Page 31 - Nursing Matters June 2021 Vol 12

current issues

to the ART regimen that the patient Figure 1 – Suggested timing of viral load testing for patients on ART.
is taking
3. The drug levels in the patient are
too low, as a result of something like Baseline If VL > 100 000 copies/mL, then
being prescribed an incorrect dose, RPV is contraindicated.
or a drug-drug interaction (such as
rifampicin’s effect on dolutegravir).
If not virally suppressed, then should
decrease;
In practice though, it can be very difficult 3 months provide adherence counselling.
10
to tease these possibilities apart. They
are also not mutually exclusive, since
non-adherence or low drug levels VL > 50 copies/mL
can lead to the development of drug 6 months
resistance.

VL < 50 copies/mL
V
How do you interpret a high
viral load? VL > 50 copies/mL
• Adherence counselling
12 months • Repeat VL in 2–3 months
It is important to realise that the
interpretation of a high viral load V
VL < 50 copies/mL
depends on the regimen the patient is
on. Non-nuclear reverse transcriptase Every VL > 50 copies/mL
inhibitors (NNRTIs) are notoriously 6–12 months

brittle, and early resistance is common
on these regimens. By contrast, protease VL < 50 copies/mL
V
inhibitors (PIs) tend to have a far higher
barrier to resistance, and are far more
forgiving of episodes of non-adherence. • There must not be any pre-existing This applies for both first- and second-
Thus, a patient should generally not be DTG resistance mutations (e.g. from line regimens (again, this assumes the
assumed to have significant resistance to having previously virological failure criteria in the previous section have been
PIs unless they have been on a PI-based on a raltegravir-based regimen). fulfilled).
regimen for more than 1-2 years.
Provided that none of the above are By contrast, since NNRTI-based regimens
A high viral load in a patient on met, it is not recommended to perform are so much less robust, resistance
dolutegravir (DTG) requires yet another resistance testing for patients on a testing is in theory more useful at an
paradigm to interpret. Because DTG has DTG-based regimen within 2 years of earlier stage. However, a resistance test
shown itself to be so robust in first and commencing it. Furthermore, patients at the point of failure of first line therapy
second-line regimens, patients on a DTG- should not be switched off a DTG is not routinely recommended, since
based regimen who have a high viral containing regime without a resistance an effective second-line regimen can
load should generally not be assumed to test documenting DTG resistance. generally be constructed without the
have resistance. Rather, non-adherence need for resistance testing.
is almost always the cause. Importantly When should a resistance test be
though, a number of other factors need ordered?
to be checked for this assumption to
hold, namely: A critical limitation of resistance testing References
• The patient’s regimen must contain is that they are generally only successful 1. Tucker JD, Bien CH, Easterbrook PJ, Doherty MC, Penazzato M,
Vitoria M, et al. Optimal strategies for monitoring response to
at least one other fully active when the patient’s viral load is >500 antiretroviral therapy in HIV-infected adults, adolescents, children
and pregnant women: a systematic review. AIDS. 2014;28
nucleoside/nucleotide (NRTI) drug copies/mL. Beyond this, knowing when Suppl 2:S151-60.
as part of its backbone. to order a resistance test also depends 2. Cohen CJ, Molina JM, Cassetti I, Chetchotisakd P, Lazzarin
A, Orkin C, et al. Week 96 efficacy and safety of rilpivirine in
• There must not be any concerns on the particular ART regimen the treatment-naive, HIV-1 patients in two Phase III randomized trials.
AIDS. 2013;27(6):939-50.
for suboptimal DTG levels as a patient is on. For patients on a DTG- or 3. Hermans LE, Carmona S, Nijhuis M, Tempelman HA, Richman
DD, Moorhouse M, et al. Virological suppression and clinical
result of drug-drug interactions (e.g. PI-based regimen, resistance testing is management in response to viremia in South African HIV
treatment program: A multicenter cohort study. PLoS Med.
rifampicin has been given but the only recommended when the viral load 2020;17(2):e1003037.
4. Nel J, Dlamini S, Meintjes G, Burton R, Black JM, Davies N,
DTG was accidentally not given is elevated for more than 2 years after et al. Southern African HIV Clinicians Society guidelines for
antiretroviral therapy in adults: 2020 update. South Afr J HIV
12-hourly to compensate for this) the regimen has been commenced. Med. 2020;21(1):1115.
HIV Nursing Matters | June 2021 | page 29