Effect of transcutaneous electrical nerve stimulation on pain, function, and quality of life in fibromyalgia: a double-blind randomized clinical trial

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

Influence of Transcutaneous Electrical Nerve Stimulation (TENS) on Pressure Pain Thresholds and Conditioned Pain Modulation in a Randomized Controlled Trial in Women With Fibromyalgia

Transcutaneous electrical nerve stimulation (TENS) effectively reduces pain in fibromyalgia (FM). The purpose of this study was to examine the influence of TENS use on pressure pain thresholds (PPT) and conditioned pain modulation (CPM) in individuals with FM using data from the Fibromyalgia Activity Study with TENS trial (NCT01888640). Individuals with FM were randomly assigned to receive active TENS, placebo TENS, or no TENS for 4 weeks. A total of 238 females satisfied the per-protocol analysis among the active TENS (n = 76), placebo TENS (n = 68), and no TENS (n = 94) groups. Following 4 weeks of group allocation, the active TENS group continued for an additional 4 weeks of active TENS totaling 8 weeks (n = 66), the placebo and no TENS groups transitioned to receive 4 weeks of active TENS (delayed TENS, n = 161). Assessment of resting pain, movement-evoked pain (MEP), PPT, and CPM occurred prior to and following active, placebo, or no TENS. There were no significant changes in PPT or CPM among the active TENS, placebo TENS, or no TENS groups after 4 weeks. Individuals who reported clinically relevant improvements in MEP (≥30% decrease) demonstrated increases in PPT (P < .001), but not CPM, when compared to MEP non-responders. There were no significant correlations among the change in PPT or CPM compared to MEP and resting pain following active TENS use (active TENS + delayed TENS). PPT and CPM may provide insight to underlying mechanisms contributing to pain; however, these measures may not relate to self-reported pain symptoms. PERSPECTIVE: Pressure pain threshold increased in individuals with clinically relevant improvement (≥30%) in MEP, indicating the clinical relevance of PPT for understanding mechanisms contributing to pain. CPM was not a reliable indicator of treatment response in MEP responders.

Minimal Clinically Important Change of Movement Pain in Musculoskeletal Pain Conditions

Movement pain, which is distinct from resting pain, is frequently reported by individuals with musculoskeletal pain. There is growing interest in measuring movement pain as a primary outcome in clinical trials, but no minimally clinically important change (MCIC) has been established, limiting interpretations. We analyzed data from 315 participants who participated in previous clinical trials (65 with chronic Achilles tendinopathy; 250 with fibromyalgia) to establish an MCIC for movement pain. A composite movement pain score was defined as the average pain (Numeric Rating Scale: 0-10) during 2 clinically relevant activities. The change in movement pain was calculated as the change in movement pain from pre-intervention to post-intervention. A Global Scale (GS: 1-7) was completed after the intervention on perceived change in health status. Participants were dichotomized into non-responders (GS ≥4) and responders (GS <3). Receiver operating characteristic curves were calculated to determine threshold values and corresponding sensitivity and specificity. We used the Euclidean method to determine the optimal threshold point of the Receiver operating characteristic curve to determine the MCIC. The MCIC for raw change in movement pain was 1.1 (95% confidence interval [CI]: .9-1.6) with a sensitivity of .83 (95% CI: .75-.92) and specificity of .79 (95% CI: .72-.86). For percent change in movement pain the MCIC was 27% (95% CI: 10-44%) with a sensitivity of .79 (95% CI: .70-.88) and a specificity of .82 (95% CI: .72-.90). Establishing an MCIC for movement pain will improve interpretations in clinical practice and research. PERSPECTIVE: A minimal clinically important change (MCIC) of 1.1- points (95% CI: .9-1.6) for movement pain discriminates between responders and non-responders to rehabilitation. This MCIC provides context for interpreting the meaningfulness of improvement in pain specific to movement tasks.

Beyond the Pain: A Systematic Narrative Review of the Latest Advancements in Fibromyalgia Treatment

Fibromyalgia is a complex chronic pain disorder that significantly impacts the quality of life of affected individuals. The etiology of fibromyalgia remains elusive, necessitating effective treatment options. This review aims to provide an overview of current treatment options for fibromyalgia and highlight recent updates in managing the condition. The methodology employed in this systematic review comprised the following key steps. We conducted a comprehensive search across various databases to identify pertinent studies published between 2000 and 2023. Inclusion criteria were defined to specifically target studies involving adult individuals diagnosed with fibromyalgia, with a focus on both pharmacological and non-pharmacological interventions for managing the condition. The review encompassed a range of study types, including randomized controlled trials, observational studies, and systematic reviews. To ensure the quality of the selected studies, we employed appropriate assessment tools, and data extraction and synthesis adhered to established guidelines. This rigorous approach allowed for a robust analysis of the literature on fibromyalgia management. In the course of our review, it became evident that a spectrum of treatment approaches holds significant promise in the management of fibromyalgia. Specifically, pharmacological interventions, including selective serotonin-norepinephrine reuptake inhibitors, anticonvulsants, cannabinoids, tropisetron, and sodium oxybate, have exhibited substantial potential in alleviating fibromyalgia symptoms. Concurrently, non-pharmacological strategies, such as cognitive-behavioral therapy, exercise regimens, and complementary and alternative therapies, have yielded positive outcomes in improving the condition's management. Recent developments in the field have introduced innovative pharmacological agents like milnacipran and pregabalin, in addition to non-pharmacological interventions like mindfulness-based stress reduction and aquatic exercise, expanding the array of options available to enhance fibromyalgia care and alleviating patient symptoms. Fibromyalgia necessitates a multidisciplinary approach to treatment, encompassing both pharmacological and non-pharmacological interventions. Recent updates in fibromyalgia management offer additional options to alleviate symptoms and improve the quality of life for individuals with fibromyalgia. Healthcare professionals should remain informed about these advancements to provide evidence-based care, addressing the complex symptoms associated with fibromyalgia and enhancing patient outcomes.

Neuronal P2X4 receptor may contribute to peripheral inflammatory pain in rat spinal dorsal horn

Objective

Intense inflammation may result in pain, which manifests as spinal central sensitization. There is growing evidence that purinergic signaling plays a pivotal role in the orchestration of pain processing. Over the last decade the ionotropic P2X purino receptor 4 (P2X4) got into spotlight in neuropathic disorders, however its precise spinal expression was scantily characterized during inflammatory pain. Thus, we intended to analyze the receptor distribution within spinal dorsal horn and lumbar dorsal root ganglia (DRG) of rats suffering in inflammatory pain induced by complete Freund adjuvant (CFA).

