What Factors Influence Persistent Neck Pain after Whiplash?

Whiplash injuries are a frequent cause of chronic neck and back pain and are common cases in the personal injury litigation arena.  Litigation of these cases is often predicated on science as much as it is predicated on the facts of the case.  The study below was recently published in Spine Journal, and will give some clarity about those factors that affect the development of chronic neck pain status post a rear-end motor vehicle accident.

Eulogio Pleguezuelos Cobo, MD; M. Engracia Pérez Mesquida; Elisabet Palomera Fanegas; Eva Moreno Atanasio; M. Beatriz Samitier Pastor; Cristina Perucho Pont; Carlos Matarrubia Prieto; Genoveva Reverón Gómez; Lluis Guirao Cano

 

Spine. 2010;35(9):E338-E343

 

Abstract and Introduction

Abstract

Study Design. Prospective longitudinal study.
Objective. To identify prognosis factors that allow us to identify patients with risk of developing chronic symptoms and disabilities after a whiplash injury.
Summary of Background Data. The prognosis factors for poor recovery in acute whiplash are not conclusive.
Methods. We included 557 patients who suffered whiplash injury after road traffic accident and visited the Department of Physical Medicine and Rehabilitation of Mataró Hospital (Spain) for medical evaluation and rehabilitation treatment. The variables were collected following a protocol designed for the study, and all patients were assessed through the Visual Analogue Scale (VAS) for the intensity of neck pain, the Goldberg Depression and Anxiety Scale and the Northwick Park Neck Pain Questionnaire (NPH) for cervical column functionality at initial evaluation and 6 months later.
Results. Factors related with VAS 6 months after the whiplash injury were women, age, number of days of cervical column immobilization, previous neck pain, self-employed workers, housewives, pensioners, students, presence of headache or dizziness, and VAS, Goldberg Depression and Anxiety scale, and NPH scores at initial evaluation. In multivaried analysis, it had been found that the variables that had influence on VAS 6 months after the whiplash injury were statistically significant for age, presence of dizziness, self-employed workers, and VAS and NPH scores at initial evaluation.
Conclusion. Our findings indicate that factors that allow us to identify patients at risk for poor recovery are age, dizziness, and initial evaluation of neck pain with VAS and cervical column functionality with NPH.

Introduction

The whiplash is a cervical column injury, which is caused when the neck is violently extended, generally produced in vehicle collisions. It was described first time by Crowe in 1928.^[1] After the Quebec Task Force on whiplash-associated disorders (WAD) study, whiplash was defined as a set of symptoms that appear after an acceleration-deceleration mechanism of energy transfer to the neck. That energy transfer mechanism may be caused by road collisions between vehicles, but it could also occur in other circumstances (i.e., diving). The energy transferred results into bone or soft tissue injuries, which could invariably lead to a variety of clinical symptoms.^[1]

The incidence is variable in different geographical areas.^[1] In the United States, 3 cases per 1000 inhabitants are diagnosed of this disease per year,^[2] in Norway, 2 cases per 1000 inhabitants per year,^[3] in Australia, 1 case per 1000 inhabitants per year,^[4] and in Quebec, 0.7 cases per 1000 inhabitants per year.^[4]

The main characteristic of this syndrome is the absence of evidence of pathology findings as detected in different imaging techniques despite the traumatism intensity, symptoms, and clinical findings. This poor evidence carries along with important social and sanitary problems. Although we could say that whiplash is a benign pathology, we should also consider that this is a disease with an high impact on health public, because the huge number of incapacities produced are defrayed by the public coffers with an estimated expenditure to the tune of 10,000 million euros per year in Europe, whereas in the United States, the numbers could rise between 4.5 and 29 billion dollars.^[5,6]

On the other hand, prognostic factors in whiplash injury can be either magnified or hidden because of the existence of court cases to obtain economic compensations. Cassidy et al^[7] showed that there is a diminution in the incidence of whiplash, being up to 28% in those patients with a better prognostic, when compensation laws regarding accidents were modified. In the literature, there are no unified criteria to identify those patients with risk of developing chronic symptoms and disabilities in the whiplash injury. The goal of this prospective longitudinal study is to identify prognostic factors for poor recovery in whiplash injury after initial evaluation at Department of Physical Medicine and Rehabilitation (DPMR), considering pain as the main variable of the study.

