Clinical effectiveness of patient-oriented depression feedback in primary care: The empirical method of the GET.FEEDBACK.GP multicenter randomized controlled trial

GET.FEEDBACK.GP(1) is a multicenter randomized controlled trial testing the efficacy of patient-oriented depression feedback in primary care. This paper describes the complex methods and procedures of the trial. The primary outcome is depression severity six months after feedback, and we vary who is the target of the feedback as follows: no one receives feedback, only general practitioners receive feedback, and both patients and general practitioners receive feedback. The procedure includes a baseline assessment in primary care practices and three telephone follow-up interviews after one, six, and twelve months. The patients completed a baseline assessment, which determined their depression severity. Those with at least a moderate depression severity (PHQ-9(5) >= 10) were randomly allocated to three groups stratified by depression severity. A standardized mean difference of d = 0.25 with power 1 - beta = 0.80 required a total sample size of N = 699. The patients provided responses regarding the primary and secondary outcomes at follow-up. The extensive planning for GET.FEEDBACK.GP involved experts from diverse medical specialties and external corporations. Of particular importance were (a) blinding in the study inclusion and random assignment with data capture software, (b) representative and unbiased patient selection in practice waiting rooms, (c) a data management and safety plan supplied by a specialized trial center, and (d) the use of participant pseudonyms supplied by a specialized service (Mainzelliste). The data collection started in July 2019 and will continue until June 2022. Five university study centers in Germany are participating in the trial.