Methods

CFA-induced peripheral inflammation was validated by mechanical and thermal behavioral tests. In order to ensure about the putative alteration of spinal P2X4 receptor gene expression qPCR reactions were designed, followed by immunoperoxidase and Western blot experiments to assess changes at a protein level. Colocalization of P2X4 with neuronal and glial markers was investigated by double immunofluorescent labelings, which were subsequently analyzed with IMARIS software. Transmission electronmicroscopy was applied to study the ultrastructural localization of the receptor. Concurrently, in lumbar DRG cells similar methodology has been carried out to complete our observations.

Results

The figures of mechanical and thermal behavioral tests proved the establishment of CFA-induced inflammatory pain. We observed significant enhancement of P2X4 transcript level within the spinal dorsal horn 3 days upon CFA administration. Elevation of P2X4 immunoreactivity within Rexed lamina I-II of the spinal gray matter was synchronous with mRNA expression, and confirmed by protein blotting. According to IMARIS analysis the robust protein increase was mainly detected on primary afferent axonterminals and GFAP-labelled astrocyte membrane compartments, but not on postsynaptic dendrites was also validated ultrastructurally within the spinal dorsal horn. Furthermore, lumbar DRG analysis demonstrated that peptidergic and non-peptidergic nociceptive subsets of ganglia cells were also abundantly positive for P2X4 receptor in CFA model.

Conclusion

Here we provide novel evidence about involvement of neuronal and glial P2X4 receptor in the establishment of inflammatory pain.

Translating Outcomes from the Clinical Setting to Preclinical Models: Chronic Pain and Functionality in Chronic Musculoskeletal Pain

Fibromyalgia (FM) is a chronic pain disorder characterized by chronic widespread musculoskeletal pain (CWP), resting pain, movement-evoked pain (MEP), and other somatic symptoms that interfere with daily functioning and quality of life. In clinical studies, this symptomology is assessed, while preclinical models of CWP are limited to nociceptive assays. The aim of the study was to investigate the human-to-model translatability of clinical behavioral assessments for spontaneous (or resting) pain and MEP in a preclinical model of CWP. For preclinical measures, the acidic saline model of FM was used to induce widespread muscle pain in adult female mice. Two intramuscular injections of acidic or neutral pH saline were administered following baseline measures, 5 days apart. An array of adapted evoked and spontaneous pain measures and functional assays were assessed for 3 weeks. A novel paradigm for MEP assessment showed increased spontaneous pain following activity. For clinical measures, resting and movement-evoked pain and function were assessed in adult women with FM. Moreover, we assessed correlations between the preclinical model of CWP and in women with fibromyalgia to examine whether similar relationships between pain assays that comprise resting and MEP existed in both settings. For both preclinical and clinical outcomes, MEP was significantly associated with mechanical pain sensitivity. Preclinically, it is imperative to expand how the field assesses spontaneous pain and MEP when studying multi-symptom disorders like FM. Targeted pain assessments to match those performed clinically is an important aspect of improving preclinical to clinical translatability of animal models.

The Influence of Opioids on Transcutaneous Electrical Nerve Stimulation Effects in Women With Fibromyalgia

Transcutaneous electrical nerve stimulation (TENS) uses endogenous opioids to produce analgesia, and effectiveness can be reduced in opioid-tolerant individuals'. We examined TENS effectiveness (primary aim), and differences in fibromyalgia symptoms (secondary aim), in women with fibromyalgia regularly taking opioid (RTO) medications compared with women not- regularly taking opioids (not-RTO). Women (RTO n = 79; not-RTO not-n = 222) with fibromyalgia with daily pain levels ≥4 were enrolled and categorized into RTO (taking opioids at least 5 of 7 days in last 30 days) or not-RTO groups. Participants were categorized into tramadol n = 52 (65.8%) and other opioids n = 27 (34.2%) for the RTO group. Participants were phenotyped across multiple domains including demographics, fibromyalgia characteristics pain, fatigue, sleep, psychosocial factors, and activity. Participants were randomized to active TENS (n = 101), placebo TENS (n = 99), or no TENS (n = 99) for 1-month with randomization stratified by opioid use. Active TENS was equally effective in movement-evoked pain in those in the RTO and not-RTO groups. Women with fibromyalgia in the RTO group were older (P = .002), lower-income (P = .035), more likely to smoke (P = .014), and more likely to report depression (P = .013), hypertension (P = .005) or osteoarthritis (P = .027). The RTO group demonstrated greater bodily pain on SF-36 (P = .005), lower quality of life on the physical health component of the SF-36 (P = .040), and greater fatigue (MAF-ADL P = .047; fatigue with sit to stand test (P = .047) These differences were small of and unclear clinical significance. In summary, regular use of opioid analgesics does not interfere with the effectiveness of TENS for movement-evoked pain. Clinical Trial Registration Number: NCT01888640. PERSPECTIVE: Individuals treated with mixed frequency TENS at a strong but comfortable intensity that was taking prescription opioid analgesics showed a significant reduction in movement-evoked pain and fatigue. These data support the use of TENS, using appropriate parameters of stimulation, as an intervention for individuals with fibromyalgia taking opioid analgesics.

