Validation and Agreement of the Taiwanese Versions of the Questionnaire of Olfactory Disorders–Negative Statements and Its Short Version

Olfactory dysfunction (OD) is a common sensory disorder that can substantially impair daily functioning and quality of life, yet objective psychophysical testing does not fully capture its patient-perceived burden. This prospective validation study translated and culturally adapted the Questionnaire of Olfactory Disorders–Negative Statements (QOD-NS) and its seven-item short version (svQOD-NS) into Traditional Chinese and evaluated their validity, reproducibility, and agreement. Between June 2025 and April 2026, 120 participants were enrolled at Taichung Veterans General Hospital, including 40 normosmic volunteers, 40 patients with hyposmia, and 40 with anosmia. All participants completed both questionnaires in randomized order. Normosmic participants repeated both questionnaires after at least 1 week. Olfactory function was classified using a phenyl ethyl alcohol odor detection threshold test. Mean item scores were compared across groups, and agreement was evaluated with paired comparisons, Bland–Altman analysis, and Spearman rank correlations. Both Taiwan-adapted Traditional Chinese instruments clearly discriminated participants with olfactory dysfunction from normosmic participants (p < 0.05), whereas neither instrument significantly differentiated hyposmia from anosmia. Test–retest identical mean-item-score agreement was 80.0% for QOD-NS and 92.5% for svQOD-NS; repeated administrations also showed strong positive rank correlations. No significant differences were observed between QOD-NS and svQOD-NS mean item scores in any group (p = 0.125, 0.316, and 0.930), and Spearman correlations between the instruments were 0.72, 0.87, and 0.86 for normosmia, hyposmia, and anosmia, respectively (all p < 0.001). Bland–Altman analysis showed minimal bias. The Taiwan-adapted Traditional Chinese QOD-NS and svQOD-NS demonstrated satisfactory construct validity, temporal reproducibility, and strong agreement. The svQOD-NS may therefore provide a practical lower-burden alternative for routine clinical assessment and research in Taiwanese populations.