(C-026) Atopic eczema and subsequent hospital-recorded diagnoses: an outcome-wide study

Background: Atopic eczema is related to adverse health outcomes. Existing work has largely focused on associations with individual outcomes, with limited work looking more comprehensively at multiple outcomes. Novel targeted therapies are currently revolutionising eczema care. To study whether these novel medications are associated with adverse outcomes, it is essential to know which outcomes are associated with eczema.

Objectives: To estimate associations between eczema and all hospital-recorded adverse health outcomes.

Methods: We harnessed UK hospital admissions data to systematically assess associations with all 2,056 category-level ICD-10 (International Classification of Diseases) morbidity codes (e.g., “J45 Asthma”, “K58 Irritable bowel syndrome“), recorded in any diagnostic position. We identified over 3 million people with eczema from primary care records (Clinical Practice Research Datalink), matched (age, sex, general practice) to over 14 million comparators without eczema. We followed participants for up to 25 years using their hospital records. We estimated associations for more than 40,000 combinations of different cohorts, outcomes, and sensitivity analyses. By mapping ICD-10 codes to Global Burden of disease (GBD) categories and phecodes, we utilised additional strategies to define diagnoses.

Results: We created excess rate profiles which allow judging the total excess of outcomes in people with eczema. For example, in childhood eczema, a third of the excess risk was for diseases of the skin and respiratory system alone. We estimated hazard ratios which can be ranked and filtered. For example, the strongest disease associations with >2000 events except skin diseases were with “J46 Status asthmaticus” [2.95, 2.79-3.13], “B00 Herpes simplex infections” [2.52, 2.38-2.67], “J30 Vasomotor and allergic rhinitis” [2.14, 2.08-2.20], “J45 Asthma” [2.12, 2.11-2.14], and “K90 Intestinal malabsorption” [1.78, 1.72-1.85].

Conclusions: In conclusion, our results give the first comprehensive overview of excess hospital diagnoses in eczema and provide a resource for generating individual association hypotheses. Together with our recently published large-scale work investigating eczema outcomes in primary care (doi: 10.1038/s41467-024-54035-1) the evidence on eczema outcomes has received a considerable update, with implications for guidelines and future research, e.g., studies on adverse effects of new medicines.