Classification, epidemiology, and natural history of fibromyalgia

Typology of patients with fibromyalgia: cluster analysis of duloxetine study patients

BACKGROUND

To identify distinct groups of patients with fibromyalgia (FM) with respect to multiple outcome measures.

METHODS

Data from 631 duloxetine-treated women in 4 randomized, placebo-controlled trials were included in a cluster analysis based on outcomes after up to 12 weeks of treatment. Corresponding classification rules were constructed using a classification tree method. Probabilities for transitioning from baseline to Week 12 category were estimated for placebo and duloxetine patients (Ntotal = 1188) using logistic regression.

RESULTS

Five clusters were identified, from "worst" (high pain levels and severe mental/physical impairment) to "best" (low pain levels and nearly normal mental/physical function). For patients with moderate overall severity, mental and physical symptoms were less correlated, resulting in 2 distinct clusters based on these 2 symptom domains. Three key variables with threshold values were identified for classification of patients: Brief Pain Inventory (BPI) pain interference overall scores of <3.29 and <7.14, respectively, a Fibromyalgia Impact Questionnaire (FIQ) interference with work score of <2, and an FIQ depression score of ≥5. Patient characteristics and frequencies per baseline category were similar between treatments; >80% of patients were in the 3 worst categories. Duloxetine patients were significantly more likely to improve after 12 weeks than placebo patients. A sustained effect was seen with continued duloxetine treatment.

CONCLUSIONS

FM patients are heterogeneous and can be classified into distinct subgroups by simple descriptive rules derived from only 3 variables, which may guide individual patient management. Duloxetine showed higher improvement rates than placebo and had a sustained effect beyond 12 weeks.

Predictors of new-onset widespread pain in older adults: results from a population-based prospective cohort study in the UK

OBJECTIVE

In older adults, widespread pain (WP) is common, although its etiology is unclear. This study sought to identify factors associated with an increased risk of developing WP in adults age ≥50 years.

METHODS

A population-based prospective study was conducted. A baseline questionnaire was administered to subjects to collect data on pain, psychological status, lifestyle and health behaviors, and sociodemographic and clinical factors. Participants free of WP (as defined by the American College of Rheumatology 1990 criteria for fibromyalgia) were followed up for 3 years, and those with new-onset WP at followup were identified. Logistic regression analyses were used to test the relationship between baseline factors and new-onset WP. Multiple imputation was used to test the results for sensitivity to missing data.

RESULTS

In this population-based study, 4,326 subjects (1,562 reporting no pain at baseline and 2,764 reporting some pain at baseline) participated at followup. Of these participants, 800 (18.5%) reported a status of new WP at followup (of whom, 121 [7.7%] had reported no pain at baseline and 679 [24.6%] had reported some pain at baseline). The majority of the study factors were associated with new-onset WP. However, only a few factors showed a persistent association with new-onset WP in the multivariate analysis, including age (odds ratio [OR] 0.97, 95% confidence interval [95% CI] 0.96-0.99), baseline pain status (OR 1.1, 95% CI 1.08-1.2), anxiety (OR 1.5, 95% CI 1.01-2.1), physical health-related quality of life (OR 1.3, 95% CI 1.1-1.5), cognitive complaint (OR 1.3, 95% CI 1.04-1.6), and nonrestorative sleep (OR 1.9, 95% CI 1.2-2.8). These associations persisted after adjustment for the presence of diffuse osteoarthritis (OA), which led to a modest increase in model fit (C-statistic 0.738, compared with 0.731 in the model excluding diffuse OA). The results were not sensitive to missing data.

CONCLUSION

Of the factors measured in this study, nonrestorative sleep was the strongest independent predictor of new-onset WP.

Worldwide epidemiology of fibromyalgia

Studying the epidemiology of fibromyalgia (FM) is very important to understand the impact of this disorder on persons, families and society. The recent modified 2010 classification criteria of the American College of Rheumatology (ACR), without the need of tender points palpation, allows that larger and nationwide surveys may be done, worldwide. This article reviews the prevalence and incidence studies done in the general population, in several countries/continents, the prevalence of FM in special groups/settings, the association of FM with some sociodemographic characteristics of the population, and the comorbidity of FM with others disorders, especially with headaches.

