AbstractBackground: Much research is currently devoted to polypharmacy, but interventional studies often fail to significantly improve patient-relevant outcomes or just measure surrogate parameters. Interventions and their settings are often complex, and a wide range of factors affect results. The aim of the AdAM study is to reduce hospitalization and death by requiring general practitioners (GPs) to use a computerized decision-support system (CDSS). The study will undergo a process evaluation to identify relevant factors for successful implementation and to assess whether the intervention was implemented as intended.Research questions: We will assess implementation (reach, fidelity, dose, tailoring) by asking the following questions: (1) Who took part in the intervention, i.e., the proportion of GPs that used the CDSS, and the proportion of patients that were enrolled by them? Information on the characteristics of GPs and patients will also be collected. (2) How many and what type of medication alerts were handled by the GPs? (3) Was the intervention implemented as intended? (4) On what days did GPs use the intervention tool? We will conduct subgroup analyses to all questions, including time effects to account for software improvements over time.Methods: The process evaluation is part of a stepped wedge cluster-randomized controlled trial. Characteristics of practices, GPs and patients using the CDSS will be compared with the non-participating population. CDSS log data will be analyzed to evaluate how the number of medication alerts changed between baseline and two months later and identify the kind of medication alerts that are given highest priority. The comparison of enrolled patients on weekdays vs weekends will shed light on whether GPs use the CDSS in the absence or presence of patients. All outcomes will be presented using descriptive statistics, and significance tests will be used to identify any associations between them.Discussion: This study protocol is the basis for conducting the analyses of the log data-based process evaluation. By providing insight into the way GPs conduct medication reviews, the evaluation will provide a context to the trial results and support their interpretation. The evaluation relies on the proper documentation of what the CDSS was used for, which may limit its explanatory power.Trial registration: ClinicalTrials.gov, NCT03430336. Registered on February 6, 2018. https://clinicaltrials.gov/ct2/show/NCT03430336