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Adherence to ARV Therapy and Resistance

HAIVNHavard Medical School AIDS

Initiative in Vietnam

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By the end of this session, participants will be able to:Present the importance of good adherence to ARV therapyList the 5 main reasons leading to non adherenceDescribe 3 types of adherenceExplain the relationship between adherence and drug resistance

Learning Objectives

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Adherence

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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.

Definition

Common types of adherence

Howard AIDS 2002; Ickovics Antiviral Ther 2002; Moss CID 2004

Adh

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Treatment time (month)

100%

0%0 12 24

Three types of patient’s adherence

Very good adherenceReduced adherenceNon adherence

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Any activity:support, or help to improve the health of people with HIV / AIDSpay attention to the care and treatment of people with HIV, including:

• Physical health status• Mental, psychosocial well-being

Extended definition of adherence

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Maximal inhibition of viral load Reduce drug resistance Ensure effect time of drug All above helps:

• Slow progression of HIV• Prolong survival

Goals of adherence to ARV drugs

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Drug resistance

Adherence: Definition

Adherence : according to Kaufman and Le Moing, WHO

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Patients who do not improve on• clinical• immunologic and • viral outcome

after starting ART therapy are considered not to respond to treatment

Non adherence: Definition

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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

Non adherence: Causes

Drug resistance

Drug resistance is often, but not always due to non adherence

How does HIV drug resistance occur?

Resistant virus

Social/ personal issuesRegimen issue

ToxicityPoor quality drugs

Wrong doseHost genetics

Poor absorption

Rapid clearance

Poor activation

Drug interaction Transmission

Poor adherence

Insufficient drug level

Viral replication in the presence of drug

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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

How does HIV develop resistance?

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Level of drugs below the threshold of treatment

Wild-type virus

Resistant virus

Effect of non adherence to the development of viral mutations

The relationship between the level of adherence and the risk of drug

resistance

Williams & Fiedland, 1997

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% Adherence0 100

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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 resistance78% of people who have HIV treatment are resistant to at least one antiviral drug

Resistant HIV

CROSS-RESISTANCE: Resistance to a drug in a group often leads to resistance to another drug in that group!

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Drug resistant HIV can transmit: to new HIV infectionsas well as to co-infections

Risk of transmission

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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

ARV therapy failure

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Good adherence will reduce the risk of the development of ARV resistance

Drug resistance is a major problem• For individuals • For society

Why is adherence mentioned?

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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

Key points

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Thank youQuestion?