Examining the Socioeconomic Gradient in Health-Related Quality of Life in Canada

CPHA Annual Conference, Halifax, Nova Scotia, June 1 – 4 2008 1

Examining the Socioeconomic Gradient in Health-Related Quality of Life in Canada

Cameron N. McIntosh and Philippe Finès

Health Information and Research DivisionStatistics Canada, Ottawa


Context and Background Despite the fundamental principle of “health for all”,

socioeconomic disparities in health persist in Canada (e.g., Choinière, Lafontaine, & Edwards, 2000; Raphael, 2000; Wilkins, Tjepkema, Choinière, & Mustard, forthcoming)

Many health indicators exhibit a socioeconomic gradient:

Overall/cause-specific mortality Risk factors Incidence/prevalence rates for chronic disease Self-perceived health


Health-Related Quality of Life “The value attached to the duration of life as

modified by the impairments, functional states, perceptions, and social opportunities that are influenced by disease, injury, treatment or policy” (Patrick & Erickson, 1993)


Rationale

Overall socioeconomic disparities in health-related quality of life well studied at the national level in Canada (e.g., Eng & Feeny, 2007)

Condition-specific disparities mainly studied sub-nationally, using small clinical samples (e.g., Marra et al., 2004)


Objectives

Quantify differences in health-related quality of life between socioeconomic strata, both generally and for specific health conditions in a representative sample of the household population

Identify areas where interventions directed at reducing disparities might produce the greatest health benefits


Data Source

2000-2001 Canadian Community Health Survey (CCHS)

Cross-sectional survey that collects information on health status, health determinants, and health care utilization

representative of the Canadian household population aged 12 and over

131,535 person records in cycle 1.1 Only cycle with HUI3 administered to all

respondents


Analysis Variables

Income adequacy: respondents’ best estimates of total household

income divided by adjusted household size, and then partitioned into deciles

Educational attainment: Less than high school High school graduation, including trades

qualification Post-secondary certificate or diploma University degree (BA or higher)


Analysis Variables

Selected Chronic Conditions “Conditions that have lasted or are expected to

last six months or more and have been diagnosed by a health professional.”

Four high impact conditions: cancer, heart disease, diabetes, and arthritis


Health-Related Quality of Life:

Health Utilities Index Mark 3

Health-related quality of life measured by the Health Utilities Index Mark 3 (HUI3)

HUI3 assesses levels of functioning on eight attributes of health status: Vision, Hearing, Speech, Ambulation, Dexterity, Emotion, Cognition, and Pain.

HUI3 score:

-0.36 0.0 1.0(worst possible DEAD (best possible health state) health state)


Methods

For the overall population and then for each chronic condition subpopulation:

Sex-specific mean global HUI3 scores and 95% confidence intervals computed for income and education categories, by 10-year age group

Used survey sampling weights and the bootstrap technique to account for the complex survey design


Figure 1: Mean HUI3 For Poorest and Richest Deciles by 10-year Age Goup, Males

Age Group

Δ=0.09

Δ=0.12Δ=0.14 Δ=0.20 Δ=0.17

Δ=0.15

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

20 30 40 50 60 70 80

Mea

n H

UI3

D1 (Poorest)

D10 (Richest)


Figure 2: Mean HUI3 For Poorest and Richest Deciles by 10-year Age Group, Females

Age Group

Δ=0.08

Δ=0.12Δ=0.13 Δ=0.14

Δ=0.12

Δ=0.08

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

20 30 40 50 60 70 80

Mea

n H

UI3

D1 (Poorest)

D10 (Richest)


Figure 3: Mean HUI3 for Most and Least Well-Educated Males, by 10-Year Age Group

Δ=0.08Δ=0.10 Δ=0.07 Δ=0.10

Δ=0.09

Δ=0.08

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

20 30 40 50 60 70 80

Mea

n H

UI3

Age Group

Less than high school

Bachelor’s degree or higher


Figure 4: Mean HUI3 for Most and Least Well-Educated Females, by 10-Year Age Group

Age Group

Δ=0.11Δ=0.10

Δ=0.10 Δ=0.07Δ=0.08

Δ=0.03

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

20 30 40 50 60 70 80

Mea

n H

UI3

Less than high school

Bachelor’s degree or higher


Table 1: Mean HUI3 for Richest and Poorest Deciles, Men Aged 75+ With Selected Chronic Conditions

Income Decile

Total Populatio

n(Men aged 75+)

Chronic Condition Subgroup

Cancer Heart Disease

Diabetes

Arthritis

D10 (Richest) 0.815 0.780 0.832 0.807 0.746

D1 (Poorest) 0.662 0.578 0.658 0.637 0.638

Δ 0.153 0.202 0.174 0.170 0.108

Data Source: 2000 – 2001 Canadian Community Health Survey.


