Development and psychometric evaluation of the Treatment Adherence Questionnaire for Patients with Combat Post-traumatic Stress Disorder

PURPOSE: Treatment adherence is one of the major strategies in treating post-traumatic stress disorder (PTSD) in combat veterans. This study developed and psychometrically assessed the Treatment Adherence Questionnaire for Patients with Combat Post-Traumatic Stress Disorder. PARTICIPANTS AND METHODS: This methodological study was conducted in Tehran, Iran, during 2016–2017 in two phases. First, the concept of treatment adherence in combatants with PTSD was analyzed using a hybrid model. This model consisted of three phases: literature review phase, fieldwork phase, and final analysis phase. The consequences and attributes of the concept of treatment adherence in combatants with PTSD were identified, and based on the findings, the Treatment Adherence Questionnaire for PTSD veterans was developed. In the second stage, the face and content validities of the questionnaire were investigated both quantitatively and qualitatively. Exploratory factor analysis and confirmatory factor analysis were used to determine the questionnaire’s validity. Internal consistency correlation coefficient of the questionnaire was estimated with Cronbach’s alpha coefficient, while the reliability of the questionnaire was established using intra-class test-retest correlation coefficient. Study participants were selected from inpatients and outpatients referred to a hospital, clinic, and health center in Tehran and Kashan, Iran. All patients were diagnosed with combat PTSD by a psychiatrist, based on psychiatric interview and other clinical findings. RESULTS: The Persian version of the Treatment Adherence Questionnaire for Patients with Combat Post-Traumatic Stress Disorder included 17 items. Exploratory factor analysis identified three factors which accounted for a total of 87.57% of the total variance of treatment adherence score. The identified factors were labeled as “maintenance of treatment”, “follow-up and treatment contribution”, and “purposefulness and responsibility”. The Cronbach’s alpha correlation coefficient was 0.92 and the intra-class correlation coefficient of the questionnaire’s reliability was estimated at 0.92 (P<0.001). CONCLUSION: The data obtained confirmed the hypothesis of the factor structure model with a latent second-order variable. The final version of the Treatment Adherence Questionnaire for Iranian combatants with PTSD can be applied as a valid and reliable questionnaire for measuring treatment adherence in these patients.