Milnacipran for the treatment of fibromyalgia in adults: A 15-week, multicenter, randomized, double-blind, placebo-controlled, multiple-dose clinical trial

Pharmacological Treatment of Fibromyalgia Syndrome: A Practice-Based Review

PURPOSE OF REVIEW

Fibromyalgia Syndrome (FMS) is a complex chronic pain condition characterized by widespread musculoskeletal pain and numerous other debilitating symptoms. The purpose of this review is to provide a comprehensive overview, based on everyday clinical practice, of the drugs presently employed in the treatment of FMS.

RECENT FINDINGS

The treatment of FMS is based on a multimodal approach, with pharmacologic treatment being an essential pillar. The drugs used include tricyclic antidepressants, serotonin and noradrenaline reuptake inhibitors, other antidepressants, anticonvulsants, myorelaxants, and analgesics. The effectiveness of these medications varies, and the choice of drug often depends on the specific symptoms presented by the patient. Many drugs tend to either address only some domains of the complex FMS symptomatology or have a limited effect on pain. Each treatment option comes with potential side effects and risks that necessitate careful consideration. It may be beneficial to divide patients into clinical subpopulations, such as FMS with comorbid depression, for more effective treatment. Despite the complexities and challenges, the pharmacological treatment remains a crucial part for the management of FMS. This review aims to guide clinicians in prescribing pharmacological treatment to individuals with FMS.

Pharmacotherapeutic advances in fibromyalgia: what's new on the horizon?

INTRODUCTION

This review delves into Fibromyalgia Syndrome (FMS), a chronic pain condition demanding thorough understanding for precise diagnosis and treatment. Yet, a definitive pharmacological solution for FMS remains elusive.

AREAS COVERED

In this article, we systematically analyze various pharmacotherapeutic prospects for FMS treatment, organized into sections based on the stage of drug development and approval. We begin with an overview of FDA-approved drugs, discussing their efficacy in FMS treatment. Next, we delve into other medications currently used for FMS but still undergoing further study, including opioids and muscle relaxants. Further, we evaluate the evidence behind medications that are currently under study, such as cannabinoids and naltrexone. Lastly, we explore new drugs that are in phase II trials. Our research involved a thorough search on PUBMED, Google Scholar, and clinicaltrials.gov. We also discuss the action mechanisms of these drugs and their potential use in specific patient groups.

EXPERT OPINION

A focus on symptom-driven, combination therapy is crucial in managing FMS. There is also a need for ongoing research into drugs that target neuroinflammation, immunomodulation, and the endocannabinoid system. Bridging the gap between benchside research and clinical application is challenging, but it holds potential for more targeted and effective treatment strategies.

Statistical modeling of acute and chronic pain patient-reported outcomes obtained from ecological momentary assessment

ABSTRACT

Ecological momentary assessment (EMA) allows for the collection of participant-reported outcomes (PROs), including pain, in the normal environment at high resolution and with reduced recall bias. Ecological momentary assessment is an important component in studies of pain, providing detailed information about the frequency, intensity, and degree of interference of individuals' pain. However, there is no universally agreed on standard for summarizing pain measures from repeated PRO assessment using EMA into a single, clinically meaningful measure of pain. Here, we quantify the accuracy of summaries (eg, mean and median) of pain outcomes obtained from EMA and the effect of thresholding these summaries to obtain binary clinical end points of chronic pain status (yes/no). Data applications and simulations indicate that binarizing empirical estimators (eg, sample mean, random intercept linear mixed model) can perform well. However, linear mixed-effect modeling estimators that account for the nonlinear relationship between average and variability of pain scores perform better for quantifying the true average pain and reduce estimation error by up to 50%, with larger improvements for individuals with more variable pain scores. We also show that binarizing pain scores (eg, <3 and ≥3) can lead to a substantial loss of statistical power (40%-50%). Thus, when examining pain outcomes using EMA, the use of linear mixed models using the entire scale (0-10) is superior to splitting the outcomes into 2 groups (<3 and ≥3) providing greater statistical power and sensitivity.

Assessing Ethnic Minority Representation in Fibromyalgia Clinical Trials: A Systematic Review of Recruitment Demographics

The under-representation of non-White participants in Western countries in clinical research has received increased attention, due to recognized physiological differences between ethnic groups, which may affect the efficacy and optimal dosage of some treatments. This review assessed ethnic diversity in pharmaceutical trials for fibromyalgia, a poorly understood chronic pain disorder. We also investigated longitudinal change to non-White participant proportions in trials and non-White participants' likelihood to discontinue with fibromyalgia research between trial stages (retention). First, we identified relevant trials conducted in the United States and Canada between 2000 and 2022, by searching PubMed, Web of Science, Scopus, and the Cochrane Library databases. In trials conducted both across the United States and Canada, and exclusively within the United States, approximately 90% of participants were White. A longitudinal analysis also found no change in the proportion of non-White participants in trials conducted across the United States and Canada between 2000 and 2022. Finally, we found no significant differences in trial retention between White and non-White participants. This review highlights the low numbers of ethnic minorities in fibromyalgia trials conducted in the United States and Canada, with no change to these proportions over the past 22 years. Furthermore, non-White participants were not more likely to discontinue with the fibromyalgia research once they were recruited.

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.

Antidepressants for pain management in adults with chronic pain: a network meta-analysis

BACKGROUND

Chronic pain is common in adults, and often has a detrimental impact upon physical ability, well-being, and quality of life. Previous reviews have shown that certain antidepressants may be effective in reducing pain with some benefit in improving patients' global impression of change for certain chronic pain conditions. However, there has not been a network meta-analysis (NMA) examining all antidepressants across all chronic pain conditions.

OBJECTIVES

To assess the comparative efficacy and safety of antidepressants for adults with chronic pain (except headache).

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, LILACS, AMED and PsycINFO databases, and clinical trials registries, for randomised controlled trials (RCTs) of antidepressants for chronic pain conditions in January 2022.

SELECTION CRITERIA

We included RCTs that examined antidepressants for chronic pain against any comparator. If the comparator was placebo, another medication, another antidepressant, or the same antidepressant at different doses, then we required the study to be double-blind. We included RCTs with active comparators that were unable to be double-blinded (e.g. psychotherapy) but rated them as high risk of bias. We excluded RCTs where the follow-up was less than two weeks and those with fewer than 10 participants in each arm.  DATA COLLECTION AND ANALYSIS: Two review authors separately screened, data extracted, and judged risk of bias. We synthesised the data using Bayesian NMA and pairwise meta-analyses for each outcome and ranked the antidepressants in terms of their effectiveness using the surface under the cumulative ranking curve (SUCRA). We primarily used Confidence in Meta-Analysis (CINeMA) and Risk of Bias due to Missing Evidence in Network meta-analysis (ROB-MEN) to assess the certainty of the evidence. Where it was not possible to use CINeMA and ROB-MEN due to the complexity of the networks, we used GRADE to assess the certainty of the evidence. Our primary outcomes were substantial (50%) pain relief, pain intensity, mood, and adverse events. Our secondary outcomes were moderate pain relief (30%), physical function, sleep, quality of life, Patient Global Impression of Change (PGIC), serious adverse events, and withdrawal.

MAIN RESULTS

This review and NMA included 176 studies with a total of 28,664 participants. The majority of studies were placebo-controlled (83), and parallel-armed (141). The most common pain conditions examined were fibromyalgia (59 studies); neuropathic pain (49 studies) and musculoskeletal pain (40 studies). The average length of RCTs was 10 weeks. Seven studies provided no useable data and were omitted from the NMA. The majority of studies measured short-term outcomes only and excluded people with low mood and other mental health conditions. Across efficacy outcomes, duloxetine was consistently the highest-ranked antidepressant with moderate- to high-certainty evidence. In duloxetine studies, standard dose was equally efficacious as high dose for the majority of outcomes. Milnacipran was often ranked as the next most efficacious antidepressant, although the certainty of evidence was lower than that of duloxetine. There was insufficient evidence to draw robust conclusions for the efficacy and safety of any other antidepressant for chronic pain.  Primary efficacy outcomes Duloxetine standard dose (60 mg) showed a small to moderate effect for substantial pain relief (odds ratio (OR) 1.91, 95% confidence interval (CI) 1.69 to 2.17; 16 studies, 4490 participants; moderate-certainty evidence) and continuous pain intensity (standardised mean difference (SMD) -0.31, 95% CI -0.39 to -0.24; 18 studies, 4959 participants; moderate-certainty evidence). For pain intensity, milnacipran standard dose (100 mg) also showed a small effect (SMD -0.22, 95% CI -0.39 to 0.06; 4 studies, 1866 participants; moderate-certainty evidence). Mirtazapine (30 mg) had a moderate effect on mood (SMD -0.5, 95% CI -0.78 to -0.22; 1 study, 406 participants; low-certainty evidence), while duloxetine showed a small effect (SMD -0.16, 95% CI -0.22 to -0.1; 26 studies, 7952 participants; moderate-certainty evidence); however it is important to note that most studies excluded participants with mental health conditions, and so average anxiety and depression scores tended to be in the 'normal' or 'subclinical' ranges at baseline already. Secondary efficacy outcomes Across all secondary efficacy outcomes (moderate pain relief, physical function, sleep, quality of life, and PGIC), duloxetine and milnacipran were the highest-ranked antidepressants with moderate-certainty evidence, although effects were small. For both duloxetine and milnacipran, standard doses were as efficacious as high doses. Safety There was very low-certainty evidence for all safety outcomes (adverse events, serious adverse events, and withdrawal) across all antidepressants. We cannot draw any reliable conclusions from the NMAs for these outcomes.

