Development and Psychometric Validation of the Olfactory Dysfunction Outcomes Rating.

ABSTRACT

Importance Olfactory dysfunction (OD) is an increasingly common and morbid condition, especially given the ongoing COVID-19 pandemic. Thus, the ability to reproducibly measure smell loss-associated quality of life (QOL) and its response to treatment is paramount. Objective: To develop and validate a concise and visually appealing smell loss-associated QOL patient-reported outcome measure for OD. Design, Setting, and Participants: A secondary analysis of comments to an online survey by 1000 patients with olfactory dysfunction published in 2013 was used as the primary source to generate items of the Olfactory Dysfunction Outcomes Rating (ODOR). In addition, 30 patients with OD enrolled in 2 clinical studies at a tertiary care medical center (Washington University) were asked to identify their main concerns associated with smell loss. And finally, 4 otolaryngologists reviewed the items generated from the online survey and the patients' interviews to identify any additional items. Prospective study design was used for data collection from the 30 patients and 4 otolaryngologists. Prospective study design was used for survey validation. Validation of the ODOR was performed with 283 patients enrolled in several prospective studies at a single institution that completed the ODOR as an outcome measure. Main Outcomes and Measures: Item generation and selection were the outcomes of ODOR development. The psychometric and clinimetric measures evaluated for validation were internal consistency, test-retest reliability, face and content validity, concurrent validity, and discriminant validity. Minimal clinically important difference was also determined. Results: The ODOR is a 28-item instrument with each item scored as either no difficulty or very rarely bothered (0) to complete difficulty or very frequently bothered (4) with a total instrument score range of 0 to 112 points. Higher scores indicate higher degree of dysfunction and limitation. Validation in the cohort of 283 patients (mean [SD] age, 47.0 [14.4] years; 198 female participants [73%]; 179 White participants [80%]) revealed that the instrument has high internal consistency (Cronbach α = 0.968), test-retest reliability (r = 0.90 [95% CI, 0.81-0.95]), face validity, content validity, concurrent validity (r = 0.87 [95% CI, 0.80-0.91] compared with the Questionnaire of Olfactory Disorders-Negative Statements; ρ = -0.76 [95% CI, -0.81 to -0.71] compared with a patient-reported symptom severity scale), and divergent validity (mean score difference, -33.9 [95% CI, -38.3 to -29.6] between normosmic patients and hyposmic/anosmic patients). The minimal clinically important difference was 15 points. The estimated time for survey completion was approximately 5 minutes. Conclusions and Relevance In this survey creation and validation study, the ODOR was shown to be a novel, concise, reliable, and valid patient-reported outcome measure of OD-associated QOL. It can be used to measure physical problems, functional limitations, and emotional consequences associated with OD and how they change after a given intervention, which is clinically applicable and particularly pertinent given the growing burden of OD associated with COVID-19.