Testing Shortened Versions of Smell Tests to Screen for Hyposmia in Parkinson's Disease

Background Hyposmia is an early feature in neurodegenerative diseases, most notably Parkinson's disease (PD). Using abbreviated smell tests could provide a cost-effective means for large-scale hyposmia screening. It is unclear whether short smell tests can effectively detect hyposmia in patient populations. Objectives To test the ability of short smell combinations to "prescreen" for probable hyposmia in people with PD and target administration of more extensive tests, such as the University of Pennsylvania Smell Identification Test. Methods We assessed the screening performance of a short 4-smell combination previously derived from use of the 40-item University of Pennsylvania Smell Identification Test in healthy older people and its ability to detect hyposmia in a large cohort of PD patients. Results The novel 4-smell combination included menthol, clove, onion, and orange and had a sensitivity of 87.1% (95% confidence interval, 84.9%-89.2%) and specificity of 69.7% (63.3%-75.5%) for detecting hyposmia in patients with PD. A different (also novel) 4-item combination developed using a data-driven approach in PD patients only achieved 81.3% (78.2%-84.4%) sensitivity for equivalent specificity. Conclusions A short 4-smell combination derived from a healthy population demonstrated high sensitivity to detect those with hyposmia and PD.