Cumulative meta-analysis of systemic antifungal agents for the treatment of onychomycosis

BACKGROUND: Onychomycosis is a common nail disease that is often chronic, difficult to eradicate, and has a tendency to recur. The most common oral therapies for dermatophyte toenail onychomycosis include terbinafine, itraconazole and fluconazole. OBJECTIVES: A cumulative meta-analysis of the randomized controlled trials (RCTs) for antimycotic agents was performed to determine whether the pooled estimate of the cure rates has remained consistent over the years. Furthermore, for each agent we compared the overall meta-analytical average of both mycological and clinical response rates of RCTs vs. open studies. METHODS: We searched MEDLINE (1966 to November 2002) for relevant studies evaluating the efficacy of the oral antifungal agents terbinafine, itraconazole (pulse or continuous), fluconazole and griseofulvin for treating dermatophyte toenail onychomycosis. Studies included in this meta-analysis required a standard accepted dosage regimen, treatment duration and follow-up period. To determine the cumulative meta-analytical average, studies were sequentially pooled by adding one study at a time according to the date of publication (i.e. earliest to the most recent). RESULTS: There were 36 studies included in the analyses. For RCTs the change in efficacy of mycological cure rates from the first trial to the overall cumulative meta-average for each drug comparator is as follows (with 95% confidence interval): terbinafine, 78 +/- 6% (n = 2 studies, 79 patients) to 76 +/- 3% (n = 18 studies, 993 patients) (P = 0.68); itraconazole pulse, 75 +/- 10% (n = 1 study, 20 patients) to 63 +/- 7% (n = 6 studies, 318 patients) (P = 0.25); itraconazole continuous, 63 +/- 5% (n = 1 study, 84 patients) to 59 +/- 5% (n = 7 studies, 1131 patients) (P = 0.47); fluconazole, 53 +/- 6% (n = 1 study, 72 patients) to 48 +/- 5% (n = 3 studies, 131 patients) (P = 0.50); and griseofulvin, 55 +/- 8% (n = 2 studies, 109 patients) to 60 +/- 6% (n = 3 studies, 167 patients) (P = 0.41). The cumulative meta-analytical average of mycological cure rates when comparing RCTs vs. open studies was: terbinafine, 76 +/- 3% (n = 18 studies, 993 patients) vs. 83 +/- 12% (n = 2 studies, 391 patients) (P = 0.0028); itraconazole pulse, 63 +/- 7% (n = 6 studies, 318 patients) vs. 84 +/- 9% (n = 3 studies, 194 patients) (P = 0.0001); and fluconazole, 48 +/- 5% (n = 3 studies, 131 patients) vs. 79 +/- 3% (n = 3 studies, 208 patients) (P = 0.0001). CONCLUSIONS: The cumulative meta-analysis of cure rates for RCTs suggests that over time, as new RCTs have been conducted, the efficacy rates have remained consistent. The efficacy rates of open studies are substantially higher compared with RCTs and may therefore overestimate cure rates.