The International Anxiety Questionnaire (IAQ) and International Depression Questionnaire (IDQ) are self-report measures of ICD-11 Generalized Anxiety Disorder (ICD-11 GAD) and ICD-11 Single Episode Depressive Disorder (ICD-11 DD). This study tested the psychometric properties of these scales in two samples of bereaved adults from the United Kingdom and the Republic of Ireland. Confirmatory factor analysis (CFA) was used to test the combined dimensionality and measurement invariance of the IAQ and IDQ across the United Kingdom (n = 1012) and Irish (n = 1011) samples. Differential item functioning (DIF) was tested using multiple indicator multiple cause (MIMIC) modelling while convergent validity was also assessed. CFA results supported a correlated two-factor model in both samples. The MIMIC model showed that the IDQ item “Had recurrent thoughts of death or suicide” showed DIF and the effect was small. Internal reliability of the scales were high and convergent validity was supported. The prevalence of ICD-11 GAD was 18.6% and 16.1% and ICD-11 DD was 13.8% and 10.5% in the United Kingdom and Irish samples, respectively. Findings of the study provide support for the validity, measurement invariance, and reliability of the IAQ and IDQ among two bereaved national samples.

中文翻译：

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评估国际焦虑问卷和国际抑郁问卷在两个全国丧亲者样本中的有效性和可靠性

国际焦虑问卷 (IAQ) 和国际抑郁问卷 (IDQ) 是 ICD-11 广泛性焦虑症 (ICD-11 GAD) 和 ICD-11 单发作抑郁症 (ICD-11 DD) 的自我报告测量。这项研究在来自英国和爱尔兰共和国的两个失去亲人的成年人样本中测试了这些量表的心理测量特性。使用验证性因子分析 (CFA) 来测试英国 ( n  = 1012) 和爱尔兰 ( n  = 1011) 样本的 IAQ 和 IDQ 的组合维度和测量不变性。使用多指标多原因（MIMIC）模型测试差异项目功能（DIF），同时还评估收敛效度。CFA 结果支持两个样本中的相关双因素模型。MIMIC模型显示，IDQ项目“经常有死亡或自杀的念头”表现出DIF，且影响较小。量表的内部信度很高，并且支持收敛效度。在英国和爱尔兰样本中，ICD-11 GAD 的患病率分别为 18.6% 和 16.1%，ICD-11 DD 的患病率分别为 13.8% 和 10.5%。该研究的结果为两个全国丧亲者样本中 IAQ 和 IDQ 的有效性、测量不变性和可靠性提供了支持。