AUTHORS' CONCLUSIONS

Our review and NMAs show that despite studies investigating 25 different antidepressants, the only antidepressant we are certain about for the treatment of chronic pain is duloxetine. Duloxetine was moderately efficacious across all outcomes at standard dose. There is also promising evidence for milnacipran, although further high-quality research is needed to be confident in these conclusions. Evidence for all other antidepressants was low certainty. As RCTs excluded people with low mood, we were unable to establish the effects of antidepressants for people with chronic pain and depression. There is currently no reliable evidence for the long-term efficacy of any antidepressant, and no reliable evidence for the safety of antidepressants for chronic pain at any time point.

Comparison of Amitriptyline and US Food and Drug Administration-Approved Treatments for Fibromyalgia: A Systematic Review and Network Meta-analysis

IMPORTANCE

Amitriptyline is an established medication used off-label for the treatment of fibromyalgia, but pregabalin, duloxetine, and milnacipran are the only pharmacological agents approved by the US Food and Drug Administration (FDA) to treat fibromyalgia.

OBJECTIVE

To investigate the comparative effectiveness and acceptability associated with pharmacological treatment options for fibromyalgia.

DATA SOURCES

Searches of PubMed/MEDLINE, Cochrane Library, Embase, and Clinicaltrials.gov were conducted on November 20, 2018, and updated on July 29, 2020.

STUDY SELECTION

Randomized clinical trials (RCTs) comparing amitriptyline or any FDA-approved doses of investigated drugs.

DATA EXTRACTION AND SYNTHESIS

This study follows the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline. Four independent reviewers extracted data using a standardized data extraction sheet and assessed quality of RCTs. A random-effects bayesian network meta-analysis (NMA) was conducted. Data were analyzed from August 2020 to January 2021.

MAIN OUTCOMES AND MEASURES

Comparative effectiveness and acceptability (defined as discontinuation of treatment owing to adverse drug reactions) associated with amitriptyline (off-label), pregabalin, duloxetine, and milnacipran (on-label) in reducing fibromyalgia symptoms. The following doses were compared: 60-mg and 120-mg duloxetine; 150-mg, 300-mg, 450-mg, and 600-mg pregabalin; 100-mg and 200-mg milnacipran; and amitriptyline. Effect sizes are reported as standardized mean differences (SMDs) for continuous outcomes and odds ratios (ORs) for dichotomous outcomes with 95% credible intervals (95% CrIs). Findings were considered statistically significant when the 95% CrI did not include the null value (0 for SMD and 1 for OR). Relative treatment ranking using the surface under the cumulative ranking curve (SUCRA) was also evaluated.

RESULTS

A total of 36 studies (11 930 patients) were included. The mean (SD) age of patients was 48.4 (10.4) years, and 11 261 patients (94.4%) were women. Compared with placebo, amitriptyline was associated with reduced sleep disturbances (SMD, -0.97; 95% CrI, -1.10 to -0.83), fatigue (SMD, -0.64; 95% CrI, -0.75 to -0.53), and improved quality of life (SMD, -0.80; 95% CrI, -0.94 to -0.65). Duloxetine 120 mg was associated with the highest improvement in pain (SMD, -0.33; 95% CrI, -0.36 to -0.30) and depression (SMD, -0.25; 95% CrI, -0.32 to -0.17) vs placebo. All treatments were associated with inferior acceptability (higher dropout rate) than placebo, except amitriptyline (OR, 0.78; 95% CrI, 0.31 to 1.66). According to the SUCRA-based relative ranking of treatments, duloxetine 120 mg was associated with higher efficacy for treating pain and depression, while amitriptyline was associated with higher efficacy for improving sleep, fatigue, and overall quality of life.

CONCLUSIONS AND RELEVANCE

These findings suggest that clinicians should consider how treatments could be tailored to individual symptoms, weighing the benefits and acceptability, when prescribing medications to patients with fibromyalgia.

The role of the vagus nerve in fibromyalgia syndrome

Fibromyalgia (FM) syndrome is a common illness characterized by chronic widespread pain, sleep problems, fatigue, and cognitive difficulties. Dysfunctional neurotransmitter systems that influence the body's endogenous stress response systems are thought to underlie many of the major FM-related symptoms. A model of FM pathogenesis suggests biological and psychosocial variables interact to influence the genetic predisposition, but the precise mechanisms remain unclear. The Polyvagal Theory provides a theoretical framework from which to investigate potential biological mechanisms. The vagus nerve (VN) has anti-inflammatory properties via its afferent and efferent fibers. A low vagal tone (as assessed by low heart rate variability), has been observed in painful and inflammatory diseases, including FM, while the ventral branch of the VN is linked to emotional expression and social engagement. These anti-inflammatory and psychological (limbic system) properties of the VN may possess therapeutic potential in treating FM. This review paper summarizes the scientific literature regarding the potential role of the VN in transducing and/or therapeutically managing FM signs and symptoms.

Efficacy and Safety of Pregabalin for Fibromyalgia in a Population of Chinese Subjects

PURPOSE

Fibromyalgia (FM) may go underdiagnosed and untreated in China in part due to a lack of awareness and understanding of the condition, and limited available treatments.

PATIENTS AND METHODS

This randomized, double-blind, Phase III local registration trial compared the efficacy and safety of pregabalin (flexibly dosed 300-450 mg/day) versus placebo for the management of pain in Chinese adults diagnosed with FM according to American College of Rheumatology 1990 criteria, across 22 centers within China. Patients reported pain score of ≥40 mm on 100-mm scale (from 0 "no pain" to 100 "worst possible pain"). The primary efficacy endpoint was change from baseline to Week 14 in mean pain score (MPS). Secondary endpoints included measures of sleep and sleep interference. Safety and tolerability were monitored throughout.

RESULTS

Median pregabalin dose was 335 mg/day. A significant reduction from baseline to Week 14 in weekly MPS was seen for patients treated with pregabalin (n=170) versus placebo (n=164) (least-squares mean difference [95% confidence interval]: -0.73 [-1.10 to -0.36]; P=0.0001). Significantly greater proportions of patients experienced ≥30% and ≥50% reductions in MPS at Week 14 with pregabalin versus placebo. Pregabalin-treated subjects demonstrated improvements in measures of sleep and sleep interference. Pregabalin was generally well tolerated. The most common adverse events were dizziness and somnolence; no serious adverse events (SAEs) occurred in pregabalin-treated subjects. Nine placebo-treated subjects experienced SAEs.

CONCLUSION

Pregabalin (300-450 mg/day) is a safe and effective treatment for reducing pain and improving sleep in native Chinese subjects with FM.

CLINICALTRIALSGOV IDENTIFIER

NCT01387607.

A combination of pain indices based on momentary assessments can predict placebo response in patients with fibromyalgia syndrome

ABSTRACT

Many factors are known to affect assay sensitivity; however, limited attention has been devoted to understanding whether characteristics of patients' baseline pain impact assay sensitivity. In this study, we tested whether a combination of 3 baseline pain indices based on ecological momentary assessments (EMA) could detect patients with enhanced responses to placebo. The analysis was conducted with secondary data from 2 clinical trials in fibromyalgia patients (N = 2084). For each patient, pain intensity, pain variability (individual SD), and pain consistency (first-order autocorrelation) were computed from baseline EMA. A latent profile analysis identified 3 subgroups of patients based on these indices. Group 1 (n = 857, 41.3%) showed the lowest pain intensity levels, coupled with the highest consistency and greatest variability of pain. Group 3 (n = 110, 5.3%) showed the opposite pattern, and group 2 (n = 1109, 53.4%) showed intermediate levels on all pain indices. It was then tested whether the subgroups moderated treatment effects (changes in pain for active treatment vs placebo) using repeated-measures analysis of variance. Treatment effects varied significantly between subgroups. Patients in group 3 demonstrated greater reduction in pain in response to placebo then those in groups 1 and 2. Further analysis showed that the removal of patients in class 3 would significantly enhance the observed treatment effect by 8% to 15%. In conclusion, profiles of pain characteristics derived from baseline EMA may be useful for detecting patient subgroups with enhanced placebo responses that can diminish assay sensitivity in pain clinical trials.

Measuring fatigue: a meta-review

There is a lack of validated tools to measure fatigue in patients with inflammatory skin, neuropsychiatric, and medical disorders. The use of nonvalidated tools may compromise the quality of data. The purpose of this meta-review was to evaluate existing fatigue scales commonly used to assess fatigue in other inflammatory conditions and to identify if there are scales that have been validated in dermatologic conditions. The PubMed/MEDLINE and SCOPUS databases were systematically searched from inception through March 10, 2020, in accordance with the PRISMA statement. Validated tools were identified and assessed according to their main measurement properties. The literature search identified 403 references, and eight studies were eligible and assessed in this review. The unidimensional fatigue scales included were the Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-F), Brief Fatigue Inventory, Fatigue Severity Scale, Numerical Rating Scale - Fatigue, and Visual Analog Scale - Fatigue. The multidimensional fatigue scales found were the Checklist Individual Strength, Chalder Fatigue Scale, Multidimensional Assessment of Fatigue, Multidimensional Fatigue Inventory Scale, and Piper Fatigue Scale. To measure fatigue, a brief scale with the ability to detect change is needed as there is a growing interest in evaluating this dimension of treatment response. In addition, a good content validity is also needed. From this systematic review, none of the selected scales have had content validation, even though the FACIT was validated in patients with psoriatic arthritis. Validation studies in specific disorders are urgently warranted.

