Starting HIV treatment reduces risky sexual behaviour among injecting drug users

Starting antiretroviral therapy is associated with reductions in sexual risk-taking and injecting among HIV-positive drug users, according to US research published in the online edition of AIDS.  There was a 75% reduction in the risk of unprotected sex, whereas the risk of injecting drugs fell by over a third. However, among the small sub-set of patients who continued to inject, the risk of sharing injecting equipment almost doubled.

Overall, the investigators were encouraged by their findings, writing: “Our data do not support the premise that HAART [highly active antiretroviral therapy] is associated with generally increased risky behavior among IDUs [injecting drug users].”

Thanks to antiretroviral therapy, many HIV-positive people now have an excellent prognosis. There is also compelling evidence that virologically effective antiretroviral treatment significantly reduces the risk of HIV transmission.

However, there is some concern that the prevention benefits of treatment could be offset by increases in levels of risky sex or injecting practices. Studies looking at this issue have yielded conflicting results.

Investigators from the AIDS Linked to the IntraVenous Experience (ALIVE) cohort therefore designed a study involving 362 HIV-positive people with a history of injecting drug use in Baltimore.

Researchers monitored sexual activity and injecting behaviour in the year before initiation of HIV therapy and for up to five years afterwards.

Most of the participants (71%) were male and African American (95%).

In the year before starting HIV therapy, 67% of participants reported any sexual activity, almost half (48%) engaged in unprotected sex, a majority (61%) injected drugs and approximately a quarter (27%) reported sharing injecting equipment.

Overall, starting antiretroviral therapy was accompanied by a decline in risky behaviour. The proportion of participants reporting any sex fell to 48%, unprotected sex to 17%, injecting drug use to 34% and sharing injecting equipment fell to 16%.

After taking into account confounding factors, the investigators calculated that starting antiretroviral therapy reduced the risk of unprotected sex by 75% (aOR = 0.25; 95% CI, 0.19-0.32).

“We found no evidence of sexual behavioral risk compensation following initiation of HAART,” comment the investigators. “Among IDUs who remained sexually active, we observed a significant decline in unprotected sex after HAART initiation.”

The risk of injecting drug use fell by 38% (aOR = 0.62; 95% CI, 0.51-0.75).

These reductions in risk behaviour were sustained for up to five years after HIV treatment was started.

However, for the 16% of participants who continued to share needles after initiating therapy, the risk of sharing injecting equipment almost doubled (aOR = 1.99; 95% CI, 1.57-2.52).

“For the small subset of IDUs who continued or resumed injecting after HAART, the odds of needle-sharing increased approximately two-fold, with no diminution of this excess risk over > 5 years of follow-up,” note the researchers. “This indicates that for a minority of IDUs unable to abstain from injecting, starting HIV treatment could mark a transition to riskier injecting.”

The investigators also examined the factors associated with continued risky behaviour after starting therapy.

They found this was associated with risky sex in the year before treatment (OR= 3.35; 95% CI, 1.87-5.95).

Similarly, injecting drug use in the year before treatment was associated with an eleven-fold increase in the risk of drug during treatment (OR = 10.9; 95% CI, 6.58-17.8). Sharing injecting equipment in the period immediately before treatment initiation more than doubled the risk of subsequent needle sharing (OR = 2.55; 95% CI, 1.70-3.83).

The authors note that their findings differ from those of several other studies conducted in other cities, which found no increase in risky injecting behaviours.

“Our results support the optimistic view that for most IDUs, risk compensation following HAART initiation is unlikely, albeit with the worrisome caveat that a small minority of active injectors may be more likely to share needles after initiating treatment,” conclude the authors. “Based on our findings, targeting risk-reduction interventions for persons with high-risk behaviors in the time-period shortly before HAART initiation should be considered.”