Baseline characteristics
A total of 31 385 survey respondents were included: 14 911 and 16 474 records from Malawi and Zimbabwe and 14 027 and 17 358 among men and women respectively. Of these, a total of 24 683 individuals were asked about HIVST, with 6,702 (21.1%) not asked about HIVST and 40 (0.12%) with missing data related to questions on sexual activity used to determine HIV risk.
A total of 78.6% and 75.4% of people reported ever having tested for HIV in Malawi and Zimbabwe, respectively (p<0.001) (Table 1). Compared to older age groups (≥25 years), a larger proportion of those never-tested were young people (aged 15-24) (39.2% vs 14.1%; p<0.001). Likewise, more women, compared to men (31.2% vs. 16.5%; p<0.001), and more urban, compared to rural, residents (24.1% vs 21.0%; p<0.001) had tested previously.
The proportion of people who had ever self-tested was similar in both countries. However, there was greater awareness of HIVST in Zimbabwe compared to Malawi (14.5% vs 11.4%; p<0.001) and for men compared to women (15.3% vs. 9.1%; p<0.001). Older (aged ≥30: 21.1% vs. aged <30: 9.1%; p<0.001), wealthier (richest: 22.8% vs poorest: 6.4%; p<0.001) and more educated individuals (17.8% vs 7.5%; p<0.001) had greater awareness of self-testing than those aged <30 years, poorer, and less educated individuals.
Willingness to self-test could only be assessed among 7,372 Zimbabwean men (48 men missing data on willingness) as only men were asked about willingness to self-test, and this question was not included in the Malawi DHS Questionnaires.
Most Zimbabwean men (84.5%) were willing to self-test. Older men (aged ≥25) reported greater willingness to self-test than younger men (aged <25) (88.7% vs. 78.8%; p<0.001). Men reporting more sexual risk behaviours also reported greater willingness to self-test than men reporting less risk (87.6% vs 78.8%; p<0.001). Most men willing to self-test had tested in the past 12 months (88.5%). However, a high proportion of men who had not tested for HIV in the previous two or more years were also willing to self-test (86.4%). (Supplementary table S1 includes for baseline characteristics of Zimbabwean men on willingness to self-test, 2015-16).
Ever tested for HIV
Factors associated with ever having tested for HIV were: being Malawian, female, older, urban residents, married or cohabitating, employed, having secondary or higher-level education, being literate, having an HIV-positive test in the survey and having either moderate or reporting more sexual risk behaviours (Table 2). HIV risk, age and HIV status appeared to modify effects in the multivariable analysis across a number of variables. Results of multivariable analysis were affected by collinearity, notably between age and HIV sexual risk, marital status and HIV sexual risk, age and education level and education level and literacy.
On multivariable analysis, after assessing for collinearity, factors that remained associated with ever having tested for HIV included being Malawian (adjusted odds ratio (aOR)=1.26; 95% confidence interval [CI]: 1.15-1.38, p<0.001), older age (e.g. for the 30-34 year olds compared to default 15-19 years, aOR=8.86; 95%CI: 7.63-10.29, p<0.001), and reporting more sexual risk behaviours (moderate vs. low: aOR=2.15; 95%CI:1.96-2.36, p<0.001, and high-risk vs. low: aOR=1.54; CI:1.80-2.49, p<0.001). Being able to read (literate vs illiterate: aOR=1.63, 95%CI:1.50-1.78, p<0.001) and actively working (working vs not working: aOR=1.16; 95%CI: 1.06-1.26, p<0.001) were also associated with previous testing as well as testing HIV-positive in the survey (for HIV-positive vs. HIV-negative: aOR =2.11, 95%CI:1.80-2.49, p<0.001). Men had substantially lower odds of having ever tested for HIV compared to women (aOR=0.36; 95%CI: 0.32-0.41, p<0.001).
Awareness and use of self-testing
Few respondents (287, 1.2%) had self-tested previously, although 12.6% were aware of self-testing. In univariable analyses, previous self-testing was associated with age (more likely to have self-tested if 20 years of age and older), urban residence, increasing affluence, better education, literate and with high HIV risk. On multivariable analysis, across wealth quintiles, being wealthier was associated with previous self-testing (p<0.001) with wealthiest men having the greatest odds of past self-testing (aOR for wealthiest vs. least wealthy=3.59; 95%CI:1.79-7.18, p<0.001). Older men, 30-34 years old, also had greater odds of past self-testing compared to younger men (age 15-19) (aOR= 2.89; 95%CI: 1.47-5.68, p<0.002). (A complete analysis of ever self-testing is shown in supplementary table S2.)
