BMI but not age and sex negatively impact on the outcome of pharmacotherapy in fibromyalgia: a systematic review

Pain and the biochemistry of fibromyalgia: patterns of peripheral cytokines and chemokines contribute to the differentiation between fibromyalgia and controls and are associated with pain, fat infiltration and content

Objectives

This explorative study analyses interrelationships between peripheral compounds in saliva, plasma, and muscles together with body composition variables in healthy subjects and in fibromyalgia patients (FM). There is a need to better understand the extent cytokines and chemokines are associated with body composition and which cytokines and chemokines differentiate FM from healthy controls.

Methods

Here, 32 female FM patients and 30 age-matched female healthy controls underwent a clinical examination that included blood sample, saliva samples, and pain threshold tests. In addition, the subjects completed a health questionnaire. From these blood and saliva samples, a panel of 68 mainly cytokines and chemokines were determined. Microdialysis of trapezius and erector spinae muscles, phosphorus-31 magnetic resonance spectroscopy of erector spinae muscle, and whole-body magnetic resonance imaging for determination of body composition (BC)-i.e., muscle volume, fat content and infiltration-were also performed.

Results

After standardizing BC measurements to remove the confounding effect of Body Mass Index, fat infiltration and content are generally increased, and fat-free muscle volume is decreased in FM. Mainly saliva proteins differentiated FM from controls. When including all investigated compounds and BC variables, fat infiltration and content variables were most important, followed by muscle compounds and cytokines and chemokines from saliva and plasma. Various plasma proteins correlated positively with pain intensity in FM and negatively with pain thresholds in all subjects taken together. A mix of increased plasma cytokines and chemokines correlated with an index covering fat infiltration and content in different tissues. When muscle compounds were included in the analysis, several of these were identified as the most important regressors, although many plasma and saliva proteins remained significant.

Discussion

Peripheral factors were important for group differentiation between FM and controls. In saliva (but not plasma), cytokines and chemokines were significantly associated with group membership as saliva compounds were increased in FM. The importance of peripheral factors for group differentiation increased when muscle compounds and body composition variables were also included. Plasma proteins were important for pain intensity and sensitivity. Cytokines and chemokines mainly from plasma were also significantly and positively associated with a fat infiltration and content index.

Conclusion

Our findings of associations between cytokines and chemokines and fat infiltration and content in different tissues confirm that inflammation and immune factors are secreted from adipose tissue. FM is clearly characterized by complex interactions between peripheral tissues and the peripheral and central nervous systems, including nociceptive, immune, and neuroendocrine processes.

Duloxetine for fibromyalgia syndrome: a systematic review and meta-analysis

INTRODUCTION

The optimal dose of duloxetine in the management of fibromyalgia remains still controversial. Therefore, a systematic review and meta-analysis to investigate efficacy and safety of duloxetine was conducted. The outcomes of interests were to assess changes in Fibromyalgia Impact Questionnaire (FIQ), Brief Pain Inventory (BPI), and Clinical Global Impression (CGI). The rate of of adverse events and those leading to therapy discontinuation were also investigated.

MATERIAL AND METHODS

This study followed the 2020 PRISMA guidelines. The literature search started in December 2022 accessing PubMed, Google scholar, Embase, and Scopus databases. All the RCTs investigating the efficacy and safety of daily administration of duloxetine for fibromyalgia were accessed. Studies reporting quantitative data under the outcomes of interest, and including a minimum of 10 patients who completed a minimum of 4 weeks follow-up, were included. Studies on combined pharmacological and non-pharmacological managements for fibromyalgia were not considered.

RESULTS

Data from 3432 patients (11 RCTs) were included. The mean age of the patients was 46.4 ± 10.7 years old, and the mean BMI 25.3 ± 3.2 kg/m². 90% (3089 of 3432 patients) were women. The 60 mg/daily cohort reported the higher FIQ, followed by the 30, 30-60, 120 mg/daily, and placebo groups, while the 60-120 mg /daily group performed the worst results. Concerning the CGI severity scale, placebo resulted in the lowest improvement, and no differences were found in the other groups. Concerning the BPI interference and severity pain scores, the 30-60 mg/daily group reported the worst result, along with the placebo group. The rate of adverse events leading to study discontinuation were lower in the 60-120 group, followed by the 30-60 and 30 mag/daily groups. Duloxetine was superior in all the comparisons to placebo, irrespective of the doses, in all endpoints analysed.

CONCLUSIONS

Duloxetine could help in improving symptoms of fibromyalgia. The dose of duloxetine should be customised according to individual patients. Irrespective of the doses, duloxetine was more effective than placebo in the management of fibromyalgia. The dose of duloxetine must be customised according to individual patients. Level of evidence I Meta-analysis of double-blind RCTs.

Fibromyalgia: Associations Between Fat Infiltration, Physical Capacity, and Clinical Variables

Background

Obesity is a risk factor for the development of fibromyalgia (FM) and generally most studies report increased Body Mass Index (BMI) in FM. Obesity in FM is associated with a worse clinical presentation. FM patients have low physical conditioning and obesity further exacerbates these aspects. Hitherto studies of FM have focused upon a surrogate for overall measure of fat content, ie, BMI. This study is motivated by that ectopic fat and adipose tissues are rarely investigated in FM including their relationships to physical capacity variables. Moreover, their relationships to clinical variables including are not known. Aims were to 1) compare body composition between FM and healthy controls and 2) investigate if significant associations exist between body composition and physical capacity aspects and important clinical variables.

Methods

FM patients (n = 32) and healthy controls (CON; n = 30) underwent a clinical examination that included pressure pain thresholds and physical tests. They completed a health questionnaire and participated in whole-body magnetic resonance imaging (MRI) to determine body composition aspects.

Results

Abdominal adipose tissues, muscle fat, and BMI were significantly higher in FM, whereas muscle volumes of quadriceps were smaller. Physical capacity variables correlated negatively with body composition variables in FM. Both body composition and physical capacity variables were significant regressors of group belonging; the physical capacity variables alone showed stronger relationships with group membership. A mix of body composition variables and physical capacity variables were significant regressors of pain intensity and impact in FM. Body composition variables were the strongest regressors of blood pressures, which were increased in FM.

Conclusion

Obesity has a negative influence on FM symptomatology and increases the risk for other serious conditions. Hence, obesity, dietary habits, and physical activity should be considered when developing clinical management plans for patients with FM.