This study found that injecting partnerships in which the participant thought that their injecting partner was HCV positive had lower odds of engaging in RNS with that partner, compared to those partnerships in which the participants reported that their partner was HCV negative. While some studies have examined the effects of one's own HCV status on injecting risk behavior,35, 36
only two other studies that we are aware of have examined the effect of perceived partner serostatus on injecting risk behavior32, 33
The study by De et al found no difference in needle/syringe sharing (both borrowing and lending studied together) by the HCV status of the participant and their partners32
The study by Burt et al found that IDU were more likely to share (borrow or lend) injection equipment (needles/syringes, cookers, cottons and water) with those of the same HCV status.33
Our finding is consistent with that of Burt et al33
and is an indication that young IDU may engage in some amount of risk calculation in order to avoid infection with HCV. However, it is not encouraging that young IDU who did not know their partner's HCV status had equal odds of engaging in RNS as those who reported that their partner was HCV negative. We found that using one's own needle/syringe only one time attenuated the association between perceiving one's partner to be HCV positive and engaging in RNS with that partner and therefore re-using one's needle/syringe may be a mediator. Those who believe that their partner is HCV positive are more likely to practice safer injecting habits overall, however the directionality of this association cannot be concluded from these cross-sectional data. None of the other variables that were associated with engaging in RNS with one's partner affected the association with believing one's partner was HCV positive.
Our second finding was those who reported that they did not know the HCV status of their injecting partner had significantly lower odds of engaging in AES with that partner as compared to those who reported that their partner was HCV negative, among those partnerships in which the partners had not engaged in sex. This association was not attenuated after adjusting for variables that were associated with engaging in AES in bivariate analyses. There was no association between the respondent's perceived HCV status of their injecting partners and engaging in AES with those partners, among the partnerships where the partners had engaged in sex in the prior month. This finding is consistent with previous studies showing increased injecting risk behavior among sexual partners.11, 14, 15, 21-23
The majority of the injecting partnerships of young IDU were between persons who were close in age, who had known each other for a median of 6 months, and who were male and female IDU (rather than the same sex), and 30% of the injecting partners had also engaged in sex. Just over half (53%) of the participants had previously been tested for HCV, and the participants did not know the HCV status of almost half (49%) of their injecting partners. This highlights that while there is a fair degree of closeness in several aspects of the injecting relationships in young IDU, HCV testing and HCV status disclosure is not the norm.
There are several limitations to note in interpreting these results. First, the data are collected by self-report, and social desirability bias may affect the results. Young IDU who have been exposed to risk reduction counseling may under-report engaging in risk behaviors, especially with known HCV positive partners, which would bias our results away from the null. However, the level of risk behavior reported is quite consistent with that observed in other studies of young IDU.25
Participants were asked to report on partnership characteristics for those partners with whom they injected most often, with a limit of three partnerships. Therefore for those with more than three partnerships, lower frequency partnerships were excluded and we therefore cannot generalize our results to all injecting partnerships. The results are also limited by the cross-sectional nature of the study.
The results from this study suggest that knowledge that one's partner is HCV positive may foster avoidance of RNS. This study highlights the potential need for broader programs of HCV testing and emphasis on partner disclosure, given that such high proportions of young IDU knew neither their own nor their partners' HCV status. However, no studies have been conducted to examine the impact of partner HCV status disclosure, while studies of the impact of knowing one's own HCV status have been mixed. A recent ethnographic study which assessed IDU's views of HCV infection in young IDU illustrated that for some young IDU, knowledge that they are infected with HCV leads them to attempt to prevent spreading the infection to others.37
On the other hand, in our population, we found that young IDU did not reduce their level of lending injecting equipment to others or engaging in AES after they were told they were infected with HCV.38
It would be important to conduct modeling studies to determine the plausible effect of a serosorting approach on reducing HCV incidence in IDU. We caution that HIV serosorting of sexual partners has been shown to have clear limitations.31, 39, 40
The results also suggest that young IDU engage in AES with sexual partners regardless of the perceived HCV status of that partner. As AES appears to be a significant route of transmission for HCV,5
this route of infection deserves more emphasis in designing programs to reduce HCV transmission.