II. Indices of Pain Intensity Derived From Ecological Momentary Assessments and Their Relationships With Patient Functioning: An Individual Patient Data Meta-analysis

Pain intensity is a complex and dynamic experience. A focus on assessing patients' average pain levels may miss important aspects of pain that impact functioning in daily life. In this second of 3 articles investigating alternative indices of pain intensity derived from Ecological Momentary Assessments (EMA), we examine the indices' associations with physical and psychosocial functioning. EMA data from 10 studies (2,660 patients) were reanalyzed to construct indices of Average Pain, Maximum Pain, Minimum Pain, Pain Variability, Time in High Pain, Time in Low Pain, Pain after Wake-up. Three sets of individual patient data meta-analyses examined 1) the test-retest reliability of the pain indices, 2) their convergent validity in relation to physical functioning, fatigue, depression, mental health, and social functioning, and 3) the incremental validity of alternative indices above Average Pain. Reliabilities approaching or exceeding a level of .7 were observed for all indices, and most correlated significantly with all functioning domains, with small to medium effect sizes. Controlling for Average Pain, Maximum Pain and Pain Variability uniquely predicted all functioning measures, and Time in High Pain predicted physical and social functioning. We suggest that alternative pain indices can provide new perspectives for understanding functioning in chronic pain. PERSPECTIVE: Alternative summary measures of pain intensity derived from EMA have the potential to help better understand patients' pain experience. Utilizing EMA for the assessment of Maximum Pain, Pain Variability, and Time in High Pain may provide an enhanced window into the relationships between pain and patients' physical and psychosocial functioning.

III. Detecting Treatment Effects in Clinical Trials With Different Indices of Pain Intensity Derived From Ecological Momentary Assessment

Pain intensity represents the primary outcome in most pain clinical trials. Identifying methods to measure aspects of pain that are most sensitive to treatment may facilitate discovery of effective interventions. In this third of 3 articles examining alternative indices of pain intensity derived from ecological momentary assessments (EMA), we compare treatment effects based on Average Pain, Maximum Pain, Minimum Pain, Pain Variability, Time in High Pain, Time in Low Pain, and Pain After Wake-Up. We also examine which indices contribute to Patient Global Impressions of Change (PGIC). Data came from 2 randomized, double-blind, placebo-controlled trials examining the efficacy of milnacipran for fibromyalgia treatment; 2,084 patients provided >1 million EMA pain intensity ratings over 24 (Study 1) or 26 (Study 2) treatment weeks. Pain Variability and Time in High Pain produced significantly smaller treatment effects than Average Pain; other pain indices showed effects that were numerically smaller, but not significantly different from Average Pain. Changes in all pain indices were significantly associated with PGIC, with improvements in Maximum Pain and in Pain Variability offering small incremental contributions to understanding PGIC over Average Pain. Results suggest that different pain indices could be used to detect treatment effects in pain clinical trials. PERSPECTIVE: Alternative summary measures of pain intensity derived from EMA may broaden the scope of outcomes useful in pain clinical trials. In this analysis of a pharmacological treatment for fibromyalgia, most pain summary measures indicated similar effects; improvements in Maximum Pain and Pain Variability contributed to understanding PGIC over Average Pain.

Polymorphisms of the μ-opioid receptor gene influence cerebral pain processing in fibromyalgia

Background

Dysregulation of the μ‐opioid receptor has been reported in fibromyalgia (FM) and was linked to pain severity. Here, we investigated the effect of the functional genetic polymorphism of the μ‐opioid receptor gene (OPRM1) (rs1799971) on symptom severity, pain sensitivity and cerebral pain processing in FM subjects and healthy controls (HC).

Methods

Symptom severity and pressure pain sensitivity was assessed in FM subjects (n = 70) and HC (n = 35). Cerebral pain‐related activation was assessed by functional magnetic resonance imaging during individually calibrated painful pressure stimuli.

Results

Fibromyalgia subjects were more pain sensitive but no significant differences in pain sensitivity or pain ratings were observed between OPRM1 genotypes. A significant difference was found in cerebral pain processing, with carriers of at least one G‐allele showing increased activation in posterior cingulate cortex (PCC) extending to precentral gyrus, compared to AA homozygotes. This effect was significant in FM subjects but not in healthy participants, however, between‐group comparisons did not yield significant results. Seed‐based functional connectivity analysis was performed with the seed based on differences in PCC/precentral gyrus activation between OPRM1 genotypes during evoked pain across groups. G‐allele carriers displayed decreased functional connectivity between PCC/precentral gyrus and prefrontal cortex.

Conclusions

G‐allele carriers showed increased activation in PCC/precentral gyrus but decreased functional connectivity with the frontal control network during pressure stimulation, suggesting different pain modulatory processes between OPRM1 genotypes involving altered fronto‐parietal network involvement. Furthermore, our results suggest that the overall effects of the OPRM1 G‐allele may be driven by FM subjects.

Significance

We show that the functional polymorphism of the μ‐opioid receptor gene OPRM1 was associated with alterations in the fronto‐parietal network as well as with increased activation of posterior cingulum during evoked pain in FM. Thus, the OPRM1 polymorphism affects cerebral processing in brain regions implicated in salience, attention, and the default mode network. This finding is discussed in the light of pain and the opioid system, providing further evidence for a functional role of OPRM1 in cerebral pain processing.

Registration, results reporting, and publication bias of clinical trials supporting FDA approval of neuropsychiatric drugs before and after FDAAA: a retrospective cohort study

Background

Mandatory trial registration, and later results reporting, were proposed to mitigate selective clinical trial publication and outcome reporting. The Food and Drug Administration (FDA) Amendments Act (FDAAA) was enacted by Congress on September 27, 2007, requiring the registration of all non-phase I clinical trials involving FDA-regulated medical interventions and results reporting for approved drugs. The association between FDAAA enactment and the registration, results reporting, and publication bias of neuropsychiatric trials has not been studied.

Methods

We conducted a retrospective cohort study of all efficacy trials supporting FDA new drug approvals between 2005 to 2014 for neuropsychiatric indications. Trials were categorized as pre- or post-FDAAA based on initiation and/or completion dates. The main outcomes were the proportions of trials registered and reporting results in ClinicalTrials.gov, and the degree of publication bias, estimated using the relative risks pre- and post-FDAAA of both the publication of positive vs non-positive trials, as well as of publication of positive vs non-positive trials without misleading interpretations. Registration and results reporting proportions were compared pre- and post-FDAAA using the two-tailed Fisher exact test, and the degrees of publication bias were compared by calculating the ratio of relative risks (RRR) for each period.

Results

The FDA approved 37 new drugs for neuropsychiatric indications between 2005 and 2014 on the basis of 142 efficacy trials, of which 101 were pre-FDAAA and 41 post-FDAAA. Post-FDAAA trials were significantly more likely to be registered (100% vs 64%; p < 0.001) and report results (100% vs 10%; p < 0.001) than pre-FDAAA trials. Pre-FDAAA, positive trials were more likely to be published (relative risk [RR] = 1.52; 95% confidence interval [CI] = 1.17–1.99; p = 0.002) and published without misleading interpretations (RR = 2.47; CI = 1.57–3.73; p < 0.001) than those with non-positive results. In contrast, post-FDAAA positive trials were equally likely to have been published (RR = 1; CI = 1–1, p = NA) and published without misleading interpretations (RR = 1.20; CI = 0.84–1.72; p = 0.30). The likelihood of publication bias pre-FDAAA vs post-FDAAA was greater for positive vs non-positive trials (RRR = 1.52; CI = 1.16–1.99; p = 0.002) and for publication without misleading interpretations (RRR = 2.06, CI = 1.17–3.61, p = 0.01).

Conclusions

The enactment of FDAAA was followed by significantly higher proportions of trials that were registered and reporting results on ClinicalTrials.gov and significantly lower degrees of publication bias among trials supporting recent FDA approval of drugs for neuropsychiatric indications.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2957-0) contains supplementary material, which is available to authorized users.

Mechanisms for Joint Pain in Rheumatoid Arthritis (RA): from Cytokines to Central Sensitization

PURPOSE OF REVIEW

Pain in rheumatoid arthritis (RA) may be due to different etiologies, ranging from peripheral inflammation to dysregulation of central nervous system (CNS) processing. This review evaluates relevant literature published on RA pain mechanisms in recent years.

RECENT FINDINGS

Despite successes of disease-modifying antirheumatic drugs (DMARDs), pain persists for many RA patients. Studies involving patient-reported outcomes, quantitative sensory testing, and neuroimaging indicate that, in addition to joint inflammation, abnormalities in CNS pain processing may contribute to pain. Some DMARDs (e.g., janus kinus inhibitors) may work via multiple pathways to decrease pain. Adjunctive treatments (e.g., antidepressants, antiepileptics) may also be useful in managing pain in RA patients with well-controlled disease. Both peripheral and central mechanisms play key roles in the expression of pain in RA. To effectively manage pain, physicians need accurate assessment tools to identify the pathways involved in each patient so that treatments may be appropriately targeted.

Ecological Momentary Assessment Methodology in Chronic Pain Research: A Systematic Review

Self-reported pain intensity assessments are central to chronic pain research. Ecological momentary assessment (EMA) methodologies are uniquely positioned to collect these data, and are indeed being used in the field. However, EMA protocols are complex, and many decisions are necessary in the design of EMA research studies. A systematic literature review identified 105 articles drawing from 62 quantitative EMA research projects examining pain intensity in adult chronic pain patients. Study characteristics were tabulated to summarize and describe the use of EMA, with an emphasis placed on various dimensions of decision-making involved in executing EMA methodologies. Most identified studies considered within-person relationships between pain and other variables, and a few examined interventions on chronic pain. There was a trend toward the use of smartphones as EMA data collection devices more recently, and completion rates were not reported in nearly one third of studies. Pain intensity items varied widely with respect to number of scale points, anchor labels, and length of reporting period; most used numeric rating scales. Recommendations are provided for reporting to improve reproducibility, comparability, and interpretation of results, and for opportunities to clarify the importance of design decisions.

