An assessment of nucleic acid amplification testing for active mycobacterial infection

Component	A Excellent	B Good	C Satisfactory
D Poor
Evidence-base^a		One or two level II studies with a low risk of bias, or an SR or several level III studies with a low risk of bias
Consistency	All studies consistent
Clinical impact				Slight or restricted
Generalisability				Population(s) studied in body of evidence differ from target population and it is hard to judge whether it is sensible to generalise to target population
Applicability				Not applicable to Australian healthcare context

^a Level of evidence determined from the NHMRC evidence hierarchy (see Table )

Source: Adapted from NHMRC (2009)

One of the studies was a high-quality multicentre RCT (conducted in South Africa, Zimbabwe, Zambia and Tanzania) with 1,502 participants, who were either assigned to AFB microscopy plus culture (n=758) or Xpert plus culture (n=744). TB-related morbidity and mortality were reported in both groups (Theron et al. 2014). The lack of AFB microscopy in the Xpert plus culture arm of the trial further limits the applicability of the findings to the proposed use of Xpert in Australia.

The second study of 477 participants was a historical control study of medium quality with some risk of bias, and was conducted in Uganda (Yoon et al. 2012). This study included consecutive hospitalised Ugandan patients with suspected TB in two phases. In the baseline phase Xpert results were not reported to clinicians, whereas in the implementation phase the results were reported. Two-month mortality was reported and compared between groups.