index smoking statusdiabetic statusHUItotal cholesterol*HDL*blood pressure*Survey sample weight

*imputed from Canadian Heart Health Surveys (1986-1992)

VALUE44maleOntarioYorknon-immigrantpost-secondaryQ4 (richest)32.2 kg/m2 (obese)smokernon-diabetic0.96 highlowhigh100.32

At beginning of each year:

• update risk factor profile

• evaluate hazard of developing disease

none in 2001

• evaluate hazard of dying

2051

3

AMI at age 45.3

Now at risk of 2nd AMI, CHF, UA, ...

2001

……..……..……..……..……..……..……..……..……..……..……..

POHEM example

2002

……..

Starting Population: Canadian Community Health Survey 2001 (CCHS)cross-sectional representation of the Canadian population aged 18+

AMI

agesexprovincehealth region immigration statuseducation levelincome quartilebody mass indexsmoking statusdiabetic statusHUItotal cholesterolHDLblood pressure

2002.3CHF UA

AMI2

4

CHF

period of comorbidity from living with OA and CHF

Osteoarthritis at age 69.4 in year 2028

…

……..

2001

……..……..……..……..……..……..……..……..……..……..……..

POHEM example

2002

……..

Starting Population: Canadian Community Health Survey 2001 (CCHS)cross-sectional representation of the Canadian population aged 18+

2003

…….. Death

at age 71.2AMI CHF OA

Congestive Heart Failueat age 66.1 in year 2023

2023.1 2028.42002.3UA

AMI2

5

2001

……..……..……..……..……..……..……..……..……..……..……..

POHEM example

2002

……..……..

Starting Population: Canadian Community Health Survey 2001 (CCHS)cross-sectional representation of the Canadian population aged 18+

2003

……..……..

…

……..…….. Death

>100,000 records on CCHS representing over 20 million Canadians in 2001

Plus New Immigrants and New 18 year olds in subsequent years

= 1 hour on a PC

New 18 year oldsNew Immigrants

6

Data Sources

• Canadian Community Health Survey (2000/01)– cross-sectional – representative of household population– starting population for POHEM (2001)

• National Population Health Survey – longitudinal from 1994-2004 (6 cycles)– model individual’s change in BMI, Smoking

• Many other data sources– survey, administrative, census, registry, vital, literature

8Coronary Heart Disease: Acute Myocardial Infarction (AMI)

Upstream health determinants

Intermediate risk factors

Intermediate diseases

Sequalae Death

AMI*

Health Person-Oriented Information (HPOI)

(HIRD)

incidence rates by province, age and sex

2nd AMI

Congestive Heart

Failure

Unstable

Angina

Death

Registered Persons database for Ontario (ICES)

(CCORT I)

survival data for each transition

*incidence-risk equation based on Framingham risk function (Wilson 1998) for “index” AMI events

competing risk of death from other causes

Vital statistics(and other POHEM disease modules)

initial values & transition models

Diabetes

Total cholesterol

& HDL

blood pressur

e

Cdn Heart Health Surveys 1986-92

age (time)

initial values

Obesity

Smoking

Nutrition

Physical activity

Alcohol

Income

Education

Region

Sex

CCHS 2001

transition models

NPHS 1994-2004

S(t)

S(t)

S(t)

S(t)

S(t)

Causal pathway

9

Data Analysis and Input to POHEM:

1. incidence rates (I) are estimated from administrative data by age, sex and province

2. Framingham risk function, obtained from literature, relates risk factors to incidence

(beta coefficients from Wilson 1998) vary by risk factor categories

α represents baseline risk by age, sex, province, calibrated to reproduce observed incidence rates (I) and takes into account the distribution of the risk factors in the population

4. initial values of risk factors from national surveys

5. models of change in risk factors based on trends from national surveys

How POHEM Generates an Incident Case of AMI

1) POHEM selects a record from CCHS in simulation year 2001:

male, age 44, Ontario, smoker, non-diabetic, high total cholesterol, low HDL, medium blood pressure...

