Psychometrics properties of type 2 diabetes treatment adherence questionnaire (DTAQ): a study based on Pender's health promotion model.

Background: Management of type 2 diabetes (T2D) as a chronic disease requires treatment adherence such as controlling the blood glucose level and adopting a healthy lifestyle. The present study aimed to develop and psychometrically evaluate a questionnaire based on the Pender's Health Promotion Model (HPM) to measure treatment adherence and the associated factors among T2D patients.

Methods: The present study was conducted in qualitative and the quantitative phases between March 2022 and March 2023. The participants were T2D patients visiting Shahid Mohammadi hospital Diabetes Clinic in Bandar Abbas in the south of Iran. The first draft of items was extracted from the qualitative phase. The present study used interviews with T2D patients, item construction, validity and reliability evaluation of the instrument, and the relevant statistical analyses. It emphasized the significance of content, face, and construct validity, along with reliability testing using Cronbach's alpha and test-retest method. Data were analyzed using SPSS software, V16 and AMOS, V23.

Results: A 97-item questionnaire was developed through the qualitative phase and, after content validity, it was reduced to 86 items. Five items were removed in face validation, and after the test-retest method, 79 items were retained. The confirmatory factors analysis confirmed a 65-item model with appropriate fitness of data. Cronbach's alpha coefficient showed an acceptable reliability of the diabetes treatment adherence questionnaire (α = 0.92).

Conclusion: The questionnaire developed based on the HPM model provides a standard and comprehensive measurement of the degree of adherence to treatment and the associated factors among Iranian T2D patients. This is especially valuable in the Iranian healthcare context, where effective management of chronic diseases such as diabetes is of a top priority. Questionnaires can help identify barriers and facilitators of treatment adherence to inform systematic and goal-oriented interventions. The proposed questionnaire had good psychometric properties, and can be used as a valid and practical instrument to measure the factors related to treatment adherence behaviors.