Division of Rheumatology and McGill Pain Centre, Department of Medicine, Montreal General Hospital, McGill University Health Centre and
1 Division of Rheumatology, Department of Medicine, St. Joseph's Hospital, McMaster University, Canada
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Abstract |
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Methods. All patients newly referred for rheumatology consultation in a 6-month period were evaluated prospectively for either a preceding, current or subsequent diagnosis of FM. Clinical characteristics, previous and subsequent management and health care utilization were assessed. The final diagnosis at 6 months was verified and accuracy regarding the diagnosis of FM was assessed.
Results. Seventy six (12%) of all new patients were either referred with a question of FM or finally diagnosed with FM. At the final evaluation the accuracy of the diagnosis regarding FM by either the referring physician or by the rheumatologist at the time of the initial visit was correct in 34% of patients. The FM group in comparison with those with some other rheumatological diagnosis had more tender points (12.5 vs 4) and were more fatigued. In contrast, prolonged early morning stiffness and limitation of lumbar spinal mobility in more than one plane was more common in the non-FM group.
Conclusion. There is a disturbing inaccuracy, mostly observed to be overdiagnosis, in the diagnosis of FM by referring physicians. This finding may help explain the current high reported rates of FM and caution physicians to consider other diagnostic possibilities when addressing diffuse musculoskeletal pain.
KEY WORDS: Fibromyalgia, Referral, Misdiagnosis.
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Introduction |
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As many patients with musculoskeletal symptoms are mostly managed by primary care physicians, accuracy in the diagnosis of musculoskeletal complaints is important. Recent reports suggest that FM may be too readily diagnosed and that other medical conditions may be overlooked [8]. The pain of FM is characteristically widespread and may have been present for many years. In addition to the complaint of pain, patients may have other non-specific symptoms including sleep disturbance, fatigue and early morning stiffness [1, 9, 10]. FM is currently a fashionable diagnosis in North America, popularized by the lay press and conscientiously advocated by patient-focused groups. The cost of this illness in the United States and Canada as well as the burden of disease, to both the patient and society, has recently been reported to be considerable with more patients seeking disability benefits [1113]. Accuracy in the diagnosis of FM is thus of increasing importance.
The aim of the present study was to determine the accuracy of the diagnosis of FM in patients referred for rheumatology consultation. In addition, we sought to identify clinical characteristics that would help discriminate between patients finally diagnosed with FM and those with some other musculoskeletal diagnosis.
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Methods |
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Data
All patients were evaluated at the baseline visit according to a predetermined protocol, which included information on patient demographics and symptoms, examination findings, previous and current investigations and management. Previous health care utilization included the category of referring physician, either primary care physician or specialist, and the number of previous physicians who had been consulted for the current musculoskeletal problem. All diagnoses were verified within a 6-month period, either by a follow-up visit, or a chart review and a telephone call to the patient. All discrepancies in diagnoses identified at the baseline visit or in follow-up by the rheumatologist were noted.
Clinical characteristics were reported as symptom description and physical examination findings. Symptoms relating to pain were recorded as follows: (i) duration of pain, defined as the time from onset of initial pain symptom; (ii) features of the onset of musculoskeletal pain were defined as: (a) pattern of onset of pain as one site (a single limb or part thereof, or a single region of the axial skeleton), multiple sites or widespread defined according to the ACR criteria as pain in the left side and right side of the body, above and below the waist and in addition, axial skeletal pain [1]; (b) location of pain at onset was categorized as spinal (cervical, thoracic or lumbar regions), root joint (shoulder or hip) or peripheral; (iii) current location of musculoskeletal pain was described as affecting the upper torso (neck, chest wall and thoracic spine), lower torso (lumbar spine and buttocks) or limbs (upper and/or lower). Additional information included a report of the following complaints: (i) disturbed sleep; (ii) early morning stiffness, defined as stiffness in the morning on rising, lasting for at least 1 h; (iii) fatigue, defined as tiredness and exhaustion sufficient to impair the patients' usual daily activities and (iv) the presence of inflammatory spinal pain [14].
The physical examination included: number of tender points according to ACR criteria [1]; spinal examination for presence of pain on movements of the cervical, thoracic and/or lumbar spine; reduction in range of motion in one or multiple planes of the cervical or the lumbar spine, or on rotation of the thoracic spine [15].
In addition, information was recorded by patient report regarding previous physicians consulted for the musculoskeletal problem, previous and current investigations, as well as treatments. All investigations performed in the preceding year for the purpose of identifying the musculoskeletal problem were noted. All current investigations requested by the consulting rheumatologist at the time of the study visit were recorded. Investigations were assigned a single value for each of the following categories: blood testing, plain radiographic studies and other investigations including scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI) scans. All treatments, both pharmacological and non-pharmacological, previously and currently prescribed were documented. Treatments were assigned a single value for each category as follows: analgesic, non-steroidal anti-inflammatory (NSAID), antidepressant, muscle relaxant, physiotherapy and other. The Montreal General Hospital University Ethics Committee approved the study and written consent was obtained from the subjects.
