HIV Treatment Failure and Second-Line ART
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Direct answer
HIV treatment failure is persistent viral replication despite antiretroviral therapy, and virological failure means a viral load above 1,000 copies per mL on two measurements at least three months apart, after adherence support. A single high result never justifies a switch. Once confirmed, failure is usually managed with a second-line regimen, most often a ritonavir-boosted protease inhibitor with two nucleoside analogues, guided by resistance testing.
What you must remember
- Virological failure: Viral load above 1,000 copies per mL on two measurements at least three months apart, obtained after adherence support.
- Immunological failure: CD4 count falls back to the pre-treatment baseline, drops by half from its peak, or stays persistently below 100 cells per microlitre.
- Clinical failure: A new or recurrent WHO stage 4 event, or a new stage 3 event, arising after at least six months on ART, with tuberculosis usually excluded from this definition.
- Monitoring schedule: Viral load about six months after starting ART, then at least yearly, since viral load is more sensitive than CD4 for detecting drug failure.
- Second-line choice: A ritonavir-boosted protease inhibitor, such as lopinavir/ritonavir, with two nucleoside reverse transcriptase inhibitors.
- Resistance testing: Genotypic assays, where available, identify NRTI, NNRTI, protease and integrase mutations and guide the switch.
- Adherence first: Enhanced adherence counselling and a repeat viral load after about three months come before any regimen change for a single high result.
A stepwise response to suspected failure
A 35-year-old on tenofovir, lamivudine and efavirenz for 14 months has a viral load of 4,500 copies per mL. The result is not yet failure, and the response is built around confirming it, fixing the cause and only then switching.
- Confirm the failure: Repeat the viral load after adherence support, since a single result above 1,000 copies per mL is not yet virological failure.
- Strengthen adherence: Assess missed doses, stigma, food effects and interacting drugs, and give enhanced counselling for about three months before retesting.
- Exclude a drug cause: Check for interacting drugs, notably rifampicin in a patient with TB, because rifampicin sharply lowers protease inhibitor levels.
- Send for resistance testing: Genotypic testing identifies the mutations that limit future drug choices, and results shape the new regimen.
- Choose the second-line regimen: Switch to a ritonavir-boosted protease inhibitor with two NRTIs, adjusted to resistance results and drugs available in the programme.
- Monitor the response: Repeat the viral load about three months after the switch, expecting renewed suppression, and escalate the work-up if it persists.
Where the exam tries to catch you
Examiners test whether the candidate waits for confirmation and recognises the interactions that make second-line ART work or fail.
- Trap: Switching regimens on a single high viral load. Correct: Adherence support and a repeat viral load come first, because a transient result may reflect missed doses rather than failure.
- Trap: Using CD4 count alone to diagnose virological failure. Correct: Viral load detects virological failure, while CD4 trends signal immunological failure, which is less sensitive.
- Trap: Continuing a boosted protease inhibitor unchanged during rifampicin treatment. Correct: Rifampicin lowers protease inhibitor levels sharply, so the combination needs a specialist-approved adjustment of either the ART or the TB drugs.
- Trap: Calling a clinical event ART failure without checking the viral load. Correct: An opportunistic infection can occur in a suppressed patient, so virological failure must be shown by viral load.
Frequently asked questions
What viral load defines virological failure in HIV?
Virological failure in HIV is a viral load above 1,000 copies per mL on two measurements taken at least three months apart, after adherence support. A single high result does not define virological failure in HIV treatment.
Which second-line ART regimen is usually used after first-line failure in HIV?
Second-line ART is usually a ritonavir-boosted protease inhibitor, such as lopinavir/ritonavir, combined with two nucleoside reverse transcriptase inhibitors. The exact combination follows resistance testing and the drugs available in the national programme.
Why does rifampicin complicate second-line ART in HIV-TB coinfection?
Rifampicin is a strong enzyme inducer that sharply lowers protease inhibitor levels, so a boosted protease inhibitor cannot be given alongside it without adjustment. The TB treatment and ART plan must be coordinated by a clinician familiar with this interaction.
What is immunological failure in HIV treatment?
Immunological failure in HIV is a CD4 count that falls back to the pre-treatment baseline, drops by half from its peak, or stays persistently below 100 cells per microlitre on ART. It signals inadequate immune recovery and is less sensitive than viral load for detecting drug failure.