Source of data
The current study is a cross-sectional analysis of nationally representative data from the 2016 South African Demographic and Health Survey (SADHS). The primary purpose of the DHS was to provide up-to-date estimates of basic demographic and health indicators which include fertility levels, maternal and childhood mortality, immunization coverage, HIV testing and counselling, and physical and sexual violence against women. Another objective was to provide estimates of health and behaviour indicators in adults aged 15 and older.
The SADHS 2016 followed a stratified two-stage sampling design with a probability proportional to size sampling of PSUs at the first stage, and systematic sampling of residential dwelling units (DUs) at the second stage. Each province was stratified into an urban, farm, and traditional areas, yielding 26 sampling strata, from which 750 PSUs were selected. DUs within each PSU were listed, and this list served as a frame for sampling DUs. Data collection for the SADHS 2016 took place from 27 June 2016 to 4 November 2016. Data were collected using questionnaires administered by conducting face-to-face interviews. Details of the questionnaires sampling and data collection procedure have been published in the final report (14). Thus, a dataset was created from information obtained from these questionnaires. From the dataset, we included 7861 all women aged 15-49 who had complete information on all the variables of interest constituted our sample.
Study variables
Outcome variables
The main outcome variable for this study was knowledge of MTCT of HIV. Three main questions on the transmission of HIV from mother to child during pregnancy, delivery and breastfeeding were used to assess MTCT knowledge. Each of these questions had three responses: Yes, No, and Don’t Know. Based on previous studies (15,16), No and Don’t know were treated as No=0 and Yes=1. Afterwards, an index was created an index was generated for all the “yes” and “no” responses, with scores ranging from 0 to 3. A score of 0 was labelled as “No”, and scores 1 to 3 as “Yes”.
Independent Variables
Based on previous studies (17–19) eleven independent variables were considered in the study. These were age (15-19, 20-24, 25-29, 30-34, 35-39, 40-44, 45-49), employment (not working, managerial, clerical, Agriculture, Home, Services, manual), marital status (Never married, married, Cohabiting, Widowed/Divorced/Separated), education (no education, primary, secondary, Higher), wealth (poorest, poorer, middle, Richer, Richest), and parity (0,1,2,3,4+). Region (Western Cape, Eastern Cape, Northern Cape, Free State, KwaZulu-Natal, Northwest, Gauteng, Mpumalanga, Limpopo), residence (urban, rural), exposure to mass media (Radio, TV and Newspaper) (Not at all, Less than once a week, At least once a week).
Statistical analyses
The data were analyzed with STATA version 14.2 for Mac OS. The analysis was done in three steps where descriptive analysis of the background characteristics was done initially, followed by calculating the prevalence and proportions of knowledge of mother to child transmission of HIV and AIDS across the socio-demographic characteristics through a cross-tabulation (see Table 1). Finally, a multivariable logistic regression analysis was done to assess the factors associated with knowledge of mother to child transmission of HIV and AIDS. All frequency distributions were weighted while the survey command (svy) in Stata was used to adjust for the complex sampling structure of the data in the regression analyses. This also ensured allocation of the samples to different regions of the country and ensured the results generated are representative at the national and regional levels. Multicollinearity was checked using the variance inflation factor, and there was no evidence of multicollinearity among the variables (Mean VIF=1.25, Maximum VIF=1.50, Minimum VIF=1.02). All results of the logistic regression analyses were presented as adjusted odds ratios (AORs) at 95% confidence intervals (CIs).
Ethical consideration
This study was based on analyses of secondary data set from the DHS program, which gave us permission for its use. The survey was approved by the Institutional Review Board (IRB) of ICF Macro International in the United States and the National Ethics Committee in the Federal Ministry of Health of South Africa. All participants in the survey gave their consent to participate.