S148 Should nucleic acid amplification tests be routine for sputum smear-positive pulmonary tb patients in london?

Abstract

Of the 2 000 people diagnosed with tuberculosis (TB) annually in London, 1%–2% present with multidrug-resistant (MDR) disease. Nucleic acid amplification tests (NAATs) on respiratory specimens can detect MDR more quickly than culture, but are used variably across London clinics. We aim to profile London MDR-TB patients to see how many had well-established risk factors for MDR to determine the use of targeted testing with NAATs. Information from routine surveillance of TB patients treated in London 2011–2016 (the London TB Register) was analysed. The prevalence of four known risk factors for MDR-TB (previous history of TB, social risk factors (homelessness, drug or alcohol misuse or imprisonment), contact with a known MDR case, risk of MDR in country of birth) were described among patients with pulmonary MDR-TB, by sputum smear status. Between 2011–2016, 8114 patients were notified with pulmonary TB, of whom 2916 were sputum smear-positive. Seventy-nine patients with pulmonary MDR-TB had data available for all four risk factors. Among the 45 sputum smear-positive MDR-TB patients, 53% had at least one MDR risk factor (29% had a social risk factor, 27% born in a high-MDR burden country, 21% previous TB diagnosis, and 9% contact of another MDR patient). 27% had more than one risk factor. Among the 34 sputum smear-negative MDR-TB patients, 44% had at least one risk factor (19% had a social risk factor, 21% born in a high-MDR burden country, 19% previous TB diagnosis, and 15% contact of another MDR patient). Almost half of patients in London with pulmonary sputum smear-positive MDR-TB had no obvious risk factor for MDR, so were likely to be assessed as low risk by clinicians. Performing NAATs on all pulmonary patients would identify these earlier, ensuring patients are appropriately isolated and not treated with ineffective regimens. While there is a need for a more nuanced approach to better define MDR risk, performing NAATs on all sputum smear-positive patients (450 per year) may be an approach for London clinics to consider.