Pain Symptoms in Fibromyalgia Patients with and without Provoked Vulvodynia

Objective. The aim of the study was to compare the pain symptoms of fibromyalgia patients exhibiting (FMS+PVD) and not exhibiting (FMS) comorbidity with provoked vulvodynia. Study Design. The case control study was performed in 39 patients who had been diagnosed with FMS and accepted to undergo gynaecological examination and in 36 healthy women (C). All patients completed standardized questionnaires for pain intensity, pain area, and psychological functioning. The gynaecological examination included vulvar pain pressure reactivity (Q-tip), pelvic tone assessment (Kegel manoeuver), and a semistructured interview collecting detailed information about pelvic symptoms and sexual function. Results. FMS+PVD patients displayed a higher number of associated symptoms than FMS patients. The vulvar excitability was significantly higher in FMS+PVD than in FMS and in both groups than in Controls. Half of FMS+PVD patients were positive to Kegel manoeuver and displayed higher scores in widespread pain intensity, STAI-Y2, and CESD levels than Kegel negative patients. Conclusions. The study reveals that increased vulvar pain excitability may occur in FMS patients independently of the presence of coital pain. Results suggest that coital pain develops in patients with higher FMS symptoms severity due to the cooperative effects of peripheral and central sensitization mechanisms.

Continuing efficacy of milnacipran following long-term treatment in fibromyalgia: a randomized trial

INTRODUCTION

Previous studies of long-term treatment response in fibromyalgia and other chronic pain states have generally been limited to approximately one year, leaving questions about the longer-term durability of response. The purpose of this study was to demonstrate continuing efficacy of milnacipran by characterizing changes in pain and other fibromyalgia symptoms after discontinuing long-term treatment. The mean length of milnacipran treatment at the time of randomized withdrawal was 36.1 months from initial exposure to milnacipran (range, 17.9 to 54.4 months).

METHODS

After completing a long-term, open-label, lead-in study of milnacipran (which followed varying periods of exposure in previous studies), adult patients with fibromyalgia entered the four-week open-label period of the current study for evaluation of ongoing treatment response. After the four-week period to confirm new baseline status, 151 patients taking milnacipran ≥100 mg/day and reporting ≥50% improvement from pre-milnacipran exposure in Visual Analogue Scale (VAS) pain scores were classified as responders. These responders entered the 12-week, double-blind withdrawal period in which they were randomized 2:1 to continue milnacipran or switched to placebo. The prespecified primary parameter was loss of therapeutic response (LTR), defined as increase in VAS pain score to <30% reduction from pre-milnacipran exposure or worsening of fibromyalgia requiring alternative treatment. Adverse events and vital signs were also monitored.

RESULTS

Time to LTR was shorter in patients randomized to placebo than in patients continuing milnacipran (P < 0.001). Median time to LTR was 56 days with placebo and was not calculable for milnacipran, because less than half of the latter group of patients lost therapeutic response by study end. Additionally, 81% of patients continuing on milnacipran maintained clinically meaningful pain response (≥30% improvement from pre-milnacipran exposure), compared with 58% of patients switched to placebo (sensitivity analysis II; P < 0.001). The incidences of treatment-emergent adverse events were 58% and 47% for placebo and milnacipran, respectively. Mean decreases in blood pressure and heart rate were found in both groups, with greater decreases for patients switched to placebo.

CONCLUSIONS

Continuing efficacy of milnacipran was demonstrated by the loss of effect following withdrawal of treatment in patients who received an average of three years of milnacipran treatment.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01014585.

Urinary albumin, protein excretion and circadian blood pressure in patients with fibromyalgia

Recent evidence suggests that patients with fibromyalgia (FM) have increased oxidative stress, inflammation, endothelial dysfunction and autonomic dysfunction. These factors are also shown to be responsible for increased urinary albumin and protein excretion and deranged circadian blood pressure (BP). However, no study has examined the 24-h urinary albumin excretion (UAE), 24-h urinary protein excretion (UPE) and 24-h ambulatory BP measurements in FM patients. The sociodemographic, laboratory parameters, depressive symptoms, sleep problems and 24-h ambulatory BPs were measured for all patients. Diagnosis of FM was based on the criteria for the classification of FM by the American College of Rheumatology. After diagnosis of FM, these patients underwent to complete the Fibromyalgia Impact Questionnaire (FIQ). In total, 30 patients with FM and 61 patients without FM were included. Among FM patients, the average number of tender points was 13.1 ± 1.57 and the mean FIQ score was 57.9 ± 8.86. The number of tender points did not show any correlation with office and ambulatory BPs. There were also no correlations between the number of tender points, UPE and UAE. The stepwise linear regression did not show any relation between UPE and FM. However, 24-h UAE was independently correlated with office systolic BP (P 0.008) and the presence of FM (P 0.045). The logistic regression analysis revealed no association between FM and non-dipping status. We suggest that circadian blood pressure and UPE are not independently associated with FM. However, UAE was related with the presence of FM. Studies are needed to confirm our findings and to highlight pathophysiologic mechanisms.