Characterising the Features of 381 Clinical Studies Evaluating Transcutaneous Electrical Nerve Stimulation (TENS) for Pain Relief: A Secondary Analysis of the Meta-TENS Study to Improve Future Research

Background and Objectives: Characterising the features of methodologies, clinical attributes and intervention protocols, of studies is valuable to advise directions for research and practice. This article reports the findings of a secondary analysis of the features from studies screened as part of a large systematic review of TENS (the meta-TENS study). Materials and Methods: A descriptive analysis was performed on information associated with methodology, sample populations and intervention protocols from 381 randomised controlled trials (24,532 participants) evaluating TENS delivered at a strong comfortable intensity at the painful site in adults with pain, irrespective of diagnosis. Results: Studies were conducted in 43 countries commonly using parallel group design (n = 334) and one comparator group (n = 231). Mean ± standard deviation (SD) study sample size (64.05 ± 58.29 participants) and TENS group size (27.67 ± 21.90 participants) were small, with only 13 of 381 studies having 100 participants or more in the TENS group. Most TENS interventions were ‘high frequency’ (>10 pps, n = 276) and using 100 Hz (109/353 reports that stated a pulse frequency value). Of 476 comparator groups, 54.2% were active treatments (i.e., analgesic medication(s), exercise, manual therapies and electrophysical agents). Of 202 placebo comparator groups, 155 used a TENS device that did not deliver currents. At least 216 of 383 study groups were able to access other treatments whilst receiving TENS. Only 136 out of 381 reports included a statement about adverse events. Conclusions: Clinical studies on TENS are dominated by small parallel group evaluations of high frequency TENS that are often contaminated by concurrent treatment(s). Study reports tended focus on physiological and clinical implications rather than the veracity of methodology and findings. Previously published criteria for designing and reporting TENS studies were neglected and this should be corrected in future research using insights gleaned from this analysis.

Test-Retest Reliability and Responsiveness of PROMIS Sleep Short Forms Within an RCT in Women With Fibromyalgia

Background: Nonrestorative sleep is commonly reported by individuals with fibromyalgia, but there is limited information on the reliability and responsiveness of self-reported sleep measures in this population.

Objectives: (1) Examine the reliability and validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) sleep measures in women with fibromyalgia, and (2) Determine the responsiveness of the PROMIS sleep measures to a daily transcutaneous electrical nerve stimulation (TENS) intervention in women with fibromyalgia over 4 weeks compared with other measures of restorative sleep.

Methods: In a double-blinded, dual-site clinical trial, 301 women with fibromyalgia were randomly assigned to utilize either Active-TENS, Placebo-TENS, or No-TENS at home. Measures were collected at baseline and after 4 weeks of treatment. To assess self-reported sleep, the participants completed three PROMIS short forms: Sleep Disturbance, Sleep-Related Impairment, Fatigue, and the Pittsburgh Sleep Quality Index (PSQI). To assess device-measured sleep, actigraphy was used to quantify total sleep time, wake after sleep onset, and sleep efficiency. Linear mixed models were used to examine the effects of treatment, time, and treatment*time interactions.

Results: The PROMIS short forms had moderate test–retest reliability (ICC 0.62 to 0.71) and high internal consistency (Cronbach's alpha 0.89 to 0.92). The PROMIS sleep measures [mean change over 4 weeks, 95% confidence interval (CI)], Sleep Disturbance: −1.9 (−3.6 to −0.3), Sleep-Related Impairment: −3 (−4.6 to −1.4), and Fatigue: −2.4 (−3.9 to −0.9) were responsive to improvement in restorative sleep and specific to the Active-TENS group but not in the Placebo-TENS [Sleep Disturbance: −1.3 (−3 to 0.3), Sleep-Related Impairment: −1.2 (−2.8 to 0.4), Fatigue: −1.1 (−2.7 to 0.9)] or No-TENS [Sleep Disturbance: −0.1 (−1.6 to 1.5), Sleep-Related Impairment: −0.2 (−1.7 to 1.4), Fatigue: –.3 (−1.8 to 1.2)] groups. The PSQI was responsive but not specific with improvement detected in both the Active-TENS: −0.9 (−1.7 to −0.1) and Placebo-TENS: −0.9 (−1.7 to 0) groups but not in the No-TENS group: −0.3 (−1.1 to 0.5). Actigraphy was not sensitive to any changes in restorative sleep with Active-TENS [Sleep Efficiency: −1 (−2.8 to 0.9), Total Sleep Time: 3.3 (−19.8 to 26.4)].

Conclusion: The PROMIS sleep measures are reliable, valid, and responsive to improvement in restorative sleep in women with fibromyalgia.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT01888640.

The use of transcutaneous electrical nerve stimulation along with functional tasks for immediate pain relief in individuals with knee osteoarthritis

BACKGROUND

Knee pain is the major complaint in individuals with knee osteoarthritis (OA), and the effects of transcutaneous electrical nerve stimulation (TENS) on knee pain are controversial. The present study applied TENS along with functional tests to investigate its effect on pain level in individuals with mild to moderate knee OA.

METHODS

Twenty volunteers with knee OA classification of graded 2-3 performed four functional tests (stair climb test - SCT, timed up and go test - TUG, 6-minute walk test - 6MWT, knee extensor strength test - KES, and 2-step test from the locomotive syndrome risk test - LSR_2ST) while wearing either an active or inactive TENS. Knee pain level before and after each test was self-accessed by the visual analog scale (VAS). The effect of TENS (active vs. inactive) on pain level was submitted to statistical analyses.

RESULTS

Knee pain during SCT, TUG, and LSR_2ST tests was significantly lower when subjects used the active TENS, compared to using the inactive unit. The effect of the active TENS on pain level was also more significant in subjects with no anxiety or depression.

CONCLUSIONS

The results provided evidence of immediate pain relief in individuals with mild to moderate knee OA when TENS is applied along with functional activities, that usually induced pain in people with knee OA.

Sensory Neurons, Neuroimmunity, and Pain Modulation by Sex Hormones

The inclusion of women in preclinical pain studies has become more commonplace in the last decade as the National Institutes of Health (NIH) released its "Sex as a Biological Variable" mandate. Presumably, basic researchers have not had a comprehensive understanding about neuroimmune interactions in half of the population and how hormones play a role in this. To date, we have learned that sex hormones contribute to sexual differentiation of the nervous system and sex differences in behavior throughout the lifespan; however, the cycling of sex hormones does not always explain these differences. Here, we highlight recent advances in our understanding of sex differences and how hormones and immune interactions influence sensory neuron activity to contribute to physiology and pain. Neuroimmune mechanisms may be mediated by different cell types in each sex, as the actions of immune cells are sexually dimorphic. Unfortunately, the majority of studies assessing neuronal contributions to immune function have been limited to males, so it is unclear if the mechanisms are similar in females. Finally, pathways that control cellular metabolism, like nuclear receptors, have been shown to play a regulatory role both in pain and inflammation. Overall, communication between the neuroimmune and endocrine systems modulate pain signaling in a sex-dependent manner, but more research is needed to reveal nuances of these mechanisms.

