A case–control study examining the role of physical trauma in the onset of fibromyalgia syndrome

A. W. Al-Allaf, K. L. Dunbar1, N. S. Hallum1, B. Nosratzadeh1, K. D. Templeton1 and T. Pullar

Rheumatic Disease Unit, Ninewells Hospital and Medical School, Dundee DD1 9SY and
1 Medical School, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK


    Abstract
 Top
 Abstract
 Introduction
 Physical trauma and FMS
 Methods
 Results
 Discussion
 References
 
Objective. To investigate whether physical trauma may precipitate the onset of fibromyalgia syndrome (FMS).

Design. A case–control study was carried out to compare fibromyalgia out-patients with controls attending non-rheumatology out-patient clinics.

Method. One hundred and thirty-six FMS patients and 152 age- and sex-matched controls completed a postal questionnaire about any physical trauma in the 6 months before the onset of their symptoms.

Results. Fifty-three (39%) FMS patients reported significant physical trauma in the 6 months before the onset of their disease, compared with only 36 (24%) of controls (P<0.007). There was no significant difference between FMS patients who had a history of physical trauma and those who did not have physical trauma with regard to age, sex, disease duration, employment status and whether their job at onset was manual.

Conclusion. Physical trauma in the preceding 6 months is significantly associated with the onset of FMS.

KEY WORDS: Fibromyalgia syndrome, Physical trauma, Occupation.


    Introduction
 Top
 Abstract
 Introduction
 Physical trauma and FMS
 Methods
 Results
 Discussion
 References
 
Fibromyalgia syndrome (FMS) is a chronic musculoskeletal condition characterized by diffuse pain and hyperalgesia at specific tender sites. It is common, with a population prevalence of 2%, and it occurs predominantly in women [1]. The prevalence has been estimated to be 5% in a general in-patient population [2]. Fibromyalgia is the third or fourth most common reason for rheumatological referral [3].

The aetiology of primary FMS remains unclear. Suggestions for possible triggering factors include disturbances in non-REM sleep [4], hormonal [5] and infectious [6, 7] factors and stressful conditions [8, 9]. A further suggestion for an aetiological trigger factor of FMS is physical trauma. Physical trauma has been implicated as a risk factor preceding other rheumatological conditions, including osteoarthritis [10, 11], rheumatoid arthritis [12, 13] and psoriasis [14, 15] and has been proposed as being causative in ankylosing spondylitis [16].


    Physical trauma and FMS
 Top
 Abstract
 Introduction
 Physical trauma and FMS
 Methods
 Results
 Discussion
 References
 
The role of physical trauma in precipitating fibromyalgia is uncertain but rheumatologists are frequently asked by their patients or their legal representatives whether trauma could have caused or aggravated their disease. The lay public has always considered physical trauma to be important in precipitating fibromyalgia.

Several studies have implied a causative role for trauma in fibromyalgia [17]. Studies have reported that between 25 and 50% [18, 19] of subjects with FMS recall an event, most often physical trauma, that immediately preceded the onset of their FMS symptoms. Waylonis and Perkins [20] implicated work injury in 12.5% of the 176 individuals they investigated for post-traumatic fibromyalgia. However, their study does not state how soon the symptoms developed following the trauma and it could be criticized for not assessing the frequency of similar precipitating factors in a matched control population. The strongest evidence of a causative link between trauma and FMS is a recently published study by Buskila et al. [21], in which the risk of developing FMS was more than 10-fold higher in adults with neck injuries than in other adults. However, this study could be criticized as most FMS tender points were around the neck and in these patients tender spots could be related to the trauma of the neck region rather to fibromyalgia.

There are arguments against an association between trauma and FMS. First, some physicians still believe that FMS dose not exist and that it is no more than hysteria or malingering [2224], or at least that it is not a distinct clinical entity [25]. The second argument is that FMS is a psychological condition rather than a physical disease [26, 27]. The third argument is that other factors, such as personality, attitudes, psychological health and litigation, are more important than trauma in determining the development of chronic symptoms after an acute injury.

FMS seems to result in significant suffering and disability and consequently the problem of trauma or work-related FMS needs to be carefully addressed. Although an association between fibromyalgia and physical trauma has been suspected, there is limited evidence either to support or to refute this [28]. Better information about its causation will be important for better understanding of risk factors and causation, secondary prevention and early intervention. The aim of this study was to investigate whether physical trauma precipitates the onset of FMS.


    Methods
 Top
 Abstract
 Introduction
 Physical trauma and FMS
 Methods
 Results
 Discussion
 References
 
A total of 288 subjects (136 FMS patients and 152 controls) were recruited as part of a hospital-based, retrospective, case–control study relating perceived trauma to the onset of FMS. The Tayside Research Committee for Medical Ethics approved the study.