PERSPECTIVE

Studies that use EMA methodologies to assess pain intensity are heterogeneous. Aspects of protocol design, including data input modality and pain item construction, have the potential to influence the data collected. Thorough reporting on design features and completion rates therefore facilitates reproducibility, comparability, and interpretation of study results.

Serotonin and noradrenaline reuptake inhibitors (SNRIs) for fibromyalgia

BACKGROUND

Fibromyalgia is a clinically defined chronic condition of unknown etiology characterized by chronic widespread pain that often co-exists with sleep disturbances, cognitive dysfunction and fatigue. People with fibromyalgia often report high disability levels and poor quality of life. Drug therapy, for example, with serotonin and noradrenaline reuptake inhibitors (SNRIs), focuses on reducing key symptoms and improving quality of life. This review updates and extends the 2013 version of this systematic review.

OBJECTIVES

To assess the efficacy, tolerability and safety of serotonin and noradrenaline reuptake inhibitors (SNRIs) compared with placebo or other active drug(s) in the treatment of fibromyalgia in adults.

SEARCH METHODS

For this update we searched CENTRAL, MEDLINE, Embase, the US National Institutes of Health and the World Health Organization (WHO) International Clinical Trials Registry Platform for published and ongoing trials and examined the reference lists of reviewed articles, to 8 August 2017.

SELECTION CRITERIA

We selected randomized, controlled trials of any formulation of SNRIs against placebo or any other active treatment of fibromyalgia in adults.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data, examined study quality, and assessed risk of bias. For efficacy, we calculated the number needed to treat for an additional beneficial outcome (NNTB) for pain relief of 50% or greater and of 30% or greater, patient's global impression to be much or very much improved, dropout rates due to lack of efficacy, and the standardized mean differences (SMD) for fatigue, sleep problems, health-related quality of life, mean pain intensity, depression, anxiety, disability, sexual function, cognitive disturbances and tenderness. For tolerability we calculated number needed to treat for an additional harmful outcome (NNTH) for withdrawals due to adverse events and for nausea, insomnia and somnolence as specific adverse events. For safety we calculated NNTH for serious adverse events. We undertook meta-analysis using a random-effects model. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We added eight new studies with 1979 participants for a total of 18 included studies with 7903 participants. Seven studies investigated duloxetine and nine studies investigated milnacipran against placebo. One study compared desvenlafaxine with placebo and pregabalin. One study compared duloxetine with L-carnitine. The majority of studies were at unclear or high risk of bias in three to five domains.The quality of evidence of all comparisons of desvenlafaxine, duloxetine and milnacipran versus placebo in studies with a parallel design was low due to concerns about publication bias and indirectness, and very low for serious adverse events due to concerns about publication bias, imprecision and indirectness. The quality of evidence of all comparisons of duloxetine and desvenlafaxine with other active drugs was very low due to concerns about publication bias, imprecision and indirectness.Duloxetine and milnacipran had no clinically relevant benefit over placebo for pain relief of 50% or greater: 1274 of 4104 (31%) on duloxetine and milnacipran reported pain relief of 50% or greater compared to 591 of 2814 (21%) participants on placebo (risk difference (RD) 0.09, 95% confidence interval (CI) 0.07 to 0.11; NNTB 11, 95% CI 9 to 14). Duloxetine and milnacipran had a clinically relevant benefit over placebo in patient's global impression to be much or very much improved: 888 of 1710 (52%) on duloxetine and milnacipran (RD 0.19, 95% CI 0.12 to 0.26; NNTB 5, 95% CI 4 to 8) reported to be much or very much improved compared to 354 of 1208 (29%) of participants on placebo. Duloxetine and milnacipran had a clinically relevant benefit compared to placebo for pain relief of 30% or greater. RD was 0.10; 95% CI 0.08 to 0.12; NNTB 10, 95% CI 8 to 12. Duloxetine and milnacipran had no clinically relevant benefit for fatigue (SMD -0.13, 95% CI -0.18 to -0.08; NNTB 18, 95% CI 12 to 29), compared to placebo. There were no differences between either duloxetine or milnacipran and placebo in reducing sleep problems (SMD -0.07; 95 % CI -0.15 to 0.01). Duloxetine and milnacipran had no clinically relevant benefit compared to placebo in improving health-related quality of life (SMD -0.20, 95% CI -0.25 to -0.15; NNTB 11, 95% CI 8 to 14).There were 794 of 4166 (19%) participants on SNRIs who dropped out due to adverse events compared to 292 of 2863 (10%) of participants on placebo (RD 0.07, 95% CI 0.04 to 0.10; NNTH 14, 95% CI 10 to 25). There was no difference in serious adverse events between either duloxetine, milnacipran or desvenlafaxine and placebo (RD -0.00, 95% CI -0.01 to 0.00).There was no difference between desvenlafaxine and placebo in efficacy, tolerability and safety in one small trial.There was no difference between duloxetine and desvenlafaxine in efficacy, tolerability and safety in two trials with active comparators (L-carnitine, pregabalin).

AUTHORS' CONCLUSIONS

The update did not change the major findings of the previous review. Based on low- to very low-quality evidence, the SNRIs duloxetine and milnacipran provided no clinically relevant benefit over placebo in the frequency of pain relief of 50% or greater, but for patient's global impression to be much or very much improved and in the frequency of pain relief of 30% or greater there was a clinically relevant benefit. The SNRIs duloxetine and milnacipran provided no clinically relevant benefit over placebo in improving health-related quality of life and in reducing fatigue. Duloxetine and milnacipran did not significantly differ from placebo in reducing sleep problems. The dropout rates due to adverse events were higher for duloxetine and milnacipran than for placebo. On average, the potential benefits of duloxetine and milnacipran in fibromyalgia were outweighed by their potential harms. However, a minority of people with fibromyalgia might experience substantial symptom relief without clinically relevant adverse events with duloxetine or milnacipran.We did not find placebo-controlled studies with other SNRIs than desvenlafaxine, duloxetine and milnacipran.

Longitudinal stability of fibromyalgia symptom clusters

Background

Using self-report questionnaires of key fibromyalgia symptom domains (pain, fatigue, sleep disturbance, function, stiffness, dyscognition, depression, and anxiety), we previously identified four unique symptom clusters. The purpose of this study was to examine the stability of fibromyalgia symptom clusters between baseline and 2-year follow-up.

Methods

Women with a diagnosis of fibromyalgia completed the Brief Pain Inventory, Profile of Mood States, Medical Outcomes Study Sleep measure, Multidimensional Fatigue Inventory, Multiple Ability Self-Report Questionnaire, Revised Fibromyalgia Impact Questionnaire, and the 36-Item Short Form Survey Instrument at baseline. Follow-up measures were completed approximately 2 years later. The hierarchical agglomerative clustering algorithm previously developed was applied; agreement between baseline and follow-up was assessed with the κ statistic.

Results

Among 433 participants, the mean age was 56 (range 20–85) years. The median Revised Fibromyalgia Impact Questionnaire total score was 57 (range 8–96). More than half of participants (58%) remained in the same cluster at follow-up as at baseline, which represented moderate agreement between baseline and follow-up (κ = 0.44, 95% confidence interval (CI) 0.37–0.50). Only two patients changed from high symptom intensity to low symptom intensity; similarly, only three moved from low to high.

Conclusions

Fibromyalgia patients classified into four unique symptom clusters based on the key domains of pain, fatigue, sleep disturbance, function, stiffness, dyscognition, depression, and anxiety showed moderate stability in cluster assignment after 2 years. Few patients moved between the two extremes of severity, and it was slightly more common to move to a lower symptom level than to worsen.

Trial registration

Not applicable.

Healthcare Costs and Medication Adherence Among Patients with Fibromyalgia: Combination Medication vs. Duloxetine, Milnacipran, Venlafaxine, and Pregabalin Initiators

OBJECTIVE

To examine medication adherence and healthcare costs for combination prescription initiators (duloxetine/milnacipran/venlafaxine with pregabalin) vs. monotherapy initiators (duloxetine, milnacipran, venlafaxine, and pregabalin) among patients with fibromyalgia syndrome (FMS).

METHODS

Our retrospective cohort study used claims data for the South Carolina Blue Cross Blue Shield State Health Plan (SHP). Patients with FMS ≥ 18 years of age, with prescription initiation from July 1, 2007, through June 30, 2010, and SHP enrollment for 12 months pre- and post-index periods were included (combination: n = 100; pregabalin: n = 665; duloxetine: n = 713; milnacipran: n = 131; venlafaxine: n = 272). Medication adherence measures included high adherence (medication possession ratio ≥ 80%) and total supply days. Healthcare costs comprised direct medical expenditures. Propensity score methods of inverse probability of treatment weights were used to control for selection bias due to differing pre-index characteristics.

RESULTS

Odds ratios for high adherence were significantly increased (P < 0.05) among the combination cohort vs. the venlafaxine (2.15), duloxetine (1.39), and pregabalin (2.20) cohorts. Rate ratios for total supply days were significantly higher (P < 0.05) for combination vs. venlafaxine (1.23), duloxetine (1.08), and pregabalin (1.32) cohorts. Expenditures for total health care were significantly higher (P < 0.05) for combination vs. duloxetine ($26,291 vs. $17,190), milnacipran ($33,638 vs. $22,886), and venlafaxine ($26,586 vs. $16,857) cohorts.

CONCLUSIONS

Medication adherence was considerably better for combination prescription initiators; however, expenditures for total health care were higher. Still, our findings suggest important clinical benefits with the use of combination prescription therapy, and prospective studies of medication adherence are warranted to examine causal relationships with outcomes not captured by healthcare claims databases.

