Abstract / Summary
Effective screening for Parkinson disease (PD) is important for symptom management and patient recruitment into disease-modifying trials. Here, we examined the performance of the PD-RISK Index toolkit in identifying PD patients at home without supervision. Between 2022-2024, we recruited 305 participants (ages, 40-85 years): 93 with typical PD; 66 had other neurological conditions; and 146 were healthy controls. Two versions of the toolkit were completed: An original, 69-item-long questionnaire with the 40-scent University-of-Pennsylvania-Smell-Identification-Test (UPSIT); thereafter, a simplified, 11-item-short questionnaire with a newly-developed 8-scent smell test and responses submitted online. The corresponding summary scores ('PD-RISK Indices') were calculated for each subject to evaluate diagnostic performances. In both versions, PD patients had higher questionnaire scores and worse olfaction than healthy controls (P<0.001), as expected; scores for subjects with other neurological conditions ranked at intermediate levels. The simplified 11-item questionnaire outperformed the original version in identifying PD. The abbreviated 8-scent smell test and the UPSIT booklet performed equally well in detecting hyposmia. The simplified PD-RISK Index showed the highest diagnostic performance in identifying PD patients amongst all participants; at a value of 23 (range, 0-100, where higher scores indicate higher PD risk), we measured a sensitivity of 0.98, specificity of 0.83, and positive and negative likelihood ratios of 5.88 and 0.02, respectively. The simplified 'PD-RISK Index' showed stable performance across sexes and disease duration. Our study reveals that unsupervised screening for manifest PD can be effectively carried out at home using an 11-item questionnaire, 8-scent smell test and online data entry.