A major issue with cross-comparison of NATs is the inconsistent reporting of results for detection of number of copies.
Reporting standards discussion goes here.
Generally, reporting guidelines for diagnostic accuracy studies such as STARD (Standards for Reporting Diagnostic Accuracy) was developed to improve the comprehensiveness and transparency of reporting studies of diagnostic accuracy, to enable readers to assess the potential for bias in the study, its generalisability and applicability (Cohen et al., 2015). The STARD comprises a list of 30 essential items divided into title, abstract, introduction, methods, results, discussion and other information that can be used as a checklist to ensure that a report of a diagnostic accuracy study are sufficiently informative (Cohen et al., 2015). Also, this could potentially facilitate cross-comparison of diagnostic accuracy studies using different diagnostic assays to identify the same disease.
Although the STARD criteria have reportedly been adopted by more than 200 biomedical journals and improvements in the adherence to STARD have been reported over time (Korevaar et al., 2016), none of the papers used in this literature review uses or mentions the STARD guidelines or any other guidelines. Consequentially, there are several inconsistencies in reporting of nucleic acid test applied in the detection of the causative agents of enteric fever. This is particularly prominent in information vital for cross-comparison such as sensitivity, specificity, duration of the technique, comparison to a standard test and controls.
The STARD criteria are essentially applicable to diagnostic and prognostic studies, experimental studies, observational studies and clinical trials where clinical sensitivity and specificity are the primary diagnostic accuracy statistics that is the tests being evaluated are tested on clinical samples and compared to a clinical reference standard (Cohen et al., 2015). It doesn’t take into account diagnostic accuracy studies based on analytical sensitivity and specificity where sensitivity measurements are a function of the lowest copy number of bacteria or nucleic acid detected and specificity, the ability to detect a specific pathogen out of a host of other similar pathogens respectively. … % of papers reported analytical and clinical measures of accuracy, … % reported analytical measures only, … % reported clinical measures only, and … % reported no sensitivity and specificity measures.  There is therefore a need for reporting guidelines specifically for the application of nucleic acid tests in the diagnosis of diseases. These guidelines would need to consider the minimum information required for reporting nucleic acid diagnostic accuracy studies that ensure that these studies are relevant, accurate, and repeatable.