IL-5 mediates monocyte phenotype and pain outcomes in fibromyalgia

ABSTRACT

Fibromyalgia (FM) is characterized by widespread chronic pain, fatigue, and somatic symptoms. The influence of phenotypic changes in monocytes on symptoms associated with FM is not fully understood. The primary aim of this study was to take a comprehensive whole-body to molecular approach in characterizing relationships between monocyte phenotype and FM symptoms in relevant clinical populations. Lipopolysaccharide-evoked and spontaneous secretion of IL-5 and other select cytokines from circulating monocytes was higher in women with FM compared to women without pain. In addition, greater secretion of IL-5 was significantly associated with pain and other clinically relevant psychological and somatic symptoms of FM. Furthermore, higher levels of pain and pain-related symptoms were associated with a lower percentage of intermediate monocytes (CD14++/CD16+) and a greater percentage of nonclassical monocytes (CD14+/CD16++) in women with FM. Based on findings from individuals with FM, we examined the role of IL-5, an atypical cytokine secreted from monocytes, in an animal model of widespread muscle pain. Results from the animal model show that IL-5 produces analgesia and polarizes monocytes toward an anti-inflammatory phenotype (CD206+). Taken together, our data suggest that monocyte phenotype and their cytokine profiles are associated with pain-related symptoms in individuals with FM. Furthermore, our data show that IL-5 has a potential role in analgesia in an animal model of FM. Thus, targeting anti-inflammatory cytokines such as IL-5 secreted by circulating leukocytes could serve as a promising intervention to control pain and other somatic symptoms associated with FM.

Reduction in movement-evoked pain and fatigue during initial 30-minute transcutaneous electrical nerve stimulation treatment predicts transcutaneous electrical nerve stimulation responders in women with fibromyalgia

ABSTRACT

We previously showed that 1 month of transcutaneous electrical nerve stimulation (TENS) reduces movement-evoked pain and fatigue in women with fibromyalgia (FM). Using data from this study (Fibromyalgia Activity Study with TENS [FAST]), we performed a responder analysis to identify predictors of clinical improvement in pain and fatigue with TENS, validated these models using receiver operator characteristic, and determined number needed to treat and number needed to harm. Participants were randomly assigned to active-TENS (2-125 Hz; highest-tolerable intensity), placebo-TENS, or no-TENS for 1 month. At the end of the randomized phase, placebo-TENS and no-TENS groups received active-TENS for 1 month. The predictor model was developed using data from the randomized phase for the active-TENS group (n = 103) and validated using data from placebo-TENS and no-TENS groups after active-TENS for 1 month (n = 155). Participant characteristics, initial response to TENS for pain and fatigue, sleep, psychological factors, and function were screened for association with changes in pain or fatigue using a logistic regression model. Predictors of clinical improvement in pain were initial response to pain and widespread pain index (area under the curve was 0.80; 95% confidence interval: 0.73-0.87). Predictors of clinical improvement in fatigue were marital status, sleep impairment, and initial response to TENS (area under the curve was 0.67; 95% confidence interval: 0.58-0.75). Number needed to treat for pain and fatigue ranged between 3.3 and 5.3. Number needed to harm ranged from 20 to 100 for minor TENS-related adverse events. The response to an initial 30-minute TENS treatment predicts who responds to longer-term TENS use in women with FM, making this a clinically useful procedure. Number needed to treat and number needed to harm suggest that TENS is effective and safe for managing pain and fatigue in FM.

Transcutaneous Electrical Nerve Stimulation Reduces Movement-Evoked Pain and Fatigue: A Randomized, Controlled Trial

Objective

Fibromyalgia (FM) is characterized by pain and fatigue, particularly during physical activity. Transcutaneous electrical nerve stimulation (TENS) activates endogenous pain inhibitory mechanisms. This study was undertaken to investigate if using TENS during activity would improve movement‐evoked pain and other patient‐reported outcomes in women with FM.

Methods

Participants were randomly assigned to receive active TENS (n = 103), placebo TENS (n = 99), or no TENS (n = 99) and instructed to use it at home during activity 2 hours each day for 4 weeks. TENS was applied to the lumbar and cervicothoracic regions using a modulated frequency (2–125 Hz) at the highest tolerable intensity. Participants rated movement‐evoked pain (primary outcome measure) and fatigue on an 11‐point scale before and during application of TENS. The primary outcome measure and secondary patient‐reported outcomes were assessed at baseline (time of randomization) and at 4 weeks.

Results

After 4 weeks, a greater reduction in movement‐evoked pain was reported in the active TENS group versus the placebo TENS group (group mean difference –1.0 [95% confidence interval –1.8, –0.2]; P = 0.008) and versus the no TENS group (group mean difference –1.8 [95% confidence interval –2.6, –1.0]; P < 0.0001). A reduction in movement‐evoked fatigue was also reported in the active TENS group versus the placebo TENS group (group mean difference –1.4 [95% confidence interval –2.4, –0.4]; P = 0.001) and versus the no TENS group (group mean difference –1.9 [95% confidence interval –2.9, –0.9]; P = <0.0001). A greater percentage of the patients in the active TENS group reported improvement on the global impression of change compared to the placebo TENS group (70% versus 31%; P < 0.0001) and the no TENS group (9%; P < 0.0001). There were no TENS‐related serious adverse events, and <5% of participants experienced minor adverse events from TENS.

Conclusion

Among women who had FM and were on a stable medication regimen, 4 weeks of active TENS use compared to placebo TENS or no TENS resulted in a significant improvement in movement‐evoked pain and other clinical outcomes. Further research is needed to examine effectiveness in a real‐world setting to establish the clinical importance of these findings.

A Multicenter, Prospective, Randomized, Placebo-Controlled, Double-Blind Study of a Novel Pain Management Device, AT-02, in Patients with Fibromyalgia

Objectives

Existing treatments for fibromyalgia have limited efficacy, and only a minority of individuals clinically respond to any single intervention. This study was a prospective, multicenter, randomized, double-blind, controlled clinical trial to evaluate the feasibility of alternating magnetic field therapy in fibromyalgia patients by comparing the Angel Touch device (AT-02) with a sham control (S-01).

