1 Journal of Psychosomatic Research 61 (2006) Relationship between posttraumatic stress disorder symptoms and the course of whiplash complaints Jan Buitenhuis a,b, 4, Peter J. de Jong c, Jan P.C. Jaspers d, Johan W. Groothoff e a Medical Department, Univé Insurance The Netherlands b Department of Social Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands c Department of Clinical and Developmental Psychology, University of Groningen, Groningen, The Netherlands d Medical Psychology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands e Department of Social Medicine, Northern Centre for Health Care Research, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands Received 12 October 2005; received in revised form 6 July 2006; accepted 11 July 2006 Abstract Objective: This study investigates the relationship between posttraumatic stress disorder (PTSD) symptoms (avoidance, reexperiencing, and hyperarousal) and the presence, severity, and duration of neck complaints after motor vehicle accidents. Methods: Individuals who had been involved in traffic accidents and had initiated compensation claim procedures with a Dutch insurance company were sent questionnaires (Q1) containing complaint-related questions and the Self-Rating Scale for PTSD. Of the 997 questionnaires that were dispatched, 617 (62%) were returned. Only car accident victims were included in this study (n=240). Complaints were monitored using additional questionnaires that were administered 6 months (Q2) and 12 months (Q3) after the accident. Results: PTSD was related to the presence and severity of concurrent. More specifically, the intensity of hyperarousal symptoms that were related to PTSD at Q1 was found to have predictive validity for the persistence and severity of at 6 and 12 months follow-up. Conclusion: Results are consistent with the idea that PTSD hyperarousal symptoms have a detrimental influence on the recovery and severity of whiplash complaints following car accidents. D 2006 Elsevier Inc. All rights reserved. Keywords: Post-whiplash ; Whiplash-associated disorder; Anxiety; Posttraumatic stress disorder; Hyperarousal; Vigilance Introduction Whiplash is one of the most prevalent posttraumatic diagnoses following traffic accidents. The term whiplash refers to the presumed movement of the neck during an accident. The distortion of the neck that can follow from such movement usually declines over subsequent days or weeks. Even in the absence of identifiable structural injuries, victims may suffer from long-lasting complaints that are characterized by persistent neck pain, often 4 Corresponding author. P.O. Box 15, 9400 AA, Assen, The Netherlands. Tel.: ; fax: address: (J. Buitenhuis). accompanied by cognitive complaints. This persistent is usually known as whiplash-associated disorder or. Studies on the etiology of this chronic have led to conflicting opinions regarding the nature of the complaints and the relevance of psychological factors [1 3]. Although the majority of victims show spontaneous recovery within the first months after the traffic accident, as many as 40% of the victims suffer from long-lasting symptoms, sometimes with severely disabling effects . Insight into factors that are responsible for this chronic course is therefore of great importance. The determination of such predictive factors may provide clues for effective interventions, in addition to its utility in the context of /06/$ see front matter D 2006 Elsevier Inc. All rights reserved. doi: /j.jpsychores
2 682 J. Buitenhuis et al. / Journal of Psychosomatic Research 61 (2006) prevention. Several prognostic factors have already been identified by earlier research . First, it has been found that high initial pain intensity, female gender, and increasing age are predictive of delayed recovery [3,4,6]. In addition, studies have shown that individual coping style may be involved in the course of whiplash complaints. More specifically, a palliative coping style has been proven to be predictive of a chronic course [3,6]. The presence of posttraumatic stress symptoms is another factor that may play an important role in the persistence of whiplash symptoms following a motor vehicle accident . Post-whiplash and posttraumatic stress disorder (PTSD) are both relatively common conditions following traffic accidents [8 11]. As many as 23% of traffic accident victims are reported to