The prevalence and etiological factors of onychomycosis in psoriatic patients

Introduction
The role of a number of inherited, acquired and environmental factors has been identified to increase the risk of onychomycosis. The literature data on psoriasis as a risk factor are contradictory. The potential relationship between these pathologies is very important as it influences the patient management.

Aim
To evaluate the frequency of onychomycosis and etiological factors in patients with psoriasis compared to controls.

Material and methods
The studied group (n = 2427) included 2325 patients with nail abnormalities raising a clinical suspicion of nail onychomycosis (with no history of psoriasis) and 102 psoriatic inpatients. The control group included 100 patients with clinically normal nails. The assessment of psoriasis severity using Nail Psoriasis Severity Index (NAPSI) and Psoriasis Area and Severity Index (PASI) was performed in all psoriatic patients. The presence of fungi was confirmed in direct microscopy and culture.

Results
A significantly higher incidence of onychomycosis was observed in psoriatic patients as well as in non-psoriatic patients with clinically abnormal nails compared to controls. The prevalence of onychomycosis did not differ significantly between psoriatic patients and non-psoriatic patients with nail alterations. The characteristics of isolated fungi differed significantly between psoriatic and non-psoriatic patients. NAPSI  40 and receiving systemic treatment increased the risk of onychomycosis in psoriatic patients.

Conclusions
The presented study showed a relatively high prevalence of onychomycosis in patients with psoriasis, what confirms the accuracy of performing screening mycological examination in this group. Further studies are warranted to evaluate the role of specific risk factors, explain the differences observed in previous studies and to determine optimal patient management.