Explaining the role of the social determinants of health on health inequality in South Africa

Figures & data

Table 1 Summary description of variables

Domains	Description	Mean/percentage
Income and poverty
Per capita household income	Average annual household per capita income. Household per capita income proxied by household expenditure	$3,000.00
Income	Ratio of average household per capita income to household reported per capita income^a	1.53
Poor household with at least one child	A household living below the poverty line (R466/month)^b with at least one child less than 5 years (1=poor with at least one child; 0=otherwise)	6.25%
Poor household with at least one adult above retirement age	A household living below the poverty line (R466/month)^b with at least one adult aged 65+ years (1=poor with at least one adult above retirement age, 0=otherwise)	2.41%
Knowledge and education
Adult completing at least secondary education	An adult (18+ years) that has completed at least secondary education (1=completed secondary education; 0=otherwise)	36.83%
Housing and infrastructure
Composite housing	Collection of five variables at the household level:
	(1) good sanitation (1=good sanitation; 0=otherwise)	78.46%
	(2) electricity available in household (1=electricity available; 0=otherwise)	87.32%
	(3) clean cooking source (1=clean source; 0=otherwise)	84.65%
	(4) clean lighting source (1=clean source; 0=otherwise)	89.76%
	(5) clean drinking water source (1=clean source; 0=otherwise)	93.09%
Community and infrastructure
Community infrastructure	A collection of two variables:
	(1) having street lighting around the household where the individual lives (1=street lighting available; 0=otherwise)	54.45%
	(2) regular rubbish/refuse removal by local authorities (1=regular removal; 0=otherwise)	65.78%
Safety	A binary variable denoting the absence or very infrequent occurrence of all of the following within the neighbourhood of the household: theft/burglary; violence among households; gangsterism, murder, shooting and stabbing in neighbourhood; and drug abuse in neighbourhood (1=safe neighbourhood; 0=otherwise)	14.73%
Social protection and employment
Private health insurance	Private health insurance membership (1=member; 0=non-member)	15.63%
Grant recipient	Receiving any form of social assistance from the government (1=receives social assistance; 0=otherwise)	52.03%
Employed adult	Being in paid employment: i.e. self-employed or working for pay as an employee or employer (1=employed; 0=not employed)	40.79%
Gender norms
Female DM1	From a household where a female member is principally responsible for making decisions about day-to-day household expenditures (1=female decision maker household; 0=otherwise)	56.12%
Female DM2	From a household where a female member is principally responsible for making decisions about large, unusual purchases (1=female decision maker household; 0=otherwise)	48.03%
Female DM3	From a household where a female member is principally responsible for making decisions about where children should go to school (1=female decision maker household; 0=otherwise)	40.49%
Female-headed household	Household is headed by a female (female household head=1; male household head=0)	54.17%
Other individual/household-specific factors
Race	Race category:
	(1) White	9.67%
	(2) Black	78.69%
	(3) Coloured	9.16%
	(4) Indian/Asian	2.49%
Provincial dummies	Province of residence of the individual (i.e. 9 dummy indicators corresponding to the 9 provinces in SA)	–
Rural	Location of individual (1=rural area; 0=urban area)	34.49%
Household size	The number of individuals living in the household. Household membership is defined as ‘spending more than 15 days in the last 12 months at the household and sharing food and resources when staying at that household’ (32)	3.27
Age	Age in years	40.08
Female	Sex (1=female; 0=male)	54.14%
Illness	Self-reported illness or injury in the past 30 days (1=reported illness/injury; 0=otherwise)	57.19%
Good SAH	Self-assessed health status (1=reporting good, very good or excellent; 0=fair or poor)	88.16%

Some of the original domains are not included. Registration domain is omitted due to redundancy as data indicate that the coverage of birth registration is in excess of 98%. Early childhood development domain is not contained here because only data on adults were used. The travel, participation, accountability, and discrimination domains are not contained here because data or proxies are not available. However, some of the variables such as race, location, sex, and other socio-economic status variables pick up some information on discrimination.

^aThis procedure was adopted to ensure that the indicators for income and poverty follow the same direction. A ratio greater than one signifies households with income less than the average income.

