Data Sheet 1_Convergent construct validity and test-retest reliability of both German versions of the original and the revised Niigata PPPD Questionnaire: NPQ and NPQ-R.pdf

BackgroundPersistent Postural-Perceptual Dizziness (PPPD) is a frequent chronic functional disorder that manifests with dizziness, unsteadiness, or non-spinning vertigo present for at least 3 months. Characteristic provocation factors are moving or complex visual stimuli and exclusion of organic diseases. To assess the severity and impact of PPPD, Japanese researchers developed the Niigata PPPD Questionnaire (NPQ). The study's aim was to evaluate the concurrent construct validity and reliability [including test-retest reliability, internal consistency, standard error of measurement (SEM), and minimal detectable change (MDC)] of the German version of the NPQ (12 items) and its revised version, NPQ-R, which contains 19 items addressing additional symptoms and symptom behavior.
MethodsThe Swiss Reha Rheinfelden and the German Center for Vertigo and Balance Disorders included 265 PPPD patients (mean age 50.2 ± 16.8 years, disease duration 46.3 ± 76.6 months). Patients completed the NPQ and the NPQ-R (twice), the DHI and potentially related constructs: anxiety (ABC-Scale, VSS), depression (HADS), and general health (SF-36) once. To assess the questionnaires' reliability and validity, several statistical measures were calculated, including Spearman's rank correlation coefficients, Intraclass Correlation Coefficients (ICC2, 1), Cronbach's alpha, SEM, and MDC.
ResultsOn average, patients scored 29.9 ± 13.2 for NPQ and 52.3 ± 19.6 for NPQ-R. Correlations between NPQ/NPQ-R and (1) disease-specific questionnaires were rs= 0.712 and rs= 0.752 (DHI), rs=0.426 and rs= 0.0.462 (VSS-V), rs= -0.500 and rs= -0.545 (ABC-Scale), (2) anxiety-specific subscales rs = 0.394 and rs = 0.430 (VSS-A) and rs= 0.354 and rs= 0.430 (HADS-A), (3) depression-related subscales rs=0.438 and rs= 0.487 (HADS-D), and (4) general health rs ranged between rs= -0.216 and −0.578 (all SF-36 subscales). Internal consistency, test-retest reliability, SEM and MDC calculated for NPQ/NPQ-R were α = 0.88/α = 0.91, ICC=0.83 (CI 0.77 to 0.0.87), SEM 5.55/8.37, and MDC 15/23 points.
ConclusionThe German versions of NPQ and NPQ-R are valid and reliable patient-reported outcome measures for assessing PPPD, demonstrating satisfactory psychometric measurement properties including convergent construct validity and reliability parameters: internal consistency, test-retest reliability, SEM, and MDC as an evaluative measure. The NPQ-R, with its additional subscales addressing associated symptoms and symptom behavior, represents both the patient and clinician perspective on PPPD-specific problems. Therefore, we recommend utilizing the NPQ-R for a comprehensive assessment of PPPD.

背景
持续性姿势-感知性头晕（Persistent Postural-Perceptual Dizziness, PPPD）是一种常见的慢性功能性眩晕障碍，以持续至少3个月的头晕、不稳感或非旋转性眩晕为主要临床表现。其典型诱发因素为运动性或复杂性视觉刺激，且需排除器质性疾病。为评估PPPD的严重程度与疾病影响，日本研究者开发了新潟PPPD问卷（Niigata PPPD Questionnaire, NPQ）。本研究旨在评估12条目原版德国版NPQ及其修订版NPQ-R的同时建构效度与信度（包括重测信度、内部一致性、测量标准误（standard error of measurement, SEM）及最小可检测变化（minimal detectable change, MDC））；其中NPQ-R包含19个条目，用于评估额外症状及症状行为表现。
方法
瑞士赖因费尔德康复中心（Swiss Reha Rheinfelden）与德国眩晕与平衡障碍中心纳入了265名PPPD患者（平均年龄50.2±16.8岁，病程46.3±76.6个月）。患者需完成NPQ、NPQ-R（共两次）以及眩晕残障量表（Dizziness Handicap Inventory, DHI），并一次性填写与疾病潜在相关的评估工具：焦虑评估采用ABC量表（ABC-Scale）与视觉眩晕量表（Visual Vertigo Scale, VSS），抑郁评估采用医院焦虑抑郁量表（Hospital Anxiety and Depression Scale, HADS），一般健康状况评估采用简明健康调查问卷（Short Form 36 Health Survey, SF-36）。为评估两份问卷的信度与效度，本研究采用了多种统计学分析方法，包括斯皮尔曼等级相关系数、组内相关系数（Intraclass Correlation Coefficients, ICC2,1）、克朗巴赫α系数、SEM及MDC。
结果
患者NPQ平均得分为29.9±13.2，NPQ-R平均得分为52.3±19.6。NPQ与NPQ-R与各评估工具的相关性如下：(1) 疾病特异性问卷：与DHI的相关系数rs分别为0.712、0.752，与VSS-V的rs分别为0.426、0.462，与ABC量表的rs分别为-0.500、-0.545；(2) 焦虑特异性亚量表：与VSS-A的rs分别为0.394、0.430，与HADS-A的rs分别为0.354、0.430；(3) 抑郁相关亚量表：与HADS-D的rs分别为0.438、0.487；(4) 一般健康状况量表：与所有SF-36亚量表的相关系数rs介于-0.216至-0.578之间。NPQ与NPQ-R的内部一致性、重测信度、SEM及MDC分别为：α系数0.88/0.91，组内相关系数ICC=0.83（95%置信区间0.77~0.87），SEM为5.55/8.37，MDC为15/23分。
结论
德国版NPQ与NPQ-R均为评估PPPD的有效且可靠的患者报告结局量表，具备良好的心理测量学特性，包括聚合建构效度及各项信度参数：内部一致性、重测信度、SEM及MDC等评价指标。NPQ-R新增了针对伴随症状及症状行为的亚量表，可同时反映患者与临床医师对PPPD相关问题的视角。因此，本研究推荐采用NPQ-R对PPPD进行全面评估。