have developed PTSD, which is known to have high psychiatric and medical comorbidity [12 15]. The symptoms of PTSD may be involved in the development of in several ways. First, anxiety is an important feature of most PTSD symptoms. Because anxiety is known to influence the perception and experience of pain, PTSD symptoms may alter the perception and experience of acute neck pain . Inflated pain levels may subsequently fuel (avoidance) behaviors that facilitate a chronic course [17 19]. Second, PTSD symptoms may result in heightened vigilance, which may inflate the perception of pain . Third, PTSD symptoms may give rise to a dysfunctional (catastrophic) interpretation of acute neck pain, which may subsequently inflate pain intensity, disability, and psychological distress, independent of the level of the actual physical impairment . Finally, PTSD shares several symptoms with acute whiplash, including insomnia, irritability, and cognitive problems. These symptoms may further intensify the perception of symptoms or lead to misattribution. In support of the idea that the presence of PTSD symptoms affects the symptomatology of whiplash, earlier research has provided preliminary evidence to indicate that the acute posttraumatic stress response (i.e., reexperiencing and avoidance symptoms) is related to the intensity of whiplash symptoms 4 weeks after the accident . In addition, the results of a recent study have provided further evidence that PTSD symptoms may also influence the course of whiplash symptoms. More specifically, the study revealed the reexperiencing and avoidance subscales of the Impact of Events Scale to be associated with relatively persistent whiplash complaints at 6 months follow-up [23,24]. Unfortunately, both previous studies tested only two of the three PTSD symptom scales and neither included the hyperarousal symptom cluster scale. Nonetheless, these symptoms may be highly relevant to the proper understanding of the relationship between PTSD and whiplash complaints . A study by Mayou and Bryant did consider all three PTSD symptoms scales. The participants that they recruited, however, included only victims who had visited an emergency room following their accidents, thereby possibly biasing the results toward patients who were more frightened or whose injuries were more serious . The present study was therefore designed to provide further testing of the robustness and validity of these earlier findings, which suggest that PTSD symptoms are related to the intensity of whiplash complaints and that they have predictive validity regarding recovery from whiplash complaints following motor vehicle accidents. This study includes the hyperarousal symptom cluster in addition to reexperiencing and avoidance symptoms. To test for generalizability, we did not restrict the range of victims to emergency-room visitors. Finally, we examined whether the relationship between PTSD symptoms and whiplash complaints had increased or decreased at prolonged (12-month) follow-up. More specifically, the present study addresses the following questions: 1. Are PTSD symptoms more frequent among individuals who have? 2. Are PTSD symptoms related to the severity of whiplash complaints? 3. Is the presence of PTSD symptoms predictive of delayed recovery from? Methods Study design We used a prospective longitudinal design. Participants were assessed at 1 month (Q1), 6 months (Q2), and 12 months (Q3) after their accidents. Participants and procedure Traffic accident victims who had initiated compensation claim procedures for personal injury with a Dutch insurance company were asked to participate in this study. In the Netherlands, settlement of personal injury claims is based on liability insurance; accident victims seek compensation from the insurance company of the driver who was at fault. The letter of invitation clearly communicated that the present study was independent of the compensation procedure. During the intake period, 997 questionnaires were dispatched. Questionnaires were not sent to claimants who were known to be younger than 18 or older than 65 years of age. The median time for dispatching the questionnaire was 21 days after the accident (mean=22.15 days, S.D.=11.197). The number of initial questionnaires that was returned was 617 (62%). The initial selection from the returned questionnaires included only the responses of victims who had been in
