Objective: To assess agreement between the original and revised versions of the University of Pennsylvania Smell Identification Test (UPSIT).

Background: Recently published age/sex-specific UPSIT percentiles, derived from 9,396 adults aged 50-95 recruited from 2007-2015 for the Parkinson Associated Risk Syndrome (PARS) and Parkinson’s Progression Markers Initiative (PPMI) studies [1], are strongly associated with cerebrospinal fluid α-synuclein seed amplification assay (SAA) positivity [2] and currently being used by PPMI as a screening strategy for identifying hyposmic individuals at high risk of Parkinson Disease (PD). However, these percentiles were derived from the original version of the UPSIT and may not be generalizable to a 2020 revised version that replaced multiple odorants (e.g., turpentine) with more internationally recognizable alternatives (e.g., garlic).

Method: We analyzed data from 88 healthy controls (HCs) and 27 PD participants with mean (SD; range) ages of 67.3 (5.1; 60-86) and 66.3 (8.3; 50-80), respectively, who completed both versions of the UPSIT at two US sites: Indiana University (IU) and Penn. We also compared original UPSIT raw scores among 5,336 females (mean [SD] age: 65.1 [7.7]) and 4,060 males (68.2 [7.8]) from the PARS/PPMI cohort to revised UPSIT raw scores among two newly enrolled cohorts. The latter included 2,176 females (mean [SD] age: 67.8 [5.6]) and 1,677 males (69.4 ± 6.1) recruited online (PPMI Online); and 4,745 females and 1,847 males aged ≥60 who provided smell tests at events (ST Direct).

Results: Among IU and Penn participants, paired t tests indicated significantly (P<0.0001) higher mean scores on the revised UPSIT than the original UPSIT, both among HCs (34.6 vs 32.9) and those with PD (19.9 vs 17.5). Similarly, relative to the original UPSIT mean scores of the PARS/PPMI cohort (32.7 for females; 30.2 for males), revised UPSIT mean scores were higher both for the PPMI Online (34.3; 31.9) and ST Direct (34.2; 31.6) cohorts.

Conclusion: These corroborating results from within-subject and between-cohort comparisons suggest that individuals tend to score moderately higher on the revised (relative to the original) UPSIT. Efforts are now underway to elucidate whether this pattern varies by age, sex, or olfactory ability; and to derive new percentiles for the revised UPSIT using data from PPMI Online and ST Direct.

References: [1] Brumm MC, Pierz KA, Lafontant DE, et al. Updated Percentiles for the University of Pennsylvania Smell Identification Test in Adults 50 Years of Age and Older. Neurology 2023.
[2] Siderowf A, Concha-Marambio L, Lafontant DE, et al. Assessment of heterogeneity and disease onset in the Parkinson’s Progression Markers Initiative (PPMI) cohort using the α-synuclein seed amplification assay: a cross-sectional study. 2023.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparison-of-original-and-revised-versions-of-the-university-of-pennsylvania-smell-identification-test/