Topology of psoriasis in routine care: results from high-resolution analysis of 2009 patients

Background: Different phenotypes have been described in psoriasis. Few details are known about the topology of patients in routine care. Objectives: To characterize the frequency and distribution of body sites affected by psoriasis in Germany. Methods: Data from a national cross-sectional study (PsoHealth2) were analysed. Each practice consecutively recruited 20 patients independently of treatment. Topical distribution was identified with a detailed grid scheme of 1424 squares filled by the patient. Psoriasis history, clinical findings, comorbidity and patient-reported outcomes were obtained. Results: In total, 2009 patients with psoriasis were observed. Nineteen per cent of patients had psoriatic arthritis, 65·4% had scalp involvement and 35·6% had nail involvement; in 40·5% of patients, their first-degree relatives also had psoriasis. In total, 1927 (95·9%) provided complete grid data. The mean number of grids marked was 152·4 ± 193·2, corresponding to 10·7% of body surface area. The most frequently affected body areas were the elbows, knees, lower legs and scalp (65–78%). In a linear regression analysis (corrected R² = 0·093), the strongest predictors of reductions in health-related quality of life (HRQoL), measured by the Dermatology Life Quality Index, were having the hands (β = 0·147; P = 0·000), arms (β = 0·097; P = 0·008), genitals (β = 0·080; P = 0·010), neck (β = –0·072; P = 0·043), scalp (β = 0·068; P = 0·010) and nails affected (β = 0·064; P = 0·005). Conclusions: Typical psoriatic lesions are found in real-world care. However, smaller areas are important determinants of reductions in HRQoL.