Psychometric testing of four transtheoretical model questionnaires for the behavior, completing health care proxies

The purpose of the study was to develop four questionnaires based on the transtheoretical model (TTM) to assess the behavior, completing a healthcare proxy (HCP). The aims were to (a) operationalize the four TTM constructs for completing a HCP and (b) evaluate the psychometric properties of the questionnaires. The questionnaires were constructed and content validity established using an expert panel. Internal consistency values for each questionnaire and subscales within each questionnaire were >.79. Confirmatory factor analysis provided evidence that decisional balance and the processes of change questionnaires each contained two factors. Our data support validity and reliability of the TTM questionnaires related to HCP completion.