A questionnaire study on the management of onychomycosis: a Canadian perspective

Onychomycosis of the toenails is a condition that responds poorly to griseofulvin. The introduction of terbinafine in Canada in May 1993 resulted in a marked shift in the choice of treatment for pedal onychomycosis.

A questionnaire survey was carried out in 1996 among Canadian dermatologists regarding the management of onychomycosis.

There were 160 respondents from the roughly 350 practicing dermatologists. The dermatologists saw 8 +/- 0.6 patients per week (average +/- standard error (SE) with suspected or diagnosed onychomycosis, with 5 +/- 0.5 patients per week consulting the dermatologists for the first time. Most dermatologists performed mycological testing prior to starting treatment for onychomycosis. The management options for onychomycosis (mean +/- SE) were oral systemic antifungal therapy 51 +/- 3%, no therapy 31 +/- 3%, and nondrug therapy 9 +/- 2%. The majority of dermatologists (83%) used terbinafine as first-line therapy if, indeed, they used oral antifungal agents. In contrast, griseofulvin and ketoconazole were used as first-line therapy in 5% and 1% of cases, respectively. In Canada, there are no monitoring requirements when using oral terbinafine for onychomycosis. Therefore, it is not surprising that only 30% of dermatologists performed monitoring with terbinafine. In contrast, the frequency of monitoring with griseofulvin and ketoconazole was 40% and 80%, respectively. The subset of dermatologists who reported monitoring carried it out in only a fraction of their patients: 47%, 53% and 83% for terbinafine, griseofulvin, and ketoconazole, respectively. Therefore, the overall number of patients in whom regular monitoring was performed was 14.1% 21.2%, and 71.4% for terbinafine, griseofulvin, and ketoconazole, respectively. The perceived cure rates with terbinafine and griseofulvin (mean +/- SE) were 83.7 +/- 1% and 41 +/- 3.1%, respectively.

In May 1996, within three years of the introduction of terbinafine to Canada, this agent has become the drug of choice for the treatment of pedal onychomycosis (at the time of the survey neither itraconazole or fluconazole were approved for onychomycosis). Terbinafine has been found to be very effective and safe, and only a minority of dermatologists perform regular monitoring with this drug.