Alternatives to Opioids in the Pharmacologic Management of Chronic Pain Syndromes: A Narrative Review of Randomized, Controlled, and Blinded Clinical Trials

Chronic pain exerts a tremendous burden on individuals and societies. If one views chronic pain as a single disease entity, then it is the most common and costly medical condition. At present, medical professionals who treat patients in chronic pain are recommended to provide comprehensive and multidisciplinary treatments, which may include pharmacotherapy. Many providers use nonopioid medications to treat chronic pain; however, for some patients, opioid analgesics are the exclusive treatment of chronic pain. However, there is currently an epidemic of opioid use in the United States, and recent guidelines from the Centers for Disease Control (CDC) have recommended that the use of opioids for nonmalignant chronic pain be used only in certain circumstances. The goal of this review was to report the current body of evidence-based medicine gained from prospective, randomized-controlled, blinded studies on the use of nonopioid analgesics for the most common noncancer chronic pain conditions. A total of 9566 studies were obtained during literature searches, and 271 of these met inclusion for this review. Overall, while many nonopioid analgesics have been found to be effective in reducing pain for many chronic pain conditions, it is evident that the number of high-quality studies is lacking, and the effect sizes noted in many studies are not considered to be clinically significant despite statistical significance. More research is needed to determine effective and mechanism-based treatments for the chronic pain syndromes discussed in this review. Utilization of rigorous and homogeneous research methodology would likely allow for better consistency and reproducibility, which is of utmost importance in guiding evidence-based care.

Adverse Effects of Antidepressants for Chronic Pain: A Systematic Review and Meta-analysis

Background

Antidepressants are widely used in the treatment of chronic pain. Applied doses are lower than those needed to unfold an antidepressive effect. While efficacy of antidepressants for chronic pain has been reported in large randomized-controlled trials (RCT), there is inconsistent data on adverse effects and tolerability. We aimed at synthesizing data from RCT to explore adverse effect profiles and tolerability of antidepressants for treatment of chronic pain.

Methods

Systematic literature research and meta-analyses were performed regarding side effects and safety of different antidepressants in the treatment of chronic pain according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The National Center for Biotechnology Information library and MEDLINE were searched. Randomized placebo-controlled trials were included in quantitative data synthesis.

Results

Out of 1,975 screened articles, 33 papers published between 1995 and 2015 were included in our review and 23 studies were included in the meta-analyses. A higher risk for adverse effects compared to placebo was observed in all antidepressants included in our analyses, except nortriptyline. The most prevalent adverse effects were dry mouth, dizziness, nausea, headache, and constipation. Amitriptyline, mirtazapine, desipramine, venlafaxine, fluoxetine, and nortriptyline showed the highest placebo effect-adjusted risk of adverse effects. Risk for withdrawal due to adverse effects was highest in desipramine (risk ratio: 4.09, 95%-confidence interval [1.31; 12.82]) followed by milnacipran, venlafaxine, and duloxetine. The most common adverse effects under treatment with antidepressants were dry mouth, dizziness, nausea, headache, and constipation followed by palpitations, sweating, and drowsiness. However, overall tolerability was high. Each antidepressant showed distinct risk profiles of adverse effects.

Conclusion

Our synthesized data analysis confirmed overall tolerability of low-dose antidepressants for the treatment of chronic pain and revealed drug specific risk profiles. This encompassing characterization of adverse effect profiles might be useful in defining multimodal treatment regimens for chronic pain which also consider patients’ comorbidities and co-medication.

A Brief Review of the Pharmacology of Amitriptyline and Clinical Outcomes in Treating Fibromyalgia

Fibromyalgia is a complex chronic condition characterized by pain, physical fatigue, sleep disorder and cognitive impairment. Evidence-based guidelines recommend antidepressants as treatments of fibromyalgia where tricyclics are often considered to have the greatest efficacy, with amitriptyline often being a first-line treatment. Amitriptyline evokes a preferential reduction in pain and fatigue of fibromyalgia, and in the Fibromyalgia Impact Questionnaire (FIQ) score, which is a quality of life assessment. The multimodal profile of the mechanisms of action of amitriptyline include monoamine reuptake inhibition, receptor modulation and ion channel modulation. Several of the actions of amitriptyline on multiple nociceptive and sensory processes at central and peripheral locations have the potential to act cumulatively to suppress the characteristic symptoms of fibromyalgia. Greater understanding of the role of these mechanisms of action of amitriptyline could provide further clues to the pathophysiology of fibromyalgia and to a preferable pharmacological profile for future drug development.

Update on Treatment Guideline in Fibromyalgia Syndrome with Focus on Pharmacology

Fibromyalgia syndrome (FMS) is a chronic condition with unknown aetiology. The pathophysiology of the disease is incompletely understood; despite advances in our knowledge with regards to abnormal central and peripheral pain processing, and hypothalamo-pituitary-adrenal dysfunction, there is no clear specific pathophysiological therapeutic target. The management of this complex condition has thus perplexed the medical community for many years, and several national and international guidelines have aimed to address this complexity. The most recent guidelines from European League Against Rheumatism (EULAR) (2016), Canadian Pain Society (2012), and The Association of the Scientific Medical Societies in Germany (AWMF) (2012) highlight the change in attitudes regarding the overall approach to FMS, but offer varying advice with regards to the use of pharmacological agents. Amitriptyline, Pregabalin and Duloxetine are used most commonly in FMS and though modestly effective, are useful adjunctive treatment to non-pharmaceutical measures.

Epidemiologic Evaluation of Cardiovascular Risk in Patients Receiving Milnacipran, Venlafaxine, or Amitriptyline: Evidence from French Health Data

BACKGROUND:

Milnacipran, a selective serotonin and norepinephrine reuptake inhibitor, is approved by the Food and Drug Administration for the management of fibromyalgia. It has been available for many years in several countries outside the US for the treatment of depression.

OBJECTIVE:

To conduct population-based analyses comparing the risk of serious cardiovascular (CV) events (eg, acute myocardial infarction, stroke, congestive heart failure) associated with treatment with milnacipran compared with venlafaxine and amitriptyline, 2 other commonly prescribed drugs that also inhibit reuptake of norepinephrine and serotonin.

METHODS:

Information from the French Thales electronic health record database from 2001 to 2007 was used. Patients with 1 or more prescriptions for milnacipran, venlafaxine, or amitriptyline; 180 or more days of continuous eligibility prior to the first prescription; and no prior CV event diagnoses during the 180-day baseline period were included. A retrospective, matched-cohort design was employed. The incidence rates of CV events between cohorts receiving milnacipran, venlafaxine, and amitriptyline were compared using unadjusted incidence rate ratio (IRR) and adjusted conditional IRR based on Poisson regression.

RESULTS:

We identified 4452 milnacipran-venlafaxine and 3761 milnacipran-amitriptyline matched pairs. The matched cohorts had similar baseline characteristics. The unadjusted IRRs of any CV events, comparing milnacipran with venlafaxine or amitriptyline, were 1.02 (95% CI 0.73 to 1.44) and 1.30 (95% CI 0.90 to 1.89), respectively. Adjusted IRRs confirmed the statistical similarity in the CV event risk between milnacipran and venlafaxine (adjusted IRR = 1.29, 95% CI 0.76 to 2.17) or amitriptyline (adjusted IRR = 1.06, 95% CI 0.59 to 1.89).

CONCLUSIONS:

This French population-based study found that the risk of CV events was not significantly different for patients receiving milnacipran versus those receiving venlafaxine or amitriptyline.

Clinical Experience With Desvenlafaxine in Treatment of Patients With Fibromyalgia Syndrome

Two multicenter, randomized, placebo-controlled, adaptive-design trials of desvenlafaxine for fibromyalgia syndrome (FMS) were conducted. In study 1, male and female patients were randomized to a 27-week treatment with placebo or desvenlafaxine 50, 100, 200, or 400 mg/d. In study 2, female patients were randomized to an 8-week treatment with placebo, desvenlafaxine 200 mg/d, or pregabalin 450 mg/d after a placebo run-in. The primary efficacy end point was change from baseline in numeric rating scale (NRS) pain score. Protocol-specified interim analyses were planned after 12 (study 1) and 8 (study 2) weeks of treatment. Safety data were collected. In all, 697 patients were randomly assigned to treatment in study 1. At the interim analysis (n = 346), none of the desvenlafaxine doses met the efficacy criteria (mean [SE] advantage over placebo, -0.21 [0.36] to 0.04 [0.35]), and the study was terminated. Study 2 was stopped for business reasons before the planned interim analysis. NRS scores in week 8 were -1.98 (0.37), -1.60 (0.37), and -1.70 (0.38) for placebo (n = 26), desvenlafaxine 250 mg/d (n = 24), and pregabalin 450 mg/d (n = 21), respectively; neither active treatment differed significantly from placebo. Desvenlafaxine was generally safe and well tolerated. Efficacy of desvenlafaxine for pain associated with FMS was not demonstrated.

Is the Efficacy of Milnacipran in Fibromyalgia Predictable? A Data-Mining Analysis of Baseline and Outcome Variables

OBJECTIVES

Minalcipran has been approved for the treatment of fibromyalgia in several countries including Australia. Australian agency considered that the overall efficacy is moderate, although clinically significant, and could be translated into a real and strong improvement in some patients. The determination of the characteristics of patients who could benefit the most from milnacipran (MLN) is the primary objective of this manuscript.

MATERIALS AND METHODS

Data from the 3 pivotal phase 3 clinical trials of the Australian submission dossier were assembled into a database. A clustering method was implemented to exhibit natural groupings of homogeneous observations into clusters of efficacy outcomes and individual patients. Next, baseline characteristics were investigated using a data-mining method to determine the clinical features that may be predictive of a substantially improved effect of MLN on a set of efficacy outcomes.