 

Materials and Methods

Study Design and Population

Prospective longitudinal study was designed to identify prognostic factors for poor recovery in whiplash injury after initial evaluation at DPMR. Five hundred fifty-seven patients who suffered neck pain due to a whiplash injury sustained in a road traffic accident and were sent to the DPMR from the Department of Orthopedic of Mataró Hospital between October 2005 and June 2007 for medical evaluation and rehabilitation treatment.

We used the modified WAD clinical classification to unify criteria to evaluate and classify the whiplash^[1] (Table 1). The inclusion criteria were as follows: age between 18 and 75 years old and WAD I or II as a result of a road traffic accident with symptoms such as neck pain, headache, or dizziness within 48 hours after injury. Patients were excluded from the study if they had WAD III or IV, fractures linked to upper and/or lower extremities, traumatic brain injury, cervical spine surgery before injury, and oncologic or rheumatic pathology. The patients were treated according to the established rehabilitation treatment protocol for neck pain after road traffic accident. The criteria used to discharge patients were symptoms resolution, complete cervical range of motion, or clinical stabilization despite the duration of treatment.

Table 1. Whiplash-Associated Disorders (WAD) Clinical Classification¹

WAD 0	No neck complaint. Absence of physical signs
WAD I	Neck complaint of pain, stiffness, or merely tenderness. No physical signs
WAD II	Neck complaint and musculoskeletal signs that include restricted range of motion and point tenderness
WAD III	Neck complaint and neurologic signs that include decreased or absent deep tendon reflexes, weakness, and sensory deficits
WAD IV	Neck complaint and fracture or dislocation

Data Collection

The following variables were collected during the first medical visit at the DPMR through a protocol designed for this particular study: Sociodemographic data: gender, age, education level (high, medium, and low), working condition before the accident (employers, self-employed workers, students, housewives, and pensioners), transitory labor disability after the accident; preexisting health problem: presence of neck, dorsal, and low back pain before the accident, drug taking including antidepressives and/or sedatives before the accident; crash-related characteristics: location of the impact (back, front, and side), situation inside the vehicle at the time of the collision (driver, codriver, and passenger); clinical variables: WAD classification, presence of headache, dizziness, dorsal pain, low back pain, shoulder pain, and temporomandibular joint pain; and others such as time (in hours) taken to get to the emergency unit, time(in days) passed before coming to the DPMR, and time (in days) of cervical column immobilization.

We used the Visual Analogue Scale (VAS) scale through a 100-mm line to gauge the pain. This is a reliable, valid, and responsive assessment tool to evaluate pain intensity with a scale from 0 to 100, being 0 no pain and 100 very severe pain. Depending on the intensity of the pain, we can divide it into three categories: 0 to 30 as mild pain, 31 to 59 as moderate pain, and 60 to 100 as severe pain.^[8,9]

The Goldberg Depression and Anxiety Scale, a self-managed by patient scale, was used to value the patients' psychopathologic state. The specificity and sensitivity of this scale were 91% and 86%, respectively, when patients were assessed with the full set of 60 questions contained in a psychiatric assessment schedule.^[10] The subscale about anxiety consist of 9 questions: a result above 4 detects 73% of anxiety cases; the subscale about depression consists of 9 questions as well: a result above 3 shows 82% of depression cases.^[9,10]

The determination of the cervical column functionality was established by the Spanish version of the Northwick Park Neck Pain Questionnaire (NPH), which is a feasible, reliable, and valid instrument to measure pain in Spanish-speaking patients with chronic neck pain. It is a 10-point questionnaire with multiple answers self-managed by patient. The final evaluation is centered on 0 to 100 interval; a lower score indicating more severe disability.^[11]

The scales and the questionnaire were applied to all patients during the medical visit at DPMR (initial evaluation) and 6 months after whiplash injury. The outcome variable of the study was VAS score 6 months after whiplash injury.

Ethical clearance for the study was obtained from the institutional Medical Ethics Committee, and all procedures were conducted according to the Declaration of Helsinki. All the subjects signed consent forms to participate in the study.

