Abstract
Background: Chronic diseases are a significant public health issue, yet the lack of a standardized definition leads to inconsistencies in care, legislation, and support, especially for young adults transitioning from pediatric to adult healthcare. This project funded by the Belgian Federal Public Services (FPS) Social Security aimed to address these gaps by developing a consensus-based definition of chronic disease and establishing clear age boundaries for young adults over 18 y, paving the way for more aligned healthcare and policy strategies.
Approach: A five-round Delphi consensus process was conducted between July and October 2024, utilizing the online platform ""Qualtrics."" Forty experts from 26 Belgian organizations, including patient advocacy groups, health insurers, research institutions, and universities, were invited to participate. Before taking part in each round, experts were required to verify their expertise in chronic disease and youth-related fields, as well as confirm their involvement in the earlier rounds.
The Delphi process was designed to ensure anonymity and iterative refinement of expert opinions. In the first round, participants addressed key issues such as criteria for defining chronic disease, age limits for youth, and metrics for assessing severity. The following rounds focused on refining these criteria based on consensus. A consensus scale was used: <50% indicated no consensus, 50-59% low, 60-69% moderate, and >70% high consensus. Criteria with ≥70% consensus were refined in the following rounds.
Results: The first round included 28 experts, representing policymakers, researchers, healthcare providers, and patient representatives. Key criteria for defining chronic disease were identified, with high consensus reached for factors such as disease duration (85%), multidisciplinary care (71%), the repetitive nature of the disease (75%), care needs (89%), quality of life (89%), patient experience (82%), and irreversibility (75%).
Out of 18 existing definitions, the International Classification of Diseases (ICD-10) definition achieved the highest consensus (72%) and was chosen as the basis for developing a new comprehensive definition.
The discussion on age limits for young adults with chronic diseases revealed divided opinions, with preferences leaning towards 25 years (35%) and 30 years (65%) as the upper age boundaries, although no consensus was achieved.
Implications: The Delphi process underscored the need for a standardized definition of chronic disease, with consensus on key factors like duration, care needs, and quality of life. The ICD-10 definition serves as a solid foundation. Ongoing debate about age limits for young adults points to the need for individualized approaches that consider developmental needs.
These findings can be applied to healthcare practice and policy to improve support for young people with chronic conditions. Further validation of the proposed definition is required to ensure its practical applicability in clinical and legislative settings.