A cost-minimization analysis of an RCT of three retention methods.

BACKGROUND: There are few cost evaluation studies of orthodontic retention treatment. The aim of this study was to compare the costs in a randomized controlled trial of three retention methods during 2 years of retention treatment. MATERIALS/METHODS: To determine which alternative has the lower cost, a cost-minimization analysis (CMA) was undertaken, based on that the outcome of the treatment alternatives was equivalent. The study comprised 75 patients in 3 groups consisting of 25 each. The first group had a vacuum-formed retainer (VFR) in the maxilla and a cuspid retainer in the mandible (group V-CTC), the second group had a VFR in the maxilla combined with stripping of the incisors and cuspids in the mandible (group V-S), and the third group had a prefabricated positioner (group P). Direct cost (premises, staff salaries, material and laboratory costs) and indirect costs (loss of time at school) were calculated. Societal costs were defined as the sum of direct and indirect costs. RESULTS: The societal costs/patient for scheduled appointments for 2 years of retention treatment in group V-CTC were euro497, group V-S euro451 and group P euro420. Societal costs for unscheduled appointments in group V-CTC were euro807 and in group V-S euro303. In group P, there were no unscheduled appointments. CONCLUSIONS/IMPLICATIONS: After 2 years of retention in compliant patients, the cuspid retainer was the least cost-effective retention appliance. The CMA showed that for a clinically similar result, there were differences in societal costs, but treatment decisions should always be performed on an individual basis.