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

Different phenotypes have been described in psoriasis. Few details are known about the topology of patients in routine care.

To characterize the frequency and distribution of body sites affected by psoriasis in Germany.

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.

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).

Typical psoriatic lesions are found in real-world care. However, smaller areas are important determinants of reductions in HRQoL.