2) Lookup baseline risk and risk factor coefficients from input parameter table.

3) Evaluate the probability (p) of AMI

using the Framingham risk function

(with rescaling):

p = F/(1+F) = 0.877

4) Convert p to an annualized hazard (h):

h = -ln(1-p) = 2.09

5) Generate a uniform random number (u) between 0 and 1

u = 0.975

6) Convert u to an annualized hazard (h*):

h* = -ln(1-u) = 3.69

7) Transform the proportional hazards to a waiting time:

t = ( h* / h ) = 1.76 years

8) AMI does not occur at age 44 in year 2001.

9) POHEM ages the person forward to next birthday and re-evaluates risk of AMI (steps 2-8).

10) Repeated for every record on CCHS, births and new immigrants

αmale,44,ON = 0.00138βsmoker = 0.523βnon-diab = 0βchol-high = 0.657βHDL-low = 0.497βBP-med = 0.283

SmokingDiabBPHDLcholeF

10

Total AMI incidence (5-year washout), Canada and provinces, 2000-2004

0

5,000

10,000

15,000

20,000

25,000

2000/01 2001/02 2002/03 2003/04 2004/05

Year

AM

I in

cid

ence

AtlanticBCONPrairiesQC

Data source: HPOI (hospital discharge abstract database); POHEM projections superimposed

Trends in overnight hospitalizations for new AMI cases (External Validation)

POHEM projections of AMI, Ontario

11

First AMIs projected* to increase in all provinces

0

5000

10000

15000

20000

25000

30000

2001 2006 2011 2016 2021

Year

Num

ber

of F

irst

AM

I cas

es

OntarioQuebecPrairiesBritish ColumbiaAtlantic

*POHEM projections

12Age-standardized rate of AMI projected to decline reduced impact from risk factors

0.0

0.5

1.0

1.5

2.0

2.5

2001 2006 2011 2016 2021

Year

Age

-sta

ndar

dize

d R

ate

of F

irst

AM

I pe

r 10

00

AtlanticOntarioCanadaQuebecPrairiesBritish Columbia

13Figure B2: Simulation projections of regular smokers from 2001 to 2021 for Canada, by sex, for selected scenarios.

0%

5%

10%

15%

20%

25%

30%

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021 _

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021 _

Female Male

Baseline Smoking -10% in 2001

14

24.4

21.7 21.420.9

19.618.7 18.6

0

5

10

15

20

25

30

2000 2001 2002 2003 2004 2005 2006

Chart 1Percentage of current smokers , Canada excluding territories, 2000 to 2006

%

Sources: Population Health Model (POHEM); Canadian Tobacco Use Monitoring Survey (CTUMS); Canadian Community Health Survey cycles 1.1, 2.1, 3,1 (CCHS)

POHEM (age 18+)

CCHS (age 18+)

CTUMS (age 15+)

15

NutritionDiabetes

Kidney Disease

Diabetic Retinopathy

Osteoarthritis

CoronaryHeart

Disease

PeripheralVascularDisease

Stroke

Obesity

Physical activity

Alcohol

25 Cancers

Region

Smoking

Cholesterol

Blood pressure

Hyper-tension

Ethnicity

Upstream health determinants

Intermediate risk factors

Intermediate diseases

Diseases Treatment

Initial state assigned from CCHS (+CHHS)

Dea

th

competing risk of death from other causes

Amputation

Dialysis

ABS

Surgery,Drugs

Surgery, Radio/Chemo/H

ormonal therapy

Cataract surgery...

Surgery,Drug,

Lifestyle

POHEM: Overall causal flow

TIME (AGE and YEAR)

other risk

factors

other diseases

Income

Education

Health-related Quality of life (e.g., HUI)

Depression

Age

Sex

Death

Obesity

Age

Sex

Region

Income

Education