measuring socioeconomic inequalities in health equality, is the state or quality of being equal;...

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Measuring Social Inequalities In Health Mohammad Hajizadeh McGill University PHO-Rounds: Epidemiology 15 August 2013

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Measuring Social Inequalities In Health

Mohammad Hajizadeh

McGill University

PHO-Rounds: Epidemiology

15 August 2013

Outline

• Equity and equality

• Issues related to choosing inequality measures

• Inequality measures: nominal social groups

• Inequality measures: ordinal social groups

• An empirical study

• Summary

• Conclusion

Equity

Equity, like beauty, is in the eye of the beholder

(Lampman, 1977).

Equal opportunity of access to services? A high

standard of service for everyone? Unequal

distribution of services to meet unequal need? Equal

health status for everyone?

Equality

Equality, is the state or quality of being equal;

correspondence in quantity, degree, value, rank, or

ability.

We can verify or falsify the following statement “the

geographic distribution of doctors in Canada is

unequal”.

• Simple or sophisticated measures of health

inequality?

– Rate ratio vs. Relative concentration index

• Is inequality relative or absolute?

– Rate ratio vs. Rate differences

– Relative concentration vs. Absolute concentration

index

Issues in choosing inequality measures

Simple or sophisticated measures

The prevalence of adult obesity in rural and urban

areas in Canada: 2000/1-2009/10

Simple or sophisticated measures

The prevalence of adult obesity among Canadian

provinces: 2000/1-2009/10 (CCHS)

Relative Measure Society A Society B

IMR in lowest SES group 60 6

IMR in highest SES group 40 4

Rate Ratio (RR) 1.5 1.5

Relative or Absolute measures

Absolute Measure Society A Society B

IMR in lowest SES group 60 6

IMR in highest SES group 40 4

Rate Difference (RD) 20 2

Example:

Infant Mortality Rate (IMR): infant deaths per 1,000 live births

Dimensions Inequality Measures

Gender

Immigrant Status

Ethnic Background

Urbanicity

Place of Residence

Religion

Rate Ratio (RR)

Rate Difference (RD)

Index of Disparity (IDP)

Between Group Variance (BGV)

Index of Dissimilarity (IDS)

Gaswirth Index of Disparity (GID)

Theil Index (T)

Mean Log Deviation (MLD)

Gini Coefficient (G)

Others

Inequality measures: Nominal social groups

Rate Ratio (RR) and Rate Difference (RD)

Obesity rates across Canadian provinces in 2009/10 (CCHS)

Index of Disparity (IDP)

Between Group Variance (BGV)

Index of Dissimilarity (IDS)

Gaswirth Index of Disparity (GID)

Theil Index (T) and Mean Log Deviation (MLD)

Gini Coefficient (G)

Line of

Equality

Lorenz Curve

0

0.25

0.5

0.75

1

0 0.25 0.5 0.75 1

Cu

mu

lati

ve %

of

healt

h

Comulative % of population, ranked based on health

The G is twice the area between the line of equality and the Lorez curve.

Dimensions Inequality Measures

Income

Education

Occupation

Rate Ratio (RR)

Rate Difference (RD)

Relative Index of Inequality (RII)

Slope Index of Inequality (SII)

Relative Concentration Index (RC)

Absolute Concentration Index (AC)

Others

Inequality measures: Ordinal social groups

Inequality measures: Ordinal social groups

• If we can rank groups (individuals) according to

socioeconomic status (SES), we can measure health

inequalities that arise from the SES of groups

(individuals).

• We can use simple measure such as RR and RD to

examine socioeconomic inequalities in health. These

measures, however, cannot capture socioeconomic

inequalities among the entire population.

Rate Ratio (RR) and Rate Difference (RD)

0

10

20

30

40

50

60

70

80

I II III IV V

Infa

nt

Mo

rta

lity

Rate

Social Classes

Example

Slope Index of Inequality (SII)

• The SII is a regression-based measure that takes the

whole socioeconomic distribution into account.

– The SII involves calculating the mean of health outcome for

each socioeconomic group and then ranking groups by

their SES.

– The SII defined as the slope of the regression line between

a group's health status and its relative rank.

Slope Index of Inequality (SII)

Socioeconomic group I II III IV V

30 50 50 60 80

Share of the overall

population 0.4 0.3 0.15 0.1 0.05

Example

Slope Index of Inequality (SII)

Slope Index of Inequality (SII)

Relative Index of Inequality (RII)

Relative Concentration Index (RC)

Cu

mu

lati

ve %

of

Healt

h

Cumulative % of population, ranked based on SES

Concentration Curve

Line of Equality

The RC is twice the area between the line of equality and the

Concentration curve.

Relative Concentration Index (RC)

• Similar to RII, the RC reflects the experience of

entire population.

• The RC is negative if health outcome is

concentrated on the lower SES group, and vice versa.

• The RC ranges from -1 to +1 with a value of zero

indicating “perfect equality”.