Methods

Two sites enrolled 44 subjects with diagnosed fibromyalgia. After informed consent, subjects taking prohibited concomitant drugs underwent a washout period of two or more weeks. All subjects then began a one-week run-in period. Numerical rating scale (NRS) pain scores were collected without device intervention for one day, followed by S-01 application to four or more painful sites for 10 minutes at each site, twice daily for six days. Subjects were then randomized to AT-02 or S-01, applied to four or more painful sites for 10 minutes at each site, twice daily for eight weeks. NRS scores were obtained twice daily during the entire treatment period.

Results

The primary end point (change in NRS ± SD at week 8 vs baseline) was –0.94 ± 1.33 in the AT-02 group and –0.22 ± 1.38 in the S-01 group. A trend toward a between-group difference in eight-week NRS scores favored the AT-02 group (–0.73, 95% confidence interval = –1.56 to 0.11, P = 0.086). An adjusted repeated measure analysis detected a significant difference in NRS scores (P = 0.039).

Conclusions

The reduction in NRS scores for AT-02 relative to sham was comparable to reductions observed in meta-analyses of fibromyalgia drug therapy. The unadjusted results and the persistence of the pain score reductions remain encouraging.

Remote Analgesic Effects Of Conventional Transcutaneous Electrical Nerve Stimulation: A Scientific And Clinical Review With A Focus On Chronic Pain

BACKGROUND

Transcutaneous electrical nerve stimulation (TENS) is a safe, noninvasive treatment for chronic pain that can be self-administered. Conventional TENS involves stimulation of peripheral sensory nerves at a strong, non-painful level. Following the original gate-control theory of pain, stimulation is typically near the target pain. As another option, remote stimulation may also be effective and offers potential advantages.

OBJECTIVE

This narrative review examines mechanisms underlying the remote analgesic effects of conventional TENS and appraises the clinical evidence.

METHODS

A literature search for English-language articles was performed on PubMed. Keywords included terms related to the location of TENS . Citations from primary references and textbooks were examined for additional articles.

RESULTS

Over 30 studies reported remote analgesic effects of conventional TENS. The evidence included studies using animal models of pain, experimental pain in humans, and clinical studies in subjects with chronic pain. Three types of remote analgesia were identified: at the contralateral homologous site, at sites distant from stimulation but innervated by overlapping spinal segments, and at unrelated extrasegmental sites.

CONCLUSION

There is scientific and clinical evidence that conventional TENS has remote analgesic effects. This may occur through modulation of pain processing at the level of the dorsal horn, in brainstem centers mediating descending inhibition, and within the pain matrix. A broadening of perspectives on how conventional TENS produces analgesia may encourage researchers, clinicians, and medical-device manufacturers to develop novel ways of using this safe, cost-effective neuromodulation technique for chronic pain.

Transcutaneous Electrical Nerve Stimulation Reduces Knee Osteoarthritic Pain by Inhibiting Spinal Glial Cells in Rats

BACKGROUND

Transcutaneous electrical nerve stimulation (TENS) is commonly used for pain control. However, the effects of TENS on osteoarthritis (OA) pain and potential underlying mechanisms remain unclear.

OBJECTIVE

The objective of this study was to investigate the effect of TENS on OA pain treatment and underlying mechanisms related to glial cell inhibition.

DESIGN

This was an experimental study.

METHODS

OA was induced by injection of monosodium iodoacetate into the synovial space of the right knee joint of rats. High-frequency (HF) TENS (100 Hz), low-frequency (LF) TENS (4 Hz), or sham TENS was applied to the ipsilateral knee joint for 20 minutes. Paw withdrawal threshold (PWT), weight bearing, and knee bend score (KBS) were measured. Immunohistochemistry for microglia and astrocytes was performed with L3 to L5 spinal segment samples. To investigate the effects of glial inhibition on OA pain, minocycline, l-α-aminoadipate, or artificial cerebrospinal fluid was injected intrathecally, and PWT and KBS were measured.

RESULTS

Compared with sham TENS, both HF TENS and LF TENS significantly increased PWT, decreased KBS, and inhibited activated microglia in the L3 to L5 segments but did not decrease the total number of microglia, except in the L4 segment (HF TENS). Astrocyte expression was significantly decreased in the L3 to L5 segments following LF TENS and in the L3 segment following HF TENS. Compared with artificial cerebrospinal fluid, both minocycline and l-α-aminoadipate increased PWT and decreased KBS.

LIMITATIONS

These results cannot be generalized to humans.

CONCLUSIONS

TENS alleviates OA pain in rats by inhibiting activated microglia and reducing astrocyte expression in the spinal cord. Although these results may not be generalizable to chronic pain in patients with OA, within the limitation of the experimental animal model used in the present study, they suggest a possible mechanism and preclinical evidence supporting further experimentation or clinical use of TENS in humans.

Effects of transcutaneous electrical nerve stimulation on pain after impacted third molar surgery

Background

The aim of this study was to assess the therapeutic effects of Transcutaneous Electrical Nerve Stimulation (TENS) on pain after the impacted third molar surgery.

Material and Methods

The study was carried out on 30 patients attending the outpatient department of the oral and maxillofacial surgery. Both sides’ impacted mandibular third molars were taken into consideration, and a total of 60 impacted third molars were undergone surgical extraction. After the first surgery, patients were given analgesic, antibiotics, and mouthwash as a routine treatment procedure. Following the second surgery, TENS was applied over the painful area of the cheek for patients in addition to routine treatment procedure. Pain was evaluated with Visual Analog Scale (VAS) at the postoperative 6, 8, 24 hours and 2,3,4 and 5 days. The Student t test was applied to compare pain levels between groups. P<0.05 and p<0.001 were considered significant in all statistical analyses.

Results

The study was carried out in 30 patients 15 (50%) female and 15 (50%) male, aged between 20 and 31 years. The mean age of the patients was 24.60 ± 4.76. There was a statistically significant difference in the evaluation of VAS levels in postoperative 6, 8, 24 hours and 2, 3, 4, and 5 days between the routine treatment group and the TENS application group.

Conclusions

TENS activates a complex neuronal network to result in a reduction in pain. In conclusion, TENS application was highly effective in pain modulation following the third molar surgery. Therefore, TENS, which is one of the non-pharmacological pain control methods after such surgeries, can be used safely in reducing postoperative pain.

Key words:Impacted teeth, third molar, pain, transcutaneous electrical nerve stimulation.

