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Relationship between compensation claims for psychiatric injury and severity of physical injuries from motor vehicle accidents

Matthew M Large
Med J Aust 2001; 175 (3): 129-132.
Published online: 6 August 2001

Abstract

Objective: To examine the relationship between compensation claims for psychiatric injury after motor vehicle accidents and physical injuries sustained.
Design: Audit of Compulsory Third Party (CTP) insurance claims.
Subjects and setting: 559 consecutive CTP claims referred by NRMA Insurance Limited to its sole provider of CTP legal services during a three-month period in 1994 after the claimant had engaged legal representation.
Main outcome measures: Claim for psychiatric injury (any psychiatric disorder excluding traumatic brain injury) supported by a medicolegal report from a psychiatrist, other medical practitioner or psychologist; pre-existing psychiatric disorders; Injury Severity Score; initial treatment setting; hospital stay; percentage of accidents involving loss of consciousness or a death.
Results: 522 claims were eligible for the study; 19.5% (102/522) included a claim for psychiatric injury. A pre-existing depression or anxiety disorder was documented in 11 claims (2.1% of all claims and 3.9% of those claiming psychiatric injury). Only very severe injuries, particularly those involving loss of consciousness, were associated with an increased rate of claims for psychiatric injury.
Conclusions: No association was found between claims for psychiatric injury and severity of physical injuries, except among those most severely injured.


More than 25 000 people are injured in motor vehicle accidents in New South Wales each year.1 Data from the NSW Motor Accidents Authority from 1998 show that about 60% of people who made a claim after a motor vehicle accident obtained legal representation,2 and that the percentage of claims with a psychiatric component rose from 2.2% to 8% between 1990 and 1998.3 NSW Motor Accidents Authority data also show that minor physical injuries result in 54% of all claims, but 77% of claims for psychiatric injury.3

Motor vehicle accidents are associated with post-traumatic stress disorder (PTSD), other anxiety disorders and depression,4,5 although most recent publications refer to PTSD rather than other syndromes.4-9 However, the true incidence of PTSD and other disorders after these accidents is unclear; most studies have sampling bias and other methodological problems.4 The extent to which motor vehicle accidents cause the observed psychiatric disorders is also uncertain. Factors associated with PTSD include those not directly related to the accident, such as past psychiatric history6-9 and involvement in litigation,6,7 and others that are difficult to assess objectively, such as victims' recollections of fear of death6-10 and self-reported loss of consciousness.6,7 The relationship between PTSD and severity of physical injuries has also been investigated,6-13 with one study finding a positive correlation.7

In this study, I examined the relationship between compensation claims for psychiatric injury after motor vehicle accidents and physical injuries sustained.


Methods

Sample

The sample comprised 559 consecutive claims on Compulsory Third Party (CTP) insurance that were referred by NRMA Insurance Limited to its sole provider of CTP legal services in a three-month period in 1994 after the claimant had engaged legal representation. All claims arose from motor vehicle accidents that occurred in New South Wales between 1989 and 1994. In this period, 39.5% of NRMA CTP claimants had legal representation.

Of the 559 claims, 37 were excluded from the study as files were missing (25), the claim was from bereaved relatives (10) or the claimant had died since the claim (2). A further 50 files had data missing on one or more of the following: injuries, demographic details, or setting of medical care. As these files did not to appear to include claims for psychiatric injuries, they were included in denominators for proportions with psychiatric injury but were excluded from further analysis.



Data collection and analysis

I collected de-identified data from the files on systematic forms. The dependent variable was a claim for psychiatric injury (defined as any psychiatric disorder, excluding traumatic brain injury) supported by a report from a psychiatrist, other medical practitioner or psychologist. I recorded the presence of one or more of these injuries or traumatic brain injury attributed to the accident by the claimant's experts, as well as any pre-existing psychiatric disorder noted by claimants' or defendants' experts.

Independent variables recorded were age and sex, type of motor vehicle accident and whether fatal (ie, any person killed), Injury Severity Score (ISS)14(calculated from information in the injury summary document in each file), setting of initial medical care (most medically intensive setting in the week after the accident), length of hospital stay, loss of consciousness during or after the accident (self-reported or corroborated), and self-reported neck or back pain (irrespective of physical or radiological signs).

Data were analysed using the computer program SPSS.15 Logistic regression was used to determine the influence of independent variables on the presence of a claim for psychiatric injury.


Results

Most claimants (380; 73%) were passengers or drivers, and the remainder were motorcyclists, cyclists or pedestrians (92; 18%). The status of another 50 (10%) was not known because of incomplete files. Mean age was 34 years (range, 2-82 years), and 49% were male.

