The MTB/RIF test is a rapid nucleic acid amplification test for TB. In a rollout in developing countries on 6,648 patients, the test was 90% sensitive for active TB, vs. 67% for smear microscopy (sputum culture was the gold standard). In smear-negative, culture-positive TB, the test was 77% sensitive and 99% specific. It also accurately detects rifampin resistance. Lancet 2011;377:1495-1505.