Cost-effectiveness analysis
Costs of both treatments were approximated using data from the DIS database of the Dutch Healthcare Authority (In this trial, all patients in the SAP group had additional DUS at 9 months’ follow-up. In practice, not all patients would actually need this additional DUS examination (that is asymptomatic patients), so an assumption had to be made regarding the percentage of patients who would actually receive an additional DUS in clinical practice. This percentage was set at 1.5 times the number of patients who received additional treatment, based on the amount of patients with persisting symptoms.The uncertainty around the estimates of the costs of the treatment was determined by means of bootstrapping and 95 per cent confidence intervals were used. The costs and effects were expressed in a cost-effectiveness plane. An intention-to treat-analysis was carried out. The CONSORT statement for non-inferiority trials was used as a guideline