Claims for psychiatric injury

Claims for psychiatric or traumatic brain injury are shown in Box 1. One hundred and two people (19.5%) claimed at least one psychiatric injury related to the accident, combined with traumatic brain injury in six cases (another 11 people claimed traumatic brain injury alone). Thirty-six people claimed more than one psychiatric injury. Pre-existing psychiatric disorders are also shown in Box 1. These were documented in 25 people (4.8%), and comprised a depressive or anxiety disorder in 11 (2.1% of all claimants, and 3.9% of those claiming psychiatric injury).

The reports supporting the psychiatric injury claims came from psychiatrists (65), psychologists (28) and other medical practitioners (9); mean time between the accidents and report dates was over two years. Experts disagreed on many claims, with treating practitioners and claimants' experts using the diagnoses of PTSD and depression (15% of claimants) more often than defendants' experts (2.5% of claimants), as described elsewhere.16

Variables associated with psychiatric injury claims

The group that claimed psychiatric or traumatic brain injury had significantly longer hospital stay and higher mean ISS and proportion of accidents involving loss of consciousness than the group who claimed neither type of injury (Box 2). The group that claimed psychiatric injury but not traumatic brain injury also had significantly more accidents involving loss of consciousness and fatal accidents compared with those who claimed neither type of injury. There were no significant differences between the groups in proportions with self-reported neck or back pain.

For the 102 who claimed psychiatric injury, the most medically intensive treatment in the week after the accident was provided by a local medical officer (33), in an emergency department (35), as a general inpatient (25) or in an intensive care unit (9).

Psychiatric injury claims and injury characteristics are shown in Box 3 by initial treatment setting. The percentage of people who claimed psychiatric injury was significantly higher in those treated initially in intensive care than in those treated elsewhere (χ2 = 6.74; df = 1; P = 0.009). The percentage who claimed for PTSD and traumatic brain injury was also higher in the intensive care group (PTSD: χ2 = 8.99; df = 1; P = 0.003; and traumatic brain injury: χ2 = 103; df = 1; P <0.001). Mean ISS, hospital stay and percentage who reported loss of consciousness were also greater in those treated in more medically intensive settings (inpatient and intensive care), supporting the use of initial treatment setting as an indicator of injury severity. However, claims for neck or back pain were lower in claimants who received inpatient or intensive care treatment (Box 3).

The percentage of people who claimed for a psychiatric injury did not increase with increasing ISS over the first nine deciles (mean, 20%). However, the percentage was significantly higher (33%) in people in the tenth ISS decile (ie, the most severely injured 10%) compared with those in the lower nine deciles (χ2= 4.34; df = 1; P = 0.04).

A logistic regression analysis was performed using variables found to be significantly related to claims for psychiatric or traumatic brain injury by previous analyses (Box 4). Loss of consciousness and a fatal accident were significant predictors of claims for psychiatric injury.


Discussion

A claim for psychiatric injury was made in 19.5% of the legally represented CTP claims in this study, which is higher than the 4.6% estimated by the NSW Motor Accidents Authority for all victims of motor vehicle accidents during the same period.3 This confirms the previously reported association between psychiatric injury and legal representation.6,7 PTSD and depression were reported more often in this sample than in a recent survey of the Australian population.17 Conversely, pre-existing psychiatric disorders were documented much less often than the estimated prevalence of all psychiatric conditions in Australia (4.7% v. 17.7%17). This suggests that medicolegal assessments may under-report pre-existing psychiatric disorders and may sometimes wrongly identify a motor vehicle accident as the cause of a depressive or anxiety disorder that was actually pre-existing.

In contrast to findings of the NSW Motor Accidents Authority,3 my study found that minor injuries were no more likely to be associated with a psychiatric injury than more severe injuries. However, a third of psychiatric injury claims (33/102) were made by people with physical injuries that were not severe enough for them to attend an emergency department or be admitted to hospital at the time of the accident. The study did find a positive relationship between the severity of physical injuries and claims for psychiatric injury in people who were very seriously injured. The psychological trauma of being severely injured may cause PTSD.5,7 Severe physical injuries may also cause psychiatric symptoms because of disability, pain or financial loss.5 However, in my study, the higher rate of claims for psychiatric injury in severely injured claimants was associated with loss of consciousness and involvement in a fatal accident rather than with other measures of injury severity. Reported loss of consciousness may be difficult to distinguish from amnesia resulting from emotional stress,18 which may predispose to psychiatric injury.19

The use of insurance claimants as the sample in this study led to selection bias and may have influenced the psychiatric injuries diagnosed by experts. The incidence and prognosis of whiplash injury are influenced by the system of assessing eligibility for compensation,20 and psychiatric injury may be similarly affected. More severely injured claimants may under-report their psychiatric symptoms because they are more concerned about their physical injuries and because the grounds for compensation for physical injuries have been clearly established. Claimants who are not seriously injured but are hurt or upset and have received less initial medical care may report more psychiatric symptoms. The opinions of expert witnesses may, in turn, be influenced by their role in the adversarial legal system.16 Under the current NSW system, some claimants may exaggerate their disability or genuinely become disabled because "significant disability" is a requirement for compensation;21 claimants who have a psychiatric injury but are less disabled are not compensated.

