Factors associated with onychomycosis in nail psoriasis: a multicenter study in Pakistan

Treatment of psoriatic nail disease is challenging, and dystrophic psoriatic nails can get secondarily infected with fungi.

This 2-year, matched case-control study was conducted at three tertiary care centers of Karachi, Pakistan. Data were collected from patients with nail psoriasis as cases with age- and gender-matched controls. A detailed questionnaire was filled for all study participants. Nail Psoriasis Severity Index (NAPSI) scoring tool was used to assess dystrophy. Fungal infection was inferred by nail clippings for fungal hyphae and culture.

Among 477 participants, 159 cases and 318 controls completed the study. Their mean age was 44 years, and one-third were female. Fungal culture positivity was statistically significant in cases as compared to the control group (P < 0.001). The most frequent species identified was Candida parapsilosis in both cases and controls. Body mass index, NAPSI scoring, socioeconomic status, elevated diastolic blood pressure, smoking status psoriasis among first-degree relatives, and longstanding disease of more than 10 years were significant factors in univariable analysis. Multivariable logistic regression identified independent factors like low to middle socioeconomic status, history of psoriasis in first-degree relative, current smoker, and obesity.

We found nearly one-third of the psoriatic patients with nail involvement having concomitant fungal infection. We emphasize that nail clipping for fungal smear and culture should be advised to those patients with coexisting factors found significant in our study results. This opinion can be incorporated in psoriasis management guidelines for improving treatment of psoriatic nails.