Interventions:
The selection of an expectant strategy as the comparator was appropriate as it represented the diagnostic strategy in the authors’ setting.
Effectiveness/benefits:
The clinical data were identified through a literature review, which is a valid approach. Some search criteria were reported, but no information was provided on the design and other characteristics of the primary sources of data. This precludes the possibility of objectively assessing the internal validity of the clinical data. The authors investigated the potential heterogeneity among the published studies, but the results of these statistical tests were not reported. Details of the assessment of utility valuations were also not reported. The instruments used to elicit preferences and the individuals (patients, general population, and health care professionals) who provided this data were not described.
Costs:
The cost categories did not reflect the perspective stated by the authors, in that they included only direct medical costs, which suggests that the viewpoint was that of the third-party payer. The authors noted that the inclusion of lost wages of haematoma patients, who received delayed surgery, would increase the costs associated with a delayed diagnosis, and would improve the cost-effectiveness of routine CT. All costs were derived from Medicare or Medicaid rates and so were not broken down into individual items. This limits the transparency and transferability of the economic analysis. The price year and the use of discounting were reported.
Analysis and results:
The costs and benefits were appropriately synthesised using an incremental approach. The expected model outcomes were reported. The issue of uncertainty was extensively addressed by means of both a deterministic and a probabilistic approach, the findings of which were presented. However, a key issue of the analysis was the large confidence intervals around the mean cost-effectiveness values, which were due to very small differences in costs and effects between the two options. The study should be considered to be specific to the authors’ setting and will not easily transfer to other settings.
Concluding remarks:
The study was well conducted, but some aspects of the analysis were not extensively reported, especially for the clinical data. Thus, the authors’ conclusions should be interpreted with some caution.