Impact of rapid molecular diagnostic tests on time to treatment initiation and outcomes in patients with multidrug-resistant TB, Tamil Nadu, India.

Dina, N.; Gangadevi, N.P .; Tripathy, J.P.; Harries, A.D.; Klinton. J.S.; Watson. B.; Gomathi. N.S.; Reddy. D.S.; Lakshmi, M.; Mohan, N.; Swaminathan, S.

Transactions of the Royal Society of Tropical Medicine and Hygiene; 2016; 110; 534-541.

Background: India is replacing culture and drug sensitivity testing (CDST) with rapid molecular tests for diagnosing multidrug-resistant TB (MDR-TB). We assessed the impact of rapid tests on time to initiation of treatment and outcomes in patients with MDR-TB compared with CDST.

Methods: A retrospective cohort study involving MDR-TB patients from six districts in Tamil Nadu state, who underwent CDST (2010–2011) and rapid tests (2012–2013).

Results: There were 135 patients in the CDST group and 389 in the rapid diagnostic test group. Median time from sputum receipt at the laboratory to initiation of MDR-TB treatment was 130 days (IQR 75–213) in the CDST group and 22 days (IQR 14–38) in the rapid diagnostic test group (p<0.001). Overall treatment success was 30% with CDST and 41% with rapid tests (p<0.05), but there was high loss to follow-up >30% in both groups and missing data were higher in CDST (13%) compared with rapid tests (3%). There were significantly higher risks of unfavourable treatment outcomes in males (aRR 1.3, 95% CI 1.1–1.5) and those with treatment initiation delays >30 days (aRR 1.3, 95% CI 1.0–1.6).

Conclusion: Rapid molecular diagnostic tests shortened the time to initiate treatment which was associated with reduced unfavourable outcomes in MDR-TB patients. This supports the policy to scale up these tests in India .

Keywords: India ; Line probe assay; Multidrug-resistant tuberculosis; Rapid molecular tests; Treatment outcomes; Xpert MTB/RIF

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