Validating a Brief Screening Tool With Biomarkers for Prediction of Chronic Post Traumatic Neck Pain: A Prospective Cohort Study

Background Post-traumatic neck pain sustained after accidents are frequent (1) and represents a huge human and societal burden that can cause significant long-term pain and disability (2-4). It has been estimated that there are 6,000 new annual cases of traffic accidents resulting in post-traumatic neck pain in Denmark (5). However, recent international research indicates that the figure may be more than double (6-8). While up to half of those injured continue to experience symptoms a year after the accident (1-3), 15-25% experience significantly more severe symptoms and functional impairment (9,10) and are at risk of leaving the labour market. The accumulated cost of post traumatic neck pain in Denmark has not been evaluated in a scientific study but it is estimated the direct and indirect economic costs of post traumatic neck pain are approximately DKK 14 billion annually (11).

Post-traumatic neck pain after accident is often accompanied by a myriad of symptoms such as headaches, fatigue, concentration problems, and sensitivity to light and sound (4,12-16). A number of studies also point to frequent psychological symptoms after injuries such as symptoms of stress, depression, and anxiety (15-17), and early post-traumatic stress has been reported to predict poorer recovery over time (18,19).

Previous studies have identified the same risk factors after whiplash injuries (20-26). Risk factors are age, high pain intensity, hypersensitivity to pain, and post-traumatic arousal symptoms (i.e. increased stress) immediately after the accident. The results suggest that the lack of efficacy of existing treatments (27-30) :is caused by not specifically targeting risk patients and the underlying related mechanisms.

Ritchie and colleagues have developed and validated a clinical prognostic screening tool to identify patients at risk of developing post traumatic neck pain (31,32). The optimal use of the screening tool is immediately after accidents. Based on simple screening questions that can be answered in less than 5 minutes regarding pain and related functional limitations, post-traumatic stress disorder (hyperarousal) and age, the screening tool can with 90% accuracy be used to identify those that do not improve after the accident and with 80% accuracy those who recovers completely. However, there is a need to test the screening tool in a Danish context in the emergency department and investigate whether biomarkers for stress can improve the predictive value of the tool.

In Denmark, the standard emergency department treatment after non traumatic accident is a thorough physical evaluation coupled with good advice, which is appropriate for a significant proportion of patients. Unfortunately, it is difficult to distinguish a normal reaction from a treatment-requiring reaction, which in turn can lead to a worsening of traumatic neck pain. In this instance the prognostic tool (31,32) will be simple and quick to use. Collection of objective biomarkers for early stress response immediately after the accident will probably strengthen the value of the tool and provide more insight into causal mechanisms in the development of chronic post-traumatic neck pain. Moreover, biomarkers such as heart rate variability (HRV) can be collected immediately after an accident and thereby predict the risk of developing PTSD. Using questionnaires this information would take weeks to collect risking delayed identification of risk patients.