What is the recommended treatment for latent tuberculosis infection (LTBI) in a patient with a positive Quantiferon (QFT) test and a negative chest X-ray (CXR)?

From the Guidelines

The recommended treatment for latent tuberculosis infection (LTBI) in a patient with a positive Quantiferon test and negative chest X-ray is isoniazid plus rifapentine once weekly for 3 months (12 doses total), with isoniazid dosed at 15 mg/kg (maximum 900 mg) and rifapentine dosed based on weight (900 mg for patients ≥50 kg). This regimen, known as 3HP, has been shown to be as safe and effective as other recommended LTBI regimens and achieves substantially higher treatment completion rates 1. The use of 3HP is now recommended for treatment of LTBI in adults and children aged 2–17 years, as well as in persons with HIV infection who are taking antiretroviral medications with acceptable drug-drug interactions with rifapentine 1.

Some key points to consider when treating LTBI include:

• Baseline liver function tests should be obtained before starting treatment
• Patients should be evaluated for potential drug interactions, especially with rifampin-containing regimens
• Regular monitoring for medication side effects is essential, particularly hepatotoxicity with isoniazid
• The shorter rifampin-containing regimens generally have better completion rates and fewer side effects than the traditional 9-month isoniazid regimen

Treatment of LTBI is crucial to prevent progression to active tuberculosis disease, as approximately 5-10% of individuals with LTBI will develop active TB during their lifetime if not treated, with most developing disease within the first 2-5 years after infection. The 3HP regimen offers a convenient and effective option for treating LTBI, with a shorter treatment duration and higher completion rates compared to other regimens 1.

From the FDA Drug Label

PRIFTIN is indicated in adults and children 2 years and older for the treatment of latent tuberculosis infection caused by Mycobacterium tuberculosis in patients at high risk of progression to tuberculosis disease PRIFTIN must always be used in combination with isoniazid as a 12-week once-weekly regimen for the treatment of latent tuberculosis infection Active tuberculosis disease should be ruled out before initiating treatment for latent tuberculosis infection.

The recommended treatment for latent tuberculosis infection (LTBI) in a patient with a positive Quantiferon (QFT) test and a negative chest X-ray (CXR) is rifapentine (PRIFTIN) in combination with isoniazid for 12 weeks as directly observed therapy 2.

• The dose of PRIFTIN should be determined based on the patient's weight, up to a maximum of 900 mg once weekly.
• The recommended dose of isoniazid is 15 mg/kg (rounded to the nearest 50 mg or 100 mg) up to a maximum of 900 mg once weekly for 12 weeks. Key considerations:
• Active tuberculosis disease should be ruled out before initiating treatment for LTBI.
• PRIFTIN should not be used in patients with a history of hypersensitivity to rifamycins.
• Patients on PRIFTIN should be monitored for symptoms of liver injury.

From the Research

Treatment of Latent Tuberculosis Infection (LTBI)

• The recommended treatment for LTBI in a patient with a positive Quantiferon (QFT) test and a negative chest X-ray (CXR) is isoniazid (INH) monotherapy for 9 months, as it can reduce the risk of active TB by as much as 90% if taken daily 3.
• Alternative regimens include:
  • 3 months of weekly rifapentine plus isoniazid (3HP) under direct observation, which has shown promising results in terms of tolerability and safety 4.
  • 4 months of rifampin, which has efficacy equivalent to 6 months of INH but with limited trial data on efficacy 3.
  • 3 or 4 months of INH and rifampin, which has efficacy equivalent to 6 months of INH but with increased hepatotoxicity 3.

Considerations for Treatment

• The decision to treat LTBI should consider the limitations of current diagnostic tests, the risk of developing active TB disease, and the potential adverse effects from chemoprophylactic therapy 5.
• Treatment adherence is crucial, and therapy should be offered within a plan that monitors for adverse drug reactions and emphasizes adherence 5.
• For patients with certain medical conditions, such as hepatic disease or immunodeficiency, the choice of regimen may need to be adjusted 5.

Safety and Efficacy of Treatment Regimens

• The 3HP regimen has been shown to have a favorable adverse event profile, with lower frequencies of hepatotoxicity compared to standard INH monotherapy 6.
• However, reporting of adverse events for many regimens is limited, and results should be interpreted cautiously 6.
• Further studies are needed to confirm the safety and efficacy of alternative regimens, such as the 3HP regimen, in different patient populations 4.