Validation of a questionnaire assessing smell loss in an international aspirin-exacerbated respiratory disease population.

Background: Olfactory dysfunction (OD) and smell loss affects aspects of patients' everyday life and lowers their quality of life. OD questionnaires are considered one of the core-outcome measures in chronic rhinosinusitis, but many existing smell loss questionnaires contained pandemic-prohibitive questions on social gatherings or restaurant visits, were too culture specific or gender specific, or were overly long and cumbersome. Objective: We aimed to develop a new brief questionnaire to assess the impact and consequences of smell loss and its burden on daily life. This study validates this new, short, multicultural, dichotomized questionnaire in an international population that has aspirin-exacerbated disease (AERD). Methods: The Consequences of Smell Loss (COSL) questionnaire was developed and content validity was assessed by experts and patients at Brigham and Women's Hospital. The questionnaire, along with other validated quality-of-life surveys, was answered by 853 patients with AERD. We evaluated the factor structure, reliability, validity, and discriminative ability of the COSL questionnaire. Results: The final version of the COSL questionnaire consisted of 13 items divided into three subdomains (emotional distress, food and safety, and physical health) through factor analysis. The Cronbach α for internal consistency was 0.82. Convergent and discriminant validity with the 22-item Sinonasal Outcome Test (SNOT-22), Healthy Days Core Module-4, Patient Health Questionnaire-4, and a specific question on taste and smell were high ( p < 0.0001 for all). The COSL questionnaire score was associated with SNOT-22 categories ( p < 0.001) and was categorized as follows: normal, 0-1 points; very few consequences, 2-3 points; few, 4 points; moderate, 5-6 points; and severe, 7-13 points. Conclusion: The COSL questionnaire is a new, brief, valid, reliable tool that can effectively screen for a high burden of OD in patients with AERD and has the potential to be used in other patient populations with OD as well.