Absolute Concentration Index (AC)

An empirical study

Socioeconomic Inequalities in Obesity Risk in Canada:

2000-2010

Reference: Hajizadeh, M. Karen Campbell MK, and Sarma S. (2013) “Socioeconomic

inequalities in adult obesity risk in Canada: trends and decomposition analyses”,

European Journal Health Economics. DOI:10.1007/s10198-013-0469-0

Socioeconomic inequalities in obesity in Canada

• While the current studies in Canada (e.g. Cairney and Wade

1998; Willms et al. 2003; Pouliou and Elliott 2010; Shields and Tjepkema 2006) shed

some light on the regional and socioeconomic

differences in obesity, the aim of these studies is not

to quantify the extent of any inequalities in obesity

risk.

• This study aimed to measure socioeconomic-related

inequality in obesity risk among Canadian adults

(aged 18-65) over the past decade.

Socioeconomic inequalities in obesity in Canada

Socioeconomic inequalities in obesity in Canada

Income-related inequalities in obesity by gender

and age group

2000/01 2003/04 2005/06 2007/08 2009/10

Canada -0.0368*** -0.0424*** -0.0349*** -0.0287*** -0.0145***

Male 0.0151* 0.0075 0.0230*** 0.0339*** 0.0492***

Male 18-34 0.0198 0.0232* 0.0285** 0.0209 0.0307**

Male 35-49 0.004 0.0065 0.0101 0.0141 0.0901***

Male 50-64 0.0212 0.0181 0.0256 0.0313* 0.0712***

Female -0.1079*** -0.1176*** -0.1228*** -0.1163*** -0.1060***

Female 18-34 -0.1269*** -0.1180*** -0.1431*** -0.1255*** -0.0909***

Female 35-49 -0.1175*** -0.1257*** -0.1430*** -0.1434*** -0.1646***

Female 50-64 -0.1070*** -0.1111*** -0.1358*** -0.1165*** -0.1147***

*** p<0.01, ** p<0.05, * p<0.1

Income-related inequalities in obesity by

rural/urban and provinces

2000/01 2003/04 2005/06 2007/08 2009/10

Rural -0.0329*** -0.0309*** -0.0649*** -0.0431*** -0.0285***

Urban -0.0344*** -0.0409*** -0.0245*** -0.0222*** -0.0068***

Newfoundland and

Labrador -0.0449*** -0.0850*** -0.0793*** -0.0950*** -0.0735***

New Brunswick -0.0707*** -0.0592** -0.0551** -0.1237*** -0.0852***

Nova Scotia -0.0626*** -0.0126 -0.0962*** -0.0800*** -0.0790***

Prince Edward Island -0.0414 -0.0782** 0.0245 -0.1116*** -0.1159***

Saskatchewan -0.0083 -0.0472** -0.0016 0.012 -0.0281

Manitoba -0.0382** -0.0592*** -0.0152 -0.0173 -0.0139

Alberta -0.0162 -0.0299** -0.0183 0.0265* 0.0541***

Ontario -0.0416*** -0.0247*** -0.0420*** -0.0269*** -0.0184**

Quebec -0.0501*** -0.0856*** -0.0203* -0.0609*** -0.0368***

British Columbia 0.0148 -0.0067 0.003 0.0095 0.0236

*** p<0.01, ** p<0.05, * p<0.1

Main findings: Empirical study

• The RCs for men indicate that obesity is

concentrated among the rich and its trend is

increasing over time.

• The findings, however, suggest that obesity is more

prevalent among economically disadvantaged women.

• The degree of socioeconomic-related inequality in

obesity is increasing in the Atlantic provinces.

Summary

• Equity is a normative concept whereas equality is a

positive concept.

• Issues to be considered in measuring health inequality:

– Simple or sophisticated measures

– Relative or absolute measures

• Inequality measures:

– Nominal social groups

– Ordered social groups

Conclusion

• To choose an appropriate measure for inequality in

health, we need to follow the following

methodological approaches:

– First, inspect the underlying subgroup-specific

health outcomes.

– Next, define the relevant question to be

answered.

– Finally, choose a summary measure of health

inequality based on whether or not social groups

do have a natural ordering.

References

• Harper, S. and Lynch, J. “Methods for measuring cancer disparities: Using data relevant to Healthy People 2010 cancer-related objectives”. National Cancer Institute, 2005.

• Wagstaff, A., Paci P. and van Doorslaer E. “On the measurement of inequalities in health”. Social Science Medicine, 1991, 33(5), 545-557.

• Mackenbach, JP. and Kunst, AE. “Measuring the magnitude of socio-economic inequalities in health: an overview of available measures illustrated with two examples from Europe”. Social Science Medicine, 1997, 44(6):757-71.

• O’Donnell, O., van Doorslaer, E., Wagstaff, A. and Lindelow, M. “Analyzing health equity using household survey data – A guide to techniques and their implementation”. The World Bank, 2008 .