ABSTRACT
BACKGROUND AND AIMS: Suspected latent tuberculosis infection (LTBI) is a common reason for referral to TB clinics. Interferon-gamma release assays (IGRAs) are more specific than tuberculin skin tests (TSTs) for diagnosing LTBI. The aim of this study is to determine if IGRA changes practice in the management of cases referred to a TB clinic for possible LTBI. DESIGN AND METHODS: A prospective study was performed over 29 months. All adult patients who had TST, CXR & IGRA were included. The original decision regarding TB chemoprophylaxis was made by TB team consensus, based on clinical history and TST. Cases were then analysed with the addition of IGRA to determine if this had altered management. An independent physician subsequently reviewed the cases. RESULTS: Of 204 patients studied, 68 were immunocompromised. 120 patients had positive TSTs. Of these, 36 (30%) had a positive QFT and 84 (70%) had a negative QFT. Practice changed in 78 (65%) cases with positive TST, all avoiding TB chemoprophylaxis due to QFT. Of the immunocompromised patients, 17 (25%) underwent change of practice. No cases of active TB have developed. CONCLUSION: This study demonstrates a significant change of clinical practice due to IGRA use. Our findings support the NICE 2011 recommendations.
Subject(s)
Interferon-gamma Release Tests , Latent Tuberculosis/diagnosis , Mycobacterium tuberculosis/immunology , Referral and Consultation , Tuberculin Test/methods , Adult , Antitubercular Agents/therapeutic use , Disease Progression , Drug Therapy, Combination , Female , Humans , Interferon-gamma Release Tests/methods , Isoniazid/therapeutic use , Latent Tuberculosis/immunology , Male , Practice Guidelines as Topic , Predictive Value of Tests , Prospective Studies , Reproducibility of Results , Rifampin/therapeutic use , Risk Assessment , Scotland/epidemiology , Sensitivity and SpecificityABSTRACT
AIM: The aim of our study was to determine the effectiveness of contact tracing for both pulmonary and non-pulmonary tuberculosis (TB). METHODS: The authors studied contact tracing in South East of Scotland, Edinburgh TB Clinic, UK, for 3 years. New index cases of both pulmonary and non-pulmonary TB were identified from reviewing TB nurses records. Pulmonary involvement was excluded from all non-pulmonary cases. Active TB was diagnosed as per the national TB guidelines. Latent TB was diagnosed based on history, tuberculin skin test and interferon γ release assay. TB contacts were identified from reviewing TB nurses notes on index TB patients. A positive screening episode was defined as identification of either active or latent TB in a contact following relevant investigations. RESULTS: Total number of positive screening episodes for pulmonary TB was 43.1% and non-pulmonary TB was 26.1%. Of these, 78.8% were household contacts and 21.2% were casual contacts. CONCLUSION: Contact tracing in low-prevalence TB countries, for both pulmonary and non-pulmonary TB, is an essential intervention to identify and reduce the number of infected patients that will progress to active disease. This is the key for effective TB control.
