An assessment of nucleic acid amplification testing for active mycobacterial infection

Population
Patients with clinical signs and symptoms of active TB whose specimen is suitable for AFB microscopy and culture, and who have had < 3 days of anti-TB treatment Subpopulations for analysis: those with a high pre-test probability of active TB, e.g. come from a country with high rates of TB, versus those with a low pre-test probability of TB
Intervention	AFB microscopy plus NAAT for the detection of MTB-complex DNA ± culture NAAT for the detection of genetic mutations on the rpoB gene associated with rifampicin resistance
Comparators	AFB microscopy ± culture No NAAT for rifampicin resistance, ongoing AFB tests to determine if patient is responding to treatment
Outcomes	Time to diagnosis of TB or alternate condition, time to diagnosis of resistance, time to appropriate treatment, rate of treatment, duration of treatment, number of contacts required to be traced, number of contacts infected, rate of rifampicin resistance
Study design	Randomised trials, cohort studies, case series or systematic reviews of these study designs
Search period	1990 – May 2014 or inception of the database if later than 1990
Language	Studies in languages other than English were excluded unless they represented a higher level of evidence than that available in the English language evidence-base

Seventeen studies reporting change in management outcomes due to NAAT were identified. Eight of these studies were conducted in developing countries with a high TB-prevalence (e.g. South-Africa, Uganda, Peru) and 8 studies were conducted in low-prevalence countries (e.g. USA, UK, Canada). The remaining study was conducted in a country with an intermediate TB burden (Korea). Only two studies used in-house NAATs and the remainder used commercial NAAT, of which 12 used the Xpert NAAT. The study profiles are summarised in Table (Appendix ) and an overall summary of the body of evidence is presented in Table .

Table Body of evidence matrix for studies reporting change in management outcomes due to NAAT