Abstract
Introduction: Emergency medicine has developed to the point that military personnel in recent conflicts (e.g. Afghanistan) are surviving physical combat injuries that would have previously resulted in mortality. The long-term health implications of such injuries are largely unknown.Aims: This thesis sets out to describe the rates of mental illness (Post-Traumatic Stress Disorder (PTSD), depression, anxiety and mental health multimorbidity) and psychological thriving (Post-Traumatic Growth (PTG)) amongst a cohort of physically injured UK military personnel and an uninjured comparison group. This thesis also explores the psychological and biological mechanisms by which PTSD and PTG are associated with cardiovascular health/cardiovascular disease risk factors.
Methods: 1145 UK military personnel completed a comprehensive health assessment as part of the ADVANCE cohort study at Defence Medical Rehabilitation Centre Headley Court (2015-2018) or Stanford Hall (2018-2020). 579 participants sustained a physical combat injury whilst on deployment to Afghanistan, and 566 were a frequency-matched uninjured comparison group based on age, rank, deployment role, regiment and deployment era. Health assessments included venous blood sampling, Vicorder assessment, dual-energy absorptiometry and validated self-report mental health questionnaires.
Statistical techniques: Logistic regression modelling, multinomial logistic regression, generalised structural equation modelling, bootstrapping and variable selection procedures including bootstrapped inclusion frequencies and model averaging.
Results: Physically combat injured personnel were more likely to report probable depression, anxiety, PTSD, mental health multimorbidity and PTG compared to the uninjured group. Heterogeneity between estimates was observed depending on subtypes of injury. Personnel with an amputation injury reported similar rates of mental illness compared to the uninjured group, and those with non-amputation injuries reported higher rates. Inversely, personnel with amputation injuries reported more PTG compared to the uninjured group, whereas those with non-amputation injuries reported similar rates of PTG. Associations between combat injury and PTG were partially mediated by depression, PTSD and current moderate-extreme pain. Investigation of PTSD symptom clusters (avoidance behaviours; emotional numbing; hyperarousal and intrusive thoughts) and cardiovascular disease risk factors found that a diverse combination of symptom clusters were associated with cardiometabolic effects (insulin resistance, visceral fat, lipids) and haemodynamic functioning (resting heart rate and systolic blood pressure), but not inflammation (high sensitivity C-reactive protein). Associations between PTG factors (appreciation of life; new possibilities; personal strength; relating to others and spiritual change) found that these were associated with mostly positive (diastolic blood pressure and lipids), but also negative (fasting blood glucose and lipids) cardiometabolic effects and haemodynamic functioning. PTG factors were not associated with inflammation (high sensitivity C-reactive protein).
Discussion: The journey to recovery for UK military personnel who survived a physical combat injury does not end after discharge from Defence Medical Rehabilitation Centre services. Those who sustained non-amputation injuries are at higher risk for probable mental illness, whilst those who sustained amputation injuries are more likely to experience PTG compared to those who deployed to Afghanistan and were uninjured. This may be due to social factors such as hierarchy of wounding or increased and easier access to therapeutic or charitable support services for those with amputation injuries, though more research is required to understand if this is true. This thesis presents evidence that PTSD symptoms are associated with increased cardiovascular risk and PTG is associated with mostly reductions in cardiovascular risk several years after exposure to warzones/injury. Whether the association between psychological symptoms and cardiovascular risk translates to later development of cardiovascular disease remains to be seen. Results from this thesis suggest that a focus on policy/intervention that facilitates both physical and psychological thriving would be beneficial for the long-term health of UK military personnel, especially if they sustained a physical combat injury.
| Date of Award | 1 Jul 2023 |
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| Original language | English |
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| Supervisor | Nicola Fear (Supervisor) & Sharon Stevelink (Supervisor) |