Statistical Analyses

Descriptive analysis of data were done by calculating means and standard deviations for quantitative variables and percentages for qualitative variables. To study the correlation between 2 quantitative or ordinal variables, the Spearman (r) correlation coefficient was used. To study the association between a continuous and a dichotomy variable, the Student t test was used, for variables that follow normal distribution, and a Mann Whitney U, for non-Gaussian variables was applied. Categorical variables were compared by χ² test. When we compared means for 3 groups, we used a Kruskal-Wallis test for variables with not normal distribution. A multivariate analysis was performed by a multiple lineal regression (stepwise method) for VAS 6 months after whiplash injury was made. Only statistically significant variables of the crude associations (P < 0.05) were included. To compare initial and final study variables, the ranks with signs of Wilcoxon test (mated data) was used for continuous variables, and McNemar test was used for categorical variables.

Results

Nine hundred seventy-six patients who suffered neck pain because of a whiplash injury sustained in a road traffic accident were sent to the DPMR. Of them, 682 met the inclusion criteria, and 557 had 6 months of follow-up. The results of descriptive variables analysis of the study are given in Table 2 . There were more women than men who predominantly were workers with employed contracts, and 41.5% of the patients had already applied for transitory labor disability after a traffic accident. Before the whiplash injury occurred almost, a quarter of the sample suffered neck and low back pain. Almost a fifth of them took drugs like antidepressives or sedatives. The crash-related characteristics of the accident were mostly back impacts, and the patients were drivers of the vehicle. Fewer were WAD I, and all the patients had neck pain after whiplash injury with headache and dizziness in most of them. The majority of them visited the emergency unit within 24 hours after whiplash injury, while the mean period of time taken before arrival at the DPMR was 29.5 days. The mean of the period of cervical immobilization was 10.7 days.

Table 2. Descriptive Analysis of Study Variables

		n
Sociodemographic variables
Sex (%)
Men	33.2	185
Women	66.8	372
Age (yr)*	35.6 ± 13.5	557
Education (low) (%)†	15.61	87
Working condition (%)
Employed contracts	60.5	337
Self employed	12.6	70
Student	10.6	59
Housewife	13.8	77
Pensioner	2.5	14
Preexisting health problem† (%)
Neck pain	23.7	132
Dorsal pain	5.8	32
Low back pain	20.3	113
Medication use before accident (%)
Tranquilizers	9.3	52
Sedatives	10.3	57
Crash-related characteristics†
Localization of the impact (%)
Back	71.1	396
Front	9.7	54
Side impact	19.2	107
Situation inside vehicle
Drivers	66.6	371
Codrivers	25.1	140
Passenger	5.9	33
Clinical variables (%)
WAD I	11.1	62
WAD II	88.9	495
Neck pain	100	557
Headache	51.9	289
Dizziness	44.8	249
Dorsal pain	5.8	32
Low back pain	7.4	41
Shoulder pain	3.9	22
Temporomandibular joint pain	5.1	28
Other variables
Hours to arrive at emergency unit (%)
<24 hr	94.3	525
>24 hr	5.7	32
Days to arrive at Department of Rehabilitation*	29.5 (14.3)
Days of cervical column immobilization*	10.7 (8.6)

*Variables expressed in mean (standard deviation).
†Variables self-reported.
n indicates frequency.

The results of scales and questionnaire are given in Table 3 . The mean of the score of VAS 6 months after whiplash injury showed a statistically significant (P < 0.001) reduction of almost 50% respect to the VAS at initial evaluation. The Goldberg Depression and Anxiety scale and NPH score had also improved (P < 0.001) 6 months after the injury. Although, at initial visit, most of the patients had a moderate level score of VAS, 6 months later, they had mostly a mild score level (P < 0.001), being an indication of a favorable evolution. Respect to NPH scores, the mean at first evaluation was 47.8, and 6 months after whiplash injury was 27.9, which evidence a favorable evolution (P < 0.001).

Table 3. Results of Scales and Questionnaire

	Initial Evaluation	Evaluation 6 mo Later	P
Neck pain intensity (VAS score)*	61 (16)	35 (2)	<0.001
Mild pain: 0–30†	27 (4.8%)	309 (56.1%)	<0.001
Moderate pain: 31–60†	277 (49.8%)	192 (34.8%)	<0.001
Severe pain: 61–100†	253 (45.4%)	50 (9.1%)	<0.001
Goldberg Scale*
Depression	3.1 (2.5)	2.2 (2.2)	<0.001
Anxiety	5.2 (3.1)	3.3 (2.9)	<0.001
Northwick Park Neck Pain*	47.8 (17.5)	27.9 (17.9)	<0.001

*Variables values expressed in mean (standard deviation).
†Variables values expressed in frequency (percentage).

