Development and Psychometric Evaluation of the Heart Failure Treatment Adherence Questionnaire (HFAQ) for Military Personnel and Their Family: A Mixed, Exploratory, and Sequential Study

Background: Heart failure (HF) is an important public health issue whose prevalence, hospitalization rate, and costs have increased over the years. Treatment adherence is the behavior of the patient in taking medications, correcting diet, and ability to change lifestyle with the recommendations of the health care provider. Poor treatment adherence contributes to worsening disease outcomes. Currently, according to the literature, no specific instrument is available to measure treatment adherence of HF patients. Objectives: The aim of this study was to develop and evaluate the heart failure treatment adherence questionnaire (HFAQ) for military personnel and their family. Methods: Items were generated by literature review, patient field interviews, and expert opinions. Content validity was assessed by measuring CVR and CVI, while face validity was evaluated by measuring the impact score of each item. The research team performed EGA, bootEGA, and CFA to assess the construct validity, and reliability was assessed by measuring ICC and Cronbach’s alpha. Results: Item pool with 86 items was generated consisting of 45 medications, 10 lifestyles, nine diet items, and 22 common items between these three categories. Forty-three items with CVR score lower than 0.62 were removed from the HFAQ. All remained items had acceptable face validity. Cronbach’s alpha and ICC of HFAQ were reported as 0.73 and 0.97, respectively. EGA results represented a four-dimension model for HFAQ with a relatively narrow confidence interval (CI 95% [3.769, 4.231]), and the stability of items, in constructs, ranged from 0.96 to 1. Goodness-of-fit results was reported as χ2 = 535.657, df = 293, χ2/df = 1.828, P-value < .001, CFI = 0.851, and RMSEA = 0.050. Conclusions: HFAQ is the first treatment adherence questionnaire developed specifically for assessing treatment adherence of HF patients and is a valid and reliable 26-item questionnaire that evaluates patients' treatment adherence in three main contexts of medication, physical activity, and diet. HFAQ has four dimensions of health literacy, social and economic, barrier, and patient-provider relationship, which can be used as an intervention for improving treatment outcomes and disease burden.