Xpert MTB/RIF Test in the Diagnosis of Pulmonary Tuberculosis

Xpert MTB/RIF Test as the Initial Diagnostic Test in the Diagnosis of Pulmonary Tuberculosis: a Pragmatic Trial

Currently in Taiwan, most clinicians use sputum smear and culture for the diagnosis of pulmonary tuberculosis (TB) and apply nucleic acid amplification (NAA) test in a selected manner. In 2013, the World Health Organization issued conditional recommendation that Xpert MTB/RIF may be used rather than conventional microscopy and culture as the initial diagnostic test in all adults suspected of having TB. The newly published Taiwan guidelines for TB diagnosis and treatment has recommended NAA test, together with smear and culture, as the initial diagnostic test in individuals suspected of having TB. The investigators conduct a prospective study to investigate the use of Xpert MTB/RIF as the initial diagnostic test of pulmonary TB under a pragmatic trial design.

In this study the investigators will respect current practice in the use of NAA in the diagnosis of pulmonary TB. Clinicians may have ordered NAA as the initial diagnostic test in adults suspected of having pulmonary TB (group A, Immediate NAA by clinician), and the investigators will not intervene. For patients who do not have NAA as the initial diagnostic test, the investigators will use random permuted blocks to randomize these participants into two groups. One group will have immediate Xpert test (intervention group) as the initial diagnostic test and another group will continue usual care without immediate Xpert test (control group).

Group A (Immediate NAA by clinician): NAA as the initial diagnostic test for pulmonary TB requested by clinicians.

Group B (Immediate NAA as intervention): NAA as the initial diagnostic test for pulmonary TB not requested by clinicians, but is performed as intervention in this study (intervention group).

Group C (No immediate NAA): NAA as the initial diagnostic test for pulmonary TB not requested by clinicians, and is not performed as the initial diagnostic test in this study (control group). NAA may be ordered at a later point in time by clinicians as an add-on test after sputum smear microscopy.

The investigators will assess pulmonary TB cases detected in all groups regarding

1. The interval between sputum examinations and initiation of ant-TB treatment.
2. The proportion of culture confirmed pulmonary TB among all pulmonary TB cases notified.
3. The proportion of TB patients who are advised to stop anti-TB treatment before completion of a treatment course.
4. Outcome of tuberculosis treatment, including patients who die before anti-TB treatment.

Among patients with NAA as the initial diagnostic test (Group A and Group B), the investigators will investigate

1. Performance (sensitivity, specificity and predictive values) of NAA in the diagnosis of culture positive pulmonary TB.
2. The incremental yield of the second and third smear in patients who have both NAA test and smear microscopy as the initial diagnostic test, aiming to determine the contribution of the second and third smear in the diagnosis of pulmonary TB.
3. The proportion of NAA positive cases who were culture negative.

Inclusion Criteria:

• All presumptive tuberculosis cases who have sputum examinations for the diagnosis of pulmonary TB

Exclusion Criteria:

• Tuberculosis cases who have been on treatment for 14 or more days who have sputum examinations for follow-up