P213 Are respiratory samples useful for the diagnosis of pulmonary tuberculosis in the absence of chest X-ray abnormalities?. (December 2018)

• Record Type: Journal Article
• Authors: Barrett, JC; Brown, A; Morgan, C; Coughlan, C; Subbarao, S; Abbara, A; John, L; Martin, L; Lynn, W; Russell, G; Kon, OM
• Is Part Of: Thorax. Volume 73(2018)Supplement 4
• Page Start: A216
• Page End: A217
• Publication Date: 2018-12
• Subjects: Chest -- Diseases -- Periodicals; Thorax; Chest -- Diseases; Periodicals; Periodicals; 617.54
• DOI: 10.1136/thorax-2018-212555.370
• Languages: English
• ISSNs: 0040-6376

Abstract

Abstract : Introduction: An abnormal chest x-ray is considered by the World Health Organisation to have a 'high sensitivity for pulmonary tuberculosis' and thus is widely relied upon to screen for active disease. 1 National Institute for Clinical Excellence recommends using chest x-ray (CXR) findings to determine which microbiological samples to collect, which may risk missing smear or culture-positive patients with normal imaging. 2 Here we assess the yield of respiratory samples for pulmonary TB patients with a normal CXR at diagnosis, and describe the characteristics of culture-positive, normal CXR patients Methods: Health records of all patients entered into the London TB Register for 6 hospitals between 2011 and 2016 with a diagnosis of pulmonary or intra-thoracic nodal tuberculosis were reviewed retrospectively. Patients with a normal CXR and no subsequent abnormal CXR within 6 weeks of starting TB therapy were identified, and radiological and microbiological findings reviewed. Duplicates and denotified patients were excluded. CT abnormalities included tree-in-bud (11%), consolidation or nodules (46%), cavitation (10%), lymphadenopathy (30%) and pleural effusion (4%). 45% had more than one abnormality. There was no significant difference in median age or biochemical markers (ESR, CRP, albumin, vitamin D) at diagnosis between the culture-positive and culture-negative groups. 7 culture-negative patients were HIV-positive, compared with 1 culture-positive patient. Discussion: 43% of patients with a normal CXR had respiratory samples which were culture positive for Mycobacterium tuberculosis (M.Tb) ; as such, we demonstrate the value of obtaining respiratory samples in patients with a suspected diagnosis of pulmonary TB, even when the CXR is normal. Yield of smear on all types of sample was low (4%–5%), however around one third of samples obtained via spontaneous, induced sputum, or BAL, were culture positive. While CT imaging usually supported the diagnosis, 3 patients in our cohort were found to be culture-positive on sputum samples despite normal CT imaging. M.Tb culture yield of respiratory samples was lower for patients diagnosed with intra-thoracic nodal TB, however few samples were sent. References: Chest Radiography in Tuberculosis Detection. Summary of current WHO recommendations and guidance on programmatic approaches 2016.http://www.who.int/tb/publications/chest-radiography/en/ Diagnosing and Managing Active Tuberculosis. NICE guidance 2016. https://www.nice.org.uk/guidance/ng33/chapter/Recommendations#active-tb