3 J. Buitenhuis et al. / Journal of Psychosomatic Research 61 (2006) car accidents (n=293). To rule out the potentially confounding influence of concurrent complaints and to obtain a homogeneous sample of participants with only soft-tissue injuries, we excluded 30 victims because of a history of whiplash or neck pain, 15 victims because of one or more fractures, and 8 victims because of the absence of physical complaints. In the final sample, therefore, the responses of 240 participants were eligible for further analysis. Questionnaires and outcome variables After a median time of 21 days after the accident, we sent each claimant a questionnaire (Q1) concerning the accident, the injuries that they had sustained, and their complaints at that time. Table 1 provides an overview of the questionnaire items. Consistent with our previous studies on, claimants who suffered from neck pain, a loss of consciousness of no longer than 1 min, and no self-reported previous neck complaints were included as patients [3,26]. The presence of PTSD was assessed using the Self-Rating Scale for PTSD (SRS-PTSD) . This questionnaire was Table 1 Overview of variables analyzed Variable Values Age Years Gender Male, female Loss of consciousness No, for a moment, b1 min, b10 min, and N10 min Hospital visit No; immediately by ambulance; immediately, on own initiative; later, after visit to GP Hospital admittance No, b1 day, and N1 day General practitioner visit No, b1 day, b1 week, and N1 week Back-pain intensity 1 (no pain) to 10 (severe pain) Neck-pain intensity a 1 (no pain) to 10 (severe pain) Headache intensity a 1 (no pain) to 10 (severe pain) Neck stiffness a 1 (no stiffness) to 10 (severe stiffness) Severity of neck 1 (no restrictions) to 10 (severe restriction) movement restriction a Radiating pain in arms a 1 (no pain) to 10 (severe pain) Severity of paresthesia in 1 (no paresthesia) to 10 (severe paresthesia) the arms a Concentration complaints a 1 (no complaints) to 10 (severe complaints) Difficulty reading a 1 (no complaints) to 10 (severe complaints) Difficulty concentrating 1 (no complaints) to 10 (severe complaints) on a conversation a Dizziness a 1 (no dizziness) to 10 (severe dizziness) Use of medication since accident No/yes (includes analgesics and/or muscle relaxants) Sleep disturbance No/yes Frequency of neck pain a,b 1 (daily) to 4 (at least once a month) Onset of neck complaints Hours after accident Posttraumatic stress Three scales questionnaire (SRS-PTSD) a Variable used in whiplash severity score. b Before analyses, recalculated by using the formula: 12 (2original value). designed as an abridged version of the Structured Interview for Posttraumatic Stress Disorder, which measures the presence and severity of PTSD symptoms from both a current and a lifetime perspective . The SRS-PTSD consists of questions that assess the three major symptom groups of PTSD, as listed in the DSM-IV. Eight questions assess the five reexperiencing symptoms; 10 questions assess the seven avoidance symptoms, and 6 questions assess the five hyperarousal symptoms. In accordance with the DSM-IV criteria for PSTD, participants were considered as suffering from PTSD if they reported at least one reexperience, three avoidance symptoms, and two hyperarousal symptoms . We monitored the course of complaints, in all participants, regardless of the presence of initial complaints, at 6 months (Q2) and 12 months (Q3) after the accident by means of the SRS-PTSD. In addition, two identical questionnaires containing questions regarding the complaints at that moment in time were completed. Data reduction PTSD symptoms A dichotomous variable was computed for each assessment point to indicate whether the diagnostic requirements for PTSD were met. In addition to this dichotomous variable, the actual number of avoidance, reexperiencing, and hyperarousal symptoms were used as independent variables. Whiplash complaints A severity score was calculated as the sum of the 11 complaint variables that are marked in Table 1 for each individual who was suffering from at each of the three assessment points. The reliability of these indices in terms of internal consistency was satisfactory (Q1: Cronbach s a=.88, n=134, mean=52.9, S.D.=20.2; Q2: Cronbach s a=.89, n=79, mean=53.5, S.D.=20.5; Q3: Cronbach s a=.91, n=62, mean=53.0, S.D.