• CHLAMYDIA INFECTION
• GONORRHOEA
• PELVIC INFLAMMATORY DISEASE

Chlamydia and gonorrhoea continue to be the most treatable bacterial infections in the UK, and they remain a considerable public health concern. The historical concern with point-of-care (POC) testing for chlamydia and gonorrhoea has been the reliance on tests with unacceptable levels of diagnostic accuracy. In this addition of STI, Turner and colleagues present an assessment of the possible costs and benefits of a ‘novel’ POC nucleic acid amplification test (NAAT). There is considerable appeal and logic in rapid and accurate diagnostic tests for these infections. When compared with laboratory-based tests, POC NAAT testing could reduce the delay in receiving test results to a matter of hours rather than days, meaning individuals are more likely to receive timely and appropriate treatment. Not only would this benefit the patients, it could also reduce costs and help to reduce the likelihood of onward infections.

Turner et al present a decision-model-based economic evaluation of POC NAAT technology. More specifically, they present an ‘early’ model-based economic evaluation of using POC NAAT for chlamydia and gonorrhoea in English genitourinary medicine clinics compared with current practice. The study is well performed in terms of adhering to most good practice principles for modelling/economic evaluation. Noticeably, the model includes the dynamic nature of the infection, although the overall time horizon for the evaluation is only 28 days. The results are presented in term costs, quality-adjusted life-years (QALYs) and the number of ‘over treatments’, pelvic inflammatory disease and onward infections prevented.

Taken at face value, the base case results are impressive. The authors find that NAAT POC testing reduces costs and produces more QALYs, meaning it ‘dominates’ standard non-POC pathways. Indeed, most, if not all, of the reported sensitivity analyses suggest that even under different scenarios POC NAAT remains the most cost-effective option.

However, as with most economic evaluations, the model contains a number of assumptions, some of which are clearly driving the results. To credit the authors, most of the key assumptions are transparent, and the study is wisely labelled as an ‘early’ evaluation. We highlight a number of these assumptions, but leave the reader to determine the levels of ‘plausibility’ since some could be context specific. First, in the base case analysis, it is assumed that the POC NAAT has the exact same diagnostic accuracy as laboratory NAAT techniques, yet the authors later clearly state that further evidence in the form of randomised trials is required to confirm this. Second, and understandably, assumptions are made with regard to services changes that are likely to be required to accommodate POC NAAT. Importantly, the assumption is that the average cost of POC testing will be lower than the standard testing pathway even when the increased cost of the POC NAAT test is included, although the latter is itself uncertain. Moreover, it is assumed that all POC patients are tested and receive their result and appropriate treatment on the same day, maximising the likelihood of positive economic results and potentially ignoring the fact that people might be testing for other STIs, meaning they still require a repeat clinic visit. Combining these assumptions of reduced costs, equivalent diagnostic accuracy with faster access to treatment, it is little surprise that lower costs and higher QALYs are reported in most of the scenarios. Finally, it should be noted that quality assurance costs of the POC testing and the costs of implementing pathway changes, such as staff training, have been explicitly excluded from the analysis.

So in answer to the question—is POC NAAT for chlamydia and gonorrhoea cost-effective?—the answer at the moment has to be that it is too early to know with reasonable certainty although the early signs are clearly encouraging.