Development of a method to maximize the transcutaneous electrical nerve stimulation intensity in women with fibromyalgia

Introduction

Transcutaneous electrical nerve stimulation (TENS) is a non-pharmacological intervention clinically used for pain relief. The importance of utilizing the adequate stimulation intensity is well documented; however, clinical methods to achieve the highest possible intensity are not established.

Objectives

Our primary aim was to determine if exposure to the full range of clinical levels of stimulation, from sensory threshold to noxious, would result in higher final stimulation intensities. A secondary aim explored the association of pain, disease severity, and psychological variables with the ability to achieve higher final stimulation intensity.

Methods

Women with fibromyalgia (N=143) were recruited for a dual-site randomized controlled trial - Fibromyalgia Activity Study with TENS (FAST). TENS electrodes and stimulation were applied to the lumbar area, and intensity was increased to sensory threshold (ST), then to "strong but comfortable" (SC1), then to "noxious" (N). This was followed by a reduction to the final stimulation intensity of "strong but comfortable" (SC2). We called this the Setting of Intensity of TENS (SIT) test.

Results

There was a significant increase from SC1 (37.5 mA IQR: 35.6-39.0) to SC2 (39.2 mA IQR: 37.1-45.3) (p<0.0001) with a mean increase of 1.7 mA (95% CI: 1.5, 2.2). Linear regression analysis showed that those with the largest increase between SC1 and N had the largest increase in SC2-SC1. Further, those with older age and higher anxiety were able to achieve greater increases in intensity (SC2-SC1) using the SIT test.

Conclusion

The SC2-SC1 increase was significantly associated with age and anxiety, with greater mean increases associated with older age and higher anxiety. Thus, although all patients may benefit from this protocol, older women and women with elevated anxiety receive the greatest benefit.

Physical activity is related to function and fatigue but not pain in women with fibromyalgia: baseline analyses from the Fibromyalgia Activity Study with TENS (FAST)

BACKGROUND

Although exercise is an effective treatment for fibromyalgia, the relationships between lifestyle physical activity and multiple symptomology domains of fibromyalgia are not clear. Thus, the purpose of this study was to comprehensively examine the relationships between lifestyle physical activity with multiple outcome domains in women with fibromyalgia, including pain, fatigue, function, pain-related psychological constructs, and quality of life.

METHODS

Women (N = 171), aged 20 to 70 years, diagnosed with fibromyalgia, recruited from an ongoing two-site clinical trial were included in this prespecified subgroup analysis of baseline data. Physical activity was assessed using self-report and accelerometry. Symptomology was assessed using questionnaires of perceived physical function, quality of life, fatigue, pain intensity and interference, disease impact, pain catastrophizing, and fear of movement. In addition, quantitative sensory testing of pain sensitivity and performance-based physical function were assessed. Correlation coefficients, regression analyses and between-group differences in symptomology by activity level were assessed, controlling for age and body mass index (BMI).

RESULTS

Lifestyle physical activity was most closely associated with select measures of physical function and fatigue, regardless of age and BMI. Those who performed the lowest levels of lifestyle physical activity had poorer functional outcomes and greater fatigue than those with higher physical activity participation. No relationships between lifestyle physical activity and pain, pain sensitivity, or pain-related psychological constructs were observed.

CONCLUSIONS

Lifestyle physical activity is not equally related to all aspects of fibromyalgia symptomology. Lifestyle physical activity levels have the strongest correlations with function, physical quality of life, and movement fatigue in women with fibromyalgia. No relationships between lifestyle physical activity and pain, pain sensitivity, or psychological constructs were observed. These data suggest that physical activity levels are more likely to affect function and fatigue, but have negligible relationships with pain and pain-related psychological constructs, in women with fibromyalgia.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01888640 . Registered on 28 June 2013.

Wireless transcutaneous electrical nerve stimulation device for chemotherapy-induced peripheral neuropathy: an open-label feasibility study

Chemotherapy-induced peripheral neuropathy (CIPN) occurs in approximately 68% of patients who receive neurotoxic chemotherapy and lasts at least 6 months post-chemotherapy in approximately 30% of individuals. CIPN is associated with decreased quality of life and functional impairments. Evidence suggests that CIPN symptoms are caused, in part, by enhanced excitability and impaired inhibition in the central nervous system. Transcutaneous electrical nerve stimulation (TENS) decreases pain by counteracting both of these mechanisms and is efficacious in other conditions associated with neuropathic pain. This single-arm study (n = 29) assessed the feasibility of investigating TENS for CIPN after chemotherapy completion using a wireless, home-based TENS device. Eighty-one percent of eligible patients who were approached enrolled, and 85% of participants who received the TENS device completed the primary (6-week) study term. Qualitative interview data suggest that use of the device on the continuous setting that automatically alternates between 1-h stimulation and rest periods for 5 h/day would be acceptable to most participants. Significant (i.e., p < 0.05) improvements were observed with the EORTC-CIPN20 (percent change from baseline: 13%), SF-MPQ-2 (52%), numeric rating scale of pain (38%), tingling (30%), numbness (20%), and cramping (53%), and UENS large fiber sensation subscore (48%). Preliminary data that support the reliability and construct validity of the UENS for CIPN in cancer survivors are also provided. Together these data suggest that it is feasible to evaluate TENS for CIPN using a wireless, home-based device and that further evaluation of TENS for CIPN in a randomized clinical trial is warranted.

Reliability and Construct Validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) Instruments in Women with Fibromyalgia

Objective

The Patient-Reported Outcomes Measurement Information System (PROMIS) was developed to standardize measurement of clinically relevant patient-reported outcomes. This study evaluated the reliability and construct validity of select PROMIS static short-form (SF) instruments in women with fibromyalgia.

Design

Analysis of baseline data from the Fibromyalgia Activity Study with TENS (FAST), a randomized controlled trial of the efficacy of transcutaneous electrical nerve stimulation.

Setting

Dual site, university-based outpatient clinics.

Subjects

Women aged 20 to 67 years diagnosed with fibromyalgia.

Methods

Participants completed the Revised Fibromyalgia Impact Questionnaire (FIQR) and 10 PROMIS static SF instruments. Internal consistency was calculated using Cronbach alpha. Convergent validity was examined against the FIQR using Pearson correlation and multiple regression analysis.