RESULTS

The clustering analysis reveals 3 symptom domains: "Pain and global," "Mood and central status," and "Function." We show that improvement in "Fatigue" goes with improvement in "Function." Furthermore, the predictive data-mining analysis exhibits 4 single baseline characteristics that are associated with a substantially improved effect of MLN on efficacy outcomes. These are high pain intensity, low anxiety or catastrophizing level, absence of major sleeping problems, and physical limitations in the daily life effort.

DISCUSSION

Clustering and predictive data-mining methods provide additional insight about fibromyalgia, its symptoms, and treatment. The information is useful to physicians to optimize prescriptions in the daily practice and to regulatory bodies to refine indications.

Fibromyalgia syndrome: novel therapeutic targets

Fibromyalgia syndrome (FMS) is a chronic disorder characterized by widespread pain and tenderness, accompanied by disturbed sleep, chronic fatigue and multiple additional functional symptoms. FMS continues to pose an unmet need regarding pharmacological treatment and many patients fail to achieve sufficient relief from existing treatments. As FMS is considered to be a condition in which pain amplification occurs within the CNS, therapeutic interventions, both pharmacological and otherwise, have revolved around attempts to influence pain processing in the CNS. In the current review, we present an update on novel targets in the search for effective treatment of FMS.

Management of fibromyalgia syndrome in 2016

Fibromyalgia syndrome is a chronic pain disorder and defies definitively efficacious therapy. In this review, we summarize the results from the early treatment research as well as recent research evaluating the pharmacological, interventional and nonpharmacological therapies. We further discuss future directions of fibromyalgia syndrome management; we specifically focus on the issues that are associated with currently available treatments, such as the need for personalized approach, new technologically oriented and interventional treatments, the importance of understanding and harnessing placebo effects and enhancement of patient engagement in therapy.

Pain Assessment--Can it be Done with a Computerised System? A Systematic Review and Meta-Analysis

Background: Mobile and web technologies are becoming increasingly used to support the treatment of chronic pain conditions. However, the subjectivity of pain perception makes its management and evaluation very difficult. Pain treatment requires a multi-dimensional approach (e.g., sensory, affective, cognitive) whence the evidence of technology effects across dimensions is lacking. This study aims to describe computerised monitoring systems and to suggest a methodology, based on statistical analysis, to evaluate their effects on pain assessment. Methods: We conducted a review of the English-language literature about computerised systems related to chronic pain complaints that included data collected via mobile devices or Internet, published since 2000 in three relevant bibliographical databases such as BioMed Central, PubMed Central and ScienceDirect. The extracted data include: objective and duration of the study, age and condition of the participants, and type of collected information (e.g., questionnaires, scales). Results: Sixty-two studies were included, encompassing 13,338 participants. A total of 50 (81%) studies related to mobile systems, and 12 (19%) related to web-based systems. Technology and pen-and-paper approaches presented equivalent outcomes related with pain intensity. Conclusions: The adoption of technology was revealed as accurate and feasible as pen-and-paper methods. The proposed assessment model based on data fusion combined with a qualitative assessment method was revealed to be suitable. Data integration raises several concerns and challenges to the design, development and application of monitoring systems applied to pain.

Treatment Patterns Associated with ACR-Recommended Medications in the Management of Fibromyalgia in the United States

BACKGROUND

Fibromyalgia (FM) affects up to 6% of U.S. adults, resulting in a significant burden on the health care system and poor quality of life for patients. Duloxetine, pregabalin, and milnacipran are approved for management of FM; however, consensus is lacking regarding optimal therapy. Patients with FM taking approved medications often do not experience meaningful symptom relief, and many experience intolerable adverse events.

OBJECTIVE

To assess treatment patterns associated with available and commonly used medications for the management of FM using U.S. health insurance claims.

METHODS

This retrospective analysis used the MarketScan claims database to identify adults with a first diagnosis of FM (ICD-9-CM code 729.1) between 2009 and 2011 with continuous health plan enrollment for 12 months pre- and post-index. Medications of interest were pregabalin, gabapentin, duloxetine, milnacipran, cyclobenzaprine, and tramadol. These are 6 of the 8 medications recommended by the American College of Rheumatology (ACR) for treating FM; the other 2 (amitriptyline and venlafaxine) were only included in some initial assessments. The Charlson Comorbidity Index (CCI) was used to assess overall comorbidity burden. Endpoints included proportion of patients treated within 1 year after first diagnosis; initial treatment pattern; adherence over the first-year follow-up period for the medications of interest; and discontinuation, switching, and combination therapy patterns among pain medications of interest at different time points. Proportion of days covered (PDC; defined as number of days in the period when the patient had drug supply divided by the number of days in the period) was used to define adherence, which was categorized as low (PDC < 50%), medium (PDC 50% to < 80%), or high (PDC ≥ 80%). The time to discontinuation (defined as the first drug supply gap ≥ 90 days) was estimated using Kaplan-Meier analysis.

RESULTS

Overall, 240,144 patients met the inclusion criteria. Patients were predominantly women (68%), had preferred provider organization insurance coverage (68%), and had a CCI score < 1 at baseline (69%). Only 31% (n = 74,738) initiated a treatment with a prescription medication listed in the ACR guidelines, and many patients received less than the recommended dose. Most (n = 70,919) patients initially received monotherapy with one of the 8 prescription medications. Of those who started with ≥ 2 medications (n = 3,819), cyclobenzaprine plus tramadol was the most frequent combination. Adherence was suboptimal for all 6 medications of interest. Duloxetine had the highest mean PDC (59%); for all other agents, mean PDC was < 50%. With the exception of duloxetine, discontinuation rates at 6 months were > 50% for all agents. Alterations in therapy were common. Among patients who discontinued their initial treatment of duloxetine, pregabalin, or milnacipran, approximately one-third had switched treatments within 90 days after their first prescription. For those who maintained their initial treatment agent, approximately 50% of patients added a second pain medication within 1 year of treatment initiation.

CONCLUSIONS

The evidence suggests that patients with FM often do not receive 1 of the prescription medications recommended by ACR guidelines, and those who do are commonly prescribed lower-than-recommended doses, potentially resulting in poor effectiveness and tolerability. Discontinuation, switching, and addition of new pain medications are common, which may indicate low levels of satisfaction with initial treatment. New therapies with improved effectiveness and better tolerability are urgently needed for patients with FM.

The Effects of Milnacipran on Sleep Disturbance in Fibromyalgia: A Randomized, Double-Blind, Placebo-Controlled, Two-Way Crossover Study

OBJECTIVE

This study examined the effects of milnacipran on polysomnographic (PSG) measures of sleep and subjective complaints in patients with fibromyalgia and disturbed sleep.

METHODS

This was a single-site, double-blind, placebo-controlled, two-period crossover PSG study. Eligible subjects (aged 28-72 y) were randomized (1:1) to milnacipran (100 mg/d) or placebo for crossover period 1, and vice versa for period 2. Each crossover period comprised a dose-escalation and dose-maintenance phase, with a 2-w taper/washout between periods. In-laboratory PSGs were collected at baseline, and at the end of each treatment period. The primary endpoints were the difference in PSG-recorded wake after sleep onset (WASO), number of awakenings after sleep onset (NAASO), and sleep efficiency (SE) between 4 w of maintenance treatment with milnacipran and placebo. Other PSG measures, subject-rated sleep, fatigue, physical functioning, and pain were assessed. Post hoc analysis was performed in subjects showing at least 25% reduction in pain from baseline in the Brief Pain Inventory Score (responders).

RESULTS

Of 19 subjects randomized, 15 completed both periods. Subjects treated with milnacipran showed no significant improvements in WASO and NAASO, but showed reduced SE (p = 0.049). Milnacipran did not show significant improvement in other PSG parameters or subjective endpoints. Two thirds of completers met responder criteria and additionally showed a significant improvement in daily effect of pain (p = 0.043) and subjective sleep quality (p = 0.040).

CONCLUSION

The data suggest that milnacipran is not sedating in most patients with fibromyalgia and improvements in sleep are likely a result of pain improvement.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier: NCT01234675.

Effect of Milnacipran on Pain in Patients with Rheumatoid Arthritis with Widespread Pain: A Randomized Blinded Crossover Trial

OBJECTIVE

Clinical trials have shown that serotonin norepinephrine reuptake inhibitors, such as milnacipran, decrease pain in noninflammatory pain conditions such as fibromyalgia and osteoarthritis. We examined the effect of milnacipran on self-reported pain intensity and experimental pain sensitivity among patients with rheumatoid arthritis (RA) with widespread pain and stable RA disease activity.

METHODS

In this double-blind, crossover study, patients with RA with widespread pain, receiving a stable treatment regimen, were randomized (by a random number generator) to receive milnacipran 50 mg twice daily or placebo for 6 weeks, followed by a 3-week washout and crossed over to the other arm for the remaining 6 weeks. The primary outcome was change in average pain intensity, assessed by the Brief Pain Inventory short form. The sample size was calculated to detect a 30% improvement in pain with power = 0.80 and α = 0.05.

RESULTS

Of the 43 randomized subjects, 41 received the study drug, and 32 completed the 15-week study per protocol. On a 0-10 scale, average pain intensity decreased by 0.39 (95% CI -1.27 to 0.49, p = 0.37) more points during 6 weeks of milnacipran treatment compared with placebo. In the subgroup of subjects with swollen joint count ≤ 1, average pain intensity decreased by 1.14 more points during 6 weeks of milnacipran compared with placebo (95% CI -2.26 to -0.01, p = 0.04). Common adverse events included nausea (26.8%) and loss of appetite (9.7%).

CONCLUSION

Compared with placebo, milnacipran did not improve overall, self-reported pain intensity among subjects with widespread pain receiving stable RA medications.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01207453.

