Effect of Disease Severity on Comorbid Conditions in Atopic Dermatitis: Nationwide Registry-Based Investigation in Finnish Adults

The majority of registry studies on atopic dermatitis include only patients and diagnoses from specialized healthcare. The aim of this retrospective, real-world cohort study was to evaluate the effect of atopic dermatitis severity on comorbidities and total morbidity, with comprehensive data from both primary and spe-cialty healthcare registries covering the entire Finnish adult population. In total, 124,038 patients were iden-tified (median age 46 years; 68% female) and strati-fied by disease severity. All regression analyses (me-dian follow-up 7.0 years) were adjusted at a minimum for age, sex, obesity, and educational level. Compared with mild atopic dermatitis, severe atopic dermatitis was significantly associated with multiple morbidities, including neurotic, stress-related and somatoform di-sorders, abscesses, erysipelas/cellulitis, impetigo, herpes zoster, extragenital herpes, bacterial conjun-ctivitis, septicaemia, lymphomas, alopecia areata, ur-ticaria, other dermatitis, contact allergy, osteoporosis, and intervertebral disc disorders (p < 0.001). In addi-tion, there were significant associations with alcohol dependence, depression, condylomas, rosacea, migrai-ne, sleep apnoea, hypertension, enthesopathies, athe-rosclerosis, and drug-induced cataract (p < 0.05). Odds ratios were modest and mostly were between 1.10 and 2.75. Furthermore, patients with severe atopic dermatitis had lower incidences of prostate cancer, cystitis, and anogenital herpes than patients with mild atopic dermatitis (p < 0.05). These results suggest that severe atopic dermatitis results in significant overall mor-bidity.