Results

PROMIS static SF instruments had fair to high internal consistency (Cronbach α = 0.58 to 0.94, P  < 0.05). PROMIS 'physical function' domain score was highly correlated with FIQR 'function' score (r = -0.73). The PROMIS 'total' score was highly correlated with the FIQR total score (r = -0.72). Correlations with FIQR total score of each of the three PROMIS domain scores were r = -0.65 for 'physical function,' r = -0.63 for 'global,' and r = -0.57 for 'symptom' domain. PROMIS 'physical function,' 'global,' and 'symptom' scores explained 58% of the FIQR total score variance.

Conclusions

Select PROMIS static SF instruments demonstrate convergent validity with the FIQR, a legacy measure of fibromyalgia disease severity. These results highlight the potential utility of select PROMIS static SFs for assessment and tracking of patient-reported outcomes in fibromyalgia.

A Mechanism-Based Approach to Physical Therapist Management of Pain

Pain reduction is a primary goal of physical therapy for patients who present with acute or persistent pain conditions. The purpose of this review is to describe a mechanism-based approach to physical therapy pain management. It is increasingly clear that patients need to be evaluated for changes in peripheral tissues and nociceptors, neuropathic pain signs and symptoms, reduced central inhibition and enhanced central excitability, psychosocial factors, and alterations of the movement system. In this Perspective, 5 categories of pain mechanisms (nociceptive, central, neuropathic, psychosocial, and movement system) are defined, and principles on how to evaluate signs and symptoms for each mechanism are provided. In addition, the underlying mechanisms targeted by common physical therapist treatments and how they affect each of the 5 categories are described. Several different mechanisms can simultaneously contribute to a patient's pain; alternatively, 1 or 2 primary mechanisms may cause a patient's pain. Further, within a single pain mechanism, there are likely many possible subgroups. For example, reduced central inhibition does not necessarily correlate with enhanced central excitability. To individualize care, common physical therapist interventions, such as education, exercise, manual therapy, and transcutaneous electrical nerve stimulation, can be used to target specific pain mechanisms. Although the evidence elucidating these pain mechanisms will continue to evolve, the approach outlined here provides a conceptual framework for applying new knowledge as advances are made.

Somatic symptom presentations in women with fibromyalgia are differentially associated with elevated depression and anxiety

This study examined whether depression and anxiety differentially relate to fatigue, sleep disturbance, pain catastrophizing, fear of movement, and pain severity in women with fibromyalgia. Baseline data from the Fibromyalgia Activity Study with Transcutaneous Electrical Nerve Stimulation were analyzed. Of 191 participants, 50 percent reported high anxiety and/or depression (17% high anxiety, 9% high depression, and 24% both). Fatigue and sleep impairment were associated with high depression (p < 0.05). Pain severity, pain catastrophizing, and fear of movement were associated with high anxiety and high depression (p < 0.05). Possible implications for underlying mechanisms and the need for targeted treatments are discussed.

Transcutaneous electrical nerve stimulation (TENS) for fibromyalgia in adults

BACKGROUND

Fibromyalgia is characterised by persistent, widespread pain; sleep problems; and fatigue. Transcutaneous electrical nerve stimulation (TENS) is the delivery of pulsed electrical currents across the intact surface of the skin to stimulate peripheral nerves and is used extensively to manage painful conditions. TENS is inexpensive, safe, and can be self-administered. TENS reduces pain during movement in some people so it may be a useful adjunct to assist participation in exercise and activities of daily living. To date, there has been only one systematic review in 2012 which included TENS, amongst other treatments, for fibromyalgia, and the authors concluded that TENS was not effective.

OBJECTIVES

To assess the analgesic efficacy and adverse events of TENS alone or added to usual care (including exercise) compared with placebo (sham) TENS; no treatment; exercise alone; or other treatment including medication, electroacupuncture, warmth therapy, or hydrotherapy for fibromyalgia in adults.

SEARCH METHODS

We searched the following electronic databases up to 18 January 2017: CENTRAL (CRSO); MEDLINE (Ovid); Embase (Ovid); CINAHL (EBSCO); PsycINFO (Ovid); LILACS; PEDRO; Web of Science (ISI); AMED (Ovid); and SPORTDiscus (EBSCO). We also searched three trial registries. There were no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-randomised trials of TENS treatment for pain associated with fibromyalgia in adults. We included cross-over and parallel-group trial designs. We included studies that evaluated TENS administered using non-invasive techniques at intensities that produced perceptible TENS sensations during stimulation at either the site of pain or over nerve bundles proximal (or near) to the site of pain. We included TENS administered as a sole treatment or TENS in combination with other treatments, and TENS given as a single treatment or as a course of treatments.

DATA COLLECTION AND ANALYSIS

Two review authors independently determined study eligibility by assessing each record and reaching agreement by discussion. A third review author acted as arbiter. We did not anonymise the records of studies before assessment. Two review authors independently extracted data and assessed risk of bias of included studies before entering information into a 'Characteristics of included studies' table. Primary outcomes were participant-reported pain relief from baseline of 30% or greater or 50% or greater, and Patient Global Impression of Change (PGIC). We assessed the evidence using GRADE and added 'Summary of findings' tables.

