The prevalence of onychomycosis in patients with psoriasis and other skin diseases.

Onychomycosis among psoriasis patients is reported with varying prevalence. This prospective, controlled study investigates the occurrence of onychomycosis among inpatients with psoriasis versus inpatients with other skin diseases. The inclusion period was 15 months. Scrapings from clinically abnormal nails (both fingernails and toenails) were examined using microscopy and culture. The prevalence of onychomycosis in patients with psoriasis was 17/79 = 21.5% compared to 18/142 = 12.7% for patients with other skin diseases (p = 0.13). In 17 mycologically positive psoriasis patients, dermatophytes, yeasts and moulds were isolated in 8, 10 and 4 cases, respectively, and in 18 mycologically positive patients with other skin diseases in 12, 7 and 5, respectively. Onychomycosis occurred more frequently in men than in women (psoriasis patients (p = 0.02), patients with other skin diseases (p = 0.03)). Psoriasis patients had a higher frequency of abnormal nails (82.3%) compared to patients with other skin diseases (37.3%) (p < 0.01) and more severe affection of their toenails than patients with other skin diseases (p < 0.01). It is concluded that the frequency of onychomycosis among inpatients with psoriasis compared to inpatients with other skin diseases is not significantly different.