P.1.g.007 How does a trivial head injury result in enduring symptoms? A prospective investigation of outcome after mild traumatic brain injury

Abstract

Background: Traumatic brain injury is one of the most common neurological conditions. However, the majority of cases 90% are actually mild. Mild traumatic brain injury (MTBI) remains a major, unrecognized public health issue and has been called a “silent epidemic” (1). A significant proportion (15-30%) of patients are at risk of developing Post Concussional Syndrome (PCS) (2)(3), which is a symptom cluster including a number of physical, cognitive, emotional?and behavioural symptoms. Objective: The aim of this study was to investigate the contributions of cognitive, emotional and behavioural factors to the development of PCS based on a cognitive-behavioural model. Methods: A prospective cohort design was employed. 126 patients met the diagnosis of MTBI (mean age 38.32 years; male 63%) completed baseline questionnaire assessments within 2 weeks after injury, and 108 patients completed follow-up questionnaire assessments at both 3 and 6 months after injury. A series of self-report measures including the Brief Illness Perception Questionnaire, the Behavioural Response to Illness Questionnaire, the Impact of Event Scale, the Hospital Anxiety and Depression Scale, the Brief Social Support Questionnaire, and the Rivermead Postconcussion Symptoms Questionnaire were used to assess baseline somatic, cognitive, behavioural and emotional responses. The primary outcome measures were the ICD-10 Diagnosis for PCS and the Rivermead Postconcussion Symptoms Questionnaire. Data from 107 patients were entered into final analysis. Demographic and clinical characteristic variables were compared between the PCS cases and non-cases using independent-sample t tests and ?² tests. Significant variables from the individual regression analysis were subjected to multiple logistic regression modelling with PCS outcome entered as the dependent variable. A stepwise backward logistic regression procedure was used to derive the model. The Likelihood Ratio Test was used to select predictor variables in the logistic regression model. Fit of the model was assessed by the Hosmer-Lemeshow ‘‘goodness of fit statistic’’ for significance. Results: Of 107 participants, 24 (23%) patients met the criteria for PCS at 3 months, and 23 (22%) at 6 months. Somatic symptoms such as headache, fatigue, sleep disturbance, were most prevalent at two follow-ups. Significant predictors indicated by individual logistic regression analysis including illness perceptions, stress, HADS anxiety and depression, and all-or-nothing behaviour, were then entered into two separate multiple regression analysis. The resultant model for PCS at 3 months included all-or-nothing behaviour, and the resultant model at 6 months included all-or-nothing behaviour and negative illness perceptions. All-or-nothing behaviour was found to be an independent predictor for PCS at 3 months (Odds Ratio 1.141, 95% confidence interval 1.050 to 1.240, p = 0.002), while negative illness perceptions was an independent predictor at 6 months after injury (Odds Ratio 1.053, 95% confidence interval 1.008 to 1.101, p = 0.021). Conclusions: The study provides good support for the proposed cognitive behavioural model for PCS. Patients’ negative illness beliefs and certain behavioural response play important roles in the development of PCS, indicating that they may be important early intervention targets.