RESUMO
Onychomycosis is a common nail disorder associated with pain, discomfort and varying degrees of physical impairment and loss of dexterity. Psychological and social limitations result from reactions of others to visible impairment. The goal of this research is to validate a questionnaire to measure the impact of toenail onychomycosis on health-related quality of life (HRQoL). One hundred and fifty onychomycosis patients were enrolled in an observational study at eight sites in the US. Attending physicians reported information on clinical status at enrolment. Patients completed a questionnaire covering HRQoL that included general and disease-specific items measuring the impact of onychomycosis on activities and appearance, plus problems and symptoms associated with toenail infection. The subscales of the instrument showed high internal consistency reliability (range = 0.63-0.95). Construct validity reflected the close association of physical functioning scores with onychomycosis impairment. Test-Retest reliability was good to excellent for all scales (ICC = 0.52-0.89). Discriminant validity was evidenced by persons who are younger and female reporting worse disease-specific HRQoL. Responsiveness to clinical change was noted for all disease-specific scale scores for improved patients. This instrument has demonstrated reliability, validity and responsiveness for use in observational and clinical studies of toenail onychomycosis patients. Data indicate that onychomycosis patients report significant pain and discomfort reflecting the need for HRQoL measurement.