MAIN RESULTS

We included eight studies (seven RCTs, one quasi-RCT, 315 adults (299 women), aged 18 to 75 years): six used a parallel-group design and two used a cross-over design. Sample sizes of intervention arms were five to 43 participants.Two studies, one of which was a cross-over design, compared TENS with placebo TENS (82 participants), one study compared TENS with no treatment (43 participants), and four studies compared TENS with other treatments (medication (two studies, 74 participants), electroacupuncture (one study, 44 participants), superficial warmth (one cross-over study, 32 participants), and hydrotherapy (one study, 10 participants)). Two studies compared TENS plus exercise with exercise alone (98 participants, 49 per treatment arm). None of the studies measured participant-reported pain relief of 50% or greater or PGIC. Overall, the studies were at unclear or high risk of bias, and in particular all were at high risk of bias for sample size.Only one study (14 participants) measured the primary outcome participant-reported pain relief of 30% or greater. Thirty percent achieved 30% or greater reduction in pain with TENS and exercise compared with 13% with exercise alone. One study found 10/28 participants reported pain relief of 25% or greater with TENS compared with 10/24 participants using superficial warmth (42 °C). We judged that statistical pooling was not possible because there were insufficient data and outcomes were not homogeneous.There were no data for the primary outcomes participant-reported pain relief from baseline of 50% or greater and PGIC.There was a paucity of data for secondary outcomes. One pilot cross-over study of 43 participants found that the mean (95% confidence intervals (CI)) decrease in pain intensity on movement (100-mm visual analogue scale (VAS)) during one 30-minute treatment was 11.1 mm (95% CI 5.9 to 16.3) for TENS and 2.3 mm (95% CI 2.4 to 7.7) for placebo TENS. There were no significant differences between TENS and placebo for pain at rest. One parallel group study of 39 participants found that mean ± standard deviation (SD) pain intensity (100-mm VAS) decreased from 85 ± 20 mm at baseline to 43 ± 20 mm after one week of dual-site TENS; decreased from 85 ± 10 mm at baseline to 60 ± 10 mm after single-site TENS; and decreased from 82 ± 20 mm at baseline to 80 ± 20 mm after one week of placebo TENS. The authors of seven studies concluded that TENS relieved pain but the findings of single small studies are unlikely to be correct.One study found clinically important improvements in Fibromyalgia Impact Questionnaire (FIQ) subscales for work performance, fatigue, stiffness, anxiety, and depression for TENS with exercise compared with exercise alone. One study found no additional improvements in FIQ scores when TENS was added to the first three weeks of a 12-week supervised exercise programme.No serious adverse events were reported in any of the studies although there were reports of TENS causing minor discomfort in a total of 3 participants.The quality of evidence was very low. We downgraded the GRADE rating mostly due to a lack of data; therefore, we have little confidence in the effect estimates where available.

AUTHORS' CONCLUSIONS

There was insufficient high-quality evidence to support or refute the use of TENS for fibromyalgia. We found a small number of inadequately powered studies with incomplete reporting of methodologies and treatment interventions.

The frequency and effect of fibromyalgia in patients with Behçet's disease

Objectives

This study aims to investigate the scores of depression, anxiety, sleep and quality of life (QoL), to identify the prevalence of fibromyalgia (FM) in Behçet's disease (BD), and to evaluate whether there is a difference between BD patients with and without FM in these scores.

Patients and methods

Between March 2008 and January 2009, 97 patients with BD and 95 age- and sex-matched healthy controls were included in the study. The patients with BD were divided into two groups according to the presence or absence of FM. All participants were evaluated by the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Pittsburgh Sleep Quality Index (PSQI), and Medical Outcomes Study Short Form-36 (SF-36).

Results

Compared to the controls, FM prevalence was higher (19.6% vs 3.2%) with increased BDI and BAI scores, while the subscores of SF-36 including physical function, physical role, pain, general health, social function, and emotional role decreased in BD patients (for all p<0.001). All BD patients with FM were females (n=19), while only 46% of BD patients without FM were females (n=36) (p<0.001). In BD patients with FM, compared to female BD patients without FM, the mean age (p=0.017), disease duration (p=0.028), and BDI scores (p=0.017) were significantly higher, while the PSQI scores (p=0.001) and SF-36 subscores, except general health (p=0.114), were significantly lower (for all p<0.05).

Conclusion

Our study results suggest that patients with BD have an increased severity of depression and anxiety, higher frequency of FM, and worsened QoL than healthy individuals. In addition, the presence of FM seems to be related with female sex, longer disease duration, older age, depression, sleep disturbance, and poor QoL in BD patients.

Stress, Inflammation and Pain: A Potential Role for Monocytes in Fibromyalgia-related Symptom Severity

The possibility that immunological changes might contribute to symptom severity in fibromyalgia (FM) prompted this proof-of-concept study to determine whether differences in monocyte subpopulations might be present in persons with FM compared with healthy controls. Relationships were assessed by comparing specific symptoms in those with FM (n = 20) and patterns of monocyte subpopulations with healthy age-matched and gender-matched controls (n = 20). Within the same time frame, all participants provided a blood sample and completed measures related to pain, fatigue, sleep disturbances, perceived stress, positive and negative affect and depressed mood (and the Fibromyalgia Impact Questionnaire for those with FM). Monocyte subpopulations were assessed using flow cytometry. No differences were observed in total percentages of circulating monocytes between the groups; however, pain was inversely correlated with percentages of circulating classical (r = -0.568, p = 0.011) and intermediate (r = -0.511, p = 0.025) monocytes in the FM group. Stress and pain were highly correlated (r = 0.608, p = 0.004) in the FM group. The emerging pattern of changes in the percentages of circulating monocyte subpopulations concomitant with higher ratings of perceived pain and the correlation between stress and pain found in the FM group warrant further investigation. Copyright © 2015 John Wiley & Sons, Ltd.

Perceived function and physical performance are associated with pain and fatigue in women with fibromyalgia

BACKGROUND

Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue and associated with significant impairment in perceived function and reduced physical performance. The purpose of this study was to determine the degree to which pain and fatigue are associated with perceived function and physical performance in women with fibromyalgia.

METHODS

Hierarchical linear regression determined the contribution of pain and fatigue (Numeric Rating Scale (NRS) for resting, movement and combined) to perceived function (Fibromyalgia Impact Questionnaire Revised - Function Subscale, FIQR-Function), Multidimensional Assessment of Fatigue - Activities of Daily Living (MAF-ADL) and SF-36 Physical Function Subscale (SF-36-PF) and physical performance (6-Minute Walk Test, 6MWT and Five Time Sit To Stand, 5TSTS) while controlling for age, body mass index, pain catastrophizing, fear of movement, anxiety, and depression in women with fibromyalgia (N = 94).

RESULTS

For perceived function, movement pain and movement fatigue together better predicted FIQR-function (adjusted R(2) = 0.42, p ≤ 0.001); MAF-ADL (adjusted R(2) = 0.41, p ≤ 0.001); and SF-36-PF function (adjusted R(2) = 0.34, p ≤ 0.001). For physical performance measures, movement pain and fatigue together predicted 6MWT distance (adjusted R(2) = 0.42, p ≤ 0.001) and movement fatigue alone predicted performance time on the 5TSTS (adjusted R(2) = 0.20, p ≤ 0.001).

CONCLUSIONS

Pain and fatigue are significantly associated with and explain more than one-third of the variance in perceived function and physical performance in women with fibromyalgia.

TRIAL REGISTRATION

NIH Clinicaltrials.gov

REGISTRATION

NCT01888640 . Registered 13 June 2013.