Prevalence, risk factors and etiologies of onychomycosis in patients with psoriasis

Psoriasis is a chronic immune mediated inflammatory disease often involving nails, presenting significant physical and psychological impacts. Onychomycosis, frequently coexists with psoriatic nail manifestations, complicating diagnosis and treatment. This study aims to evaluate the prevalence, etiology, and risk factors for onychomycosis among psoriasis patients in a tertiary public hospital in Malaysia.

A prospective cross-sectional study was conducted involving 191 psoriasis patients from October 2023 to August 2024. Nail involvement was assessed using the Nail Psoriasis Severity Index (NAPSI), and fungal diagnostics included potassium hydroxide microscopy, fungal cultures, and polymerase chain reaction. Associations between clinical variables and onychomycosis were analyzed.

The prevalence of onychomycosis was 13.6%, with dermatophytes being the most common etiological agent (69%), followed by moulds (23%) and yeasts (8%). Higher NAPSI scores were significantly associated with increased odds of onychomycosis (Adj. OR: 1.02, p=0.001). Smoking also emerged as a potential risk factor (p=0.054). Other variables, including diabetes, treatment for psoriasis and BMI, were not significantly associated with onychomycosis in this study.

Onychomycosis is prevalent among psoriasis patients, particularly those with severe nail involvement. Dermatophytes remain the primary pathogens, although moulds account for a notable proportion in this tropical setting. These findings underscore the importance of incorporating fungal diagnostics in psoriasis management to optimize outcomes and break the cycle of worsening disease.