2.1. Participant Eligibility and Recruitment

We included Dutch CKD patients with LHL (n = 19) and HCPs (n = 15) from general practices and nephrology clinics, as well as educators (n = 3) and students in nursing and medicine (n = 4) from two universities and two nephrology clinics. These participated in at least one step of our study. Our recruitment started with the HCPs, educators and students. They received an e-mail about our research, which asked consent for participation. In each GP and nephrology clinic, one HCP became a contact person. This HCP supported the inclusion of additional HCPs via snowball sampling, and approached patients to include in steps 2 and 3 of the IM protocol. Patients were eligible if they (1) were adult, (2) experienced >3 months of CKD, stages 2–5, and (3) had LHL, measured with the All Aspects of Health Literacy Scale [33]. Major cognitive problems and terminal illness were reasons for exclusion. The HCPs received the eligibility criteria and a checklist, explaining signs of LHL, based on scientific evidence [34,35].

Firstly, the HCPs approached 46 eligible patients by phone or during consultations and provided them with an information letter. Secondly, the first author provided patients with further information; 19 patients were eligible and included. In steps 2 and 3, it became clear that the problems, needs and context of dialysis patients greatly differed from patients in ambulatory settings (CKD-stages 2–4). The intervention produced in step 4 was targeted towards ambulatory setting. Therefore, we excluded the eleven dialysis patients from that moment. Of the remaining eight eligible patients, four patients dropped out because of SARS-COVID-19 anxiety (n = 2), severe illness (n = 1), and losing interest (n = 1).