=20.2). In addition, a dichotomous variable was computed for each assessment point to indicate whether whiplash (i.e., persistent neck pain) was still present. Analysis Categorical variables were recoded into appropriate dummy variables before they were used in the regression analyses. The independent variables used in the regression analyses were first analyzed in associated groups. When analyzing the relationship between PTSD symptoms and the intensity of concurrent complaints (Section 3.3), the groups consisted of the following: first group: hospital visit, hospital admission, and visit GP; second group: medication since accident, backpain complaints, and onset of neck complaints. Variables with significant properties were then simultaneously included in the final regression analysis, together with
4 684 J. Buitenhuis et al. / Journal of Psychosomatic Research 61 (2006) age, gender, and the categorical PTSD variable or the PTSD symptoms. When analyzing the relationship between initial PTSD symptoms and the persistence and severity of at 6 and 12 months follow-up (Section 3.4), the groups consisted of the following: first group: hospital visit, hospital admission, and visit GP; second group: back pain intensity, headache intensity, use of medications since accident, concentration, difficulty reading, difficulty concentrating on a conversation, and dizziness; third group: neck-pain intensity, frequency of neck pain, onset of neck complaints, neck stiffness, severity of neck movement restriction, radiating pain in arms, and severity of paresthesia in the arms. Variables with significant properties were then simultaneously included in the final regression analysis, together with age, gender, and the categorical PTSD variable or the PTSD symptoms. Next, using a backward stepwise selection procedure, the least significant variables were removed (visit GP, headache intensity, back-pain intensity, and, when analyzing the PTSD symptoms, dizziness), using the drop-in-deviance test to compare the new model with the last model, while retaining age, gender, and the PTSD variable(s) in the model. The final models therefore contain age, gender, the PTSD variable(s), and significant confounders. Results General results Table 2 provides an overview of the basic characteristics of participants (n=240). Of the 240 participants in the final sample, 32 (20 with on Q1) did not return the second questionnaire, and 18 (11 with postwhiplash on Q1) did not return the third questionnaire. Analysis indicated no significant differences between those who did and those who did not return the questionnaire with respect to their scores during the first assessment. Table 2 provides an overview of the characteristics of both groups of participants (i.e., those with and those without) as well as descriptive variables on Q1. Using univariate logistic regression, Table 2 Basic characteristics of the eligible group (n=240) at Q1, 1 month after the accident Post-whiplash No Yes Whole group Number of participants Age, mean (S.D.) 35.6 (13.4) 36.3 (12.3) 36.0 (12.8) Male gender, n (%) a 48 (45.3) 39 (29.1) 87 (36.3) Loss of consciousness, n (%) No 95 (89.6) 120 (89.6) 215 (89.6) For a moment 8 (7.5) 14 (9.5) 22 (9.2) Less than 1 min 0 4 (3.0) 4 (1.7) Less than 10 min More than 10 min 3 (2.8) 0 3 (1.3) Hospital visit, n (%) No 62 (58.5) 70 (52.2) 132 (55.0) Immediately, by ambulance 32 (30.2) 38 (28.4) 70 (29.2) Immediately, on own initiative 7 (6.6) 13 (9.7) 20 (8.3) Later, after a visit to a general practitioner 5 (4.7) 13 (9.7) 18 (7.5) Hospital admission, n (%) No 96 (90.6) 123 (91.8) 219 (91.3) Yes, 1 day or shorter 7 (6.6) 8 (6.0) 15 (6.3) Yes, more than 1 day 3 (2.8) 3 (2.2) 6 (2.5) Visit to general practitioner, n (%) b No 48 (45.3) 20 (14.9) 68 (28.3) Yes, the same day 19 (17.9) 27 (20.1) 46 (19.2) Yes, within 1 week 31 (29.2) 71 (53.0) 102 (42.5) Yes, after more than 1 week 8 (7.5) 16 (11.9) 24 (10.0) Neck-pain intensity, n (%) c 6.5 (2.25) Neck-pain frequency, n (%) d Daily 116 (86.6) More then 3 h per week 8 (6) At least once a week 9 (6.7) At least once a month 0 a Univariate logistic regression, odds ratio=2.016, 95% CI= b Univariate logistic regression, reference category bno,q dummy variable (dv) 1: odds ratio=3.411, 95% CI= ; dv 2: odds ratio=5.497, 95% CI= ; dv 3: odds ratio=4.800, 95% CI= c Information on other variables available from the first author. d One missing case.
