Effects of a Co-Design-Based Invitation Strategy on Participation in a Preventive Health Check Program: Randomized Controlled Trial.

Background: Preventive primary care programs that aim to reduce morbidity and mortality from lifestyle-related diseases are often affected by low-to-moderate participation rates. Improving participation rates is essential for clinical effectiveness and cost-effectiveness. In 2016-2017, we conducted a pilot study (TOF pilot1) for a preventive primary care intervention (TOF is the Danish abbreviation for "Early Detection and Prevention").