Chronic whiplash-associated disorders (WAD) is a condition believed to be culturally-dependent. In Australia, up to half of the people with whiplash injury develop persistent pain and disability after a motor vehicle collision. In Singapore, an Asian country, chronic WAD is purported to be less prevalent. The influence of culture on the long-term outcome of WAD was studied in this thesis by comparing a spectrum of factors between two countries with different rates of chronic WAD, namely Queensland in Australia and Singapore. The cultural difference in prevalence of chronic WAD is proposed to be related to the community expectations of recovery and whiplash beliefs in different populations. The first study of this thesis assessed the cross-cultural differences in expectations of recovery and whiplash beliefs of laypersons in Brisbane (Queensland, Australia) and Singapore. Physiotherapists’ beliefs about WAD could potentially influence the condition’s long-term outcome. The second study determined the physiotherapists’ beliefs about WAD in Queensland and Singapore. In Western countries, chronic WAD is demonstrated to be a heterogeneous condition with physical impairments and psychological distress variably present in injured people. Endogenous pain inhibition is a possible mechanism underlying persistent pain in WAD but very little data is available. The clinical presentation of chronic WAD in Singapore is unknown. Besides investigating the physical presentation of chronic WAD in Singapore, one of the aims of this thesis was to determine endogenous pain modulation processes in chronic WAD. This thesis also undertook to assess cross-cultural differences in the physical and psychological presentation of chronic WAD between Queensland and Singapore.
An on-line survey was undertaken to determine laypersons’ whiplash beliefs and expectations of recovery in Brisbane and Singapore. Physiotherapists’ beliefs about WAD were investigated through a pen-and-paper survey conducted on musculoskeletal physiotherapists practising in Queensland and Singapore. Physical impairments of neck motion, brachial plexus provocation test responses, pressure and cold pain threshold, cold pressor pain threshold and tolerance were assessed in patients with chronic WAD in Singapore. Endogenous pain modulation processes in chronic WAD were explored by comparing conditioned pain modulation in participants with WAD against age, sex and ethnicity-matched healthy controls in Singapore. Pressure and thermal pain threshold, cold pressor pain threshold and tolerance and conditioned pain modulation were compared between Australians and Singaporeans with chronic WAD. Psychological features including posttraumatic stress symptoms, fear-avoidance, depression, perceived injustice, catastrophising, illness perceptions and self- efficacy were compared between Australians and Singaporeans with WAD.
The results demonstrate laypersons’ beliefs about whiplash injury were generally similar in Brisbane and Singapore, with the majority of both samples having positive whiplash beliefs and expectations of a fast recovery. Physiotherapists practising in Queensland and Singapore held beliefs that were generally consistent with current practice guidelines for WAD. There were a few differences in the whiplash beliefs of physiotherapists in Queensland and Singapore.
Similar to physical impairment and sensory disturbances reported in Western countries, reduced neck range of motion, cold pain intolerance, mechanical and cold hyperalgesia were demonstrated in patients with chronic WAD in Singapore. The finding of less efficacious conditioned pain modulation indicating dysfunctional endogenous pain inhibition was also evident in Singaporeans with chronic WAD. Cross-cultural comparisons of the physical presentation of chronic WAD between participants in Queensland and Singapore showed similarities in neck range of motion, pressure and thermal pain thresholds and conditioned pain modulation, suggesting similarities in motor dysfunction, central nervous system hyper-excitability and dysfunctional endogenous pain inhibition mechanisms in chronic WAD. However, participants from Singapore were more sensitive and exhibited less pain tolerance than those from Queensland with the cold pressor test. Psychologically, participants with chronic WAD from Queensland and Singapore were not significantly different in depression severity, posttraumatic stress symptom severity, fear-avoidance, self-efficacy and catastrophising beliefs. Australians demonstrated lower perceived injustice and more positive illness perceptions than Singaporeans with chronic WAD.
In summary, there were many similarities but also several differences between Queensland and Singapore in terms of community expectations of recovery and whiplash beliefs, physiotherapists’ whiplash beliefs, physical and psychological presentation of chronic WAD which could potentially influence the beliefs and presentation of people with WAD in both cultures. The lower cold pressor pain sensitivity and higher cold pressor pain tolerance, as well as the more positive illness perceptions and lower perceived injustice in participants from Queensland do not explain the relatively worse long-term outcome of WAD in Queensland. The results of this thesis do not give clear support to the notion of WAD being a culturally-dependent condition.