UK investigators have developed an online resource that can
help doctors select the most effective combination of anti-HIV drugs for
patients with extensive experience of antiretroviral therapy. Evaluated in two
studies published in the January edition of AIDS
Patient Care and STDs, suggestions made by the tool led to doctors
changing their initial treatment decision in a third of cases. Physicians found
the resource easy to use, and the majority said that they would consider using
it in the future.
An updated version of the resource, the HIV Treatment
Response Prediction System (HIV-TRePS), is now
freely available on the internet, and is based on a computer model that
includes information gathered from 65,000 HIV-positive patients across the
Doctors enter information about their patients, including
resistance to HIV drugs, antiretroviral treatment history, CD4 cell count, and
viral load. The programme then suggests the five combinations of drugs which
are likely to be most effective.
“HIV-TRePS is an innovative and important tool to improve
the health of people with HIV”, said Dr Julio Montaner of the British Columbia
Centre for Excellence in HIV/AIDS. His clinic was involved in the development
of the resource.
There are now 25 antiretroviral drugs available and the goal
of HIV therapy is an undetectable viral load. However, many patients do not
achieve this outcome and selecting the best combination of drugs for patients
with extensive experience of therapy anti-HIV medications, especially if they
have drug resistance, can be difficult.
A group of investigators therefore came together to develop
a computer model that could accurately predict responses to antiretroviral
therapy. The UK-based researchers collaborated with HIV physicians in 15
Initial analysis showed that a programme could help doctors
make treatment decisions. But before making the models available the
investigators wished to test their “potential utility in clinical practice.”
Two studies were designed. It was intended to recruit 150
patients to a prospective study. However, only ten individuals were recruited
to the study when it was stopped early because of the introduction of three new
drugs (etravirine, maraviroc and raltegravir) that provide important options
for heavily treated patients.
The second study was retrospective and reviewed 104 cases. In both studies, doctors entered into
the model the genotypic resistance profiles of their patients, together with HIV
treatment histories, viral load and CD4 cell count.
Doctors were also asked to input the combination of drugs
they were considering for their patients.
Five treatment combinations most likely to suppress viral
load were then suggested by HIV-TRePS. The 24 physicians who participated in
the study then entered the therapy they actually prescribed, and results showed
that in a third of cases they changed their initial treatment decision after
using the programme.
In only five instances did the doctors actually use a
combination suggested by the programme. In the other 33 cases, doctors amended
the recommendation to take into account patient preference, their own judgment,
Nevertheless, after using the programme doctors were more
likely to prescribe a regimen that consisted of only three drugs.
“Review of the report led to physicians to reflect on their
treatment decisions and the final decision reached was improved as a result –
with fewer drugs and a superior predicted response,” comment the investigators.
Physicians found the programme easy to use. Most said it was “quite useful” (22%)
or “satisfactory” in making
treatment decisions, a 30% reported they would use it “often,” and 48%
“sometimes.” Only one doctor indicated that he would never use it, and this was
because the individual provided care to patients whose treatment was
“The encouraging results indicate that the system is easy to
use and has potential to provide significant benefits in terms of simplicity
and acceptability of therapy, the virologic response to that therapy and its
costs,” conclude the researchers, who believe the results warrant "further development and clinical study."
An updated version of the system has been made available,
and an experiment tool for resource limited settings tool that does not require
resistance data is being developed.