National survey of knowledge, attitude and practice of fibromyalgia among rheumatologists in China

AIM

Fibromyalgia (FM) is a chronic disorder characterized by widespread musculoskeletal pain and fatigue. It is a less frequently diagnosed disease in China, thus Chinese rheumatologists may have lower awareness of FM compared with colleagues in Western countries. The aim of this study is to investigate the perceptions of FM in Chinese rheumatologists and analyze their therapeutic approach in clinical practice.

METHOD

An anonymous questionnaire survey was conducted among a nationwide sample of Chinese rheumatologists at the 15th National Rheumatology Conference in 2010. The 20-question survey included questions regarding background, work experience, perceptions of diagnosis and behaviors of treatment related to FM. Continuing medical education (CME) information was also collected in the survey.

RESULTS

Seven hundred and seven rheumatologists responded to the questionnaire, a response rate of 60%. Less than one-fifth of the respondents were experienced in dealing with FM. Although most of the respondents regarded FM as a distinct pathological entity, nearly 30% of Chinese rheumatologists believed that FM was only a psychological disorder. The respondents recognized some of the FM-related symptoms, but had limited knowledge on the diagnostic criteria. Eighty percent of the respondents declared they had difficulties in treating FM patients. However, nearly all (90.8%) respondents believed that the prognosis of FM patients was usually benign. Our data also showed that most Chinese rheumatologists were eager for CME on FM.

CONCLUSION

The awareness and perception of FM are still low among Chinese rheumatologists. CME on FM is needed for improving the quality of health care in China.

Complementary and alternative exercise for fibromyalgia: a meta-analysis

Complementary and alternative medicine includes a number of exercise modalities, such as tai chi, qigong, yoga, and a variety of lesser-known movement therapies. A meta-analysis of the current literature was conducted estimating the effect size of the different modalities, study quality and bias, and adverse events. The level of research has been moderately weak to date, but most studies report a medium-to-high effect size in pain reduction. Given the lack of adverse events, there is little risk in recommending these modalities as a critical component in a multimodal treatment plan, which is often required for fibromyalgia management.

Neuropathic pain and use of PainDETECT in patients with fibromyalgia: a cohort study

Backround

Fibromyalgia has a plethorae of symptoms, which can be confusing and even misleading. Accurate evaluation is necessary when patients with fibromyalgia are treated. Different types of instruments are available for the clinicians to supplement evaluation. Our objective was to study the applicability of the PainDETECT instrument to screen neuropathic pain in patients with fibromyalgia.

Methods

158 patients with primary fibromyalgia underwent a neurological examination including bedside sensory testing. They also fulfilled four questionnaires: PainDETECT, Beck depression inventory IA (BDI IA), Fibromyalgia Impact Questionnaire (FIQ) and a self-made questionnaire regarding present pain and pain relieving methods of the patients. The results of the clinical evaluation and questionnaires were then compared.

Results

Clinically verified neuropathic pain was diagnosed in 53/158 [34% (95% Cl: 26 to 41)] patients. The ROC curve achieved a maximum Youden´s index at score of 17 when sensitivity was 0.79 (95% Cl: 0.66 to 0.89) and specificity 0.53 (95% Cl: 0.43 to 0.63). The PainDETECT total score (OR: 1.14 95% Cl: 1.06 to 1.22), FM as the worst current pain (OR: 0.31; 95% 0.16 to 0.62), body mass index (BMI) (OR: 1.05; 95% Cl: 1.00 to 1.11) and the intensity of current pain (OR: 1.20; 95% Cl: 1.01 to 1.41) were significantly associated with the presence of neuropathic pain in univariate analyses.