The results of the crude associations between VAS 6 months after whiplash injury and study variables are shown in Table 4 and Table 5 . The results of the VAS criteria 6 months after whiplash injury and quantitative variables are shown in Table 6 . The factors related with poor recovery of VAS 6 months after whiplash injury were the following: women, old age, housewives, pensioners, preexisting neck pain, presence of headache or dizziness, days of cervical column immobilization, initial VAS, NPH and Anxiety and Depression Goldberg Scale scores, and NPH and Goldberg Depression and Anxiety Scale scores after 6 months of the injury. Factors related with good recovery of VAS 6 months after whiplash injury were self-employed workers and students.

Table 4. Crude Associations Between VAS 6 Months After Whiplash and Qualitative Variables

	VAS 6 mo After Whiplash*	P
Sex
Men/women	3.16 (2.06)/3.63 (2.00)	0.004
Working condition†
Employed contracts (yes/no)	3.49 (2.02)/3.47 (2.04)	NS
Self-employed (yes/no)	2.90 (1.97)/3.56 (2.03)	0.008
Student (yes/no)	2.93 (2.07)/3.54 (2.02)	0.024
Housewife (yes/no)	4.21 (2.08)/3.36 (2.00)	0.001
Pensioner (yes/no)	5.21 (2.12)/3.43 (2.01)	0.002
Preexisting health problem†
Neck pain (yes/no)	3.92 (2.06)/3.34 (2.00)	0.003
Dorsal pain (yes/no)	4.00 (2.08)/3.44 (2.02)	NS
Low back pain (yes/no)	3.51 (1.87)/3.47 (2.07)	NS
Medication use before accident
Antidepressives (yes/no)	3.90 (2.05)/3.43 (2.02)	NS
Sedatives (yes/no)	3.84 (2.07)/3.43 (2.02)	NS
Characteristics in relation with accident†
Localization of the impact
Posterior (yes/no)	3.55 (2.04)/3.29 (2.00)	NS
Lateral (yes/no)	3.25 (2.13)/3.53 (2.00)	NS
Situation inside vehicle
Driver (yes/no)	3.39 (2.05)/3.63 (1.97)	0.091
Copilot (yes/no)	3.53 (1.95)/3.46 (2.06)	NS
Passenger (yes/no)	3.73 (2.18)/3.46 (2.02)	NS
Symptomatology at initial valuation†
WAD I/WAD II	4.00 (1.41)/3.48 (2.05)	NS
Headache (yes/no)	3.79 (2.02)/3.13 (1.99)	0.0001
Dizziness (yes/no)	3.98 (2.04)/3.06 (1.94)	0.0001
Dorsal pain (yes/no)	3.63 (1.98)/3.47 (2.04)	NS
Low back pain (yes/no)	3.88 (2.27)/3.44 (2.01)	NS
Temporomandibular joint pain (yes/no)	4.04 (2.01)/3.44 (2.03)	0.085

†Variables reported by patient.
*Variables values expressed in mean (standard deviation).

Table 5. Crude Associations Between Quantitative Variables and VAS 6 Months After Whiplash

	r	P
Age	0.209	<0.001
Hours to arrive at emergency unit	−0.007	NS
Days to arrive at DPMR	−0.02	NS
Days of cervical column immobilization	0.097	0.022
VAS score*	0.366	<0.001
Goldberg Scale*
Depression	0.252	<0.001
Anxiety	0221	<0.001
NPH*	0376	<0.001
Goldberg Scale†
Depression	0441	<0.001
Anxiety	0432	<0.001
NPH†	0704	<0.001

*Results at initial valuation.
†Results 6 mo after whiplash.

