From the Guidelines
A 15-year-old with a positive Interferon-Gamma Release Assay (IGRA) should be treated for latent tuberculosis infection (LTBI) to reduce the risk of progression to active TB disease. The recommended treatment options include isoniazid 10-15 mg/kg daily (maximum 300 mg) for 9 months, or alternatively, rifampin 10-20 mg/kg daily (maximum 600 mg) for 4 months, as outlined in the 2015 World Health Organization guidelines for low tuberculosis burden countries 1. Another option is a 3-month regimen of once-weekly isoniazid plus rifapentine, which has been shown to be safe and effective in adolescents aged 2-17 years, according to the 2018 update of recommendations for use of once-weekly isoniazid-rifapentine regimen to treat latent mycobacterium tuberculosis infection 1. Before starting treatment, active TB disease must be ruled out through a thorough clinical evaluation, chest X-ray, and possibly sputum tests. Some key points to consider when treating LTBI in adolescents include:
- Baseline liver function tests should be obtained, and the patient should be monitored monthly for side effects, particularly hepatotoxicity, as recommended by the World Health Organization guidelines 1.
- Adolescents are at lower risk for isoniazid-related hepatotoxicity compared to adults but still require monitoring.
- Treatment is important because adolescents have a higher risk of progression from latent to active TB compared to adults, and treating LTBI significantly reduces this risk by approximately 60-90% 1.
- Adherence counseling and directly observed therapy may be considered to ensure treatment completion, as emphasized in the 2018 update of recommendations for use of once-weekly isoniazid-rifapentine regimen to treat latent mycobacterium tuberculosis infection 1.
From the FDA Drug Label
Isoniazid is recommended as preventive therapy for the following groups, regardless of age. ... Candidates for preventive therapy who have HIV infection should have a minimum of 12 months of therapy. ... All infants and children younger than 4 years of age with a > 10 mm skin test are included in this category. ... Children who are less than 4 years old are candidates for isoniazid preventive therapy if they have > 10 mm induration from a PPD Mantoux tuberculin skin test ... persons under the age of 35 with a tuberculin skin test reaction of 10 mm or more are also appropriate candidates for preventive therapy
The 15-year-old patient has a positive Interferon-Gamma Release Assay (IGRA), which is indicative of latent tuberculosis infection. Although the label does not explicitly mention IGRA results, it does discuss tuberculin skin test reactions. Latent tuberculosis infection treatment is recommended for individuals with a positive skin test reaction, and since the patient is under 35, they may be a candidate for preventive therapy. However, the label does not provide a direct correlation between IGRA results and treatment. Given the patient's age and positive IGRA result, preventive therapy may be considered, but the decision should be made on an individual basis, taking into account the patient's overall health and risk factors 2.
From the Research
Treatment of Latent Tuberculosis Infection
- A 15-year-old with a positive Interferon-Gamma Release Assay (IGRA) can be treated for latent tuberculosis infection, as IGRA is used to diagnose latent TB infection 3, 4, 5.
- The treatment of latent TB infection is based on the positive IGRA result, and the goal is to prevent the development of active TB disease 3, 6.
- Studies have shown that preventive chemotherapy can effectively reduce the risk of TB development in IGRA-positive individuals, including children and adolescents 3, 6.
IGRA Results and Treatment
- A positive IGRA result indicates that the individual has been infected with Mycobacterium tuberculosis, and treatment is recommended to prevent the development of active TB disease 3, 4, 5.
- The treatment of latent TB infection typically involves the use of isoniazid prophylaxis, which has been shown to be effective in reducing the risk of TB development in IGRA-positive individuals 3, 6.
- The number of patients needed to be treated to prevent one case of TB disease varies, but studies have reported numbers ranging from 22 to 38 3, 6.
Age and IGRA Results
- IGRA can be used to diagnose latent TB infection in children and adolescents, including those as young as 3 months old 4, 5.
- Studies have reported good agreement between positive IGRA results and active TB disease in children, suggesting that IGRA is a sensitive diagnostic tool in this population 4, 5.
- However, the interpretation of IGRA results in children should take into account the potential for cross-reactivity with BCG vaccination or non-tuberculous mycobacterial disease 4, 5.