5 J. Buitenhuis et al. / Journal of Psychosomatic Research 61 (2006) the group of individuals with consisted of significantly more women than men. In addition, victims with had visited their general practitioners relatively frequently. None of the other variables showed significant differences between the groups. PTSD symptoms at 1, 6, and 12 months The presence of PTSD and the mean number of symptoms for each symptom cluster at each assessment point are shown in Table 3. At all assessment points (i.e., Q1, Q2, and Q3), PTSD was more prevalent in the group of victims with postwhiplash than it was among the participants who did not report these symptoms (chi-square with Yates continuity correction: v 2 =8.53, df=1, P=.003; v 2 =21.56, df=1, Pb.001; and v 2 =8.65, df=1, P=.003, respectively). For all assessments, the mean number of reexperiencing, avoidance, and hyperarousal symptoms was relatively high in the group with (t test, t values b 3.4, P values b.001). This pattern remained unaffected when the results were corrected for age and gender using analysis of covariance ( F values N13.73, P values b.001). Of the 26 individuals who conformed to the diagnosis of PTSD at Q1, 5 (19%) had not visited any doctor after the accident, 11 (42%) had been to a hospital immediately after the accident, and 5 (19%) had been admitted. PTSD symptoms and the intensity of concurrent complaints Using the whiplash severity score at the three assessment points as dependent variables and all remaining variables from Table 1 as independent variables, linear regression analysis yielded the following results. The use of medication (b=0.289, Pb.001), the severity of back pain (b=0.275, Pb.001), and the presence of PTSD (b=0.329, Pb.001) at Q1 were all associated with the whiplash severity score at Q1 (independent variables simultaneously included in the analysis: age, gender, back-pain intensity, use of medication, and categorical diagnosis of PTSD at Q1). In a subsequent regression analysis, we substituted the number of PTSD symptoms for the three symptom clusters for the categorical diagnosis of PTSD (independent variables simultaneously included in the analysis: age, gender, back-pain intensity, use of medication, number of reexperiencing, avoidance, and hyperarousal symptoms). This analysis revealed that the number of posttraumatic avoidance (b=0.303, Pb.001) and hyperarousal symptoms (b=0.471, Pb.001) was statistically significantly associated with the concurrent whiplash severity score at Q1, whereas the number of reexperiencing symptoms at Q1 (b= 0.091, P=.191) was not. The use of medication (b=0.247, P=.03), the severity of back pain (b=0.238, P=.026), and the presence of PTSD (b=0.285, P=.012) at Q2 were all associated with the concurrent whiplash severity score. In a subsequent regression analysis (independent variables simultaneously included in the analysis: age, gender, back-pain intensity, use of medication, and number of reexperiencing, avoidance, and hyperarousal symptoms), the number of avoidance symptoms (b=0.308, P=.028) 6 months after the accident was associated with the whiplash severity score at Q2. The number of reexperiencing (b=0.003, P=.980) and hyperarousal symptoms (b= 0.242, P=.088) at 6 months follow-up provided no statistically significant association with whiplash severity at Q2. The use of medication (b=0.267, P=.031) at Q3 was associated with the concurrent whiplash severity. No statistically