Milnacipran for pain in fibromyalgia in adults

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 3, 2012. That review considered both fibromyalgia and neuropathic pain, but the efficacy of milnacipran for neuropathic pain is now dealt with in a separate review.Milnacipran is a serotonin-norepinephrine (noradrenaline) reuptake inhibitor (SNRI) that is licensed for the treatment of fibromyalgia in some countries, including Canada, Russia, and the United States.

OBJECTIVES

To assess the analgesic efficacy of milnacipran for pain in fibromyalgia in adults and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE to 18 May 2015, together with reference lists of retrieved papers and reviews, and two clinical trial registries. For the earlier review, we also contacted the manufacturer.

SELECTION CRITERIA

We included randomised, double-blind studies of eight weeks' duration or longer, comparing milnacipran with placebo or another active treatment in fibromyalgia in adults.

DATA COLLECTION AND ANALYSIS

We extracted efficacy and adverse event data, and two review authors examined issues of study quality independently.

MAIN RESULTS

We identified one new study with 100 participants for the pooled analysis. We identified two additional reports of a study using an enriched enrolment randomised withdrawal (EERW) design that included participants from earlier randomised controlled trials and an open-label study. Because this study used the same participants already included in our main analysis, and a different design, we dealt with it separately.The main analysis included six studies (five from the earlier review; 4238 participants in total), all of which were placebo-controlled, and used titration to a target dose of milnacipran 100 or 200 mg, with assessment after 8 to 24 weeks of stable treatment. There were no studies with active comparators. Study quality was generally good, although the imputation method used in analyses of the primary outcomes could overestimate treatment effect.Both doses of milnacipran provided moderate levels of pain relief (at least 30% pain intensity reduction) to about 40% of participants treated, compared to 30% with placebo, giving a number needed to treat for an additional beneficial outcome (NNT) of 6 to 10 (high quality evidence). Using a stricter definition for responder and a more conservative method of analysis gave lower levels of response (while maintaining a 10% difference between milnacipran and placebo) and increased the NNT to 11 (high quality evidence). One EERW study was broadly supportive.Adverse events were common in both milnacipran (86%) and placebo (78%) groups (high quality evidence), but serious adverse events did not differ between groups (less than 2%) (low quality evidence). Nausea, constipation, and headache were the most common events showing the greatest difference between groups (number needed to treat for an additional harmful outcome (NNH) of 5.7 for nausea, 13 for constipation, and 29 for headache) (moderate quality evidence).Withdrawals for any reason were more common with milnacipran than placebo, and more common with 200 mg (NNH 9) than 100 mg (NNH 23), compared with placebo. This was largely driven by adverse event withdrawals, where the NNH compared with placebo was 14 for 100 mg and 7.0 for 200 mg (high quality evidence). Withdrawals due to lack of efficacy were less common with milnacipran than placebo but did not differ between doses (number needed to treat to prevent an additional unwanted outcome (NNTp) of 41) (moderate quality evidence).

AUTHORS' CONCLUSIONS

The evidence available indicates that milnacipran 100 mg or 200 mg is effective for a minority in the treatment of pain due to fibromyalgia, providing moderate levels of pain relief (at least 30%) to about 40% of participants, compared with about 30% with placebo. There were insufficient data to assess substantial levels of pain relief (at least 50%), and the use of last observation carried forward imputation may overestimate drug efficacy. Using stricter criteria for 'responder' and a more conservative method of analysis gave lower response rates (about 26% with milnacipran versus 17% with placebo). Milnacipran was associated with increased adverse events and adverse event withdrawals, which were significantly greater for the higher dose.

An update on pharmacotherapy for the treatment of fibromyalgia

INTRODUCTION

Fibromyalgia is a syndrome characterized by chronic generalized pain in addition to different symptoms such as fatigue, sleep disturbances, stiffness, cognitive impairment, and psychological distress. Multidisciplinary treatment combining pharmacological and nonpharmacological therapies is advised.

AREAS COVERED

Publications describing randomized controlled trials and long-term extension studies evaluating drug treatment for fibromyalgia were searched in PubMed and Scopus and included in this review.

EXPERT OPINION

Different drugs are recommended for the treatment of fibromyalgia by different published guidelines, although only three of them have been approved for this indication by the US FDA, and none have been approved by the European Medicines Agency. According to the available evidence, pregabalin, duloxetine and milnacipran should be the drugs of choice for the treatment of this disease, followed by amitriptyline and cyclobenzaprine. Other drugs with at least one positive clinical trial include some selective serotonin reuptake inhibitors, moclobemide, pirlindole, gabapentin, tramadol, tropisetron, sodium oxybate and nabilone. None of the currently available drugs are fully effective against the whole spectrum of fibromyalgia symptoms, namely pain, fatigue, sleep disturbances and depression, among the most relevant symptoms. Combination therapy is an option that needs to be more thoroughly investigated in clinical trials.

Preliminary experience using milnacipran in patients with juvenile fibromyalgia: lessons from a clinical trial program

BACKGROUND

There are no approved medications for juvenile fibromyalgia (JFM), a disorder that is often under-diagnosed. The effects of milnacipran, a drug approved for the management of fibromyalgia (FM) in adults, was assessed in a clinical trial program for JFM.

METHODS

Patients, ages 13-17 years who met the Yunus and Masi criteria for JFM and/or 1990 American College of Rheumatology criteria for FM, were enrolled in a responder-enriched, randomized withdrawal trial. After receiving open-label milnacipran (8 weeks), patients with ≥50 % improvement in pain underwent double-blind randomization (1:2) to either placebo or continuing treatment with milnacipran (8 weeks). All patients, including those who did not meet the randomization criteria for double-blind withdrawal, were allowed to enter an extension study with open-label milnacipran (up to 52 weeks). The primary endpoint was loss of therapeutic response (LTR) during the double-blind period. Additional outcome measures included the Patient Global Impression of Severity (PGIS), Pediatric Quality of Life Inventory (PedsQL: Generic Core Scales, Multidimensional Fatigue Scale), and Multidimensional Anxiety Scale for Children (MASC). Safety assessments included adverse events (AEs), vital signs, electrocardiograms, and laboratory tests.

RESULTS

The milnacipran program was terminated early due to low enrollment. Because only 20 patients were randomized into the double-blind withdrawal period, statistical analyses were not conducted for the LTR endpoint. However, 116 patients entered the open-label period of the initial study and 57 participated in the open-label extension study. Their experience provides preliminary information about the use of milnacipran in JFM patients. During both open-label periods, there were mean improvements in pain severity, PGIC, PedsQL, and MASC scores. No unexpected safety issues were detected. The most commonly reported treatment-emergent AEs were nausea, headache, vomiting, and dizziness. Mean increases in heart rate and blood pressure were observed, and were consistent with the AE profile in adults with FM.

CONCLUSIONS

The open-label findings provide preliminary evidence that milnacipran may improve symptoms of JFM, with a safety and tolerability profile that is consistent with the experience in adult FM patients. Future trial designs for JFM should consider the relatively low recognition of this condition compared to adult FM and the difficulties with enrollment.

TRIAL REGISTRATION

NCT01328002 ; NCT01331109.

Effects of milnacipran on clinical pain and hyperalgesia of patients with fibromyalgia: results of a 6-week randomized controlled trial

Milnacipran is a serotonin-norepinephrine reuptake inhibitor that was approved by the U.S. Food and Drug Administration as effective therapy for fibromyalgia (FM) symptoms. However, its analgesic mechanism of action is not well understood. We hypothesized that improvement of mechanical and heat hyperalgesia would be a critical component of overall milnacipran efficacy in FM. We used a novel quantitative sensory testing protocol for assessment of mechanical and heat pain sensitivity that can be used for testing of peripheral and central pain mechanisms and their impact on clinical pain over time. We applied tonic mechanical and heat pain stimuli to 46 patients with FM during a randomized controlled trial with either 50 mg milnacipran (n = 23) or placebo (n = 23) twice daily over 6 weeks. During this trial, mean clinical pain (standard deviation) was evaluated daily, and mechanical and heat pain sensitivity every 2 weeks. At study entry, clinical pain was 5.0 (1.8) and 5.5 (1.8) visual analog scale units for patients with FM randomized to placebo and milnacipran, respectively (P > .05). Over 6 weeks, clinical pain of patients with FM significantly declined by 15%, but this improvement was not statistically different between milnacipran and placebo. However, repeated measures of mechanical and heat pain sensitivity reliably predicted up to 80% of the variance in clinical FM pain at every time point. Clinical pain and mechanical/heat pain sensitivity of patients with FM steadily declined during this trial, but the effects of milnacipran were not found to be superior to placebo. Repeated measures of mechanical/heat hyperalgesia reliably predicted large amounts of the variance in clinical pain across all participants, indicating their relevance for FM pain.

PERSPECTIVE

Although clinical pain and hyperalgesia decreased during this 6-week trial, the efficacy of milnacipran was not superior to placebo. The high correlations between clinical pain and hyperalgesia ratings at every time point seem to emphasize the relevant contributions of mechanical and heat hyperalgesia to clinical FM pain.

