Evaluation and Differential Diagnosis of Fibromyalgia

Integrated weighted gene co-expression network analysis with an application to chronic fatigue syndrome

Background

Systems biologic approaches such as Weighted Gene Co-expression Network Analysis (WGCNA) can effectively integrate gene expression and trait data to identify pathways and candidate biomarkers. Here we show that the additional inclusion of genetic marker data allows one to characterize network relationships as causal or reactive in a chronic fatigue syndrome (CFS) data set.

Results

We combine WGCNA with genetic marker data to identify a disease-related pathway and its causal drivers, an analysis which we refer to as "Integrated WGCNA" or IWGCNA. Specifically, we present the following IWGCNA approach: 1) construct a co-expression network, 2) identify trait-related modules within the network, 3) use a trait-related genetic marker to prioritize genes within the module, 4) apply an integrated gene screening strategy to identify candidate genes and 5) carry out causality testing to verify and/or prioritize results. By applying this strategy to a CFS data set consisting of microarray, SNP and clinical trait data, we identify a module of 299 highly correlated genes that is associated with CFS severity. Our integrated gene screening strategy results in 20 candidate genes. We show that our approach yields biologically interesting genes that function in the same pathway and are causal drivers for their parent module. We use a separate data set to replicate findings and use Ingenuity Pathways Analysis software to functionally annotate the candidate gene pathways.

Conclusion

We show how WGCNA can be combined with genetic marker data to identify disease-related pathways and the causal drivers within them. The systems genetics approach described here can easily be used to generate testable genetic hypotheses in other complex disease studies.

A comparison of pain measures used with patients with fibromyalgia

The objective of the present study was to evaluate instruments used to assess pain in patients with fibromyalgia (FMS). Participants were 602 patients with FMS. Pain was measured with five scales: a visual analog scale (VAS), the Pain Rating, Present Pain, and Number of Words Chosen Indexes from the McGill Pain Questionnaire; and intensity of pain obtained from a manual tender point exam. The VAS had the highest correlations with other measures of pain and with self-efficacy for pain, physical functioning, fatigue, and stiffness. The correlations between the VAS and fatigue and stiffness were significantly higher than those of other pain measures (p < .01). Our findings suggest that the easy-to-administer VAS may be the most useful measure of pain with patients with FMS.

A comparison of three types of neck support in fibromyalgia patients

OBJECTIVE

To determine the effectiveness of 3 types of neck support for patients with fibromyalgia (FMS) and their preference for the type of support.

METHODS

Thirty-five patients with FMS chose the order of application and used each type of neck support for a 2-week period, followed by a 2-week washout. The same schedule was repeated a second time. The neck supports included a Shape of Sleep pillow, two neck ruffs with one standard pillow, and a single standard pillow. All subjects received a physiotherapy treatment and educational program in the home. Outcome measures included visual analog scales (VAS) for neck pain and quality of sleep, the Fibromyalgia Impact Questionnaire (FIQ), and a neck and shoulder pain distribution diagram.

RESULTS

Analysis using Friedman's 2-way analysis of variance revealed no significant differences in any outcome measure, although there was a trend towards improvement in the FIQ and VAS neck pain and quality of sleep scores for some patients. Most participants (62.9%) preferred the Shape of Sleep pillow, 20.0% preferred cervical ruffs with one standard pillow, and 17.1% preferred a single standard pillow.

CONCLUSIONS

The results of this study are inconclusive due to the small sample size. However, from a patient's perspective, neck support is an important part of a comprehensive physiotherapy program. Most participants preferred the more rigid support of a Shape of Sleep pillow. Further research into the efficacy of the use of neck support in people with FMS is warranted.

Work disability evaluation and the fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a common and costly cause of work disability. Patients with FMS, nevertheless, encounter considerable difficulties in their assessment of claims for disability payments. Factors that contribute to FMS as an important cause of disability are its high prevalence, the patients' perception of severe discomfort, and poor function. Disability evaluation in FMS is controversial for several reasons including lack of acceptance of the diagnosis, concurrent psychological abnormalities, difficulties in objectifying disability, deficiencies in instruments of evaluation, the uncertain efficacy of treatment, and physician attitudes. Third parties appear to have inappropriate expectations of the physician's role in determining disability. We suggest that the process of disability evaluation be improved by more objective assessments and by the inclusion of other health professionals in assessing disability and necessary retraining. Further research is needed to develop better instruments for measuring disability, to assess the long-term effects of various treatments, and to clarify the contributions of the work place and of compensation in causing or aggravating FMS.

Sleep apnea in male patients with the fibromyalgia syndrome

PURPOSE

Fibromyalgia is a common pain syndrome that is often associated with sleep disturbances. The most characteristic pattern noted on formal sleep study is alpha-wave intrusion on delta-wave sleep. This nonrestorative sleep pattern may be endogenous, or caused by any of a number of sleep disturbances. Our goal was to determine the frequency of sleep apnea and its relationship to a nonrestorative sleep pattern in our patients with fibromyalgia syndrome.

PATIENTS AND METHODS

All new fibromyalgia patients seen in the Rheumatology Clinic at Fitzsimons Army Medical Center were screened using history and physical examination for suspicion of sleep apnea. When this condition was suspected, the patients underwent formal polysomnography to delineate any sleep disturbance.

RESULTS

Four of 92 women, and 13 of 25 men with the new diagnosis of fibromyalgia syndrome underwent polysomnography. Of the women, 2.2% (2 of 92) had significant sleep apnea at formal evaluation; both were obese and had obstructive findings. In contrast, 44% (11 of 25) of the men had significant sleep apnea.

CONCLUSIONS

Sleep apnea is not a significant cause of fibromyalgia symptoms in females. In male patients with fibromyalgia, sleep apnea was observed in a large percentage. Fibromyalgia may be a marker for occult sleep apnea in males.