Privacy-Preserving Self-Registration to a Large-Scale Randomised Controlled Clinical Screening Trial in Austria.

Atrial fibrillation (AF) is the most common cardiac arrhythmia in adults and often remains undetected until a clinical sequelae such as a stroke occurs. To enable early detection, a large-scale screening trial is being established in Austria using a smartphone app. This paper outlines the process and IT infrastructure supporting participant self-registration. Citizens receive a postal invitation with a QR code linking to the registration web app, which collects eligibility data, baseline information, and informed consent. Participants are randomised to the intervention or control group, with household members assigned to the same group via address-based pseudonymisation using hashed postal data. The randomisation concept was validated on an Austrian address database. The self-registration app was successfully piloted with 120 patients in Innsbruck and Graz. The approach proved feasible and will be implemented in the nationwide trial starting in Q2 2026.