Phenotypic or genotypic susceptibility score

Several studies have now reported baseline susceptibility and responses using a phenotypic or genotypic susceptibility score (PSS or GSS). This measure assigns a numerical value to a drug based on the degree of susceptibility shown to it. It allows susceptibility to be expressed in terms of partial or full susceptibility, thus placing value on the contribution of drugs to which an individual might be partially susceptible.

An analysis of the ACTG 364 study showed that using a continuous susceptibility score rather than a binary score more accurately predicted treatment outcome for up to three years after changing treatment on the basis of a phenotypic resistance test. 1


  1. Katzenstein D et al. Phenotypic susceptibility and virological outcome in nucleoside-experienced patients receiving three or four antiretroviral drugs. AIDS 17: 821-830, 2003
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.