Reform of the rules on expert evidence designed to reduce bias22,23 and a move to more detailed assessment of the cause of psychiatric symptoms after motor vehicle accidents may reduce the pressure for the NSW government to further limit psychiatric injury claims.



Acknowledgements

I would like to acknowledge NRMA Insurance Limited and Mr Victor Kelly of Abbott Tout Solicitors, Sydney, NSW, for making claimants' files available; Dr Timothy Heath (Concord Repatriation and General Hospital, Sydney, NSW) for his help with data analysis; and Dr Olav Nielssen (Psychiatrist, Sydney, NSW) for his assistance with the manuscript. The study was not funded.

References

  1. Motor Accidents Authority and Roads and Traffic Authority of New South Wales. Road safety statistics, 2000. Available at <http//www.maa.nsw.gov.au/proftest/statistics/injury/report05.htm> (last sighted Jul 2001).
  2. Motor Accidents Authority and Road Traffic Authority of New South Wales. Compulsory third party statistics, 1999. Available at <http//www.maa.nsw.gov. au/professionals/statistics/CTP_stats_98.htm>
  3. Suhood S. Claims involving psychological disturbance, September 2000. Sydney: Motor Accidents Authority and Road Traffic Authority of NSW, 2000.
  4. Blaszczynski A, Gordon K, Silove D, et al. Psychiatric morbidity following motor vehicle accidents: a review of methodological issues. Compr Psychiatry 1998; 39: 111-121.
  5. Mayou R. The psychiatry of road traffic accidents. In: Mitchell M, editor. The aftermath of road traffic accidents. London: Routledge Press, 1997: 33-48.
  6. Ehlers A, Mayou RA, Bryant B. Psychological predictors of chronic posttraumatic stress disorder after motor vehicle accidents. J Abnorm Psychol 1998; 107: 508-519.
  7. Blanchard EB, Hickling EJ, Taylor AE, et al. Who develops PTSD from motor vehicle accidents? Behav Res Ther 1996; 34: 1-10.
  8. Mayou R, Bryant B, Duthie R. Psychiatric consequences of road traffic accidents. BMJ 1993; 307: 647-651.
  9. Ursano RJ, Fullerton CS, Epstein RS, et al. Acute and chronic posttraumatic stress disorder in motor vehicle accident victims. Am J Psychiatry 1999; 156: 589-595.
  10. Green MM, McFarlane AC, Hunter CE, Griggs WM. Undiagnosed post-traumatic stress disorder following motor vehicle accidents. Med J Australia 1993; 159: 529-534.
  11. Feinstein A, Dolan R. Predictors of post traumatic stress disorder following physical trauma: an examination of the stressor criterion. Psychol Med 1991; 21: 85-91.
  12. Bryant RA, Harvey AG. Initial posttraumatic stress responses following motor vehicle accidents. J Trauma Stress 1996; 9: 223-234.
  13. Blanchard EB, Hickling EJ, Taylor AE, Loos W. Psychiatric morbidity associated with motor vehicle accidents. J Nerv Ment Dis 1995; 183: 495-503.
  14. Baker SP, O'Neill B, Haddon W, Long WB. The Injury Severity Score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma 1974; 14: 187-196.
  15. SPSS for Windows. Release 9.0.1. Chicago: SPSS Inc, 1999.
  16. Large M, Nielssen O. An audit of medico-legal reports prepared for claims of psychiatric injury following motor vehicle accidents. Aust N Z J Psychiatry. In press.
  17. Henderson S, Andrews G, Hall W. Australia's mental health: an overview of the general population survey. Aust N Z J Psychiatry 2000; 34: 197-205.
  18. Kopelman MD. Fear can interrupt the continuum of memory. J Neurol Neurosurg Psychiatry 2000; 69: 431-432.
  19. Mayou RA, Black J, Bryant B. Unconsciousness, amnesia and psychiatric symptoms following road traffic accident injury. Br J Psychiatry 2000; 177: 540-545.
  20. Cassidy JD, Carroll LJ, Cote P, et al. Effect of eliminating compensation for pain and suffering on the outcome of insurance claims for whiplash injury. N Engl J Med 2000; 342: 1179-1186.
  21. Motor Accidents Compensation Act (NSW) 1999.
  22. Friston M. New rules for expert witnesses: The last shots of the medico-legal hired gun. BMJ 1999; 318: 1365-1366.
  23. Federal Court of Australia. Practice direction: guidelines for expert witnesses. Canberra: Federal Court of Australia, 1998. Available at <http://www. fedcourt.gov.au/pracproc/practice_direct.html> last sighted Jul 2001.