After gaining permission from each subject's general practitioner (GP), we sent questionnaires inviting subjects to participate in our study. One hundred and ninety FMS patients were identified from the Patient Record System, which was established in September 1994, at the Ninewells Rheumatology Unit. The diagnosis was in accordance with the American College of Rheumatology (ACR) criteria [29]. For each FMS patient, two age- and sex-matched controls were invited to participate. Controls were attending an out-patient clinic for a non-rheumatological disease in the same hospital during the same period and were deliberately recruited from many different medical clinics to avoid any bias that may have resulted from using a control group with a specific disease.

The questionnaire asked the FMS patients and controls to describe any trauma they had suffered in the 6-month period prior to the first symptom of their disorder. The 6-month period was chosen to limit recall bias. Trauma was used to describe fracture, surgery, childbirth or miscarriage, a road traffic or other accident, for which the individual had attended an accident and emergency department (A & E), their GP or another medical speciality. Individuals were also asked to state the exact number of months (1–6) prior to the onset of the disease in which the trauma had occurred. To decrease the possibility of recall bias and to try to control for disease duration, each control subject was given a specific date coinciding with the onset of fibromyalgia in their matched FMS patient and asked to complete the questionnaire about trauma in the 6 months before the onset of their own disease and in the 6 months before the onset of fibromyalgia symptoms in their matched FMS patient. The questionnaire also asked FMS patients and controls to describe their work situation at the time of diagnosis (full-time, part-time, manual job, sedentary job or not working).

Randomized samples of questionnaires (33%) from each group were compared for accuracy with their GP's medical records. Written consent to review notes was obtained from the GPs. At this time we looked for the presence of trauma and recorded the interval between trauma and the onset of disease. A total of 77% of cases and 75% of controls were found to have 100% concordance concerning the record of trauma and its date (within 1 month), with no difference between FMS patients and controls. We took the history of the trauma as being that recorded by the patient in the questionnaire, as we felt that some traumas may have been missing from the GP records for different reasons, such as the patient having attended A & E or having moved from another area without the full medical record being transferred. More importantly, there were no differences between patients and controls in the concordance rate of GP document figures.

Data obtained from the questionnaires were analysed using the SPSS software (SPSS, Chicago, IL, USA). Normally distributed data were assessed with the t-test. Data that were not normally distributed were analysed with the {chi}2 or Mann–Whitney test. A P value of <=0.05 was considered statistically significant.


    Results
 Top
 Abstract
 Introduction
 Physical trauma and FMS
 Methods
 Results
 Discussion
 References
 
Of the original 190 questionnaires sent to FMS patients, only 136 (71.6%) were returned following a second reminder. Only 152 questionnaires (40%) were returned from controls. This low response rate for controls occurred because we did not send a reminder to the controls as enough had been recruited. The above FMS patients and controls were assessed for trauma prior to the onset of their condition. The patient and control groups were comparable with regard to mean age [49.2±9.8 (S.D.) and 48.9±10.1 yr respectively], percentage of females (92.7 and 94%) and disease duration (6.68±6.2 and 6.06±7.8 yr).

Trauma and onset of FMS
The types of trauma in both groups are shown in Table 1Go. Each trauma type was analysed independently and in total. Only those persons who stated they were in full- or part-time employment at the time of onset were included in the analysis of injury at work. Individuals over the age of 45 yr were not included in the childbirth/miscarriage analysis and all missing values were excluded from the statistical analysis. In total, 53 out of 136 (39%) FMS patients gave a history of trauma in the 6 months prior to the onset of their disease, compared with 36 out of 152 (24%) control subjects. The difference was highly significant (P=0.007). A similar significant result was obtained on matching the onset of disease between patients with FMS and controls. A significant result was also obtained when childbirth was excluded (P=0.006). On subgroup analysis, surgery and injury at work were found to be significantly more likely to be reported prior to the onset of FMS when compared with controls, and on matching the onset of disease all the subgroups of trauma tested, except road traffic accidents, were significantly more frequent in the FMS patients (P values ranged from 0.05 to 0.000).


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TABLE 1.  Trauma incidence in the 6 months preceding diagnosis in both groups: number (%)

 
There was no significant difference between FMS subjects with and without trauma in any of the characteristics studied (mean±S.D. age, 49.3±10.9 and 49.2±9.1 yr respectively; percentage of females, 90.6 and 94.0; disease duration, 7.8±6.8 and 5.9±5.7 yr; number of children per person, 2.3±0.9 and 2.4±1.4; working at disease onset, 43.4 and 56.6%; having a manual job at onset, 75.8 and 69.8%).


