Purpose To analyze the psychometric properties of the Niigata Questionnaire (NPQ) for use in a European population with persistent postural-perceptual dizziness (PPPD). Methods Observational study included 140 patients with different vestibular conditions. Construct validity, internal consistency and concurrent validity were analyzed. Intra-class correlation coefficient (ICC), standard error of measurement (SEM) and minimal detectable change (MDC) were calculated. Receiver operating characteristic (ROC) curve was used to test diagnostic values. Results Of the 140 patients, 47 had a diagnosis of PPPD. Factorial analysis showed a single-factor structure and concurrent validity analysis showed strong correlations with other instruments. Cronbach alpha coefficients of 0.938 for the total score, 0.869 for the standing and gait subscale, 0.803 for the subscale of movements and 0.852 for the visual stimulation subscale were obtained. The reproducibility was substantial except for the standing subscale, which could be considered moderate. For the standing, movement and visual stimulation subscales and for the total score, the SEM was 3.27, 2.41, 2.50 and 6.63, respectively, and the MDC was 6.40, 4.72, 4.91 and 12.99, respectively. The NPQ total score showed an area under the curve (AUC) of 0.661, a sensitivity of 72.34 and a specificity of 55.91 for discriminating between PPPD and other vestibular disorders. Conclusions The NPQ is feasible for use in a Western population and presents a uni-factorial structure, high internal consistency and strong correlation with other instruments. The reliability can be considered substantial. The NPQ has low accuracy in discriminating between subjects with or without PPPD.

BackgroundThis study aimed to analyze the psychometric properties of the Activities-specific Balance Confidence Scale Short Version (ABC-6) in vestibular patients.MethodsThe sample consisted of 87 subjects aged over 18 years with vestibular pathology. Construct validity, internal consistency, test-retest reliability, concurrent validity, and capacity to discriminate between subjects with or without risk of falling as measured with the ABC-16 standard version were analyzed.ResultsThe ABC-6 showed a unifactorial structure. Cronbach's alpha was 0.873. The reliability was moderate for each of the items and substantial for the total score (intraclass correlation coefficient = 0.778). The standard error of measurement was 10.24, with a minimum detectable change of 20.07. The ABC-6 version showed a strong correlation with physical and functional measures, moderate correlation with emotional measures, and poor correlation with the Physical Component Summary of SF-12 and retrospective 12-month falls. A cutoff point ≤55 showed a sensitivity = 94.44% and a specificity = 92.75% in differentiating between patients with or without risk of falling measured with the ABC-16 standard version, with an area under the curve = 0.975.ConclusionsThe ABC-6 showed acceptable psychometric properties for measuring balance confidence and risk of falling in vestibular patients.