How often does oral treatment of toenail onychomycosis produce a disease-free nail? An analysis of published data.

OBJECTIVE To analyze studies on oral treatment of toenail onychomycosis so as to aid clinicians and patients in making informed decisions. DATA SOURCES Studies dealing with treatment of toenail onychomycosis were identified by means of 2 MEDLINE search strategies. One was a title search using the word "toenail"; the other search used the combined Medical Subject Headings "onychomycosis" and "therapy". STUDY SELECTION Articles were read to ascertain that they (1) described results in toenails, (2) used both culture and microscopy, and (3) included a clinical evaluation. Not included were case reports, series of fewer than 15 subjects, reports that combined fingernail onychomycosis and toenail onychomycosis in their statistics, and articles reporting only the total number of toenails cured without providing data as to how many subjects were cured. DATA EXTRACTION This elimination process left 26 articles, which were then analyzed by means of a checklist that included a morphologically normal nail, mycological findings, and methodological items including recurrence rate, intent-to-treat analysis, placebo group, and whether terms were defined. DATA SYNTHESIS When there was sufficient data, the frequency with which the treatment achieved normal mycological results, a clinically normal nail, and a disease-free nail (normal-appearing nail plus normal mycological results) was calculated. Confidence intervals were calculated for disease-free nail results. CONCLUSIONS Standard courses of terbinafine achieved a disease-free nail in approximately 35% to 50% of patients. For itraconazole, the relevant disease-free nail rate was about 25% to 40%. Disease reappearance is an important issue; unfortunately data are lacking as to its frequency.