Screening performance of abbreviated versions of the UPSIT smell test

Abstract

Background Hyposmia can develop with age and in neurodegenerative conditions, including Parkinson’s disease (PD). The University of Pennsylvania Smell Identification Test (UPSIT) is a 40-item smell test widely used for assessing hyposmia. However, in a number of situations, such as identifying hyposmic individuals in large populations, shorter tests are preferable. Methods We assessed the ability of shorter UPSIT subsets to detect hyposmia in 891 healthy participants from the PREDICT-PD study. Shorter subsets included Versions A and B of the 4-item Pocket Smell Test (PST) and 12-item Brief Smell Identification Test (BSIT). Using a data-driven approach, we evaluated screening performances of 23,231,378 combinations of 1–7 smell items from the full UPSIT to derive “winning” subsets, and validated findings separately in another 191 healthy individuals. We then compared discriminatory UPSIT smells between PREDICT-PD participants and 40 PD patients, and assessed the performance of “winning” subsets containing discriminatory smells in PD patients. Results PST Versions A and B achieved sensitivity/specificity of 76.8%/64.9% and 86.6%/45.9%, respectively, while BSIT Versions A and B achieved 83.1%/79.5% and 96.5%/51.8%. From the data-driven analysis, 2 “winning” 7-item subsets surpassed the screening performance of 12-item BSITs (validation sensitivity/specificity of 88.2%/85.4% and 100%/53.5%), while a “winning” 4-item subset had higher sensitivity than PST-A, -B, and even BSIT-A (validation sensitivity 91.2%). Interestingly, several discriminatory smells featured within “winning” subsets, and demonstrated high-screening performances for identifying hyposmic PD patients. Conclusion Using abbreviated smell tests could provide a cost-effective means of large-scale hyposmia screening, allowing more targeted UPSIT administration in general and PD-related settings. Electronic supplementary material The online version of this article (10.1007/s00415-019-09340-x) contains supplementary material, which is available to authorized users.

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

“…The performance of 5 smells (menthol, clove, onion, gingerbread, and orange) achieved a balance between brevity and high performance for identifying people with hyposmia against the full 40-item UPSIT (sensitivity 94.1%) in the PREDICT-PD pilot cohort's healthy participants (n = 891 for discovery and 191 for validation, as described previously 8 ).…”

“…Positive and negative screens for hyposmia were compared with hyposmia defined by performance on the full 40-item test using the same age-specific and gender-specific thresholds described previously. 8…”

“…7 We previously identified short smell combinations derived from the 40-item UPSIT that could be cost-effective for large-scale hyposmia screening before targeted administration of the UPSIT. 8 That work was conducted in the healthy general population recruited to the PREDICT-PD cohort study and was compared with only a small sample of patients with PD. Here we tested the screening performance of several short smell combinations in the Tracking Parkinson's study that includes data from 1222 people with PD.…”

Maximising information on smell, quantitative motor impairment and probable REM-sleep behaviour disorder in the prediction of Parkinson’s disease

“…We further examined the results of a 6-item smell test which was based on the four odours that discriminated most between those with and without hyposmia from previous work, plus a further two odours that most discriminated between PD and controls (menthol, clove, orange, onion, coconut and cherry). 13,19 For the BRAIN test, results for the worst of KS and AT scores from each hand were adjusted by performing a median regression of scores against age and gender among controls, then either subtracting (for KS) or dividing (for AT) all participants' scores by the expected score from the regression equations. Fits of adjusted BRAIN test scores to Gaussian distributions were assessed by inspection of probability plots.…”

The sniffing bead system: an olfactory dysfunction screening tool for geriatric subjects: A prospective cross-sectional study

“…If the ability to discriminate or identify an odour is diminished, an impairment of the central nervous system may be suspected, whereas isolated threshold de cits may suggest peripheral damage [18]. A marked decrease in the olfactory identi cation scores was apparent in subjects with dementia, and a loss of odour identi cation has been proposed as a predictive marker of the conversion from mild cognitive impairment to AD [9,20].…”