Transcript Session 4 - Teaching Slides

Adherence to ARV
Therapy and Resistance
HAIVN
Havard Medical School AIDS
Initiative in Vietnam
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Learning Objectives
By the end of this session, participants
will be able to:
 Present the importance of good
adherence to ARV therapy
 List the 5 main reasons leading to
non adherence
 Describe 3 types of adherence
 Explain the relationship between
adherence and drug resistance
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Adherence
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Definition


Adherence means taking right drugs,
in proper dose and on time
To achieve the best effect with ARV
therapy, adherence rate is required
to be above 95%
• Example: If medications are prescribed
2 times a day, don’t forget more than 2
doses a month.
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Common types of adherence
Three types of patient’s adherence
Very good
adherence
Adherence
100%
0%
Reduced
adherence
Non adherence
0
12
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Treatment time (month)
Howard AIDS 2002; Ickovics Antiviral Ther 2002; Moss CID 2004
Extended definition of adherence
Any activity:
 support, or help to improve the
health of people with HIV / AIDS
 pay attention to the care and
treatment of people with HIV,
including:
• Physical health status
• Mental, psychosocial well-being
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Goals of adherence to ARV drugs




Maximal inhibition of viral load
Reduce drug resistance
Ensure effect time of drug
All above helps:
• Slow progression of HIV
• Prolong survival
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Drug resistance
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Adherence: Definition
Clinical
status
• Improve physical health
• No more opportunistic infections
• CD4 count increases:
Immunology*
Virology
• At least from 50-150 cells in the first
year
• Increase 50-100 cells in the second
year
• Viral load is undetectable after 12
months
Adherence : according to Kaufman and Le Moing, WHO
Non adherence: Definition

Patients who do not improve on
• clinical
• immunologic and
• viral outcome
after starting ART therapy are
considered not to respond to
treatment
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Non adherence:
Causes



Resistance leads to the failure of ARV
therapy
Intolerance with ARV drugs
aggravates the disease
Drug interactions causes ARV levels
below the threshold of viral
suppression
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Drug resistance
Drug level below the
threshold of viral
suppression
Viral replication
continues with the
presence of drugs
DRUG RESISTANCE
Drug resistance is often, but not always due
to non adherence
How does HIV drug resistance
occur?
Social/ personal issues
Poor quality drugs
Wrong dose
Host genetics
Regimen issue
Toxicity
Poor adherence
Poor absorption
Insufficient drug level
Rapid clearance
Poor activation
Viral replication in
the presence of drug
Drug interaction
Resistant virus
Transmission
How does HIV develop resistance?



HIV has an extremely high rate of
replication
The new generation of virus is little
different from the previous
generation
Some structural changes can
improve the ability of viral replication
• When virus can multiply in the presence
of ARV drugs, it can be said that virus is
resistant to drugs
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Effect of non adherence to the
development of viral mutations
Level of drugs below the
threshold of treatment
Wild-type virus
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Risk of drug resistance
The relationship between the level of
adherence and the risk of drug
resistance
0
100
% Adherence
Williams & Fiedland, 1997
Resistant HIV
Some comments:
 50% of people living with HIV (not taking
into account the current status of
treatment) there is evidence for at least
one drug resistance
 78% of people who have HIV treatment
are resistant to at least one antiviral drug
CROSS-RESISTANCE: Resistance to a drug in a group often
leads to resistance to another drug in that group! 17
Risk of transmission
Drug resistant HIV can transmit:

to new HIV infections

as well as to co-infections
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ARV therapy failure


ARV therapy failure is often, but not
always, due to drug resistance
Failure of ARV therapy is expressed
by:
• Increased viral load
• Reduced CD4 count + T cells
• Progression to AIDS
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Why is adherence mentioned?


Good adherence will reduce the risk
of the development of ARV
resistance
Drug resistance is a major problem
• For individuals
• For society
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Key points
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Good adherence to ARV therapy is
necessary but very difficult
Non adherence results in low drug
concentration in the blood and allows
the development of drug resistant HIV
ARV resistance leads to treatment
failure
Transmission of drug-resistant virus
from one person to another occurs and
is a public health problem
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Thank you
Question?
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