The app-based test required a mean of 142 seconds to complete and was evaluated using diagnostic performance measures, according to a diagnostic study.
A novel, self-administered, mobile application–based olfactory screening test achieved an area under the curve of 0.87, with a sensitivity of 74% and a specificity of 86% compared with a validated psychophysical comparator. Participants with self-reported olfactory dysfunction had significantly lower test scores than those with normosmia and test performance declined with increasing age.
The study enrolled 484 English-speaking adults aged 18 years or older at a tertiary academic medical center in the US between June 1 and December 31, 2024. The mean age of participants was 53.4 years, and 33% were aged 65 years or older. Overall, 15% of participants reported subjective olfactory dysfunction. Demographic data, clinical history, and self-reported smell and taste ratings were collected for all participants. All participants completed the novel olfactory test, and a randomly selected subset of 62 participants also completed the Brief Smell Identification Test, which served as the reference standard for diagnostic accuracy analyses. Scores of eight or less on the comparator test were indicative of olfactory dysfunction.
The investigational screening tool consisted of a five-item smell identification test delivered through a mobile application and paired with rub-and-sniff scent cards. Each card included a unique QR code that linked to the application and prompted participants to identify odors from multiple-choice options. Two distinct test sets were used, each containing five odorants, with automated scoring ranging from zero to five and centralized cloud-based data storage. The mean time to complete the novel test was approximately 142 seconds.
Mean novel test scores were significantly lower among participants with subjective olfactory dysfunction compared with those without dysfunction (2.54 vs 3.50). Diagnostic performance was assessed at a cut point of fewer than three correct identifications. When analyzed separately, test set A demonstrated higher sensitivity, whereas test set B demonstrated lower sensitivity and specificity with different optimal cut points. Novel test scores correlated with comparator test scores as well as with self-reported smellratings. Internal consistency across test versions was acceptable.
The investigators noted several limitations. The study was conducted at a single center, which may limit generalizability. Only a subset of participants completed the comparator test, reducing the sample size for diagnostic accuracy analyses. Differences in optimal cut points and psychometric performance indicate that the two test sets are not interchangeable. In addition, the test assessed odor identification only and did not evaluate other domains of olfactory function, such as threshold or discrimination. Reliance on smartphone technology may also limit accessibility for certain populations.
“This diagnostic study suggests that the investigated novel test is a rapid, reliable, and scalable olfactory screening tool that correlates with validated psychophysical tests,” wrote lead author Benjamin J. Bernard, MD, of the Department of Otolaryngology–Head and Neck Surgery, University of California, San Diego, La Jolla, and colleagues.
Derek Toomre, PhD, reported founding U-Smell-It LLC and holds equity and patent interests in the company; no additional disclosures were reported.