(Received 31 Jul 2000, accepted 3 May 2001)



Authors' details

Department of Psychiatry, Royal Prince Alfred Hospital, Sydney, NSW.
Matthew M Large, FRANZCP, Staff Specialist Psychiatrist.

Reprints will not be available from the author.
Correspondence: Dr M M Large, Department of Psychiatry, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050.
mlargeATozemail.com.au


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1: Number of people claiming psychiatric or traumatic brain injuries and pre-existing psychiatric disorders among 522 insurance claimants
Injury or disorder Injury claim Pre-existing disorder

Traumatic brain injury (TBI) 17 (3.3%) 0
Post-traumatic stress disorder 48 (9.2%) 0
Depressive disorders 46 (8.8%) 8 (1.5%)
Anxiety disorders 15 (2.9%) 3 (0.6%)
Somatoform disorders 8 (1.5%) 3 (0.6%)
Adjustment disorders 12 (2.3%) 0
Substance abuse 3 (0.6%) 4 (0.8%)
Dementia or low IQ 0 3 (0.6%)
Schizophrenia 0 2 (0.4%)
Other 6 (1.1%) 2 (0.4%)
Total*
  Psychiatric injury 102 (19.5%) 25 (4.7%)
  Psychiatric injury or TBI 113 (21.6%) 25 (4.7%)

*36 people claimed more than one psychiatric injury.
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2: Demographic, injury and accident characteristics among 472 insurance claimants* (95% CI)
Variable No psychiatric or
traumatic brain injury
(n=359)
Psychiatric injury
(n=102)
Psychiatric or traumatic
brain injury
(n=113)

Age in years (95% CI) 33.4 (31.8-35.1) 36.4 (35.5-39.1) 35.7 (33.0-38.3)
% Male 49% (44%-54%) 46% (36%-56%) 49% (39%-58%)
Hospital stay in days 4 (3-5) 8 (4-12) 11 (6-16)
Injury Severity Score† 11.7 (11.0-12.5) 14.0 (12.1-15.9) 16.1 (13.1-18.4)
% With loss of consciousness 9% (6%-12%) 25% (16%-33%) 31% (23%-39%)
% In fatal accident 1% (0-3%) 8% (3%-13%) 7% (2%-12%)
% With neck or back pain 62% (57%-67%) 68% (59%-77%) 64% (55%-73%)

Values in bold are significantly different from values for group with no psychiatric injury or TBI, as defined by non-overlapping 95% CIs.
* 50 claimants were excluded from this analysis as no information was available on one or more of the following: nature of physical injuries, demographic details, or setting of medical care.
† Maximum possible score, 75.
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3: Psychiatric injury claims and injury characteristics among 472 insurance claimants,* according to initial treatment setting† (95% CI)
Local medical
officer (n=177)
Emergency
department (n=146)
General
inpatient (n=129)
Intensive
care unit (n=20)

% With psychiatric injury 19%
(13%-24%)
24%
(17%-31%)
19%
(12%-26%)
45%
(26%-63%)
% With post-traumatic
stress disorder
10%
(6%-14%)
10%
(5%-15%)
8%
(3%-12%)
30%
(10%-50%)
% With traumatic
brain injury
0.6%
(0-1.7%)
0.7%
(0-2.0%)
5%
(1%-8%)
45%
(23%-67%)
Mean Injury
Severity Score
8.0
(7.5-8.5)
10.3
(9.5-11.0)

18.5
(17.0-20.0)

36.7
(31.3-42.0)
Mean hospital stay (days) 0 1 13 (9-17) 40 (24-56)
% With loss of consciousness 2%
(0-4%)
12%
(6%-18%)
27%
(19%-35%)
60%
(38%-82%)
% With neck or back pain 81%
(75%-87%)
71%
(64%-78%)
33%
(24%-41%)
20%
(2%-38%)

PTSD=Post-traumatic stress disorder. TBI=Traumatic brain injury.
* 50 claimants were excluded from this analysis as no information was available on one or more of the following: nature of physical injuries, demographic details, or setting of medical care.
† Most medically intensive treatment setting in the week after the accident.
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4: Multivariate logistic regression analysis of variables potentially associated with psychiatric injury claims
Odds ratio (95% CI) P

Injury severity score* 0.98 (0.95-1.02) 0.29
ICU treatment 1.86 (0.80-4.35) 0.15
Hospital stay (days)* 1.00 (0.98-1.02) 0.45
Loss of consciousness 1.82 (1.20-2.88) 0.006
Fatal accident 3.47 (1.52-7.92) 0.003

ICU=Treatment in intensive care unit during first week. *Continuous variables.
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Received 25 September 2018, accepted 25 September 2018

  • Matthew M Large


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