significant relationship was found with the presence of PTSD at that assessment point (b=0.205, P=.102). In a subsequent regression analysis (independent variables simultaneously included in the analysis: age, gender, back-pain intensity, use of medication, and number of reexperiencing, avoidance, and hyperarousal symptoms), the number of hyperarousal symptoms (b=0.435, P=.007) at Q3 were associated with the concurrent whiplash severity score. The number of reexperiencing (b= 0.026, P=.869) and avoidance symptoms (b=0.167, P=.238) provided no significant association at Q3. Table 3 Frequency of PTSD and symptom scales at 1, 6 and 12 months Assessment point (months after the accident) Q1 (1) Q2 (6) Q3 (12) Without With Without With Without With Number of participants With PTSD, n (%) 4 (3.8) 22 (16.4) 4 (3.1) 20 (25.3) 5 (3.9) 11 (17.7) Reexperiencing symptoms, mean (S.D.) 1.16 (1.442) 2.11 (1.684) 0.63 (1.125) 1.59 (1.581) 0.67 (1.102) 1.44 (1.543) Avoidance symptoms, mean (S.D.) 0.66 (1.004) 1.38 (1.381) 0.50 (0.772) 1.80 (1.409) 0.45 (0.895) 1.77 (1.311) Hyperarousal symptoms, mean (S.D.) 0.49 (0.928) 1.66 (1.420) 0.42 (0.826) 1.95 (1.440) 0.37 (0.752) 1.79 (1.332)
6 686 J. Buitenhuis et al. / Journal of Psychosomatic Research 61 (2006) Table 4 Multiple logistic regression model Variable Coefficient (b) S.E. Wald v 2 P value Odds ratio 95% CI Lower Upper Post-whiplash at Q2 Constant Gender Age PTSD Neck pain Dizziness Post-whiplash at Q3 Constant Gender Age PTSD Neck pain Dizziness Post-whiplash at Q2 and Q3 was used as the dependent variable. Explanatory variables are from Q1, including PTSD. Initial PTSD symptoms and the persistence and severity of at 6 and 12 months follow-up Table 4 shows the results of two multiple logistic regression models after stepwise backward modeling, while retaining age, gender, and the PTSD variable, using the presence of at Q2 and Q3 as the dependent variable and the variables from Q1 as independent variables. Most important for the present context, results indicated that the categorical presence of PTSD at Q1 had no independent predictive value for the presence of postwhiplash at Q2 and Q3. Since the inclusion of neck complaints in the equation may result in an underestimation of the actual strength of the association between PTSD and subsequent complaints (i.e., to the extent that neck pain lies in the causal pathway between PTSD and whiplash complaints), we performed an additional regression analysis in which we did not correct for neck pain at Q1. This additional regression analysis, with only age, gender, and the categorical presence of PTSD at Q1, revealed that the presence of PTSD at Q1 had an independent predictive value for the presence of postwhiplash at Q2 (odds ratio=13.941, 95% CI= ) and Q3 (odds ratio=7.518, 95% CI= ). In a subsequent analysis, we substituted the number of PTSD symptoms for the three symptom clusters at Q1 for the categorical diagnosis of PTSD. Table 5 shows the results Table 5 Multiple logistic regression model Variable Coefficient (b) S.E. Wald v 2 P value Odds ratio 95% CI Lower Upper Post-whiplash at Q2 Constant Gender Age Reexperiencing symptoms Avoidance symptoms Hyperarousal symptoms Neck pain Post-whiplash at Q3 Constant Gender Age Reexperiencing symptoms Avoidance symptoms Hyperarousal symptoms Neck pain Post-whiplash at Q2 and Q3 was used as the dependent variable. Explanatory variables are from Q1, including PTSD symptoms.
