The two studies that provided direct evidence are likely not generalisable to the Australian setting and the results are probably confounded; therefore, the results are unreliable.
Culture is an imperfect reference standard; thus, a large proportion of false-positive patients (i.e. NAAT-positive and culture-negative) will likely have clinical disease (see ‘Comparison of NAAT and culture, using clinical diagnosis as a reference standard’).
Economic issues
The cost of NAAT is the main driver of the incremental costs in the economic modelling. Large variations in test cost were observed across Australian pathology providers.
The cost-effectiveness of NAAT is highly sensitive to reductions in the prevalence of TB in the tested population and reductions in the specificity parameters of NAAT.
Financial issues
The population eligible for NAAT may be an overestimate, as the approach used may include patients who are ineligible for NAAT, such as those suspected of Mycobacterium leprae, patients receiving testing across multiple years for the same infection, or patients who do not have clinical signs and symptoms of a mycobacterial infection.
As NAAT is currently being used (the extent of which is uncertain), some shifting of costs from the states to the federal health budget is likely but has not been costed in the financial analyses.
