RT Journal Article SR Electronic T1 Nationwide epidemiological approach to identify associations between keratoconus and immune-mediated diseases JF British Journal of Ophthalmology JO Br J Ophthalmol FD BMJ Publishing Group Ltd. SP bjophthalmol-2021-318804 DO 10.1136/bjophthalmol-2021-318804 A1 Janneau L J Claessens A1 Daniel A Godefrooij A1 Gerko Vink A1 Laurence E Frank A1 Robert P L Wisse YR 2021 UL http://bjo.bmj.com/content/early/2021/04/19/bjophthalmol-2021-318804.abstract AB Background The aetiology of keratoconus (KC) remains poorly understood. KC has typically been described as a non-inflammatory disorder of the cornea. Nonetheless, there is increasing presumptive evidence for the role of the immune system in the pathogenesis of KC.Aim To evaluate the association between KC and immune-mediated diseases on a population level. We hypothesise that KC is immune-mediated rather than a predominantly degenerative disease.Methods Data were obtained from the largest health insurance provider in the Netherlands. Dutch residents are obligatorily insured. The data contained all medical claims and sociodemographic characteristics from all KC patients plus all those data from a 1:6 age-matched and sex-matched control group. The primary outcome was the association between KC and immune-mediated diseases, as assessed by conditional logistic regression.Results Based on our analysis of 2051 KC cases and 12 306 matched controls, we identified novel associations between KC and Hashimoto’s thyroiditis (OR=2.89; 95% CI: 1.41 to 5.94) and inflammatory skin conditions (OR=2.20; 95% CI: 1.37 to 3.53). We confirmed known associations between KC and atopic conditions, including allergic rash (OR=3.00; 95% CI: 1.03 to 8.79), asthma and bronchial hyperresponsiveness (OR=2.51; 95% CI: 1.63 to 3.84), and allergic rhinitis (OR=2.20; 95% CI: 1.39 to 3.49).Conclusion Keratoconus appears positively associated with multiple immune-mediated diseases, which provides a population-based argument that systemic inflammatory responses may influence its onset. The identification of these particular diseases might shed light on potential comparable pathways through which this proinflammatory state is achieved, paving the way for pharmacological treatment strategies.Data may be obtained from a third party (Achmea) and are not publicly available.