More ubiquitous effects from non-pharmacologic than from pharmacologic treatments for fibromyalgia syndrome: a meta-analysis examining six core symptoms

This study aimed to characterize and compare the efficacy profile on six fibromyalgia syndrome (FM) core symptoms associated with pharmacologic and non-pharmacologic treatments. We screened PubMed, Embase and the Cochrane Library for FM articles from 1990 to September 2012 to analyse randomized controlled trials comparing pharmacologic or non-pharmacologic treatments to placebo or sham. Papers including assessments of at least 2 of the 6 main FM symptom domains - pain, sleep disturbance, fatigue, affective symptoms (depression/anxiety), functional deficit and cognitive impairment - were selected for analysis. Studies exploring pharmacologic approaches (n = 21) were mainly dedicated to treating a small number of dimensions, mostly pain. They were of good quality but were not prospectively designed to simultaneously document efficacy for the management of multiple core FM symptom domains. Only amitriptyline demonstrated a significant effect on as many as three core FM symptoms, but it exhibited many adverse effects and was subject to early tachyphylaxis. Studies involving non-pharmacologic approaches (n = 64) were typically of poorer quality but were more often dedicated to multidimensional targets. Pool therapy demonstrated significant effects on five symptom domains, repetitive transcranial magnetic stimulation on four domains, balneotherapy on three domains and exercise, cognitive behaviour therapy and massage on two domains each. Differences between pharmacologic and non-pharmacologic approaches may be related to different modes of action, tolerability profiles and study designs. Very few drugs in well-designed clinical trials have demonstrated significant relief for multiple FM symptom domains, whereas non-pharmacologic treatments with weaker study designs have demonstrated multidimensional effects. Future therapeutic trials for FM should prospectively examine each of the core domains and should attempt to combine pharmacologic and non-pharmacologic therapies in well-designed clinical trials.

Development and initial validation of a brief self-report measure of cognitive dysfunction in fibromyalgia

Pain is often the focus of research and clinical care in fibromyalgia (FM); however, cognitive dysfunction is also a common, distressing, and disabling symptom in FM. Current efforts to address this problem are limited by the lack of a comprehensive, valid measure of subjective cognitive dysfunction in FM that is easily interpretable, accessible, and brief. The purpose of this study was to leverage cognitive functioning item banks that were developed as part of the Patient Reported Outcomes Measurement Information System (PROMIS) to devise a 10-item short form measure of cognitive functioning for use in FM. In study 1, a nationwide (U.S.) sample of 1,035 adults with FM (age range = 18-82, 95.2% female) completed 2 cognitive item pools. Factor analyses and item response theory analyses were used to identify dimensionality and optimally performing items. A recommended 10-item measure, called the Multidimensional Inventory of Subjective Cognitive Impairment (MISCI) was created. In study 2, 232 adults with FM completed the MISCI and a legacy measure of cognitive functioning that is used in FM clinical trials, the Multiple Ability Self-Report Questionnaire (MASQ). The MISCI showed excellent internal reliability, low ceiling/floor effects, and good convergent validity with the MASQ (r = -.82).

PERSPECTIVE

This paper presents the MISCI, a 10-item measure of cognitive dysfunction in FM, developed through classical test theory and item response theory. This brief but comprehensive measure shows evidence of excellent construct validity through large correlations with a lengthy legacy measure of cognitive functioning.

A double-blind, placebo-controlled, parallel-group pilot study of milnacipran for chronic radicular pain (sciatica) associated with lumbosacral disc disease

OBJECTIVE

The current study investigates whether milnacipran, an equipotent serotonin-norepinephrine reuptake inhibitor, is effective in reducing chronic radicular pain in patients (N = 11) with lumbosacral disc disease.

METHOD

This study is a 10-week randomized, parallel-group, double-blind, placebo-controlled trial of milnacipran (100-200 mg/d, dosed twice a day). Subjects (enrolled from October 2010 to September 2011 through the Duke University Pain and Palliative Care Clinic, Durham, North Carolina) included patients with radiologically confirmed disc disease with nerve root compression. The primary outcome measure was radicular pain measured by visual analog scale score (VAS-Rad); patients were asked to specifically rate radicular pain ("shooting or electrical or prickly pain in 1 or both legs"). Secondary outcome measures included nociceptive low back pain by visual analog scale (VAS-Noc), Oswestry Low Back Pain Disability Questionnaire, Neuropathic Pain Questionnaire, Medical Outcomes Study (MOS) 36-Item Short-Form Health Survey, Beck Depression Inventory, and State-Trait Anxiety Inventory. Between-group changes in outcome measures between baseline and endpoint were analyzed using Mann-Whitney U nonparametric measure of central tendency.

RESULTS

Milnacipran treatment yielded statistically significant reduction in radicular pain (VAS-Rad, P = .01) and nociceptive low back pain (VAS-Noc, P = .04) compared to placebo. No statistically significant between-group differences were observed in the other secondary outcome measures.

CONCLUSIONS

In this small pilot study, milnacipran treatment was associated with reduction in radicular and nociceptive low back pain in patients with lumbosacral disc disease. Larger studies of milnacipran in this population are warranted.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01777581.

Comparison of the effects of escitalopram and nortriptyline on painful symptoms in patients with major depression

OBJECTIVE

Unexplained painful physical symptoms are commonly reported by depressed patients. The evidence suggests that dual-action antidepressants are potent in relieving pain in depression. However, a direct comparison of the effects of selective serotonergic and selective noradrenergic antidepressants on painful symptoms has not been investigated so far.

METHOD

Sixty patients who participated in the Genome-based Therapeutic Drugs for Depression study with a diagnosis of moderate or severe episodes of depression according to the International Classification of Diseases, 10th Revision, and the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria were involved. All the participants were randomly allocated to receive nortriptyline or escitalopram. The severity of depression was measured using the Montgomery-Åsberg Depression Rating Scale, the Hamilton Depression Rating Scale and the Beck Depression Inventory at weeks 0, 2, 4, 6 and 8. The intensity of pain was measured on the Visual Analog Scale at the same points of the study.

RESULTS

At "week 0," 83.3% of the patients later randomized to treatment with escitalopram and 86.7% of those treated with nortriptyline reported at least one painful symptom. A significant decrease of pain intensity was observed after 2 weeks of treatment. The two groups did not differ in degree of pain reduction at weeks 2, 4, 6 and 8 in comparison to baseline values. A 50% reduction in pain intensity preceded the 50% reduction of depression severity. The intensity of pain at "week 0" did not differ in remitted or nonremitted patients at week 8.

CONCLUSION

Both selective serotonergic and selective noradrenergic antidepressants are equally effective in alleviations of painful physical symptoms of depression. The presence of painful symptoms before the onset of treatment did not determine the final response.

Efficacy of long-term milnacipran treatment in patients meeting different thresholds of clinically relevant pain relief: subgroup analysis of a randomized, double-blind, placebo-controlled withdrawal study

Background

Fibromyalgia patients from a long-term, open-label study of milnacipran (50–200 mg/day) were eligible to participate in a 12-week, randomized, placebo-controlled withdrawal study. The withdrawal study evaluated loss of therapeutic response in patients who achieved ≥50% pain improvements after receiving up to 3.25 years of milnacipran. This post-hoc analysis investigated whether patients who met lower thresholds of pain improvement also experienced worsening of fibromyalgia symptoms upon treatment withdrawal.

Method

Among patients who received milnacipran ≥100 mg/day during the long-term study, three subgroups were identified based on percentage of pain reduction at randomization: ≥50% (protocol-defined “responders”; n=150); ≥30% to <50% (patients with clinically meaningful pain improvement; n=61); and <30% (n=110). Efficacy assessments included the visual analog scale (VAS) for pain, Fibromyalgia Impact Questionnaire-Revised (FIQR), 36-Item Short-Form Health Survey Physical Component Summary (SF-36 PCS), and Beck Depression Inventory (BDI).

Results

In the ≥30 to <50% subgroup, significant worsening in pain was detected after treatment withdrawal. The difference between placebo and milnacipran in mean VAS score changes for this subgroup (+9.0, P<0.05) was similar to the difference in protocol-defined responders (+9.4, P<0.05). In the <30% subgroup, no worsening in pain was observed in either treatment arm. However, patients in this subgroup experienced significant worsening in FIQR scores after treatment withdrawal (placebo, +6.9; milnacipran, −2.8; P<0.001), as well as worsening in SF-36 PCS and BDI scores.

Conclusion

Patients who experienced ≥30% to <50% pain reduction with long-term milnacipran had significant worsening of fibromyalgia symptoms after treatment withdrawal. These results suggest that the conventional ≥30% pain responder cutoff may be adequate to demonstrate efficacy in randomized withdrawal studies of fibromyalgia. Patients in the <30% pain reduction subgroup had worsening scores on the FIQR and other multidimensional measures after treatment withdrawal, indicating the importance of identifying and managing the multiple symptoms of fibromyalgia.

Beyond pain in fibromyalgia: insights into the symptom of fatigue

Fatigue is a disabling, multifaceted symptom that is highly prevalent and stubbornly persistent. Although fatigue is a frequent complaint among patients with fibromyalgia, it has not received the same attention as pain. Reasons for this include lack of standardized nomenclature to communicate about fatigue, lack of evidence-based guidelines for fatigue assessment, and a deficiency in effective treatment strategies. Fatigue does not occur in isolation; rather, it is present concurrently in varying severity with other fibromyalgia symptoms such as chronic widespread pain, unrefreshing sleep, anxiety, depression, cognitive difficulties, and so on. Survey-based and preliminary mechanistic studies indicate that multiple symptoms feed into fatigue and it may be associated with a variety of physiological mechanisms. Therefore, fatigue assessment in clinical and research settings must consider this multi-dimensionality. While no clinical trial to date has specifically targeted fatigue, randomized controlled trials, systematic reviews, and meta-analyses indicate that treatment modalities studied in the context of other fibromyalgia symptoms could also improve fatigue. The Outcome Measures in Rheumatology (OMERACT) Fibromyalgia Working Group and the Patient Reported Outcomes Measurement Information System (PROMIS) have been instrumental in propelling the study of fatigue in fibromyalgia to the forefront. The ongoing efforts by PROMIS to develop a brief fibromyalgia-specific fatigue measure for use in clinical and research settings will help define fatigue, allow for better assessment, and advance our understanding of fatigue.