What Proportion of Female Sex Workers Practise anal Intercourse and How Frequently? A Systematic Review and Meta-analysis

Abstract

HIV is more efficiently acquired during receptive anal intercourse (AI) compared to vaginal intercourse (VI) and may contribute substantially to female sex workers' (FSW) high HIV burden. We aim to determine how common and frequent AI is among FSW globally. We searched PubMed, Embase and PsycINFO for studies reporting the proportion of FSW practising AI (prevalence) and/or the number of AI acts (frequency) worldwide from 01/1980 to 10/2018. We assessed the influence of participant and study characteristics on AI prevalence (e.g. continent, study year and interview method) through sub-group analysis. Of 15,830 identified studies, 131 were included. Nearly all (N = 128) reported AI prevalence and few frequency (N = 13), over various recall periods. Most studies used face-to-face interviews (N = 111). Pooled prevalences varied little by recall period (lifetime: 15.7% 95%CI 12.2-19.3%, N = 30, I² = 99%; past month: 16.2% 95%CI 10.8-21.6%, N = 18, I² = 99%). The pooled proportion of FSW reporting < 100% condom use tended to be non-significantly higher during AI compared to during VI (e.g. any unprotected VI: 19.1% 95%CI 1.7-36.4, N = 5 and any unprotected AI: 46.4% 95%CI 9.1-83.6, N = 5 in the past week). Across all study participants, between 2.4 and 15.9% (N = 6) of all intercourse acts (AI and VI) were anal. Neither AI prevalence nor frequency varied substantially by any participant or study characteristics. Although varied, AI among FSW is generally common, inconsistently protected with condoms and practiced sufficiently frequently to contribute substantially to HIV acquisition in this risk group. Interventions to address barriers to condom use are needed.

Keywords: Anal intercourse; Female sex workers; HIV; Sexual behaviour.

Fig. 1

Pooled estimates of the prevalence of anal intercourse over each recall period reported. AI anal intercourse, NA not applicable, 95% CI 95% confidence interval. The top of each diamond represents the pooled estimate, while furthest points represent 95% CI. I² and Q Test are both measures of heterogeneity, with higher values in both indicating greater heterogeneity. I² ranges from 0–100%. The results of the Q Test are displayed in bold when the p-value is < 0.05, which indicates that the level of heterogeneity found is statistically significant

Fig. 2

Pooled estimates of the prevalence of anal intercourse and vaginal intercourse unprotected by condoms, by recall period. Pooled estimates of the proportion of those who report any AI unprotected by condoms among those reporting any AI over the most commonly reported recall periods, and the equivalent pooled estimates for UVI. UAI anal intercourse unprotected by condoms, UVI vaginal intercourse unprotected by condoms, 95% CI 95% confidence interval, general report that condom use is anything other than ‘always’ using condoms

Fig. 3

Proportion of intercourse acts that are anal by selected study and participant characteristics Scatter plots of the proportion of intercourse acts that are anal among the whole sample (i.e. including those reporting no AI) participant characteristics and study characteristics. ACASI audio computer assisted self-interview, CD coital diary, CRS cluster-randomised sampling, FTFI face-to-face interview, Mix data only available for men and women combined, NS not stated, RCT randomised controlled trial, RDS respondent-driven sampling, SAQ self-administered questionnaire, SRS simple randomised sampling, TLS Time-location sampling