In this study by Vedhara and colleagues, they found that illness beliefs predicted mortality and time to death in diabetic patients with foot ulcers.
The results from their study, without replacing missing data, revealed that ischemia (an inadequate blood supply to an organ or part of the body), coherence (assessed by asking patients ‘How well do you feel you understand your ulcer?’), and identity beliefs (‘How much do you experience symptoms?’) predicted time to death. Specifically, the researchers found that death occurred more quickly in individuals with less ischemia, who perceived their ulcers were associated with greater symptoms and had a poorer understanding of their condition. When these analyses were repeated with the imputation, or replacement of missing data, for both predictor and outcome variables, the findings were largely unchanged, with degree of ischemia and identity beliefs as significant predictors of both mortality and time to death in all analyses.
Kavita Vedhara , Karen Dawe, Jeremy N. V. Miles, Mark A. Wetherell, Nicky Cullum, Colin Dayan, Nicola Drake, Patricia Price, John Tarlton, John Weinman, Andrew Day, Rona Campbell, Jenna Reps, and Daniele Soria
University of Nottingham, University of Bristol, University of Northumbria, University of Manchester, University of Cardiff, King’s College London, University Hospitals Bristol, Southmead Hospital, United Kingdom, and Rand Corporation, United States
The researchers examined the role of depression and illness beliefs in predicting mortality in patients with type 1 and type 2 diabetes and with a diabetic foot ulcer. In line with previous research, they hypothesised that the time to death would be shorter in patients with negative beliefs. They also specifically expected to find that beliefs regarding symptoms, personal control, and/or coherence would be related to mortality given their role in predicting foot self-care in this patient group. Furthermore, given the prominence of depression as a predictor of mortality in diabetes, their predictive models were constructed to examine whether illness beliefs predicted mortality after examining the role of potential demographic and clinical factors and depression.
The researchers suggested that the evidence regarding the relationship between psychological functioning and outcomes in patients with foot ulcers was limited in two main ways. First, it had largely focused on depression and second, the evidence pertaining to the role of depression was mixed. Furthermore, emerging evidence on illness beliefs from patients with diabetes and other chronic conditions suggested they these beliefs may be influential in predicting a range of clinical outcomes, including mortality.
The researchers collected clinical and demographic data from 160 diabetic patients. Participants also completed self-report measures of illness beliefs and depression at baseline. Data on survival were collected after the survival census point (1st November 2011).
ScientiFix tip: The researchers acknowledged that their understanding of the relationship between identity beliefs and mortality was limited by the fact that their understanding of patients’ beliefs was limited to responses to a single item. While practical, by decreasing questionnaire length, this did not give them insight into the types of symptoms that patients were considering when responding. They recommended that future research use either qualitative methods, and/or capture illness beliefs using more detailed methods, which could help to examine the relationship between identity beliefs and mortality. Similarly, the researchers measured ischemia using a single assessment, despite the accurate measurement of ischemia requiring multiple methods. They noted that while they used single measures that could be conducted rapidly across all clinics, their ability to accurately measure patients’ beliefs and ischemia likely lacked precision and this may have contributed to their finding. This makes it difficult to determine just how accurate or sensitive their outcome measures were. Researchers always need to consider the trade-off between session length, number of assessments, and potential participant fatigue and attrition (or drop-out) when designing their studies, all the more challenging when testing patient populations.