How to use: interferon γ release assays for tuberculosis.

Area of Science:

• Infectious Diseases
• Immunology
• Microbiology

Background:

• Latent tuberculosis infection (LTBI) diagnosis and treatment are vital to prevent active tuberculosis (TB).
• The tuberculin skin test (TST) has historically been used but has limitations in sensitivity and specificity.
• Interferon-gamma release assays (IGRA) were developed as a more specific alternative to TST for LTBI detection.

Purpose of the Study:

• To review the current literature on the sensitivity and specificity of IGRA for LTBI diagnosis.
• To summarize NICE recommendations for using IGRA in conjunction with TST.
• To discuss the utility and limitations of IGRA in diagnosing active TB.

Main Methods:

• Literature review of current research on IGRA and TST performance.
• Analysis of diagnostic accuracy data for IGRA in LTBI and active TB.
• Summary of clinical practice guidelines and recommendations (NICE).

Main Results:

• IGRA may offer improved specificity over TST, especially in BCG-vaccinated individuals.
• IGRA's superiority to TST in children has not been established, and IGRA have their own limitations.
• Neither TST nor IGRA can distinguish between latent infection, past infection, or active TB disease.
• IGRA lack sufficient sensitivity and specificity to rule in or out active TB disease on their own.

Conclusions:

• IGRA are valuable tools for LTBI diagnosis, often used alongside TST, but limitations exist.
• Current diagnostic tests, including IGRA, cannot definitively diagnose active TB disease.
• Microbiological confirmation remains the gold standard for active TB diagnosis.