Italian validation of the Niigata Questionnaire to assess the severity of persistent postural-perceptual dizziness

Objective. The Niigata persistent postural-perceptual dizziness (PPPD) Questionnaire (NPQ), developed by Yagi et al. in 2019, assesses the severity of PPPD. Initially available in English, it was later adapted into Spanish, German, and Indian versions. This study aimed to validate the NPQ in Italian to provide a reliable tool for assessing severity of PPPD. Materials and methods. Fifty PPPD patients (21 men, 29 women; aged 49-73) meeting diagnostic criteria were enrolled. Cross-cultural adaptation followed a standardised protocol with input from bilingual specialists and an expert committee. The questionnaire was administered during clinical evaluation and re-administered after one month, prior to treatment. Internal consistency and test-retest reliability were analysed using Cronbach's alpha and Pearson's correlation coefficients. Results. Internal consistency was excellent (alpha = 0.95). Pearson's correlation exceeded 0.80 for total, posture/gait, movement, and visual stimulation scores. Concordance for concentration was also high (0.999; 95% CI: 0.999-0.999). Conclusions. The Italian NPQ is a valid and reliable instrument for quantifying PPPD severity. It can assist clinicians in diagnosis and follow-up, supporting monitoring of disease progression and effectiveness of treatment.