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.
Issues in choosing inequality measures 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
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 or Absolute measures Example: Infant Mortality Rate (IMR): infant deaths per 1,000 live births 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 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
Inequality measures: Nominal social groups Dimensions Gender Immigrant Status Ethnic Background Urbanicity Place of Residence Religion Inequality Measures 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
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)
Cumulative % of health Gini Coefficient (G) The G is twice the area between the line of equality and the Lorez curve. 1 0.75 0.5 Line of Equality Lorenz Curve 0.25 0 0 0.25 0.5 0.75 1 Comulative % of population, ranked based on health
Inequality measures: Ordinal social groups Dimensions Income Education Occupation Inequality Measures 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 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.
Infant Mortality Rate Rate Ratio (RR) and Rate Difference (RD) Example 80 70 60 50 40 30 20 10 0 I II III IV V Social Classes
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) Example 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
Slope Index of Inequality (SII)
Slope Index of Inequality (SII)
Relative Index of Inequality (RII)
Cumulative % of Health Relative Concentration Index (RC) The RC is twice the area between the line of equality and the Concentration curve. Concentration Curve Line of Equality Cumulative % of population, ranked based on SES
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.
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