Kidney Disease Improving Global Outcomes (KDIGO) has recently updated the Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (CKD). This update follows large placebo-controlled randomized trials, which established sodium-glucose cotransporter 2 inhibitors (SGLT2i) as an additional treatment option to reduce the risk of progression to kidney failure and cardiovascular disease in patients with CKD, both with and without diabetes or albuminuria. As a result, SGLT2i is now recommended to a broad range of CKD patients by KDIGO, along with established medical therapies such as renin-angiotensin system inhibition (RASi). Despite the significant adverse consequences of CKD and substantial evidence supporting guideline-directed medical therapy (GDMT) to improve patient outcomes, awareness of CKD among patients and providers remains disproportionately low. Innovative solutions are needed to increase awareness of CKD. Such a solution could potentially be the use of electronic nudge letters delivered to patients with CKD and their general practitioners (GPs) that highlight the importance of GDMT and inform them of updated guidelines.

This study will investigate whether digital nudge letters delivered via the official Danish electronic letter system directly to patients with CKD and their associated GPs will improve GDMT in patients with CKD when compared to no letters.

The study is a prospective, 2x2 factorial, registry-based, randomized, open-label implementation trial. The study population will consist of Danish adults diagnosed with CKD. Participants will be identified through Danish nationwide health registries using codes from the International Classification of Diseases, 10th revision (ICD-10).

The primary objective of this study is to investigate the effects of electronically sent nudging letters delivered directly to (1) patients with CKD and, separately, (2) electronically sent nudge letters delivered to GPs of the included CKD patients on the primary outcome of use of GDMT defined as at least one prescription of RASi or SGLT2i 6 months after intervention delivery in patients with CKD.

Patients with CKD will be randomized (1:1) to either a control arm (no digital nudge letters sent to the patient) or an intervention arm (a digital nudge letter). GPs of the enrolled patients with CKD will be randomized (1:1) to a control arm (no digital nudge letters sent to the GP) or an intervention arm (a digital nudge letter). The letters will inform the recipients about the importance of GDMT in CKD and that updated Danish guidelines for treating CKD are available. The letter to the GPs will also include the definition of CKD and a summary of the guidelines.

The interventions will be delivered through the official, mandatory Danish electronic letter system. All subject data will be retrieved from the Danish nationwide registries except for information on intervention allocation. Endpoints will be retrieved at prespecified dates using prespecified search algorithms.

This study will coincide with the release of the updated clinical guidelines on the treatment of CKD by the Danish Society of Nephrology.

Inclusion criteria

1. Age +18 years
2. Diagnosis of CKD defined as at least one hospital encounter with the following ICD-10 codes in the primary diagnostic positions within ≤ 5 years: N18- N19, I12, E102, E112, E132, E142.

Exclusion criteria

For patient-level intervention comparisons:

1) Exemption from the official, mandatory Danish electronic mailbox system.

For general practice-level intervention comparisons:

1. Individuals on a patient list of general practice clinics run by Danish administrative Regions.
2. Individuals not on a patient list of a general practice.

Data will be collected from Danish administrative health registries, which are subject to Danish legislation and can only be made available to a third party under certain conditions. Please contact the sponsor-investigator in case of any inquiries.