Prognostic factors of mycological cure following treatment of onychomycosis with oral antifungal agents.

BACKGROUND There is considerable literature on the efficacy and safety of various drugs used in treating onychomycosis; however, little information is available regarding prognostic factors which may be associated with non-response to conventional treatment. OBJECTIVES To identify parameters influencing mycological cure at 72 weeks following treatment of toenail onychomycosis with oral antifungal agents. METHODS Univariate and multivariate logistic regression analysis from a randomized double-blind controlled trial including 496 patients with toenail onychomycosis caused by dermatophytes. RESULTS Baseline parameters including patient's age, gender, weight, number of toenails involved, percentage of nail involvement, duration of infection, history of previous treatment were not associated with mycological cure. In the multivariate prognostic factor analysis based on factors assessed at week 12, positive mycological culture at 12 weeks [odds ratio (OR): 0.583; 95% confidence interval (CI): 0.370-0.918] was negatively associated with mycological cure at 72 weeks. Similarly, in the multivariate prognostic factor analysis based on factors assessed at week 24, positive direct microscopy at 24 weeks (OR: 0.373; 95% CI: 0.211-0.659) and mycological culture at 24 weeks (OR: 0.293; 95% CI: 0.168-0.513) were negatively associated with mycological cure at 72 weeks. CONCLUSIONS Mycological culture at 12 and 24 weeks and direct microscopic examination at 24 weeks can help in early identification of patients failing to respond to conventional oral antifungal treatment.