7 J. Buitenhuis et al. / Journal of Psychosomatic Research 61 (2006) of the two models. With respect to the PTSD symptoms, only the number of hyperarousal symptoms at Q1 provided additional predictive value for the presence of subsequent at 6 and 12 months follow-up. Linear regression using the whiplash severity score as the dependent variable yielded similar results, showing hyperarousal symptoms at Q1 to be related to the severity of whiplash complaints at 6 months (Q2) and 12 months (Q3; b=0.350, P=.013, and b=0.325, P=.045, respectively). No relationship emerged between the number of reexperiencing and avoidance symptoms at Q1 and the whiplash severity score at either Q2 or Q3. Discussion The major results of the present study can be summarized as follows: 1. PTSD and the number of its symptoms are more prevalent among car accident victims who have postwhiplash than they are among victims who do not have. 2. The presence of PTSD symptoms was associated with relatively more severe concurrent complaints. 3. Specifically, the initial number of hyperarousal symptoms was found to have predictive validity for the persistence and severity of at 6 and 12 months follow-up. In accordance with earlier research, PTSD and its symptoms were found to be more prevalent among victims who had in the first 6 months following their accidents [22,23]. Since earlier research has shown that the development of PTSD is not substantially related to either the severity of the accident or the severity of the sustained injury, differences in the frequency of PTSD are not readily explained by any apparently terrifying aspect of the accident [30,31]. The current results seem to correspond with earlier research that suggests that victims with postwhiplash generally considered the accident more frightening than did other car accident victims . Because perceived threat is of paramount importance in developing PTSD, it could be speculated that the presence of whiplash complaints is threatening and induces anxiety complaints. This would make the accident more frightening and could subsequently lead to a relatively high number of posttraumatic stress complaints. Previous research showing a relationship between postwhiplash and PTSD has relied predominantly on victims who were recruited in emergency rooms, thereby possibly biasing the results toward patients who were more frightened or whose injuries were relatively serious . In the present study, only a small minority of the car accident victims who were included had actually visited a hospital following the accident. The present finding that the relationship between and PTSD can also be found in a broader sample underlines its generalizibility and indicates that this relationship reflects a robust phenomenon. The relationship between complaints and PTSD symptomatology was especially pronounced for the PTSD-related hyperarousal symptoms. The mean number of hyperarousal symptoms was three to five times higher among participants with at all three assessment points. Because the hyperarousal symptom cluster closely resembles anxiety disorder symptoms, this finding may indicate that general anxiety symptoms bear an important influence on the perceived severity of postwhiplash. The present finding that victims who reported neck complaints visited their general practitioners more frequently than did those who had no neck complaints provides further indication that anxiety is involved. In other words, although a visit to the general practitioner may be interpreted as indicating that the initial symptoms in this group were relatively severe, it may also reflect reassuranceseeking behavior due to relatively high levels of anxiety. One way to test this idea would be to focus on anxiety reduction during initial interventions. If indeed heightened anxiety levels act in a way to inflate whiplash complaints, anxiety reduction should have a beneficial influence on the intensity of whiplash complaints. In contrast to earlier research, we found no evidence of a relationship between reexperiencing symptoms and postwhiplash [22,23]. One possible explanation could be that we were able to control for hyperarousal symptoms in our analysis. Even after discarding the hyperarousal symptoms, however, we found no significant role for reexperiencing symptoms. The difference may therefore be caused by the present recruitment strategy. It may well be that the relationship between reexperiencing symptoms and is evident only in victims who have visited an emergency room. Several earlier studies of posttraumatic stress symptoms have used the Impact of Events Scale . While this scale includes the first two major symptom clusters, it does not address hyperarousal symptoms. Our results clearly show that the hyperarousal symptoms have the most marked relationship with. We therefore recommend that future research on the role of PTSD in postwhiplash consider all three symptoms scales. In addition, future research should provide further investigation of the apparent role of hyperarousal symptoms in postwhiplash. It should be acknowledged that the present prognostic design does not allow for strong conclusions regarding causal mechanisms that may underlie the co-occurrence of and PTSD symptoms. Nonetheless, the present pattern of results is clearly consistent with the idea that the concurrent presence of PTSD may have an undesirable influence on the course of whiplash complaints.
