How common and frequent is heterosexual anal intercourse among South Africans? A systematic review and meta-analysis

Abstract

Background: HIV is transmitted more effectively during anal intercourse (AI) than vaginal intercourse (VI). However, patterns of heterosexual AI practice and its contribution to South Africa's generalized epidemic remain unclear. We aimed to determine how common and frequent heterosexual AI is in South Africa.

Methods: We searched for studies reporting the proportion practising heterosexual AI (prevalence) and/or the number of AI and unprotected AI (UAI) acts (frequency) in South Africa from 1990 to 2015. Stratified random-effects meta-analysis by sub-groups was used to produce pooled estimates and assess the influence of participant and study characteristics on AI prevalence. We also estimated the fraction of all sex acts which were AI or UAI and compared condom use during VI and AI.

Results: Of 41 included studies, 31 reported on AI prevalence and 14 on frequency, over various recall periods. AI prevalence was high across different recall periods for sexually active general-risk populations (e.g. lifetime = 18.4% [95%CI:9.4-27.5%], three-month = 20.3% [6.1-34.7%]), but tended to be even higher in higher-risk populations such as STI patients and female sex workers (e.g. lifetime = 23.2% [0.0-47.4%], recall period not stated = 40.1% [36.2-44.0%]). Prevalence was higher in studies using more confidential interview methods. Among general and higher-risk populations, 1.2-40.0% and 0.7-21.0% of all unprotected sex acts were UAI, respectively. AI acts were as likely to be condom protected as vaginal acts.

Conclusion: Reported heterosexual AI is common but variable among South Africans. Nationally and regionally representative sexual behaviour studies that use standardized recall periods and confidential interview methods, to aid comparison across studies and minimize reporting bias, are needed. Such data could be used to estimate the extent to which AI contributes to South Africa's HIV epidemic.

Keywords: Anal intercourse; South Africa; heterosexual; sexual behaviour.

Figure 1.

Prevalence of AI over the various recall periods reported. Study estimates of AI prevalence among heterosexual men and women among (a) general-risk study participants and (b) higher-risk study participants. Shown on the graph, study estimates are ordered by survey year and 95% confidence intervals (95% CI) and Higgins I² [29]. I² can lie between 0 and 100%; where 0% and 100% indicate no and the most observed heterogeneity across study estimates. ^aAI prevalence with steady partners has been grouped with any partner type here. ^bEstimates are for unprotected AI only. ^C12 of the 18 school classes recruited used ACASI, the remainder used SAQ. ^dRecruited from shebeens. ^eRecruited from the community. ACASI = audio computer-assisted self-interview, FTFI = face-to-face interview, SAQ = self-administered questionnaire; F = female, M = male, Mix = data available for mixed gender only; Clients = clients of female sex workers, FSW = female sex workers, High risk = defined by authors as being at high risk of HIV infection (79% were FSW), STI = STI clinic patients.

Figure 2.

Forest plot of sub-group analyses of prevalence of AI among sexually active general-risk populations; study and participant characteristics. Results are presented for recall periods reported by at least five studies (lifetime and three months) on (A) study and participant characteristics and (B) study quality.I² is calculated as described in Higgins et al. [39]. I² lies between 0 and 100 %; 0 % indicates no observed heterogeneity and larger values show increasing heterogeneity. AI = anal intercourse, UAI = unprotected anal intercourse, ACASI = audio computer-assisted self-interview, FTFI = face-to-face interview, SAQ = self-administered questionnaire, CRS = cluster random sampling, RCT = randomized control trial, NS = not stated. Shebeens are informal alcohol serving establishments. One study reported prevalence for casual and steady partners over three month recall. Prevalence for steady partners only was pooled from this study, except when comparing prevalence by partner type. Mean age was not examined in three month recall as all studies recruiting from the community either did not report on mean age, or had a mean age of 25+ years. Sub-group analysis of population (school vs. community) acts as proxy for analysis by age. Neither of the studies reporting on past three months explicitly included heterosexuals only.

Figure 2.

(Continued)

Figure 3.

Bar chart of fraction of sex acts that are AI and fraction of unprotected acts that are UAI. Among (A) general-risk study participants and (B) higher-risk study participants. AI = anal intercourse, VI = vaginal intercourse, UAI = unprotected anal intercourse, ACASI = audio computer-assisted self-interview, FTFI = face-to-face interview, SAQ = self-administered questionnaire, F = female, M = male, Mix = data available for mixed gender only, N = sample size, FSW = female sex workers, High risk = defined by authors as high risk of HIV infection, 79% were FSW, STI clinic = sexually transmitted infections clinic patients, VCT = voluntary counselling and testing,. Cli = with clients, Cas = with casual partners, Pri = with primary partner, Ste = with steady partner. Sheb = Shebeen, which are informal drinking establishments. All studies with available data were included.