Clinical characteristics, symptoms and burden of psoriasis and atopic dermatitis in adults

Summary Background There is debate as to whether psoriasis and atopic dermatitis (AD) belong to the same disease spectrum. Objectives To describe and compare disease characteristics, lifestyle factors and disease burden in adult patients with psoriasis and AD. Methods We linked registry data with clinical and patient‐reported outcomes from the Danish Skin Cohort, containing 3348 and 3834 adults with dermatologist‐verified psoriasis or AD respectively, and 2946 adults from the general population. Results The participants were predominantly women and middle‐aged. Patients with psoriasis mostly reported disease onset throughout adulthood, but with a distinct early incidence peak in those with a positive family history or severe disease. AD predominantly began in childhood, with only a very discrete incidence peak in adulthood. Scalp, extremity, chest and abdomen involvement was common to both diseases. Scalp/hairline, elbows, nails, intergluteal cleft, umbilicus, knees and legs were most frequently affected in patients with psoriasis. In AD, periocular, neck, antecubital fossae, back of the hands, interdigital areas and popliteal fossae were commonly affected. Patients with psoriasis (but not AD) were generally more overweight, obese and physically inactive, and had a positive smoking history, compared with the general population. Patients with both diseases experienced more frequent flares with increasing disease severity. Patients generally displayed uncontrolled disease despite being on systemic therapies. Itch and skin pain were much more severe in patients with AD, whereas joint pain was more common in patients with psoriasis. Conclusions We identified important similarities and differences in the clinical characteristics of adults with psoriasis and AD; these should help clinicians to prioritize and improve patient management. What's already known about this topic? Psoriasis and atopic dermatitis in adults are increasingly being compared, and there is discussion as to whether they are part of the same disease spectrum. What does this study add? In this comparative study, patient‐reported disease burden was markedly higher in atopic dermatitis than in psoriasis, whereas lifestyle‐associated cardiometabolic risk factors were more frequent in psoriasis. In both disease groups, the condition in the majority of patients was uncontrolled even while they were on systemic therapy. The contrasting presentations highlight that these diseases are two distinct and