Statistical analysis
A univariate logistic regression analysis was performed on all independent variables. All variables with a P<0.2 were included in the multivariable logistic regression analysis. A stepwise procedure was used for final model selection. An exact method was utilized to determine the estimates and P values. All statistical analyses were performed using SAS/STAT (version 8.2; SAS Institute Inc., Cary, NC, USA) software.
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Results |
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When the 10 patients with FM-like symptoms were compared with the 29 with definite FM, there were no significant differences observed for demographic or clinical data (results not shown), with the exception of more tender points present in the FM group (14 vs 8, P < 0.0001). For this reason the FM and FM-like groups were combined and analysed as a single group called the FM group. The patients with some other rheumatological diagnosis constituted the non-FM group.
Analysis of the FM and non-FM groups for demographic data and referral pattern was comparable. Ninety per cent of patients in each group were referred by primary care physicians, with four patients in each group being referred by some other specialist, a neurologist in two, and one each by the following specialists: cardiologist, gynaecologist, haematologist, orthopaedic surgeon, plastic surgeon and psychiatrist. Thirty-six per cent of patients in the FM group and 32% in the non-FM group had consulted some other specialist for their musculoskeletal complaint.
On analysis of all the independent variables collected, the following variables were significant in the stepwise logistic regression between the FM and non-FM groups, respectively: number of tender points 12.5 vs 4 (P< 0.0001), fatigue 79 vs 38% (P=0.0003), early morning stiffness 28 vs 49% (P=0.0014) and limitation of lumbar spine mobility in more than one plane 15 vs 30% (P=0.0115). Comparisons between the FM and non-FM groups for the following parameters are shown as follows: clinical symptoms in Table 1, physical examination in Table 2
, and management and health care utilization in Table 3
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Discussion |
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Aside from the ACR criteria regarding tender point count for FM, our cohort of FM patients differed from the non-FM group in reporting more fatigue, but less early morning stiffness. There was an equally high rate of reporting of disturbed sleep in the two groups. Although disturbed sleep is a common complaint in FM, our results indicate that this symptom is as common in the non-FM group and thus may not be a useful discriminating symptom. In contrast, prolonged early morning stiffness, which is considered a marker of inflammatory musculoskeletal disease, although present in a quarter of the FM patients, was a significant discriminating clinical characteristic. Although almost half of the FM group reported that musculoskeletal pain was diffuse rather than localized at onset, supporting the concept of dysregulation of central pain processing mechanisms, this feature did not specifically help identify the FM patients. FM patients complained equally of upper and lower torso pain, which is in contrast to other reports indicating more neck pain in FM [12, 17]. Wolfe [17] has even suggested that axial pain in FM patients could be due to an increase in subclinical spinal disease, particularly in the older age group. Objective limitation in spinal mobility was not a prominent finding in the FM patients, but a complaint of pain was noted in half during lumbar spinal movement, and to a lesser extent on movement of the thoracic and cervical spines. The finding of mostly normal mobility of the spine on examination in FM suggests absence of significant disease of the axial skeleton and supports the concept of some other explanation for the report of pain.
Symptoms of FM are generally poorly responsive to various treatment interventions. It is therefore not surprising that there was a trend that the FM group had tried more therapeutic interventions prior to presenting to the rheumatologist. Our findings of 2.2 treatment categories tried by the FM group are in agreement with those of Campbell et al. [9], who reported that FM patients had used an average of three treatment interventions compared with 1.8 in patients with other musculoskeletal complaints. Previous investigations occurred with equal frequency in the two groups, but the FM group tended to be less likely to be further investigated by the rheumatologist. Although previous reports indicate that FM patients often undergo extensive and unnecessary investigations before the diagnosis is finally confirmed, this was not a finding in the present study [18].
The diagnosis of FM remains problematic. Previous studies have noted an increasing prevalence of this condition, especially within the community. Our study further raises the concern of the inaccuracy of the diagnosis of FM, predominantly by primary care physicians. Buskila et al. [19] have recently reported the lack of familiarity of family physicians with the diagnostic criteria for FM, which may be an explanation for the inaccuracy in both under- and overdiagnosis observed in the present study. A limitation of the present study is that our patients were assessed in a single rheumatology referral clinic and there could have been a selection bias towards more diagnostically challenging patients. It is also well recognized that rheumatological conditions may evolve, with the assignment of a final definitive diagnosis over time.
We have observed a disturbing inaccuracy in the diagnosis of FM in patients referred for rheumatology consultation. Common rheumatological conditions were overlooked and incorrectly labelled as FM, and in addition the diagnosis of FM was missed. We recommend caution in simply ascribing the diagnostic label of FM to patients with diffuse musculoskeletal symptoms and urge physicians to be more rigorous in the evaluation of rheumatological conditions. This high rate of inaccuracy in the diagnosis of FM should alert physicians to consider a wider spectrum of diagnostic possibilities in patients presenting with ill-defined aches and pains.
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Acknowledgments |
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Notes |
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References |
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