Factor analysis of the questionnaire of olfactory disorders in patients with chronic rhinosinusitis.

Background: Olfactory‐specific quality of life (QOL) can be measured using the Questionnaire of Olfactory Disorders–Negative Statements (QOD‐NS), which examines various aspects of olfactory dysfunction. It is unknown if certain factors of the QOD‐NS differentially impact QOL. Methods: Patients with chronic rhinosinusitis (CRS) completed the QOD‐NS, 22‐item Sino‐Nasal Outcome Test (SNOT‐22), Medical Outcomes Study Short Form 6‐D (SF‐6D) health utility measure, and Patient Health Questionnaire‐2 (PHQ‐2) depression screen. Exploratory factor analysis of the QOD‐NS was performed. Associations between QOD‐NS factors and other QOL metrics were analyzed before and after endoscopic sinus surgery (ESS). Results: Outcomes were examined on 132 patients. The QOD‐NS contains 4 distinct factors. There was no difference in associations between the different factors and baseline clinical characteristics. ESS had greatest effect size (d) on factors 2 and 4 (d = 0.29 and 0.27, respectively, p < 0.05). Postsurgical changes in the SF‐6D and SNOT‐22 had the strongest correlation with factor 2 scores (r = 0.29 and 0.34, respectively, p < 0.05), and changes in the PHQ‐2 had the strongest correlation to factor 3 (r = 0.24, p < 0.05). Abnormal QOD‐NS scores at baseline were associated with effect size increases of 50% to 100% (p < 0.05). Conclusion: The QOD‐NS measures 4 distinct factors. Eating‐related questions had the greatest improvement after ESS. Health utility and CRS‐specific QOL improvement most strongly associated with factor 2, while PHQ‐2 changes are most highly associated with factor 3, suggesting a differential impact of the factors of the QOD‐NS on varying aspects of QOL. [ABSTRACT FROM AUTHOR]