Development and testing of an instrument to measure contextual factors influencing self-care decisions among adults with chronic illness

Background Decisions about how to manage bothersome symptoms of chronic illness are complex and influenced by factors related to the patient, their illness, and their environment. Naturalistic decision-making describes decision-making when conditions are dynamically evolving, and the decision maker may be uncertain because the situation is ambiguous and missing information. Contextual factors, including time stress, the perception of high stakes, and input from others may facilitate or complicate decisions about the self-care of symptoms. There is no valid instrument to measure these contextual factors. The purpose of this study was to develop and test a self-report instrument measuring the contextual factors that influence self-care decisions about symptoms. Methods Items were drafted from the literature and refined with patient input. Content validity of the instrument was evaluated using a Delphi survey of expert clinicians and researchers, and cognitive interviews with adults with chronic illness. Psychometric testing included exploratory factor analysis to test dimensionality, item response theory-based approaches for item recalibration, confirmatory factor analysis to generate factor determinacy scores, and evaluation of construct validity. Results Ten contextual factors influencing decision-making were identified and multiple items per factor were generated. Items were refined based on cognitive interviews with five adults with chronic illness. After a two round Delphi survey of expert clinicians (n = 12) all items had a content validity index of > 0.78. Five additional adults with chronic illness endorsed the relevance, comprehensiveness, and comprehensibility of the inventory during cognitive interviews. Initial psychometric testing (n = 431) revealed a 6-factor multidimensional structure that was further refined for precision, and high multidimensional reliability (0.864). In construct validity testing, there were modest associations with some scales of the Melbourne Decision Making Questionnaire and the Self-Care of Chronic Illness Inventory. Conclusion The Self-Care Decisions Inventory is a 27-item self-report instrument that measures the extent to which contextual factors influence decisions about symptoms of chronic illness. The six scales (external, urgency, uncertainty, cognitive/affective, waiting/cue competition, and concealment) reflect naturalistic decision making, have excellent content validity, and demonstrate high multidimensional reliability. Additional testing of the instrument is needed to evaluate clinical utility.