Optimizing invitation letters for national cancer screening programs: Qualitative usability testing.

Objectives: Participation in the Netherlands' three national cancer screening programs (breast, cervical, colorectal) is generally declining, especially among underserved populations. This study aimed to improve the official invitation letters distributed to eligible individuals by the National Health Screening Organization, in collaboration with the National Institute for Public Health and the Environment, thereby supporting informed decision-making about participation in the national screening programs. Two revised invitation letters were developed based on recommendation derived from previous research, aimed at improving design and communication. Methods: Usability testing was conducted among 27 Dutch adults (aged 30-75): approximately two-thirds of whom had a lower level of education, lower socioeconomic status, or a migration background. Participants reviewed the two revised invitation letters either online or in person and provided feedback through semi-structured interviews and using the think-aloud method. Responses were qualitatively analyzed, using the framework method, cluster analysis and mind mapping, to identify and structure key themes. Results: Participants found the revised letters clearer, more concise, and better structured than the original letters. Bolded key information and accessible contact details were appreciated and evaluated as means to ease access and comprehension. Icons generally did not improve the understandability of the letters and were considered unnecessary. Additionally, participants suggested adopting a more personal tone and adding information about the benefits of screening. Conclusion: Our findings show that co-creating revised screening invitation letters with end users improves clarity and accessibility, supporting informed decision-making and more inclusive public health communication. Innovation: This research is innovative by co-creating cancer screening invitation letters with end-users, especially those among underserved groups, and led to several participant-driven improvements which will be adopted in the national population-based cancer screening program.