Reliability and validity of the Korean version of the Questionnaire of Olfactory Disorders

The Questionnaire of Olfactory Disorders (QOD) is a self-report questionnaire that provides subjective information about olfactory dysfunction. The QOD is widely used in clinical practice because of its high level of reliability and efficacy in Western countries. In this study we evaluated the reliability and validity of the Korean version of the QOD.

A total of 213 patients with subjective olfactory dysfunction completed 2 different surveys (the QOD and the 36-item Short-Form Health Survey [SF-36]). Patients' olfactory function was evaluated by a screening cross-cultural smell identification test or the Korean version of the Sniffin' Sticks (KVSS) II Test. The Korean version of the QOD was evaluated for split-half reliability and internal consistency. Criterion validity of QOD was determined by comparing with the SF-36.

The split-half reliability was 0.967. Cronbach α coefficients for internal consistency of the QOD parosmia statements (QOD-P), QOD life quality statements (QOD-LQ), QOD sincerity statements (QOD-S), and QOD visual analog scale statements (QOD-VAS) were 0.705, 0.909, 0.243, and 0.953, respectively. There were statistically significant correlations between the SF-36 and the QOD-P, QOD-LQ, QOD-S, and QOD-VAS scores. There were no significant differences in QOD scores among patients with anosmia, hyposmia, and normosmia on the olfactory function test. Mean scores on the QOD-P, QOD-LQ, and QOD-VAS were significantly higher in 15 patients with normosmia on the olfactory function test when compared with 13 healthy controls.

The Korean version of the QOD has proven to be a generally reliable and valid questionnaire to assess the degree of subjective olfactory dysfunction in the evaluation of Korean patients suspected of having olfactory dysfunction.