Understanding Global Access to Topical Onychomycosis Therapy: A Systematic Review and Meta-Analysis

Introduction: Equal access to medicines is crucial to ensuring public health, but access is difficult to measure, especially for infections where changes in infective species make treatment choices highly dynamic. This study investigated if the combination of infection prevalence with medicine efficacy and regulatory availability could access medicines access of topical onychomycosis medicines.

Methods: Two databases, PubMed and Web of Science, were used to identify relevant information published between 1990 and 2019. For the meta-analysis, human onychomycosis investigations using PCR analysis were included. Reviewers independently selected eligible articles, extracted data and assessed the study quality. A random-effects meta-analysis model with a Freeman-Tukey transformation was employed to the PCR data. For the meta-analysis, the global infection trends and regional differences in the infective organisms were determined.

Results: Of the 26 studies analysed, the PCR analysis in 18 studies confirmed onychomycosis in about half of the visually suspected cases (55%, CI 43%-67%). Across all 26 studies dermatophytes were the most prevalent infective organism (57%, CI 37%-76%), but a sub-group analysis showed yeasts predominated in females (31%, CI 0%-84%) (p < 0.0001), in fingernail infections (42%, CI 21%-65%) (p < 0.0001) and in arid countries (p < 0.0001). Combining these results with medicine efficacy data showed that residents from 83 of the 92 countries assessed (90%) could not access the most efficacious topical product, and 22% could not access any broad-spectrum agents. Countries in Africa had the poorest access to topical onychomycosis medicines.

Conclusion: This study identified that access to effective topical products for onychomycosis is a global problem. This issue appeared to be due to under-representation of candida infections in pivotal clinical studies of topical onychomycosis products. A head-to-head multicentre study for topical efinaconazole or a novel broad spectrum topical agent is needed to help resolve these access problems.

Protocol registration: PROSPERO-CRD42023464744.