Discriminant content validity of a theoretical domains framework questionnaire for use in implementation research

Background: To improve the implementation of innovations in healthcare settings, it is important to understand factors influencing healthcare professionals' behaviors. We aimed to develop a generic questionnaire in English and in Dutch assessing the 14 domains of behavioral determinants from the revised TDF (Cane et al., 2012) that can be tailored to suit different targets, actions, contexts, and times of interest, and to investigate questionnaire items' discriminant content validity. Methods: We identified existing questionnaires including items assessing constructs within TDF domains and developed new items where needed. Nineteen judges allocated 79 items to one or more TDF domains. One-sample t-tests were used to examine the discriminant content validity of each item, i.e., whether items measured intended domains or whether items measured a combination of domains. Results: We identified items judged to discriminately measure 11 out of 14 domains. Items measuring the domains Reinforcement, Goals, and Behavioral regulation were judged to measure a combination of domains. Conclusions: We have developed a questionnaire in English and in Dutch able to discriminately assess the majority of TDF domains. The results partly support Cane et al.'s (2012) 14-domain validation of the TDF and suggest that Michie et al.'s (2005) 12-domain original version might be more applicable in developing a TDF-based questionnaire. The identified items provide a robust basis for developing a questionnaire to measure TDF-based determinants of healthcare professionals' implementation behaviors to suit different targets, actions, contexts, and times. Future research should investigate the concurrent and predictive validity and reliability of such a questionnaire in practice.