This study aims to validate and evaluate the psychometric properties and reliability of the Italian version of the Expanded Prostate Cancer Index Composite – Short Form (EPIC-26), a measure of quality of life (QoL) for prostate cancer patients. Two hundred and eighty-four prostate cancer patients completed the Italian version of the EPIC-26 questionnaire at 45 days (T1) and 3 months (T2) after robot-assisted radical prostatectomy (RARP). Psychometric properties were evaluated using structural equation modeling: the goodness of fit of the correlated five-factor model (CFFM) for the EPIC-26 was assessed using the confirmatory factor analysis (CFA), while longitudinal invariance was conducted to assess the ability of the EPIC-26 to measure QoL construct over time. Test-retest reliability was assessed as well by considering intraclass correlations. At T1, the CFFM model displayed a good fit to data. Similarly, the model showed an adequate fit also at T2. Results of the reliability analysis attested the acceptable internal consistency and test-retest reliability of each dimension: all Cronbach’s alphas could be classified as acceptable (i.e., above .65) except for low Cronbach’s alpha for hormonal dysfunction at T1 (i.e., .638) and urinary irritation at both waves. (i.e., respectively .585 and .518). Finally, psychometric properties were invariant over time and each of the five dimensions of QoL displayed from moderate (all ICCs above .500) to good test-retest reliability (i.e. ICC for urinary incontinence = .764). Results of the CFA and the measurement invariance analysis demonstrated the validity of the Italian version of the EPIC-26 to assess QoL in prostate cancer patients. Its reliability and good psychometric qualities are well-supported, thus providing a valid tool to assess health-related quality of life and its change over time in prostate cancer patients.

中文翻译：

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义大利语版本的前列腺癌男性患者的缩写扩展前列腺癌指数复合物（EPIC-26）的验证

这项研究旨在验证和评估意大利语版“扩展前列腺癌综合指数-简表”（EPIC-26）的心理计量学特性和可靠性，这是对前列腺癌患者的生活质量（QoL）的一种度量。284名前列腺癌患者在机器人辅助根治性前列腺切除术（RARP）后的45天（T1）和3个月（T2）时完成了意大利语版本的EPIC-26问卷调查。使用结构方程模型评估心理计量学特性：使用验证性因子分析（CFA）评估EPIC-26的相关五因子模型（CFFM）的拟合优度，同时进行纵向不变性以评估EPIC-26的能力。 EPIC-26，用于测量随时间变化的QoL结构。还通过考虑组内相关性来评估重测信度。在T1时，CFFM模型显示出对数据的良好拟合。同样，该模型在T2时也显示出足够的拟合度。可靠性分析的结果证明了每个维度的内部一致性和重测可靠性：所有Cronbach's alpha都可以归类为可接受的（即，高于.65），除了T1激素功能障碍的Cronbach's alpha低（即，.638）之外。和两个波尿刺激。（即分别为.585和.518）。最后，心理测量特性随时间而不变，并且从中等（所有.500以上的所有ICC）到良好的再测信度（即尿失禁的ICC = 0.764），QoL的五个维度中的每一个都显示出来。CFA的结果和测量不变性分析证明了意大利版本的EPIC-26在评估前列腺癌患者的QoL方面的有效性。