Biomarkers of autonomic regulation for predicting psychological distress and functional recovery following road traffic injuries: protocol for a prospective cohort study

Abstract

IntroductionPsychological distress is a prevalent condition often overlooked following a motor vehicle crash (MVC), particularly when injuries are not severe. The aim of this study is to examine whether biomarkers of autonomic regulation alone or in combination with other factors assessed shortly after MVC could predict risk of elevated psychological distress and poor functional recovery in the long term, and clarify links between mental and physical health consequences of traffic injury.Methods and analysisThis is a controlled longitudinal cohort study, with follow-up occurring at 3, 6 and 12 months. Participants include up to 120 mild to moderately injured MVC survivors who consecutively present to the emergency departments of two hospitals in Sydney and who agree to participate, and a group of up to 120 non-MVC controls, recruited with matched demographic characteristics, for comparison. WHO International Classification of Functioning is used as the framework for study assessment. The primary outcomes are the development of psychological distress (depressive mood and anxiety, post-traumatic stress symptoms, driving phobia, adjustment disorder) and biomarkers of autonomic regulation. Secondary outcomes include indicators of physical health (presence of pain/fatigue, physical functioning) and functional recovery (quality of life, return to function, participation) as well as measures of emotional and cognitive functioning. For each outcome, risk will be described by the frequency of occurrence over the 12 months, and pathways determined via latent class mixture growth modelling. Regression models will be used to identify best predictors/biomarkers and to study associations between mental and physical health.Ethics and disseminationEthical approvals were obtained from the Sydney Local Health District and the research sites Ethics Committees. Study findings will be disseminated to health professionals, related policy makers and the community through peer-reviewed journals, conference presentations and health forums.Trial registration numberACTRN12616001445460.

Clinical relevance of stress biomarkers as health-disease indicators

“…1,20 At the psychological level, it is related to post-traumatic stress disorders of mood and sleep disorders. 16,21…”

“…The production of ACTH and corticosteroids results in an increase in blood pressure and blood volume. 16,28 Heart rate is determined both by the joint activity of the sympathetic and parasympathetic (vagal) nerves that occur in the sinoatrial node and by intrinsic cardiac mechanisms. There is evidence that cortical activity is capable of modulating cardiac function, both in animals and in humans.…”

“…This decrease in HRV correlates with greater sympathetic activation, as well as poorer health. 5 Low levels of HRV are associated with poor regulation of stress, depression, anxiety, [42][43][44] poor cognitive and social performance, as well as a general increase of morbidity and mortality in the population, 14,16 for which a low level of HRV is considered a good predictor of disease. 36…”

“…36 It has been shown that psychological intervention is capable of stabilizing the biochemical levels altered by different diseases, 14 as is the case of cancer (prostate, colon, lung, breast), not only in patients, but also in their primary caregivers, 29,48 strengthening the person's resilience and ability to adapt to adverse conditions. 16 A much more precise understanding of the relationship between stress and health would involve the analysis of different biomarkers; analyzing a single marker is not enough to understand the complex activity of the autonomic nervous system. 16 Some authors emphasize the importance of combining up to 10 biomarkers belonging to the different systems, such as neuroendocrine, metabolic, cardiovascular and anthropometric measurements in order to diagnose the level of allostatic load of the individual, 22 as well as psychometric tests, questionnaires and clinical interviews.…”

“…14,15 Environmental and social factors, such as socioeconomic level, support networks and ability to access health systems, are also capable of modulating the level of stress affectation. 16 Stress measurement ranges from paper and pencil tests to the use of different biomarkers, such as salivary cortisol or heart rate variability (HRV). 5 Currently, the implementation of biomarkers allows for a quantitative index of stress in the person, parallel to their subjective perception, which facilitates the development of more accurate diagnoses of stress levels and their negative consequences, facilitating the development of better therapeutic strategies, capable of reducing the levels of morbidity and mortality in the population and the secondary consequences associated.…”