Adherence to HIV post-exposure prophylaxis
(PEP) among victims of sexual assault is poor, according to the results of a
meta-analysis and systematic literature review published in Sexually Transmitted Infections.
Approximately 40% of patients did not return
for follow-up appointments. The investigators also found that few studies
examined the efficacy of adherence support.
“Our review confirms an overall low rate of
adherence to PEP among victims of sexual assault with a considerable variation
in rates of adherence and defaulting across a broad range of settings,” write
the authors. “Low adherence is a concern as it is associated with a risk of
reduced efficacy and increased risk of resistance to antiretroviral therapy.”
Treatment with a short course (28 days) of
combination antiretroviral viral therapy can reduce the risk of infection with
HIV after possible sexual exposure to the virus. In many settings, PEP is
offered to the victims of sexual assault. The therapy has the potential to make
a significant impact on HIV incidence. In Kenya, which has a generalised HIV
epidemic, a quarter of women report being raped and about 4% of HIV infections
in adolescents have been attributed to sexual assault.
Adherence to PEP can be challenging, and
the results of studies conducted in a variety of settings have suggested that
completion rates of the treatment following sexual assault are lower following
sexual assault compared with possible exposure after consensual sex. Factors
associated with poor adherence could include stigma, trauma following rape and
assault, treatment side-effects and lack of support.
However, rates of adherence to PEP
following sexual exposure and the factors affecting them are poorly understood.
Therefore an international team of investigators conducted a literature review
and meta-analysis to establish a better appreciation of these issues.
A total of seven electronic databases were
screened by the investigators in June 2011.They identified a total of 24
studies. Most were observational and retrospective. Only three assessed
interventions to improve adherence. The overall standard of the studies was
poor, and there was no consistency in assessing adherence
Two studies assessed adherence through pill
count, seven via patient self-report, and two by pharmacy visit. The other
studies did not state how adherence was assessed.
Overall rates of adherence ranged from 12%
to 74%, with an overall pooled average of 40%. Adherence appeared to be higher
in resource-limited settings than in industrialised countries (53% vs. 33%).
A total of 19 studies reported on the
patients who defaulted from PEP (usually defined as failure to return for
follow-up appointments). The proportion ranged from 3% to 76%, with an average
Refusal rates ranged from 0.09% to 72%
(average 29%). The proportion of patients who did not attend for follow-up
appointments was between 3% and 65%, with an overall pooled proportion of 33%.
Five studies reported on the impact of
side-effects on adherence. Three found a relationship between poorer adherence
and the presence of side-effects.
Three studies examined interventions to
improve adherence. One found that the introduction of nurse-centred post-rape
care increased self-reported rates of adherence compared to the previous model
of care. Moreover, the patients’ understanding of therapy was also improved.
“Future research should be directed to
assess reasons for poor adherence and therefore potential interventions that
could address these issues and improve adherence to PEP,” conclude the authors.