1 Journal of Orthopaedic Surgery 2011;19(3): Predictors of neck pain after motor vehicle collisions: a prospective survey Ian A Harris, 1 Jane M Young, 2 Bin B Jalaludin, 3 Michael J Solomon 2 1 Department of Orthopaedics, and South Western Sydney Clinical School, University of New South Wales, Liverpool Hospital, Liverpool, 2170, NSW, Australia 2 Surgical Outcome Research Centre, P.O. Box M157, Missenden Road, NSW, Australia 3 Centre for Research, Evidence Management and Surveillance, Liverpool Hospital, Liverpool, NSW, Australia ABSTRACT Purpose. To identify possible predictors (psychosocial) of neck pain in patients with acute injuries following motor vehicle trauma. Methods. 221 male and 85 female patients aged 18 to 85 (mean, 38) years who had acute fractures of the humerus, radius, ulna, pelvis, femur, patella, tibia, talus or calcaneus following motor vehicle trauma were prospectively recruited. No patient sustained a cervical spine injury. Patients sustaining minor trauma were excluded. As putative predictors of neck pain, data relating to demographics, injury, socio-economic status, and compensation were collected at the time of presentation and at month 6. Neck pain was measured by adapting the bodily pain questions from the SF-36 general health survey. Simple unadjusted and multiple regression analyses were conducted. Results. 232 (76%) of the 306 patients completed the 6-month questionnaire. In multiple regression analysis, neck pain at 6 months was significantly associated with female gender, having a primary level of education only, and use of a lawyer. Conclusion. Adversarial legal and compensation involvement may attribute to the development and continuation of neck pain after motor vehicle trauma. Key words: accidents, traffic; compensation and redress; neck pain; whiplash injuries INTRODUCTION Neck pain is the most frequent injury sustained by motor vehicle occupants in the USA. 1 In developed countries, claims for whiplash injury cost billions of dollars each year. 2 4 Neck pain after motor vehicle injury may involve the intervertebral discs, facet joints, and the spinal cord, and is associated with atypical manifestations of carpal tunnel syndrome. 5 7 No theory for whiplash based on physical damage has been widely accepted. 8,9 The prevalence of neck pain in uninjured controls is similar. 10,11 Changes in the incidence of whiplash has been noted after legislative changes. 12,13 Such observations have led Address correspondence and reprint requests to: Prof Ian A Harris, Department of Orthopaedics, Liverpool Hospital, Liverpool, NSW, 2170, Australia.
2 318 IA Harris et al. Journal of Orthopaedic Surgery to the proposal of alternative theories implicating psychosocial factors in neck pain after motor vehicle collisions. 14,15 Non-physical factors attributing to the development of whiplash include compensation, litigation and legislation, 3,12,13 blame, 14 post-traumatic stress, 16 and symptom expectation. 11,17 Many related studies have been retrospective, have used insurance data that may be unreliable, have used secondary outcomes measures (return to work or case closure), and were prone to selection bias by only including patients seeking compensation. We identified possible psychosocial predictors of neck pain in patients with acute injuries following motor vehicle trauma. MATERIALS AND METHODS Between August 2004 and October 2005, 221 male and 85 female patients aged 18 to 85 (mean, 38) years who had acute fractures of the humerus, radius, ulna, pelvis, femur, patella, tibia, talus or calcaneus following motor vehicle trauma were prospectively recruited from hospitals in the state of New South Wales, Australia. No patient sustained a cervical spine injury. Patients sustaining minor trauma were excluded. A sample size of 240 would be sufficient to investigate 16 variables. Allowing for 20% loss to follow-up, 300 patients were to be recruited. Approval was granted from the Human Research Ethics Committees of the supervising university and each of the participating hospitals. Patients and their treating doctors were asked to complete a questionnaire to provide demographics (age, gender, hospital, country of birth, job satisfaction, and presence of co-morbidities [chronic bronchitis or asthma, heart disease, kidney disease, stroke, high blood pressure, arthritis, cancer, diabetes and liver disease]). In addition, injury details (mechanism [car occupant, motorcyclist, or bicyclist/pedestrian], number of fractures, and presence of orthopaedic and non-orthopaedic injuries) were recorded, as were socio-economic data (highest education level attained, annual household income, and employment status at the time of injury). Six months after the injury, patients were sent a questionnaire to confirm fracture union and compensation-related matters (the use of a lawyer, claim made, claim type, and blame for the injury). The severity of neck pain and functional limitation due to neck pain were measured using the 2 bodily pain questions in the SF-36 general health survey, 18 in which the words neck pain were substituted for bodily pain. The 2 questions were How much neck pain have you had in the last 4 weeks? and During the past 4 weeks, how much did neck pain interfere with your normal work (outside and inside home)? Both questions had been piloted in hospital outpatients and showed good test-retest reliability and were strongly associated with the Neck Disability Index. 