Socioeconomic Inequalities in Adult Obesity Prevalence in South Africa: A Decomposition Analysis
Abstract
:1. Introduction
2. Methods
2.1. Data
2.2. Measures
2.2.1. Health Indicators
2.2.2. Measurement of Inequality
2.2.3. Explaining Inequality: Decomposition of the Concentration Index
2.2.4. Construction of the Living Standard Measure: Asset Index
2.2.5. Other Variables
2.3. Data Analysis
3. Results
3.1. Descriptive Statistics
Variables | Male 4,983 (44%) | Female 6,343 (56%) | Total 11,326 |
---|---|---|---|
Unstandardized obesity (age-standardized * ) | 11% (12%) | 36% (35%) | 24% (25%) |
Age in years (standard deviation) | 37 (13.9) | 39 (16.1) | 38 (15.2) |
Marital status | |||
Married | 46% | 44% | 45% |
Widowed | 5% | 15% | 10% |
Never married | 49% | 41% | 45% |
Education | |||
No school | 7% | 11% | 9% |
Primary | 21% | 21% | 21% |
Secondary | 60% | 58% | 59% |
Tertiary | 12% | 10% | 11% |
Employment status | |||
Employed | 60% | 38% | 43% |
Unemployed | 40% | 62% | 52% |
Residence | |||
Urban | 64% | 59% | 61% |
Rural | 36% | 41% | 39% |
Race | |||
African | 81% | 80% | 80% |
Coloured | 7% | 8% | 8% |
Asian | 2% | 2% | 2% |
White | 10% | 10% | 10% |
Lifestyle factors | |||
Physical exercise | 40% | 20% | 28% |
Smoking | 40% | 9% | 23% |
3.2. Inequalities in Obesity
3.2.1. Wealth Distribution
3.2.2. Concentration Indices
Method | Female | Male | Total | |||
---|---|---|---|---|---|---|
Standardization method | CI | 95% confidence interval | CI | 95% confidence interval | CI | 95% confidence interval |
Unstandardized | 0.11 | (0.06–0.16) | 0.28 | (0.18–0.38) | 0.13 | (0.009–0.17) |
Age standardized only | 0.13 | (0.05–0.19) | 0.26 | (0.17–0.35) | 0.13 | (0.09–0.17) |
Age and non–confounding variables | 0.09 | (0.03–0.14) | 0.27 | (0.17–0.36) | 0.12 | (0.06–0.17) |
3.3. Explaining Obesity Inequalities
3.3.1. Results of the Linear Regression
Variables | Female | Male | |||
---|---|---|---|---|---|
Coefficients | Standard Error | Coefficients | Standard Error | ||
Age | 0.008 | 0.00 | 0.003 | 0.00 | |
Socioeconomic status (asset index) | 0.051 | 0.01 | 0.018 | 0.01 | |
Employment Status | |||||
Unemployed | (base) | ||||
Employed | 0.050 | 0.02 | 0.034 | 0.01 | |
Education | |||||
No school | (base) | (base) | |||
Primary | 0.094 | 0.03 | 0.058 | 0.02 | |
Secondary | 0.098 | 0.03 | 0.096 | 0.03 | |
Tertiary | 0.058 | 0.05 | 0.132 | 0.04 | |
Marital status | |||||
Married | (base) | (base) | |||
Widowed | −0.048 | 0.03 | −0.073 | 0.04 | |
Never married | −0.079 | 0.02 | −0.049 | 0.02 | |
Area of residence | |||||
Urban | (base) | (base) | |||
Rural | −0.028 | 0.02 | −0.005 | 0.01 | |
African | (base) | ||||
Coloured | −0.021 | 0.04 | 0.015 | 0.03 | |
Asia/India | −0.124 | 0.07 | 0.050 | 0.09 | |
White | −0.036 | 0.05 | 0.070 | 0.04 | |
Physical activity | −0.098 | 0.03 | −0.036 | 0.02 | |
Smoking | −0.107 | 0.04 | −0.058 | 0.01 | |
