of HIV therapy in British Columbia has been accompanied by a 42% reduction in
HIV incidence and 80% reductions in the incidence of both AIDS and HIV-related
mortality, investigators report in PLOS
“Our results show
that HAART [highly active antiretroviral therapy] expansion in BC [British
Columbia] between 1996 and 2012 was strongly and statistically significantly
associated with sustained population-level decreases in HIV/AIDS related
morbidity and mortality, as well as concomitant decreases in new HIV diagnoses,
and estimated HIV incidence,” comment the investigators. “Expansion of HAART
coverage was also associated with increased adherence rates, increased rates of
viral suppression, and decreased rates of HIV resistance.”
improvements in antiretroviral treatment, most people living with HIV in
resource-rich settings now have a normal or near-normal life expectancy. HIV therapy also has public health benefits,
as treatment that suppresses viral load to undetectable levels is associated
with a near-zero risk of transmission to sexual partners.
therefore been calls for the scale-up of antiretroviral therapy, with the use
of HIV treatment as prevention.
Data collected in
British Columbia, Canada, are capable of providing real-world population-level
evidence of the effectiveness and sustainability of such a strategy.
information collected by province-wide registries between 1996 and 2012 to
examine trends in the use of HIV therapy, viral load, CD4 cell count, the
incidence of AIDS and HIV-related mortality, the annual number of new HIV
diagnoses and HIV incidence.
HIV prevalence in
the province increased from 7900 cases in January 1996 to 11,972 cases in
January 2012, a statistically significant 52% increase (p < 0.001). Over the
same period, the number of people taking potent HIV therapy increased from
837 to 6772 (709%; p < 0.001). The estimated proportion of HIV-positive
patients taking treatment therefore increased from 11 to 57% (p = 0.0004) during
the study period.
There were 253
AIDS deaths in 1996 and 59 AIDS deaths in 2011. The HIV-related mortality rate
fell from 6.5 to 1.3 per 100,000 during 1996-2011 – an 80% decrease (p =
0.0115). The rate of AIDS diagnoses fell from 6.9 to 1.4 per 100,000 – also
representing an 80% decrease (p = 0.0330).
Baseline CD4 cell
count at the initiation of HIV therapy increased from a median of 270 cells/mm3
to 380 cells/mm3 (p < 0.001). The proportion of patients with
optimal levels of adherence (95% and above) increased from 37% in 1996 to 71%
by 2012 (p = 0.032).
copies/ml as the cut-off, the proportion of treated patients with virological
suppression increased from 8 to 74% between 1996 and 2012 (p < 0.001). When the more stringent value of 50 copies/ml
was used, the proportion of people with suppressed viral load increased from 6 to 59% (p
The prevalence of
drug resistance decreased during the study period from 85 to 31% (p <
There was a steady
decrease in the number of new HIV diagnoses, from 702 cases in 1996 to 238
cases in 2012, a significant 66% reduction (p = 0.004).
HIV incidence fell
from an estimated 632 cases per year to 368 cases per year, a 42% fall (p =
individuals on HIV therapy decreased HIV incidence by an estimated 1.2% and
each 1% increase in the proportion of treated patients with viral suppression
decreased HIV incidence by 1%.
support the long-term population-level effectiveness and sustainability of the
treatment as prevention strategy,” comment the authors. “It is reassuring to
note that evidence in support of a population-based impact of treatment on the
prevention of HIV transmission continues to emerge in diverse global settings.
Such effects have been described in Taiwan, and more recently in Vancouver,
Baltimore, San Francisco, China and KwaZulu-Natal.”