Table 2: Mean HUI3 for Most and Least Well-Educated Males, Aged 75+ with Selected Chronic Conditions

Educational Level Total Population(Men aged

75+)

Chronic Condition Subgroup

Cancer

Heart Disease

Diabetes

Arthritis

E4 (Bachelor’s degree or higher) 0.788

0.775 0.764 0.836 0.741

E1 (Less than high school) 0.709

0.586 0.639 0.628 0.623

Δ 0.079

0.189 0.125 0.208 0.118

Data Source: 2000 – 2001 Canadian Community Health Survey.


Limitations

Causality should not be inferred between socioeconomic status (SES) and health-related quality of life

Potential self-report bias on CCHS Income concept broadly defined (based on total

household income) Limited to household population (institutional

residents excluded)


Discussion

Robust socioeconomic disparities in health-related quality of life exist in Canada

Magnitude of these disparities often differs by age, sex, definition of SES, and health condition

Interventions directed at reducing disparities in health-related quality of life could produce substantial gains at the population level


Discussion

Within chronic condition subgroups, why do persons of higher SES have better health-related quality of life than lower SES persons? Possibly due to…

Higher pre-condition health status Better condition management Better physical and social environments

Further investigation is required to disentangle the potential reasons

Demonstrates importance of SES for burden of disease studies and cost-effectiveness analysis of treatments


Future Directions

Integrate mortality and health-related quality of life data to provide a more complete picture of socioeconomic differentials in health (e.g., Wolfson, McIntosh, Finès, & Wilkins, forthcoming)

Use a broader range of income concepts to define SES (e.g., personal earnings versus total household income)

Examine socioeconomic differentials in health-related quality of life for other health conditions

Investigate the pathways through which SES produces different health outcomes


References

Choinière R, Lafontaine P, Edwards AC. Distribution of cardiovascular disease risk factors by socioeconomic status among Canadian adults. CMAJ 2000; 162 (9 Suppl): S13-S24.

Eng K, Feeny D. Comparing the health of low income and less well educated groups in the United States and Canada. Population Health Metrics 2007; 5: 10.

Feeny D, Furlong W, Torrance GW, Goldsmith CH, Zhu Z, DePauw S, Denton M, Boyle M. Multiattribute and single-attribute utility functions for the Health Utilities Index Mark 3 system. Med Care 2002;40(2):113-28.


References

Marra CA, Lynd LD, Esdaile JM, Kopec J, Anis AH. The impact of low family income on self-reported health outcomes in patients care environment. Rheumatology 2004;43:1390-1397.

Patrick DL, Erickson P. Health Status and Health Policy: quality of life in health care evaluation and resource allocation. New York: Oxford University Press; 1993.

Raphael D. Health inequalities in Canada: current discourses and implications for public action. Critical Public Health 2000;10(2):193-216


References

Wilkins R, Tjepkema M, Choinière R, Mustard C. The 1991 census mortality follow-up study: Cohort mortality by individual, family, household and neighbourhood characteristics, based on a 15% sample of the Canadian adult population. Health Reports (forthcoming).

Wolfson MC, McIntosh CN, Finès P, Wilkins R. Refining the measurement of health inequalities in Canada: new data, new approaches. Paper to be presented at the 30th General Conference of the International Association for Research in Income and Wealth, Portoroz, Slovenia, August 24-30, 2008.


Acknowledgements

The guidance and feedback of Russell Wilkins and

Michael Wolfson are gratefully acknowledged.


Contact Information

Cameron N. McIntoshAnalystHealth Information and Research Division24-L R.H. Coats BuildingStatistics Canada | 100 Tunney's Pasture

DrivewayGovernment of CanadaOttawa, Ontario K1A 0T6phone: 613-951-3725 | fax: 613-951-3959email: [email protected]

Examining the Socioeconomic Gradient in Health-Related Quality of Life in Canada

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