Interventions:
The rationale for the selection of the comparators was clear as the proposed intervention was compared with the usual diagnostic approach, which was overnight polysomnography in a sleep laboratory and this was considered to be the gold standard for patients with suspected sleep apnoea or hypopnoea syndrome.
Effectiveness/benefits:
The clinical analysis was based on a single group of patients who underwent both diagnostic techniques and so these patients acted as their own controls. The consecutive enrolment of patients, with a random order for the two procedures, should limit potential selection bias. To reduce assessment bias, the assessors were blinded to the technique performed. Extensive statistical tests were used to assess the significance of differences between the two procedures. The instrument used to evaluate the clinical impact of the two procedures was appropriate. Two potential limitations were that no justification was given for the study sample size and patients were enrolled from a single institution, which might not have been representative of other patient populations.
Costs:
The economic viewpoint was not explicitly stated, but appears, from the categories of costs and their sources, to have been that of the hospital. Some key information on the resource quantities and costs was provided, but the price year was not clearly reported, which limits the possibility of replicating the analysis in other time periods. The costs were treated deterministically and no statistical tests were carried out. The authors stated that the purchase cost of the devices was not included because this was difficult to calculate for instruments that were used for several years. The costs of disposable items were not considered, as they were similar for the two procedures.
Analysis and results:
The results were clearly presented and illustrated. A cost-consequences analysis was carried out and this might limit the possibility of comparing these results with those from other studies, given the lack of a summary benefit measure and a formal cost-effectiveness ratio. The issue of uncertainty was not addressed and sensitivity analyses were not carried out. The authors stated that their results should be considered to be specific to their institution and were not transferable to other contexts.
Concluding remarks:
The study was generally well conducted, but the analysis focused mainly on the clinical and diagnostic features of the two strategies. The authors’ conclusions appear to be valid for the specific context.