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**Overview**: Quantiferon-TB Gold Plus Panel**Introduction**: The Quantiferon-TB Gold Plus Panel is a diagnostic tool designed for enhanced tuberculosis screening using whole blood samples. In India, QFT-Plus improves sensitivity in immunocompromised patients (HIV, diabetes) by adding CD8 T-cell response to TB antigens, detecting LTBI with higher accuracy than QFT-Gold in high-burden settings. High morbidity from under-testing in rural/low-SES high-risk groups, limited IGRA labs, delayed preventive therapy leading to active TB. Per TB practices aligned with NTEP and ICMR guidelines, the test employs immunoassay for TB Antigen 1, TB Antigen 2, CD4/CD8 response, and interferon-gamma release over 1-2 days with high accuracy, valuable for LTBI diagnosis in vulnerable populations. This diagnostic falls under TB screening and targets contacts, HIV patients, or healthcare workers, addressing accurate detection to guide isoniazid preventive therapy. With elevated morbidity due to under-screening, the test supports public health efforts by enabling enhanced LTBI identification and reducing active TB incidence. Its whole blood-based approach ensures reliable multi-response assessment.**Other Names**: QFT Plus Pnl.**FDA Status**: FDA approved, CLIA certified for hematology/immunology, compliant with 2025 standards.**Historical Milestone**: QFT-Plus introduced 2017; in India, expanding in NTEP high-risk screening.**Purpose**: The test assesses 5 parameters including TB Antigen 1 to guide enhanced TB screening, detect LTBI, inform preventive therapy.**Test Parameters**: 1. TB Antigen 1, 2. TB Antigen 2, 3. CD4 Response, 4. CD8 Response, 5. Interferon-Gamma Release.**Pretest Condition**: No fasting required; patients should have TB exposure risk.**Specimen**: 3 mL whole blood in specialized TB tubes, transported within specified times to maintain sample viability.**Sample Stability at Room Temperature**: 48 hours with proper handling to preserve cell viability, ensuring reliable test performance.**Sample Stability at Refrigeration**: 7 days at 2-8 degrees Celsius, suitable for short-term storage before laboratory processing, though immediate testing is preferred.**Sample Stability at Frozen**: Not applicable (fresh sample preferred for IGRA).**Medical History**: Patients should provide details on TB contact, immunosuppression.**Consent**: Written informed consent is required, detailing the test's purpose, potential risks of undetected LTBI including active TB, benefits of enhanced screening, and minimal discomfort from blood draw.**Procedural Considerations**: The test involves sample processing using immunoassay by trained personnel to ensure sterile technique and interpret IFN-gamma within 1-2 days using provided controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.**Factors Affecting Result Accuracy**: Delays beyond stability periods, improper storage conditions, or severe immunosuppression can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.**Clinical Significance**: Positive response (CD4/CD8) indicates LTBI, necessitating specialist input.**Specialist Consultation**: Pulmonologists or TB specialists should be consulted for management.**Additional Supporting Tests**: Chest X-ray, TST for confirmation.**Test Limitations**: Does not distinguish active/LTBI; comprehensive approach required.**References**: Indian Journal of Tuberculosis 2024, TB Studies India 2023. |
