Nail psoriasis in Germany: epidemiology and burden of disease.

BACKGROUND Although nail psoriasis affects a marked proportion of patients with psoriasis and causes significant psychological stress, only few epidemiological data characterizing patients with nail involvement are available. OBJECTIVES To gain robust data on the epidemiology and disease burden of nail psoriasis in Germany. METHODS Two nationwide, noninterventional, cross-sectional studies on psoriasis health care were conducted in 2005 and 2007, involving 48 (2005) and 130 (2007) German office-based and clinic-based dermatological centres. Data of n=3531 patients with psoriasis were collected using standardized questionnaires and physical examinations by trained dermatologists. Patients with nail psoriasis were compared with patients without any nail involvement concerning sex, age, disease duration, family history, disease severity, presence of psoriatic arthritis (PsA), health-related quality of life (HRQoL), number of inpatient therapies, and days off work. RESULTS Nail psoriasis was diagnosed in 40·9% of the patients; prevalence was 11·2 percentage points higher in men than in women. Patients with nail involvement had a longer disease duration (21·9 vs. 18·1 years), higher disease severity (mean Psoriasis Area and Severity Index 12·7 vs. 9·3), higher frequency of PsA (26·0% vs. 12·7%), stronger impairment of HRQoL (mean Dermatology Life Quality Index 8·9 vs. 7·3), and a 2·5-fold higher rate of inpatient treatments. CONCLUSIONS Nail involvement is a relevant manifestation of psoriasis and is associated with a higher disease severity and quality of life impairment. Accordingly, management of psoriasis should include a special focus on nail involvement.