Table 3 provides outcomes from univariable and multivariable analysis for awareness of HIV self-testing. On univariable analysis, the following variables were significantly associated with being aware of HIVST: being from Zimbabwe, male, older (≥20 years), urban, wealthy, married, actively employed, more educated, literate, moderate or high-risk, and having tested previously.
On multivariable analysis, the following variables were significantly associated with being aware of HIVST: being male (male vs female: aOR=1.55;95%CI:1-37-1.75, p<0.001), older than 15-19 years (particularly those aged 25-29 years: aOR=1.76; 95%CI:1.43-2.17, p<0.001 and aged 35-39 years: aOR=1.69; 95%CI: 1.34-2.12, p<0.001), wealthy (wealthiest vs least wealthy: aOR=3.03; 95%CI: 2.46-3.73, p<0.001), working (working vs not working: aOR=1.25; 95%CI: 1.12-1.42, p>0.001), able to read (literate vs illiterate: aOR= 1.17; 95%CI: 1.01-1.36, p<0.035) and having previously tested for HIV compared to those who never tested (aOR=1.89; 95%CI:1.65-2.17, p<0.001). Being from Malawi and from a rural setting were negatively associated with awareness of self-testing (see Table 3).
Willingness to self-test among Zimbabwean men
On crude analysis, older aged Zimbabwean men who were working, those with moderate to high-risk, and men who had previously tested men reported greater willingness to self-test (Table 4).
On univariable analysis, the following were significantly associated with overall willingness to self-test (unstratified): being older (aged 25-29 vs aged 15-19: OR=2.07, 95%CI: 1.78-2.42, p<0.001), married or living together (married/living together vs single: OR=2.06, 95%CI: 1.77-2.40, p<0.001), actively working (working vs not working: OR=1.71, 95%CI: 1.48-1.97,p<0.001), having better education (secondary or higher education vs primary or less education: OR=1.36, 95%CI: 1.16-1.59, p<0.001), able to read (literate vs illiterate: OR=1.42, 95%CI: 1.19-1.69, p<0.001), with moderate or high sexual HIV risk (moderate vs low: OR=2.16, 95%CI: 1.83-2.54, p<0.001; high vs low: OR=1.92, 95%CI: 1.54-2.39, p<0.001), and having previously tested (previously tested vs never tested: OR=1.24, 95%CI: 0.97-1.57, p<0.001).
The relationship between willingness to test and socio-economic variables (wealth and working) and HIV status, substantially differed according to both high and low-sexual risk (Table 4): see for example univariable OR for HIV status and employment. Thus, we adapted our planned multivariable analysis to account for effect-modification between HIV sexual risk categorization and socioeconomic variables. On multivariable analysis, comparing men with high-risk behaviour to those with low-risk behaviour, high-risk men were more likely than low-risk men to express willingness to self-test if they were also from higher socioeconomic quintiles, not working, in rural settings and tested previously (interaction terms: socioeconomic status, p = 0.066, rural residence, p=0.071, employment p=0.003, literacy, p=0.225, married, p=0.401, aware of self-test, p=0.605, previous testing, p=0.001, and HIV status p = 0.162) (Table 4).
On multivariable analysis of high-risk men, willingness to self-test increased with age (p<0.030) with the strongest association for those aged 35-39 compared to those aged 15-19 (aOR=4.87; 95%CI: 2.14-11.07, p<0.001). Similarly, willingness in high-risk men increased with greater wealth quintile (wealthiest vs least wealthy: aOR=3.74, 95%CI:1.39-10.53, p=0.009) and in rural settings (rural vs urban: aOR=3.56, 95%CI: 1.61-7.90, p=0.002).
While employment in high-risk men was associated with less willingness to self-test (working vs not working: aOR: 0.57, 95%CI: 0.34-0.95, p=0.030), employed low-risk men were significantly more willing than unemployed low risk men to self-test (aOR 1.41; 95%CI: 1.13-1.77, p=0.003). The association with previous testing and willingness to test was also more pronounced factor for low risk men (previously tested vs never tested: aOR 1.48; 95%CI: 1.18-1.85, p<0.001) than high risk men (previously tested vs never tested: aOR 1.20; 95%CI: 0.76-1.90, p=0.435), while associations with age (p=0.106) and wealth (p=0.102) were less pronounced than for high risk men (described above).
We additionally conducted an a priori-defined stratified analysis to investigate whether willingness to self-test varied by past HIV-testing behaviour (i.e. previously tested or not) and HIV testing history (supplementary table S3). Patterns of willingness to self-test were similar for the 2,437/7,372 (33.1%) men who had never previously tested as for those with at least one past HIV test, with greater willingness in older men. Those not previously tested who tested HIV-positive in the survey were however more likely to be willing to self-test (aOR=1.83, 95%CI: 1.03-3.24, p=0.039), which was not significant among ever-tested men.