Investigating factors that potentially influence recruitment into secondary prevention trials and proposing strategies to increase recruitment using ischemic stroke as exemplary disease

The recruitment of patients into clinical trials is challenging and the efforts needed to enroll an sufficient amount of patients is often underestimated for various reasons. Recruitment is even more challenging in certain patient groups such as stroke patients. Stroke patients often have a mild cognitive deficit due to their disease and are overall rather old patients, which often suffer from other diseases. Trial participation might appear burdensome to these patients, while they in fact could benefit from it. Furthermore, these issues may result in only certain subgroups participating in stroke clinical trials such as rather young and healthy patients. Currently, there is especially a knowledge gap how to best care for stroke patients after they have been discharged from the hospital. Stroke patients have a high risk for another stroke and thus need increased monitoring and guidance for a healthier lifestyle. Therefore, within this thesis we firstly established a post-stroke care program based on high qualitative guidelines that we deemed suitable to guide patients into taking up a healthier lifestyle and thus reduce their risk for another stroke or similar cardiovascular event. Second, we conducted interviews with patients taking part in a post-stroke care program. We wanted to assess which parts of the trial patients understood well and which were difficult to understand. We wanted to use these re- sults to develop suggestions or strategies how understanding of a clinical trial can be improved among stroke patients. The improved understanding might then also lead to a higher willingness to take part in the trials. Third, we conducted a study comparing the characteristics of patients taking part in a post-stroke care program with a German registry, which contains general in- formation on all German stroke patients. The aim of the analysis was to investigate in which aspects the trial patients differ from the whole patient group. Again, we then developed sugges- tions how the differences can be overcome so that generalization of trial results can be improved. We successfully developed a post-stroke care trial for ischemic stroke patients with 30 par- ticipating centers in Germany. An interdisciplinary team developed a complex intervention and the study was successfully pre-tested and then conducted between Jan 2019 and Dec 2022. Within this trial, we conducted interviews with 146 patients. The overall understanding of the trial among the participating patients was estimated as sufficiently high also in comparison to similar studies. Patients had especially good understanding of their patients rights, while only 25% of the patients could state a benefit of participation and 56% knew the goal of the trial. Patients that were younger, had a higher school education and that took part in the intervention group tended to better understand the contents of the trial. Potential ways for improvement of understanding could include greater attention to groups at risk for poor comprehension and im- plementation of written materials better targeted to stroke patients. Lastly, we found that stroke patients taking part in secondary prevention trials tend to be younger, less often female and have slightly less comorbidities compared to the whole group of German stroke patients. Potentially, more individualized recruitment strategies that put greater focus on the patients’ needs as well as improved training of recruiting study personnel could help to reduce this bias. Overall, the results of this thesis contribute to the current body of knowledge about secondary prevention after stroke, recruitment difficulties and selection of stroke patients into trials. Both short-term and long-term solutions to improve these problems were suggested an include person- alized recruitment strategies, communication training for study personnel as well as provision of sufficient resources for hospitals that recruit patients into trials. Subsequently, the true effect of suggested measures should be investigated in further studies.