|
UPDATE ON LOW SPEED IMPACT MEDICAL LITERATURE
Patrick A. Nee FRCS, FRCP, FCEM
Consultant in Emergency Medicine
Whiston Hospital, Merseyside
Predictors of persistent neck pain after whiplash injury
Atherton, K et al, 2006 (1)
This paper represents the first large-scale epidemiological study to examine prospectively the human and crash-related factors predicting persistent neck pain after a motor vehicle collision (MVC). It is a cohort study of 765 patients attending four Emergency Departments (EDs) in Manchester with neck pain within 24hours of a MVC during a 16-month study period. Four hundred and eighty patients completed follow-up questionnaires at 1,3 and 12 months post incident. The direction of impact was:
Rear 257, rear shunt 33, front 77, side 98, other 15.
Fifty nine per cent still complained of neck pain at three months and 27% were symptomatic for at least 12 months. Pre-existing physical and psychological health, and severity and extent of early whiplash associated disorder (WAD) symptoms were predictive of persistent symptoms. By contrast, crash-related factors were not relevant.
Persistent neck pain was more likely after a medium or high severity crash, self-reported using a visual analogue scale. Nevertheless, low severity crashes led to persistent symptoms in seven per cent of patients, compared with nine per cent in medium and ten per cent in high severity crashes. Importantly, the reported (approach) speed of the other vehicle was not significant, 26.6% of patients experienced persistent neck pain at >25mph, whilst the frequency at <25mph was 27.3%.
The authors suggest that a prediction model, including five factors, easily recorded in the ED, could identify patients with an 80% risk of persistent symptoms compared to a 14% rate when all five elements are absent:
-
Pre-collision widespread pain
-
Vehicle type – car occupant vs. other vehicle
-
Number of WAD symptoms- 5 vs. fewer
-
Neck Disability Index -19 vs. fewer (2)
-
Psychological distress measured by the General Health Questionnaire (3)
Interpretation
This study adds to the body of modern literature on outcome after whiplash injury. It is a large-scale study, UK-based, and it concerns real patients involved in real-world crashes. The biggest group were rear end crashes and 75% of the patients had mild injuries, classified as WAD grade I (neck pain only with normal range of motion and no bony tenderness). Only patients followed up for a year were included. It is therefore much more representative than the historical, small-scale volunteer experiments, which involved staged collisions in heavily modified cars, trucks and sleds. Findings are dissimilar to other studies; in that there is no increase in risk of persistent symptoms with female gender, rear impact vector or lack of awareness of impending collision. The demographic data, injury severity distribution and the outcomes are similar to others’ findings, however.
In the present study group, neck pain was still present at three months in the majority of patients. The incidence of similar symptoms at one year was 27 per cent. Unsurprisingly, chronic symptoms were more likely in self-reported severe crashes, but the difference in numbers of symptomatic patients at 12 months was not great; 32 after low, 45 after medium and 48 after high severity crashes.
The use of delta-V, the change in velocity of a struck vehicle, is irrelevant in the analysis of a real world crash since it cannot be calculated with any degree of accuracy and it does not predict injury risk in any event. The authors of the present study do not, therefore, address this experimental concept. They deal instead with data likely to be available to the examining clinician in the ED –the patient’s estimate of his/her own speed and the closing speed of the bullet vehicle. They find no correlation between these parameters and the risk of persistent neck pain at 12 months. This suggests that collision factors, including estimates of speed and severity, should not be used to refute causation in whiplash cases. Finally, the high prevalence of persistent symptoms after whiplash injury is re-affirmed.
References
(1) Atherton K, Wiles NJ, Lecky FE, Hawes SJ, Silman AJ et al. Predictors of persistent neck pain after whiplash injury
Emerg Med J 2006;23:195-201
(2) Vernon H and Mior S. The neck disability index: a study of reliability and validity
(3) Goldberg DP and Williams P. A users guide to the General Health Questionnaire. Windsor Nfer-Nelson 1988
Osti OL et al. Potential risk factors for prolonged recovery after whiplash injury. European Spine Journal 2005; 14(1):90-94
This article, from an Australian group, investigated predictors of prolonged recovery in 600 adults seeking compensation after a motor vehicle crash. They considered human and crash-related variables in 300 claimants whose claims were settled within 9 months and a similar number who settled more than two years after the crash. Late settlement was considered a marker of prolonged symptoms. Consulting a solicitor was associated with a four-fold increase in late settlement. Prior neck disability and treatment were weakly associated with prolonged settlement. Interestingly, there was no correlation between the time to settlement of the claim and vehicle damage as indicated by the cost of repairs. This paper adds to the growing body of contemporary literature demonstrating the lack of reliability of engineering evidence in predicting injury risk and duration of symptoms.
|