Table 6. Crude Associations Between Quantitative Variables and VAS Categorization 6 Months After Whiplash*

	VAS ≤30			VAS 31–59			VAS ≥60–100			P
	N	Mean	SD	N	Mean	SD	N	Mean	SD
Age	309	32.85	12.16	192	38.97	14.03	50	40.76	15.59	<0.001
Hours to emergency unit	309	25.48	6.39	192	24.62	4.55	50	25.92	6.58	NS
Previous accidents	309	1.08	0.29	192	1.11	0.39	50	1.14	0.35	NS
Days of immobilization	309	9.79	8.30	192	12.04	9.36	50	11.08	7.83	0.024
Days to arrive at DPMR	309	30.31	15.40	192	27.91	12.90	50	30.48	13.67	NS
VAS score†	309	56.6	15.9	192	67.8	14.8	50	68.8	18.1	<0.001
NPH score†	309	42.74	16.26	192	54.39	17.20	50	55.69	15.37	<0.001
Goldberg Scale†
Depression	309	2.57	2.22	192	3.80	2.58	50	3.98	2.71	<0.001
Anxiety	309	4.74	3	192	5.63	3.05	50	6.24	3.13	<0.001
NPH‡	309	17.77	12.14	192	38.61	14.58	50	49.78	16.63	<0.001
Goldberg Scale‡
Depression	309	1.36	1.76	192	3.14	2.45	50	3.82	2.40	<0.001
Anxiety	309	2.27	2.38	192	4.31	3.15	50	5.40	3.30	<0.001

*Variables values expressed in means (standard deviation).
†At initial evaluation.
‡At 6 mo after whiplash evaluation.
DPMR indicates Department of Physical Medicine and Rehabilitation.

In the multivariate analysis, we found that the variables who had statistically significant influence on VAS score 6 months after whiplash injury were old age (P < 0.001), self-employed workers (P = 0.016), presence of dizziness (P = 0.02), initial VAS score (P < 0.001), and initial NPH score (P < 0.001). Old age, presence of dizziness, a higher initial VAS score, and a higher initial NPH score were associated with a higher VAS score 6 months after the whiplash, and to be self-employed worker was associated with lower VAS score 6 months after whiplash. The results are tabulated in Table 7 .

Table 7. Multivariate Analysis

	β	P
Constant	−0.003
VAS score	0.237	<0.001
Age	0.180	<0.001
NPH score	0.309	<0.001
Dizziness	0.391	0.020
Self-employed	−0.578	0.016

Dependent variable: VAS 6 mo after whiplash. Determination coefficient = 0.348. Excluded variables were sex, days of cervical immobilization with collar, Anxiety and Depression Goldberg subscale, preexisting neck pain, students, and presence of headache. R ² = 0.203 (to specify the model adjustment).

Discussion

The majority of patients who had suffered whiplash injury normally recover within the first weeks after the accident; nevertheless, a significant proportion of patients (19%–60%) have constant neck pain, being severe in 10% of this population.^[12] The proportion of patients who are still absent from work after 6 months of whiplash injury is estimated between 9% and 26%.^[13] Chronic WAD is usually defined as symptoms and disabilities, which persist more than 6 months after whiplash injury.^[13] The lack of a unified criterion about poor recovery prognostic factors in whiplash injury prompted us to develop a study to detect them at the patient initial evaluation at DPMR, for what we could determine the risk of chronification of the symptomatology to be able to act consistently. Following the biopsychosocial model of pain, the natural course of chronic whiplash would be determined by a wide range of factors, the reason why recent studies are based on this model.^[13–16]

Attention must be drawn to the high prevalence (66.8%) of women who ask for medical assistance after whiplash injury. In our study, to be women is a poor recovery prognostic factor, in agreement with the data found in the systematic review concerning prognosis factors of Cote et al^[16] and Hendriks et al,^[15] and who differs with the one of Scholten-Peters et al.^[13] Despite our study result, because of the existence of variability between the results of different reports regarding female gender as a prognostic factor, and because the prevalence among women is higher in the majority of the studies, we should consider female gender a low important prognostic factor. Similar to others reports,^[7,17,18] in our study, the age is a bad prognosis factor for whiplash injury. This result is congruent with the one of a better clinical evolution of students. On the other hand, the self-employed do not earn if they do not work. In our study, being self-employed is a good clinical evolution prognosis factor, which is important because although neck pain associated with whiplash injury exists, we think that it can be magnified or modified by patient attitude and probable benefits, which can get with its presence and maintenance. The presence of neck pain before the accident has been recently reported as a bad prognostic factor,^[19] nevertheless, in our study, this symptom was not a predictive factor.

