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 center dot 4% had scalp involvement and 35 center dot 6% had nail involvement; in 40 center dot 5% of patients, their first-degree relatives also had psoriasis. In total, 1927 (95 center dot 9%) provided complete grid data. The mean number of grids marked was 152 center dot 4 +/- 193 center dot 2, corresponding to 10 center dot 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 R-2 = 0 center dot 093), the strongest predictors of reductions in health-related quality of life (HRQoL), measured by the Dermatology Life Quality Index, were having the hands (beta = 0 center dot 147; P = 0 center dot 000), arms (beta = 0 center dot 097; P = 0 center dot 008), genitals (beta = 0 center dot 080; P = 0 center dot 010), neck (beta = -0 center dot 072; P = 0 center dot 043), scalp (beta = 0 center dot 068; P = 0 center dot 010) and nails affected (beta = 0 center dot 064; P = 0 center dot 005). Conclusions Typical psoriatic lesions are found in real-world care. However, smaller areas are important determinants of reductions in HRQoL.