COURSE AND PROGNOSIS OF WAD AFTER A MOTOR VEHICLE CRASH

COURSE AND PROGNOSIS OF WAD AFTER A MOTOR VEHICLE CRASH

Course of Recovery

Understanding the course and prognosis in WAS is critical. Will people recover from this common injury? Is so, when? If the injury is transient and self-limiting, there would be no need for major prevention and intervention strategies. The natural course and prognosis of WAD has been a controversial matter. Some claim that the prognosis is solely determined by the physical injury and its severity, and that pre- and post-psychosocial factors are not relevant in recovery. Others claim that persistent WAD is mainly a ‘psycho-cultural’ illness, and refer to studies from Lithuania and Greece where there is no or little awareness or reporting of WAD resulting from a whiplash mechanism. Studies from these countries report that 2% or less of study participants report long-lasting symptoms after car collisions. However, drawing firm conclusions based on the findings of these studies is inappropriate, since ‘psychocultural’ factors were not studied per se. Nevertheless, when persons who do not experience neck pain following a car collision have been asked to report on which symptoms they would expect after neck injury or minor head injury, those from Lithuania and Greece do not expect to have as many symptoms or do not have as long-lasting symptoms compared to persons in Canada.

In the majority of studies, the recovery rate is substantially lower than recovery rates reported in Greece and Lithuania. Some report a 66-68% recovery rate at one year after the injury, whereas others report a less than 40% recovery rate at a similar time point. Differences in recovery rates are at least partially due to selection bias. For instance, in the study by Miettinen et al., only 58% of the invited study population was followed up 12 months post injury, so it was unknown what the recovery rate was for the 42% of participants who could not be contacted at follow-up.

Prognostic Factors

A prognostic factor is a factor that is independently associated with the prognosis, and which can contribute to or work against recovery from a condition. Some factors known to contribute to a poor prognosis in WAD are similar to those for other forms of persistent neck pain. These factors include, among others, passive coping strategies, poor mental health, high level of stress, high pain intensity and more ‘associated’ symptoms, such as arm pain, headache and nausea. Similar to the literature on neck pain in the general population, gender does not seem to be a clear prognostic factor in WAD, after adjustments have been made for psychosocial factors. This suggests that the observed poor prognosis in females in some studies might be explained in terms of the psychosocial factors rather than the biological factors of gender. Furthermore, societal factors, such as insurance systems with possibilities to claim for pain and suffering, and extensive healthcare utilization in the early stage of the injury, have been suggested to be associated with delayed recovery in WAD.

Surprisingly, the bulk of evidence suggests that crash-related factors (e.g. impact direction, awareness of collision, head position) are not associated with the prognosis.

There is evidence that people’s lowered expectations of recovery and return to work, assessed early in the process of recovery, are an important predictor for long-lasting WAD, even after controlling for other factors, such as prior health, pain areas and acute post-traumatic stress symptoms. An expectation is defined as a degree of belief that some as being tied to an outcome, such as a recovery state or return to work, rather than the individual behaviors required to achieve that outcome (self-efficacy expectations). It is believed to be influenced by personal and psychological features, such as anxiety, self-efficacy, coping abilities and fear, and recent studies have demonstrated that in those with WAD, initial pain, depressive symptomatology, and some crash and demographic factors were associated with recovery and return-to-work expectation.

Health expectations are postulated to be primarily learned from the cultural environment, and based on ‘prior knowledge’. The mechanism by which expectations influence emotional and physical reactions may also actually affect the autonomic nervous system, involving biochemical processes, which may explain some of the power observed in studies of the placebo and nocebo effect. These mechanisms help to explain why persons who strongly anticipate they will recover really do, and why strong expectations about bad health actually lead to bad health. A concept that is closely related to expectations is a person’s belief—the lens through which a person views the world—which is shaped by the environment. In a study where injured persons were asked about their belief of the origin of their neck pain (casual belief), those who believed that something serious had happened to their neck had greater perceived disability during follow-up compared to those who did not have such beliefs.

WAD and Widespread Pain

One important aspect about the course of recovery from WAD is whether the neck injury is a trigger for subsequent widespread body pain. This has been suggested from cross-sectional studies, but knowing whether widespread pain came before the neck injury remains unclear from this type of study design. A potential aetiological explanation is a neurophysiological disturbance in the peripheral and central nervous system, which, in some stances, leads to an increased sensitivity to pain in other ‘uninjured’ areas. Another possible explanation for widespread pain is that new tissue damage may result from an altered pattern of movement in the body due to the neck pain. The exact aetiology of widespread pain is that new tissue damage may result from an altered pattern of movement in the body due to the neck pain. The exact aetiology of widespread pain is probably complex and multifactorial, but there are no indications that it would be specific to WAD. It can also occur after surgical intervention or any tissue damage. In addition, large prospective studies on pain of other aetiology have demonstrated that psychosocial factors at work, repetitive strains or other physical strains at work, awareness of symptoms and illness behavior may increase the risk of development of widespread pain. Thus, it seems that biological as well as psychological and social factors contribute to the development of widespread pain.

Prospective studies on WAD and its association with widespread pain are sparse and the evidence is not clear. The results from one study suggest a relationship between the onset of neck pain or other associated symptoms as well as self-perceived injury severity, after an MVC, and subsequent widespread pain. However, age, gender, health behavior and somatic symptoms prior to collision were at least as important. Another study investigated the incidence of onset of more extensive pain during 12 months of follow- up of WAD claimants, and associated factors with such an outcome. In that study, a less conservative definition of widespread pain was used and probably have resulted in higher incidences. The main conclusions were that widespread pain was common over a 12-month period (21%), but most improved over the follow- up period. Female gender, poor prior health, greater initial symptomatology (including pain intensity) and more depressive symptoms were associated with the development of extensive pain. The authors also found that local neck/ back pain, raising the question of the potential cause of widespread pain in other studies.

Work absenteeism and work disability

Many persons with acute WAD also have some absence from work, and no clear difference occurs between ‘blue’ and ‘white’ collar workers. In one population- based study, 46% persons had been off work due to the injury. A similar figure (49%) was seen in a Dutch study. The majority of people returned to work within a few days and only 4-9% were reported to be off work at six months past injury. In a study form the Netherlands, factors associated with not returning to work were older age and concentration problems. There was no association between degrees of manual labor, (‘blue’ or ‘white’ collar work).