Others studied variables in our study, such as previous consumption of sedatives or antidepressives, are not related with a worse clinical evolution, data that are consistent with other studies.^[20–22] According to these results, the presence of a psychologic illness before the accident is not a factor, which has influence on posterior clinical evolution. Although only ~10% of our patients consume sedatives or antidepressives, in early scores in Goldberg scale, they had a high percentage of anxious and depressive symptoms, probably related to a secondary psychologic symptoms because of the accident.^[23–25] Moreover, in agreement with data from Peolsson et al,^[26] patients with an exaggerated answer to pain or catastrophic ideas, which can develop compensatory strategies, should be assessed of the spread of pain, cognitive, and neuropsychologic symptoms, and depressive and catastrophic thoughts and strategies.

In multivariate analyses of our study, the presence of dizziness is a whiplash injury poor recovery prognostic factor. In a previous research on subjects with whiplash injury, it has been determined that those reporting dizziness and unsteadiness have greater deficits in balance than those who do not complain of these symptoms.^[27] Others studies^[28,29] confirm that balance impairments are greater in patients with neck pain caused by a whiplash injury than in those with an idiopathic neck pain and that this is not related to anxiety or pain and disability levels.

Regarding the number of days of cervical immobilization, although in bivariate analysis, it is correlated with VAS scores 6 months after whiplash injury, in a multivariate analysis, this correlation does not exist. Despite the fact that in our study, 90% of patients were immobilized with collar during almost 2 days comparing with others studies,^[15,16,30] in which, the percentage was less than 28.8%, there was no evidence that the use of a cervical collar is associated with a bad clinical evolution, in contrast to what has been published in other reports.^[31,32] Therefore, our data would suggest that cervical immobilization with collar does not influence on whiplash injury clinical evolution, in agreement with Kongsted et al.^[33]

In our study, initial evaluation of cervical spine functionality with NPH specific questionnaire is a poor evolution prognosis factor, more important when its score is higher. The medium of initial score in patients with more pain was 55.69. Other studies to evaluate cervical spine functionality use more frequently generic scales like SF-36, EuroQol, Scales of LiSat-11, and SCL-90.^[15,26,33] Although they can be useful in the prognostic in whiplash injury, these scales are difficult and awkward to make and take a long time to evaluate, whereas in our study, we use a specific user-friendly test that provides an immediate result.

In our study, the mean of initial VAS score in patients with poor recovery 6 months after whiplash injury was 68.8 mm. Similar to others reports,^[14–16] we could confirm that VAS score at first visit is the more significant prognostic factor for clinical evolution.

One of the limitations in this study is that the statistical analysis has not been adjusted for the presence or not of a judicial process; 95.6% of the patients (87.6% posterior impact and 8% lateral impact) are not the people to blame for the accident, hence, they have right to economic compensations, reason for what this factor has not been considered as a possible bias in the results obtained. Another limitation is, in contrast to others reports,^[34–36] the number of days between the occurrence of accident and the time at the first evaluation at DPMR does not show any correlation with a bad clinical evolution. This finding in our study can be influenced because in Spain, the Insurance Agreement Business Association (UNESPA) has a protocol, being the medical visit after traffic accident each 15 days, reason for which patients are sent to DPMR between 3 and 6 weeks after the traumatism.

In summary, in our study, poor recovery prognosis factor in whiplash injury are pain intensity, functional repercussion, age, and presence of dizziness. We propose that initial evaluation to be made with validated, simple, and specific scales, such as VAS and NPH, for obtaining results at the same visit and, therefore, to start interdisciplinary actions at the beginning to improve results.

Sidebar

Key Points

• Factors related with VAS 6 months after a whiplash injury were women, age, number of days of cervical column immobilization, previous neck pain, self-employed workers, housewives, pensioners, students, presence of headache or dizziness, and VAS, Goldberg Depression and Anxiety Scale, and NPH scores at initial evaluation.
• In multivaried analysis, it had been found that the variables that had influence on VAS 6 months after a whiplash injury were statistically significant for age, presence of dizziness, self employed workers, and VAS and NPH scores at initial evaluation.
• We propose that initial evaluation be made with validated, simple, and specific scales, such as VAS and NPH, for obtaining results at same visit, so to start interdisciplinary actions to improve results.

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