A novel 6-item screening questionnaire for Parkinsonism: validation and comparison between different instruments

BACKGROUND: Several instruments have been developed to screen Parkinson's disease (PD); yet, there is no consensus on the items, number of questions, and diagnostic accuracy. We aimed to develop a new questionnaire combining the best items with highest validity to screen parkinsonism and to compare its diagnostic value with that of the previous instruments using the same database.

METHODS: 157 patients with parkinsonism and 110 healthy controls completed a comprehensive screening questionnaire consisting of 25 items on different PD symptoms used in previous studies. To select the optimal items, clinical utility index (CUI) was calculated and those who met at least good negative utility (CUI ≥0.64) were selected. Receiver operating characteristics (ROC) curves analysis was used to compare the area under the curve (AUC) of different screening instruments.

RESULTS: Six items on 'stiffness & rigidity', 'tremor & shaking', 'troublesome buttoning', 'troublesome arm swing', 'feet stuck to floor' and 'slower daily activity' demonstrated good CUI. The new screening instrument had the largest AUC (0.977) compared to other instruments.

CONCLUSIONS: We selected a new set of six items to screen parkinsonism, which showed higher diagnostic values compared to the previously developed questionnaires. This screening instrument could be used in population-based PD surveys in poor-resource settings.