^bThe average nominal exchange rate is $1=R10. Although SA does not have a unique national poverty line, one of the widely used poverty lines (47) was updated and used to categorise households as poor/non-poor.

Table 2 Decomposition of health inequality, South Africa, 2012/13

	Concentration index^a (a)	Elasticity (b)	Contribution^b (c)=(a)×(b)
Income and poverty
Income	−0.5318*** (0.0047)	−0.0009	0.0005 (0.0018)
Poor household with at least one adult above retirement age	−0.6322*** (0.0122)	0.0012	−0.0007* (0.0004)
Poor household with at least one child	−0.6749*** (0.0091)	−0.0002	0.0001 (0.0006)
Knowledge and education
Adult completing at least secondary education	0.3026*** (0.0094)	0.0161	0.0049*** (0.0011)
Housing and infrastructure
Good sanitation	0.1093*** (0.0033)	−0.0054	−0.0006 (0.0008)
Electricity available in household	0.0432*** (0.0024)	−0.0077	−0.0003 (0.0007)
Clean cooking source	0.0828*** (0.0026)	0.0004	0.00003 (0.0010)
Clean lighting source	0.0420*** (0.0020)	−0.0367	−0.0015* (0.0008)
Clean drinking water source	0.0316*** (0.0016)	−0.0210	−0.0007** (0.0003)
Community and infrastructure
Having street lighting where the individual lives	0.2065*** (0.0068)	−0.0069	−0.0014 (0.0014)
Regular rubbish/refuse removal by local authorities	0.1894*** (0.0050)	0.0153	0.0029* (0.0016)
Safety	−0.1052*** (0.0179)	0.0010	−0.0001 (0.0002)
Social protection and employment
Private insurance	0.6362*** (0.0126)	0.0034	0.0022 (0.0015)
Grant recipient	−0.2812*** (0.0088)	−0.0125	0.0035*** (0.0014)
Employed adult	0.2621*** (0.0087)	0.0233	0.0061*** (0.0012)
Gender norms
Female DM1	−0.0939*** (0.0080)	−0.0107	0.0010 (0.0008)
Female DM2	−0.1304*** (0.0093)	−0.0014	0.0002 (0.0009)
Female DM3	−0.1958*** (0.0098)	−0.0036	0.0007 (0.0010)
Female-headed household	−0.1181*** (0.0085)	0.0059	−0.0007 (0.0007)
Other individual/household-specific factors
Age	0.0199*** (0.0034)	−0.1555	−0.0031 (0.0021)
Age squared	0.0286*** (0.0068)	−0.0476	−0.0014 (0.0017)
Female	−0.0763*** (0.0090)	−0.0061	0.0005 (0.0003)
Household size	−0.2338*** (0.0046)	0.0205	−0.0048*** (0.0016)
Illness	0.0056 (0.0081)	−0.0788	−0.0004 (0.0005)
Rural	−0.3080*** (0.0106)	−0.0017	0.0005 (0.0014)
Race	–	–	0.0003 (0.0002)
Provincial dummies	–	–	0.0003 (0.0002)
Residual			0.0001 (0.0027)
Concentration index			0.0080*** (0.0030)

^aAnalytical standard errors are in parenthesis; ^bbootstrap standard errors in parenthesis using 1,000 replications; *p<0.10, *p<0.05, ***p<0.01.

Fig. 1 The contribution of social determinants of health to health inequality in South Africa, 2012/13. The error bars represent 95% confidence intervals based on bootstrapped standard errors using 1,000 replications.

Table 3 Percentage contribution of the ‘domains’ to health inequality in South Africa, 2012/13

	Percentage contribution to the concentration index
Social protection and employment	149.33
Knowledge and education	61.78
Community and infrastructure	17.27
Gender norms	14.96
Income and poverty	−1.90
Housing and infrastructure	−39.23

Fig. 2 Selected public expenditure categories as a share of total public expenditure, South Africa 1994–2012. From ref. (51).

[PubMed CentralFull Text] The Presidency (2012). Development indicators, 2012. Pretoria: The Presidency, Republic of South Africa..

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Reserve Bank. Government finance statistics of South Africa: 1994–2012 supplement to the South African Reserve Bank Quarterly Bulletin. 2013; Pretoria: South African Reserve Bank.

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