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
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
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
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”.
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.
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 .