Background: The Questionnaire of Olfactory Disorders-Negative Statements (QOD-NS) is a valuable instrument in the measurement of olfactory-specific quality of life (QOL). In the clinical setting, patients can be overwhelmed with the time required to complete questionnaires. Our objective was to develop a brief version of the QOD-NS to streamline clinical care and research.
Methods: QOD-NS scores from 221 subjects were used to determine which subset of the 17 QOD-NS questions best correlated with total and subdomain QOD-NS scores. An initial pool of 11 questions was made by removing items with ρ < 0.80 to their respective subdomain scores. Next, 500 bootstrapped samples were taken. On each sampe, an all-subsets regression was performed with total QOD-NS scores and QOD-NS subdomain scores as the outcomes. From this, our "top" and "bottom" 10 subsets were identified based on mean r2 value, representation in bootstrap analysis, and number of items.
Results: All of our top subsets had excellent correlation with total and subdomain QOD-NS scores (mean r2 > 0.90). Our top choice has 7 total questions, is representative of all subdomains, has a mean r2 = 0.92, and was represented in 323 of our 500 bootstrapped samples. The worst-performing subset has 5 items, mean r2 = 0.81, and was represented in only 1 bootstrapped sample.
Conclusions: Using less than half of the questions in the QOD-NS, excellent correlations with both total and domain-specific scores are achieved. A brief version of the QOD-NS may prove useful in future clinical and research settings.
Keywords: olfaction; quality of life; questionnaire of olfactory disorders; sinusitis; smell.
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