What is the recommended antiretroviral regimen for a patient co‑infected with human immunodeficiency virus (HIV) and hepatitis B virus (HBV)?

Treatment of HIV-HBV Coinfection

All patients with HIV-HBV coinfection requiring antiretroviral therapy should be treated with a regimen containing tenofovir (TDF or TAF) plus either emtricitabine or lamivudine as the NRTI backbone, combined with a third antiretroviral agent. 1

Core Treatment Principles

Mandatory Dual-Active Therapy

• Never use lamivudine or emtricitabine alone for HBV in the setting of HIV coinfection, as this creates high risk (up to 90% at 4 years) of HBV resistance and potential HIV resistance mutations. 1
• The regimen must contain two agents with anti-HBV activity (tenofovir plus lamivudine/emtricitabine) to prevent resistance development to either virus. 1, 2
• Tenofovir-based regimens are superior because tenofovir has potent anti-HBV activity with a high barrier to resistance. 1

Preferred Regimens

First-line options:

• Tenofovir alafenamide (TAF) or tenofovir disoproxil fumarate (TDF) + emtricitabine + integrase inhibitor (dolutegravir, bictegravir, or raltegravir) 1, 3
• TAF is preferred over TDF in patients with renal impairment (eGFR 30-60 mL/min) or bone disease, as TDF carries higher risk of nephrotoxicity and bone mineral density loss. 1
• Recent data confirms bictegravir/emtricitabine/TAF achieves 82% dual suppression (both HIV and HBV) at 24 weeks in coinfected patients. 3

When Tenofovir Cannot Be Used

• If tenofovir is contraindicated (severe renal disease with eGFR <30 mL/min), use entecavir for HBV in addition to a fully suppressive antiretroviral regimen for HIV. 4
• Critical caveat: Entecavir must never be used if HIV is not fully suppressed, as it can select for lamivudine- and emtricitabine-resistant HIV mutations. 1
• Adefovir 10mg daily is an alternative for HBV-only treatment in coinfection, but has lower potency. 1

Treatment Initiation Criteria

When Both HIV and HBV Need Treatment

• Start antiretroviral therapy immediately with dual-active agents (tenofovir + lamivudine/emtricitabine). 1
• Current HIV guidelines recommend HAART initiation regardless of CD4 count in coinfected patients. 1

When Only HIV Needs Treatment

• If HBV DNA >2000 IU/mL: Use dual-active regimen to prevent immune reconstitution hepatitis. 1
• If HBV DNA <2000 IU/mL without cirrhosis: May use non-HBV-active regimen but requires close HBV monitoring. 1

When Only HBV Needs Treatment (Rare)

• Pegylated interferon alfa may be considered for HBeAg-positive patients not yet requiring HIV therapy. 1, 5
• Adefovir 10mg daily (does not induce HIV resistance). 1
• Avoid lamivudine or emtricitabine monotherapy due to rapid resistance development. 6

Critical Monitoring Requirements

Viral Load Monitoring

• Measure HIV RNA and HBV DNA every 3 months initially, then every 6 months once stable/undetectable. 5
• Monitor ALT levels every 3-6 months. 7

Renal Function Surveillance

• Check eGFR, urinalysis, and proteinuria at baseline and every 6 months on tenofovir-containing regimens. 1
• TDF requires more intensive renal monitoring than TAF, especially when combined with boosted protease inhibitors. 1

Hepatic Function

• Baseline and periodic liver function tests for both medications. 2
• Monitor for hepatitis flares, particularly during treatment changes or immune reconstitution. 1

Common Pitfalls to Avoid

Regimen Changes

• Never discontinue tenofovir, lamivudine, or emtricitabine without ensuring alternative anti-HBV coverage, as this risks severe HBV reactivation and hepatitis flares. 1
• When modifying HAART regimens, always maintain agents with anti-HBV activity unless HBV treatment cessation criteria are met. 1

Resistance Prevention

• Lamivudine monotherapy leads to 90% resistance at 4 years and creates cross-resistance to other nucleoside analogues. 1
• Transmission of lamivudine-resistant HBV now occurs in up to 10% of new HBV infections in Western countries. 6
• Lamivudine resistance may select for vaccine escape mutants. 6

Drug Interactions

• Avoid combining medications with overlapping toxicity (e.g., zidovudine with tenofovir increases renal toxicity). 8
• Do not use Combivir (zidovudine/lamivudine) and Truvada (tenofovir/emtricitabine) together—this creates redundant NRTI exposure without benefit. 8

Prognostic Considerations

Impact of Coinfection on Outcomes

• HIV-HBV coinfected patients have 8 times higher mortality from liver disease compared to HIV monoinfection and 19 times higher than HBV monoinfection. 1
• Coinfection accelerates progression to cirrhosis and hepatocellular carcinoma compared to HBV alone. 1
• Appropriate dual-active antiretroviral therapy significantly improves these outcomes. 3