Interventions:
The selection of the comparators was appropriate because they reflected the two available approaches for the diagnosis of thyroid nodules in the authors’ setting, where UG-FNAB was usually performed after an inconclusive FNAB.
Effectiveness/benefits:
The authors did not provide any information on the methods used to select the sources of evidence. Furthermore, the characteristics of the primary studies, such as the patient samples, the study design, and the follow-up, were not described. This precludes the possibility of judging the validity of the clinical estimates. Only the sensitivity and specificity of FNAB was varied in the sensitivity analysis. The benefit measure (the number of correctly identified cases) is commonly used for diagnostic studies, but it is disease-specific and therefore difficult to compare with the benefits of other health care interventions.
Costs:
The analysis of costs was consistent with the perspective. The three main cost categories were reported as macro-data and a breakdown of cost items was not provided. This is consistent with the source used to derive these costs, but it limits the transparency of the cost estimates. The price year was not reported, which limits the possibility of making reflation exercises in other time periods. The authors acknowledged that their costs reflected those borne by a large tertiary care centre and might not be transferable to other medical centres.
Analysis and results:
The use of an incremental analysis to synthesise the costs and benefits was appropriate. The issue of uncertainty was only partially investigated as the sensitivity analyses focused on single model inputs which were varied individually. The results of both the base-case and the sensitivity analyses were clearly presented. The decision model was described. The use of a disease-specific measure for the cost-effectiveness ratio raises the question of what the value of a correctly diagnosed case is to society.
Concluding remarks:
The analysis appears to have been based on a valid methodology, although the clinical part was poorly reported. The authors’ conclusions appear to be valid.