19 The neck pain score ranged from 2 (no pain and no functional interference) to 11 (maximal pain and functional interference). General health was also measured. Unadjusted (univariate) analyses were conducted using Pearson s correlation coefficient for continuous variables (e.g. age), and Student s t test and analysis of variance for categorical independent variables. Multiple linear regression analysis was performed, with the neck pain score as outcome. A backward, step-wise process was used, resulting in a model containing variables with a p value of <0.05. Interaction terms were tested in the final model and retained if they were significant at a p value of RESULTS Of 306 patients, one died, 4 were uncontactable (overseas), 13 withdrew consent after recruitment, and 232 (76%) returned the 6-month questionnaire. On comparing variables in responding and nonresponding patients, the latter had lower household incomes (p=0.02). At 6 months, the mean neck pain score was 3.3 (standard deviation, 2.2; range, 2 11). Unadjusted (univariate) associations between possible variables and neck pain score are shown in Table 1. Younger patients were more likely to report neck pain. Mean neck pain scores were significantly lower with each higher income band. In multiple regression analysis, only female gender, use of a lawyer, and having a primary level of education were significant predictors of neck pain (Table 2). The final model included data from 226 patients and accounted for 18.3% of the variation in the neck pain scores. Interaction terms introduced into the final model were not significant. DISCUSSION The higher rate of neck pain in females after motor vehicle collisions has been reported. 13,21 23 Lower education levels have also been associated with neck pain This may be due to differences in coping skills or physical activities, which may reflect differences in the background prevalence of neck pain, rather than differences resulting from the injury. In other words, neck pain may be more common in
3 Vol. 19 No. 3, December 2011 Predictors of neck pain after motor vehicle collisions 319 Table 1 Unadjusted (univariate) association between variable and neck pain Variable % p Value Mean (95% CI) neck pain score Demographic factors Gender Male ( ) Female ( ) Hospital admitted 0.19 Liverpool Hospital ( ) Other ( ) Country of birth 0.03 Australia ( ) Other ( ) Chronic illnesses 0.77 None ( ) ( ) Job satisfaction (if 0.73 employed) Very satisfied ( ) Somewhat satisfied ( ) Somewhat dissatisfied ( ) Very dissatisfied ( ) Injury factors Mechanism Car driver/passenger ( ) Motorcycle rider ( ) Pedestrian/cyclist ( ) No. of fractures ( ) ( ) Other injuries 0.05 No ( ) Yes ( ) Socioeconomic factors Highest education level Primary ( ) Secondary ( ) Certificate/Diploma ( ) Bachelor degree ( ) Annual income $ ( ) $ ( ) $ ( ) $ ( ) Employed at time of 0.03 injury No ( ) Yes ( ) Claim-related factors Previous claim made 0.97 No ( ) Yes ( ) Claim made No ( ) Yes ( ) Claim type (if made) 0.89 Workers compensation ( ) (no-fault system) Third party (fault-based) ( ) Other ( ) Lawyer used No ( ) Yes ( ) Blame Self ( ) Someone else ( ) Don t know ( ) Fracture union 0.23 No ( ) Yes ( ) Table 2 Multiple regression analysis for significant predictors of neck pain Variable Change in mean neck p Value pain score Female gender < Use of a lawyer Education level Primary (reference) - - Secondary Diploma/certificate Degree < people with lower education (owing to employment factors), even without involvement in a motor vehicle accident. The lack of uninjured controls limited our ability to explore this further. Neck pain has been associated with the use of a lawyer, 12,13,21,27 but 2 systematic reviews of whiplash injury provide different conclusions regarding the role of legal/compensation involvement. 28,29 Insurance and compensation systems have a large impact on recovery from acute whiplash injuries, 29 based on findings of the Quebec Task Force on Whiplash- Associated Disorders. 30 Nonetheless, these studies were limited by small sample sizes, poor followup, lack of statistical analysis, recourse to indirect outcomes (such as return to work), retrospective and before-and-after timelines, and varying definitions of legal and compensation involvement. The association between legal involvement and increased reporting of symptoms after traumatic injury has been attributed to coaching by lawyers, symptom magnification for secondary gain, and stresses related to the adversarial legal system. 11,31,32 Such stresses include the need for repeated presentations for examination, dealing with administrative complexities, uncertainty regarding the outcome of the claim, challenges to the patient s veracity, and court appearances. Although it is possible that patients with neck pain were more likely to engage the services of a lawyer, the lack of any association with physical factors makes the consideration of non-physical predictors such as legal involvement reasonable. Blaming others for an injury has been associated with increased reporting of symptoms, and these patients may be more likely to consult a lawyer. Nonetheless, the multiple regression analysis showed that the use of a lawyer was a stronger predictor than blame. Studies have reported no significant association between neck pain and injury severity or vehicular damage. 9,27,30 Our study strengthened theories purporting a greater role for psychosocial factors over physical factors in neck pain after motor vehicle trauma. This
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