Development and Validation of the 9-item Parkinson’s Disease Screening Questionnaire

Objective: We aimed to develop and validate a brief, self-administered questionnaire integrating motor and prodromal non-motor symptoms for screening Parkinson's disease (PD).Methods: We conducted a three-phase study.Phase 1 used a prospectively registered systematic review of 107 studies to generate a 52-item draft.In Phase 2, the draft was refined in 205 participants (122 with early PD and 83 healthy controls) using item-level areas under the receiver operating characteristic curves (AUCs) and age-and sex-adjusted multivariable logistic regression.Phase 3 validated the 9-item Korean PD Screening Questionnaire (KPDSQ) in an independent cohort (n = 246; 122 PD, 45 essential tremor [ET], and 79 controls), and included a 4-week test-retest reassessment.Results: The final 9-item KPDSQ comprises seven motor items (rest tremor, shuffling or shortstep gait, slow daily activities, decreased arm swing, soft voice, masked face, and freezing of gait) and two non-motor items (hyposmia and dream-enactment behavior).At a cutoff of ≥2, sensitivity was 88.5% and specificity was 92.4% for distinguishing PD from controls (AUC = 0.970; 95% CI, 0.946-0.984;p < 0.001).At ≥3, the KPDSQ distinguished PD from ET (AUC = 0.774; 95% CI, 0.680-0.847;p < 0.001).Internal consistency was high (Cronbach's α = 0.800), test-retest reliability was excellent (ICC = 0.921), and scores correlated with MDS-UPDRS Part III scores in patients with PD (Spearman's ρ = 0.330; p < 0.001).Conclusions: The 9-item KPDSQ is a reliable, clinically valid screening tool combining motor and prodromal non-motor features.Prospective community-based validation is warranted.