Intercept | 0.024 | 0.05 | −0.062 | 0.05 | |
Observations | 6816 | 4510 | |||
R2 | 0.88 | 0.09 |
3.3.2. Decomposition of Socioeconomic Inequality in Obesity
Variables | Female | Male | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Elasticity | CI | Contribution | Elasticity | CI | Contribution | |||||||
Age | 0.865 | 0.003 | 0.000 (0%) | 1.080 | 0.021 | 0.023 (8.5%) | ||||||
Socioeconomic status (asset index) | 0.028 | 2.614 | 0.054 (71.4%) | 0.045 | 1.767 | 0.067 (24.8%) | ||||||
Employment Status | ||||||||||||
Unemployed | (base) | (base) | (base) | (base) | (base) | (base) | ||||||
Employed | 0.054 | 0.124 | 0.007 (10.0%) | 0.184 | 0.100 | 0.018 (6.6%) | ||||||
Education | ||||||||||||
No school | (base) | (base) | (base) | (base) | (base) | (base) | ||||||
Primary | 0.055 | −0.179 | −0.010 (−14.3%) | 0.107 | −0.247 | −0.026 (−9.6%) | ||||||
Secondary | 0.159 | 0.082 | 0.013 (18.6%) | 0.527 | 0.060 | 0.032 (11.9%) | ||||||
Tertiary | 0.017 | 0.450 | 0.008 (11.4%) | 0.141 | 0.466 | 0.066 (24.4%) | ||||||
Marital status | ||||||||||||
Married | (base) | (base) | (base) | (base) | (base) | (base) | ||||||
Widowed | −0.021 | −0.026 | 0.001 (1.4%) | −0.030 | −0.004 | 0.000 (0.0%) | ||||||
Never married | −0.089 | −0.059 | 0.005 (7.1%) | −0.219 | −0.066 | 0.014 (5.2%) | ||||||
Area of residence | ||||||||||||
Urban | (base) | (base) | (base) | (base) | (base) | (base) | ||||||
Rural | −0.031 | −0.453 | 0.014 (20.0%) | −0.017 | −0.447 | 0.008 (3.0%) | ||||||
Black | (base) | (base) | (base) | (base) | (base) | (base) | ||||||
Coloured | −0.005 | 0.43 | −0.002 (−2.9%) | 0.010 | 0.359 | 0.003 (1.1%) | ||||||
Asian/Indian | −0.008 | 0.66 | −0.005 (−7.1%) | 0.010 | 0.501 | 0.005 (1.9%) | ||||||
White | −0.10 | 0.67 | −0.007 (−10.0%) | 0.061 | 0.645 | 0.040 (14.8%) | ||||||
Lifestyle | ||||||||||||
Physical activity | −0.054 | 0.370 | −0.020 (−28.6%) | −0.130 | 0.102 | −0.013 (−4.8%) | ||||||
Smoking | −0.028 | 0.290 | −0.008 (−11.4%) | −0.209 | −0.023 | 0.005 (1.9%) | ||||||
Residual * | 0.017 | 0.029 |
4. Discussion
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Alaba, O.; Chola, L. Socioeconomic Inequalities in Adult Obesity Prevalence in South Africa: A Decomposition Analysis. Int. J. Environ. Res. Public Health 2014, 11, 3387-3406. https://doi.org/10.3390/ijerph110303387
Alaba O, Chola L. Socioeconomic Inequalities in Adult Obesity Prevalence in South Africa: A Decomposition Analysis. International Journal of Environmental Research and Public Health. 2014; 11(3):3387-3406. https://doi.org/10.3390/ijerph110303387
Chicago/Turabian StyleAlaba, Olufunke, and Lumbwe Chola. 2014. "Socioeconomic Inequalities in Adult Obesity Prevalence in South Africa: A Decomposition Analysis" International Journal of Environmental Research and Public Health 11, no. 3: 3387-3406. https://doi.org/10.3390/ijerph110303387