About 20% of Iranian noninjecting FSWs reported having sex with at least one IDU during past month. Our findings suggest that a lower tendency toward unprotected sex with an IDU amongst sex workers with higher educational levels increased perceived HIV risk and family intimacy among childhood. HIV knowledge, however, failed to be predictive of sex with IDUs in our study. These findings shed more light on a previously understudied outcome—unprotected sex with IDUs committed by noninjecting Iranian FSWs
Having a higher educational level (OR = −0.018) was shown to be associated with unprotected sex with IDUs among Iranian FSWs. Although most of studies have shown an association between educational level and risky behaviors [
13–
15], there are studies that have reported a lack of association [
16]. Based on the Strain Theory, delinquencies may occur among those who get frustrated by the inability to succeed in school [
17]. The Social Control Theory also suggests that this association results from the protective effect of institutions on instilling social norms and sanctioning deviance [
17]. The Primary Socialization Theory suggests that weak school bonds may increase the amount of time spent with deviant peers [
18]. All these theories can be used to explain an association between education level and risk-taking. In addition, it is possible that those with lower education may overreport behavior problems, while those with higher education may underreport behavior problems [
19].
Higher perceived HIV risk (OR = −0.046) was another protective factor against unprotected sex with IDU(s). Most, [
20,
21] but not all, [
22] studies support our findings, and this inconsistency might be explained by measurement incompatibility, subpopulation and behavioral differences, and unexamined critical factors constructing perceived risk [
22] across studies. Perceived risk is a construct of the Health Belief Model (HBM), which has been widely used for HIV prevention interventions. The Health Belief Model has been utilized over time by many authors to explain high-risk sexual behaviors among commercial sex workers previously. In a study conducted on 211 male street prostitutes, between the ages of 18 and 51 in the USA, perceived HIV risk was not significantly associated with their high-risk behaviors [
23]. Other studies have shown that perceived susceptibility to HIV and perceived benefits of condom use may reduce HIV risk-taking [
23]. Additionally, in another study, perceived susceptibility to STDs was a predictor of condom use among FSWs in Indonesia [
24].
As reported by the United Nations, the Health Belief Model is one of the models that can be used as a basis for prevention of HIV via sexual behaviors [
25]. Perceived HIV risk is a complex construct because female sex workers may be seen as at risk, not because of their current behavior, but because of their past behaviors or because of their partner [
25].
More family intimacy during childhood may protect FSWs from unprotected sex with IDUs (OR = −0.012). Several studies have shown negative impact of childhood violence, physical abuse [
26–
28], and even witnessing family violence on future engagement in high-risk behaviors [
29]. The protective role of family connectedness against deviances has been widely acknowledged [
30]. As it has been suggested before, strengthening family ties and family involvement may have a protective effect on sexual risk taking of girls [
31].
Low efficacy of programs that only promote HIV knowledge in relation to risky behaviors has been previously reported [
32]. Program planners may consider focusing on perceived HIV risk to reduce instances of unprotected sex amongst Iranian female sex workers with IDU(s). Although this study only measured individual level data, proper prevention interventions should consider interpersonal, environmental, and structural context in which sexual behaviors occur, as well [
33].
Some researchers have argued that the ultimate target for any program for FSWs should be their empowerment to quit prostitution [
6]. Sex work is different in different settings [
34], and such diversities should be considered when a program is designed or implemented [
25].
Because of its cross-sectional design, our study is not conclusive about causal relations. The considerable amount of missing data was another limitation in this study. As the data were collected via self-report, overreporting and/or underreporting are possible consequences [
35]. Small sample size and the use of respondent-driven sampling may also have limited our study. In addition, we did not collect data regarding whether the IDU is a regular or temporary client of the sex worker. This study also has not measured the context in which sex has taken place. Finally, a portion of FSWs who did not reported sex with IDUs may likely be unaware of their sexual partner's injection behavior. However, due to cultural, political, and religious circumstances, few studies have been done on Iranian FSWs [
36]. Therefore, even with the aforementioned limitations, this study sheds light on risk-taking behavior of FSWs, and it may help harm reduction practice in Iran.
In conclusion, public health officials should not assume that providing educational information about HIV transmission would lead to behavioral change among sex workers. We instead suggest theory-based interventions, with perception of risk as the integral component to reducing risky behaviors and increasing condom use among Iranian female sex works.