8 688 J. Buitenhuis et al. / Journal of Psychosomatic Research 61 (2006) One way in which PTSD symptoms may influence the course of whiplash complaints is via the anxiety features of PTSD that may alter the perception and experience of the physical complaints . Furthermore, PTSD symptoms may fuel a vulnerability to the misinterpretation and catastrophization of the physical sensations that accompany hyperarousal and are associated with pain. These sensations may subsequently be attributed to or aggravate its symptoms [1,32 34]. In addition, anxiety-induced heightened vigilance may inflate the perception of pain . Consistent with this idea, the present study has provided evidence that the intensity of PTSD symptoms at Q1 has predictive value for the course of whiplash complaints at follow-up. More specifically, it was found that the presence of a relatively large number of hyperarousal symptoms was related to more intense complaints at 6 and 12 months follow-up. These results suggest that general anxiety symptoms are more relevant in this respect than are PTSD symptoms that are more specific (e.g., reexperiencing and avoidance symptoms). The hyperarousal symptom cluster closely resembles irritability, insomnia, hypervigilance, and similar symptoms. Hypervigilance, which is unique to PTSD, is known to be correlated with higher reported pain intensity, negative affectivity, and catastrophic thinking . Accordingly, it may be that symptom amplification and catastrophization may play a role in the consolidation and perceived severity of, independent of anxiety as such . One way to explore this possibility would be to conduct a prospective study to test the predictive value of catastrophic thoughts regarding either the attribution of somatic complaints or the expected course of complaints. It is important to note that the PTSD hyperarousal scale addresses symptoms regarding concentration, memory function, feelings of insecurity, and nervousness. Some of these symptoms are also often attributed to. It is therefore possible that the predictive properties of the hyperarousal scale are at least partially caused by the fact that this scale measures complaints that are associated with. The present pattern of results, which indicates that only hyperarousal and none of the other PTSD symptoms are related to the prognosis of postwhiplash, further substantiates this idea. The present pattern of results is also consistent with the idea that at least some complaints are actually symptoms of PTSD. The pattern further highlights the importance of considering PTSD, particularly the hyperarousal features, when diagnosing and treating individuals with apparent complaints . With respect to earlier research, a number of comments regarding the relatively low number of participants who had PTSD and those who suffered from both and PTSD after 1 month (11% and 16%, respectively) are in order [30,36]. One explanation might be that research designs that rely on recruiting participants from among emergency-room visitors or from referring doctors may overestimate the frequency of PTSD after motor vehicle accidents, as they may concentrate on a group of victims who are more seriously injured or, more important, more frightened than the average victim is. The lower prevalence of PTSD may therefore have been caused by the fact that we were able to include a considerable number of participants who had not visited an emergency room, or even a medical doctor, following their accidents. The variable findings that are reported in the literature may thus reflect the nature of samples and methodology, at least in part . Additional comments regarding the research sample are in order. The study group consisted of participants who had initiated compensation claim procedures. Since the threshold for starting such procedures is low in the Netherlands, there seems to be no strong reason to suspect that this introduced a bias toward patients whose complaints were more serious . First, the damage-report forms that are used for claiming car damage, and which are usually completed within a few days after the accident, contain a section for the names of victims and their complaints. We invited all claimants directly from these forms, including victims who had not visited an emergency room or sought medical help at the time of the accident. Second, although the insurance company and victims can be seen as opposing parties, most personal injury claims in the Netherlands, even large ones that involve serious injuries, are settled out of court. None of the participants was in actual litigation. Nevertheless, some studies have recently found that compensation is a critical factor to consider when studying [39,40]. Therefore, the personal injury claimant context should be taken into account when interpreting or generalizing our findings. Furthermore, since the exact nature and expectations of compensation may vary greatly from country to country, we advise caution when extrapolating results of one population onto another. Finally, it should be acknowledged that PTSD is not a questionnaire diagnosis. The presence of the minimum number of symptoms required in the three major symptom clusters does not necessarily imply the presence of PTSD. Structured DSM interviews identify a smaller percentage of victims of PTSD than do self-report questionnaires . Questionnaire results, including those that are used here, should therefore be interpreted with caution. Our results confirm earlier research, which showed that recovery from after 6 and 12 months is related to the severity of initial symptoms [3 6]. Furthermore, the present results replicated previous findings that indicated that women are overrepresented among accident victims with [3,6]. To conclude, a considerable number of individuals with were also found to suffer from
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