New versatile version of HIV-TRePS launched

New versatile version of HIV-TRePS launched

Dear subscriber / HIV-TRePS user,

We are writing to you today to announce the release of a new, versatile version of HIV-TRePS, incorporating our latest models that predict the absolute viral load changes following the introduction of a new antiretroviral regimen, as well as some that use time on therapy to help in their predictions and others that can cope with certain missing data, e.g. a baseline CD4 counts.

The models, which were recently published in JAIDS, were developed in response to feedback from HIV-TRePS users in low and middle-income settings that use a higher definition of virological response than the 50 copies HIV RNA/ml used by our standard models. Rather than predicting the probability of the viral load falling to below this level, the new models predict the absolute viral load change over time, out to a year after the start of the new regimen. These predictions are plotted on a graph so that user can see whether the viral load is likely to go below their threshold for response, whichever one they use, e.g. 200, 400 or the 1,000-copy threshold used by the WHO. The models will be uploaded to the HIV-TRePS system shortly.

Here is the press release, which is going out later today.



New versatile version of HIV-TRePS launched

New models can be used in diverse settings with different virological response definitions and with various data available

London, UK; 02 April, 2019: A new, extra versatile version of the RDIaEUR(TM)s HIV Treatment Prediction System (HIV-TRePS) was launched today. The system uses different sets of mathematical models to predict how a patient will respond to any new combination of HIV drugs, according to the data available to the clinician at the time and the local definition of response.

"This new, versatile version of HIV-TRePS makes possible the individualisation of therapy for many more patients in many more low- and middle-income settings," commented Brendan Larder, Scientific Chair of the RDI.

The system can use previous models developed by the RDI that estimate the probability that the level of HIV in the plasma will fall below 50 copies HIV-RNA/ml in response to treatment, a stringent definition of virological response in widespread use in high-income countries. Many groups, particularly in low- and middle-income countries, use higher thresholds for response such as 200, 400 or, in the case of the World Health Organisation, 1,000 copies/ml. New models predict the absolute level of HIV over time and can therefore be used in any setting, regardless of their definition of response. These models were recently published online ahead of print in the Journal of AIDS (JAIDS).

Other new models enable HIV-TRePS to produce predictions with or without a baseline HIV genotype, with or without a baseline CD4 count and with or without the time on HIV therapy being known.

"These advances enable many more clinicians in a diverse range of situations to use the system, even when some of the baseline data are missing," commented Andrew Revell, Executive Director of the RDI. "While it cannot yet handle every combination of missing data, we are continuing to work to make the system even more 'forgiving' in the future."

Currently, in low- and middle-income countries changes to HIV treatment are not generally individualized but made according to set protocols. This can lead to sub-optimal treatments being introduced that can enable the development of drug resistance. Resistance is on the increase in such settings, which poses a threat not only to the individual but to entire populations through the increased risk of onward transmission of drug-resistant virus. This more versatile version of HIV-TRePS increases the usability for clinicians in such settings, enabling them to optimise their patients' treatment on an individual basis.

HIV-TRePS, is freely available online at

The RDI's participation in this project is through a subcontract with Leidos Biomedical Research, the prime contractor for the Frederick National Laboratory for Cancer Research, sponsored by the National Cancer Institute.

The RDI is an independent, not-for-profit international research collaboration set-up in 2002 with the mission to improve the clinical management of HIV infection through the application of bioinformatics to HIV drug resistance and treatment outcome data. Over the 14 years since its inception, the RDI has worked with many of the leading clinicians and scientists in the world to develop the world's largest database of HIV drug resistance and treatment outcome data, containing information from approximately 240,000 patients in more than 30 countries.

HIV-TRePS is an experimental system intended for research use only. The predictions of the system are not intended to replace professional medical care and attention by a qualified medical practitioner and consequently the RDI does not accept any responsibility for the selection of drugs, the patient's response to treatment or differences between the predictions and patients' responses.

For further information contact:

Andrew Revell (Executive Director, RDI) on +44 207 226 7314, +44 7967 126498 (mobile) or or visit :

Date published: 2nd April 2019


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