Background Dermatophyte infections lead to high costs and differentially affect certain groups. Previous population studies have been limited in size, duration, and representativeness.
Methods Using the National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) (1995–2004), a cross-sectional analysis of ambulatory visits in the USA was performed. Outpatients presenting with International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)-coded diagnoses of tinea unguium, tinea corporis/manuum, tinea pedis, tinea capitis, and tinea cruris were identified. Trends, descriptive epidemiology, and point prevalence estimates for these conditions were determined using stratification and standardization.
Results There was an estimated average of 4,124,038 ± 202,977 annual visits for dermatophytoses during the study period. Tinea unguium, tinea corporis, tinea pedis, tinea capitis, and tinea cruris represented 23.2%, 20.4%, 18.8%, 15.0%, and 8.4%, respectively, of such infections; 71.6% of tinea unguium visits occurred among those older than 45 years. Tinea capitis was significantly more common among the black than the white population (prevalence odds ratio = 12.4; 95% confidence interval, 9.9–15.7). Ineffective treatment of tinea pedis, tinea corporis, and tinea cruris with polyenes, such as nystatin, commonly occurred.
Conclusions Improved healthcare provider education is needed to ensure judicious antidermatophyte drug management. Further studies, including proven diagnoses via fungal microscopy and culture, are needed to explain the prevalence discrepancy of tinea capitis among black children and tinea unguium in older adults, focusing on preventable risk factors.