    Discussion
 Top
 Abstract
 Introduction
 Physical trauma and FMS
 Methods
 Results
 Discussion
 References
 
The mean age and sex distribution of our FMS patients were consistent with those of subjects in other studies [18, 19, 30].

Our study assessed a history of trauma (that led to the subject seeking medical help) that, according to the subject's memory, occurred in the 6 months prior to FMS symptoms. For a random sample (33%) of subjects, the GP's record was reviewed to confirm the accuracy of the data, and this showed that there was a reasonable concordance rate in both groups. This implies that the trauma included was significant and that the data provided by our study subjects were reasonably reliable. The choice of a 6-month cut-off for reported trauma was arbitrary but in keeping with previous studies, which have used periods varying from days to 18 months [17]. For example, Buskila et al. [21] found that the mean period between the trauma and the development of FMS was 3.2±1.1 (S.D.) months. We felt that 6 months was a realistic period for accurate recall and, as the mechanism for trauma acting as a trigger for FMS is unknown and may not be immediate, we chose a period longer than a few weeks.

Our results suggest that physical trauma was significantly associated with the onset of FMS. Thirty-nine per cent of the FMS patients had a history of physical trauma in the preceding 6 months compared with only 24% of the controls (7.9% in the controls on matching for the onset of disease). The second comparison, with matching onset, was done in an attempt to limit the possibility of recall bias. Either way, the difference was highly significant (P<0.007 and P<0.000 respectively). Similar significant results were obtained when we excluded childbirth and abortion, because of the possible role of hormonal changes (P<0.006 and P<0.000). We found that significantly more FMS patients had surgery and injury at work prior to the onset of their disease compared with controls; on matching for the onset of disease, all types of trauma, when analysed individually, were significantly more frequent in patients with FMS, apart from road traffic accidents (P values ranging from 0.05 to <0.000).

The type of job (manual or sedentary) could not explain this difference. Among those who were working at the onset, more patients with FMS were in manual jobs (72.4%) compared with the control group (58%), but the difference was not significant (P=0.07).

Our finding that 39% of FMS patients reported trauma before the onset of FMS was consistent with some studies in which the incidence of reported trauma prior to FMS onset was reported as between 25 and 50% [18, 19]. However, our figure of 39% was higher than that reported by other studies. Aaron et al. [30] found that 21.1% of their FMS patients, who had been referred to their out-patient clinic, had a history of physical trauma compared with 15.2% of community FMS patients, who had not been referred to the out-patient clinic. However, their study did not include non-FMS controls.

Buskila et al. [21] found that 21.6% of adults with neck injuries developed FMS within 1 yr of their injury. However, they found that only one out of 59 adults with lower extremity fractures developed FMS. One criticism of their study is that the majority of the population in the study were males, in whom FMS generally is less common. Another criticism relates to an inherent bias in ascertaining the diagnosis of FMS in individuals with neck injuries, as 10 out of 18 tender points specified by the 1990 ACR criteria were in the neck and shoulder girdle area. However, results from this study suggest that specific types of trauma may be more important in the development of FMS.

There were no significant differences between FMS patients with and without trauma with respect to mean age, sex distribution, disease duration, number of children per person, number employed at onset and number who were in a manual job at disease onset. Accordingly, none of the above factors can explain the significant difference between FMS with and without trauma. This was consistent with the results of Greenfield et al. [18], who also found no significant difference between FMS patients with and without trauma with respect to mean age, sex distribution, disease duration and employment status at the time of diagnosis of their disease.

Our own results are, of course, retrospective and may be influenced by recall bias, but if they are confirmed in a prospective study this would lead us to speculate on the mechanisms by which trauma might precipitate FMS. It is still not clear why major trauma is not associated with any sequelae in most individuals, while others develop or experience exacerbated symptoms leading to specific disease. Patients who are genetically predisposed to develop such disease may have a response that is different from that of normal subjects exposed to the same trauma, or perhaps there are factors more important than trauma in determining chronic symptoms after an acute trauma.

In conclusion, our study suggests that physical trauma in the 6 months before the onset of symptoms is significantly associated with the onset of FMS in patients attending a rheumatology out-patient clinic. Further prospective studies are needed to confirm this association and to determine whether trauma has a causal role or if there are more important factors in the development of FMS.


    Notes
 
Correspondence to: A. W. Al-Allaf, University Department of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK. Back


    References
 Top
 Abstract
 Introduction
 Physical trauma and FMS
 Methods
 Results
 Discussion
 References
 

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Submitted 5 February 2001; Accepted 2 November 2001