Teo Vivien, Weinman John, Yap Kai Zhen
Institute of Pharmaceutical Sciences, King's College London, Franklin-Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom; Department of Pharmacy, National University of Singapore, 18 Science Drive 4, 117543, Singapore; Division of Pharmacy, Tan Tock Seng Hospital, Singapore, 11 Jalan Tan Tock Seng, 308433, Singapore.
Institute of Pharmaceutical Sciences, King's College London, Franklin-Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom.
J Psychosom Res. 2025 Jan;188:111969. doi: 10.1016/j.jpsychores.2024.111969. Epub 2024 Nov 8.
To examine the psychometric properties of the Intentional Non-adherence Scale (INAS) among people with type 2 diabetes mellitus (PwT2D) in Singapore.
This study consisted of Phase 1: translation and adaptation of the questionnaire into local Mandarin and English and Phase 2: a longitudinal validation study at the outpatient clinics of a hospital in Singapore. In Phase 1, cognitive interviews were conducted with 20 PwT2D and healthcare providers to examine the content validity of the INAS. In Phase 2, 290 PwT2D were recruited. Fifty-three of them were involved in test-retest reliability analysis, while 185 were followed-up in 3-6 months to assess the predictive validity of the INAS. The INAS was also evaluated for its structural validity, construct validity and internal reliability.
Exploratory factor analysis revealed four factors, namely "Resisting illness and medication", "Sensitivity to medication", "Testing treatment" and "Inconvenience". All INAS factors showed good internal consistency (Cronbach's alpha = 0.84-0.94) and moderate test-retest reliability (intraclass correlation coefficient = 0.50-0.62). Construct validity of the INAS was demonstrated in its relationship with medication adherence, glycated haemoglobin (HbA1c), beliefs about medications, illness perception and mood. Quantile and linear regression for medication adherence and HbA1c in 3-6 months did not show statistical associations with the INAS after adjusting for potential confounders.
Our study supports the reliability and most aspects of validity of the INAS, which revealed new factors that may affect medication adherence and HbA1c. In clinical settings, healthcare providers may consider using this questionnaire to evaluate potential intentional nonadherence.
检验新加坡2型糖尿病患者中故意不依从量表（INAS）的心理测量特性。
本研究包括两个阶段：第一阶段，将问卷翻译成当地的普通话和英语并进行改编；第二阶段，在新加坡一家医院的门诊进行纵向验证研究。在第一阶段，对20名2型糖尿病患者和医疗服务提供者进行了认知访谈，以检验INAS的内容效度。在第二阶段，招募了290名2型糖尿病患者。其中53人参与了重测信度分析，185人在3至6个月内接受随访，以评估INAS的预测效度。还对INAS的结构效度、构想效度和内部信度进行了评估。
探索性因素分析揭示了四个因素，即“抗拒疾病和药物治疗”、“对药物敏感”、“测试治疗效果”和“不便之处”。所有INAS因素均显示出良好的内部一致性（Cronbach's α = 0.84 - 0.94）和中等的重测信度（组内相关系数 = 0.50 - 0.62）。INAS的构想效度体现在其与药物依从性、糖化血红蛋白（HbA1c）、对药物的信念、疾病认知和情绪的关系中。在调整潜在混杂因素后，3至6个月内药物依从性和HbA1c的分位数和线性回归与INAS未显示出统计学关联。
我们的研究支持INAS的信度及效度的大多数方面，该量表揭示了可能影响药物依从性和HbA1c的新因素。在临床环境中，医疗服务提供者可考虑使用该问卷来评估潜在的故意不依从情况。
