Illness mindsets in health and disease: development and validation of the Illness Mindset Inventory (IMI).

Being diagnosed with a chronic illness is a life-altering experience that can be shaped, for better or worse, by psychological factors. How patients think about their illness-their core beliefs about what it means and what it might bring such as whether it is catastrophic, manageable, or even an opportunity-can influence how they respond and adapt. This research introduces the concept of illness mindsets and presents the initial validation of the Illness Mindset Inventory (IMI), a new tool designed to assess these beliefs and their implications for health and well-being. Study 1 examines the factor structure, internal reliability, and discriminant validity of the 9-item IMI in N = 201 healthy participants and N = 200 participants with cancer, diabetes, cardiovascular disease, and/or chronic pain. Study 2 investigates cancer patients (N = 463) with different degrees of illness severity and tests the pre-registered hypothesis that the IMI will account for variability in functioning over and above measures of illness severity. In Study 1, illness mindsets were associated with between 5.7 and 12.1% additional variance in physical, social, and emotional functioning, above and beyond disease status. In Study 2, illness mindsets accounted for between 6.9 and 12.0% additional variance in physical functioning, social functioning, and emotional distress in people diagnosed with cancer above and beyond cancer stage, cancer status, trait optimism, and self-efficacy. Illness mindsets may help account for variance in individual functioning beyond disease status and disease severity. Future research can probe the IMI's utility in supporting patient care; in predicting functioning before, during, and after a diagnosis; and as a potential target for intervention.