Exploring international classification of functioning, disability and health applicability for coding work-related disability: a study on depression and fibromyalgia in Swedish sick leave certificates

Objective: This study explores the effectiveness of using the International Classification of Functioning, Disability and Health (ICF) as a coding framework to document work-related disability information in sick leave certificates, focusing on depression and fibromyalgia in Sweden. Design: A qualitative ICF linking study was conducted, mapping information from 200 certificates per diagnosis to ICF. Methods: ICF linking rules were followed strictly. The coverage of ICF and ICF Core Sets was evaluated, proposing additional ICF categories when relevant categories were not included. Saturation of ICF categories was considered achieved if no new categories appeared in the last 5 certificates. Results: The study found high ICF coverage (85% for depression, 78% for fibromyalgia) in capturing work-related disability information. However, there was limited coverage in ICF Core Sets due to an excess of ICF categories in the Core Sets. Also, 2 additional relevant ICF categories for depression and 3 for fibromyalgia were identified. Conclusion: This study confirms that the International Classification of Functioning, Disability and Health is suitable for coding work-related disability in sick leave certificates. However, the identified limitations in ICF Core Sets highlights the need for context-specific subsets to enhance their relevance for depression and fibromyalgia in work-related disability.