Conclusion

This study highlights the importance of thorough clinical examination. The Neuropathic pain screening tool PainDETECT is not as useful in patients with fibromyalgia as in patients with uncompromised central pain control.

Clinical overview of fibromyalgia

Fibromyalgia (FM) is a complex disorder that affects up to 5% of the general population worldwide, more frequently in women than in men. In addition to chronic widespread pain, patients with FM usually experience other characteristic symptoms, including fatigue, disturbed sleep, stiffness, reduced functioning, dyscognition, and depressed mood. Many patients also have comorbid conditions such as depression, irritable bowel syndrome, temporomandibular disorder, or migraine. Although the etiology of FM remains unclear, evidence suggests that biologic, genetic, and environmental factors are involved. The variability of symptoms and the frequency of comorbidities among patients with FM make this a difficult disorder to diagnose. Diagnosis may be further complicated by the stigmatization of this disorder among treatment providers, the health insurance industry, and the general population. Treating chronic pain disorders such as FM can be time consuming and costly, and other issues such as polypharmacy, treatment adherence, and access to treatment often need to be addressed. The aim of this article is to provide physicians with a general overview of FM, including a brief review of the pathophysiology that explains the biologic and genetic bases of this disorder. Also included is a synopsis of new diagnostic criteria and other useful diagnostic tools and a discussion of various treatment challenges and strategies.

Survey of physician experiences and perceptions about the diagnosis and treatment of fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a condition characterized by widespread pain and is estimated to affect 0.5-5% of the general population. Historically, it has been classified as a rheumatologic disorder, but patients consult physicians from a variety of specialties in seeking diagnosis and ultimately treatment. Patients report considerable delay in receiving a diagnosis after initial presentation, suggesting diagnosis and management of FM might be a challenge to physicians.

METHODS

A questionnaire survey of 1622 physicians in six European countries, Mexico and South Korea was conducted. Specialties surveyed included primary care physicians (PCPs; n=809) and equal numbers of rheumatologists, neurologists, psychiatrists and pain specialists.

RESULTS

The sample included experienced doctors, with an expected clinical caseload for their specialty. Most (>80%) had seen a patient with FM in the last 2 years. Overall, 53% of physicians reported difficulty with diagnosing FM, 54% reported their training in FM was inadequate, and 32% considered themselves not knowledgeable about FM. Awareness of American College of Rheumatology classification criteria ranged from 32% for psychiatrists to 83% for rheumatologists. Sixty-four percent agreed patients found it difficult to communicate FM symptoms, and 79% said they needed to spend more time to identify FM. Thirty-eight percent were not confident in recognizing the symptoms of FM, and 48% were not confident in differentiating FM from conditions with similar symptoms. Thirty-seven percent were not confident developing an FM treatment plan, and 37% were not confident managing FM patients long-term. In general, rheumatologists reported least difficulties/greatest confidence, and PCPs and psychiatrists reported greatest difficulties/least confidence.

CONCLUSIONS

Diagnosis and managing FM is challenging for physicians, especially PCPs and psychiatrists, but other specialties, including rheumatologists, also express difficulties. Improved training in FM and initiatives to improve patient-doctor communication are needed and may help the management of this condition.

Fibromyalgia syndrome: an overview of pathophysiology, diagnosis and management

Fibromyalgia Syndrome (FMS) is a chronic condition causing pain, stiffness, and tenderness of the muscles, tendons, and joints. It is also characterized by restless sleep, tiredness, fatigue, anxiety, depression, and disturbances in bowel functions. The etiology of fibromyalgia remains unknown, but recent advances and discoveries have helped to unravel some of the mysteries of this disease. Research highlights some of the biochemical, metabolic, and immunoregulatory abnormalities associated with fibromyalgia. Management of FMS at the present time is very difficult as it has multiple etiological factors and psychological predispositions; however, a patient centered approach is essential to handle this problem.

Safety and efficacy of esreboxetine in patients with fibromyalgia: a fourteen-week, randomized, double-blind, placebo-controlled, multicenter clinical trial

OBJECTIVE

To evaluate the efficacy, tolerability, and safety of multiple fixed dosages of esreboxetine for the treatment of fibromyalgia.

METHODS

Patients meeting the American College of Rheumatology criteria for fibromyalgia were randomized to receive esreboxetine at dosages of 4 mg/day (n=277), 8 mg/day (n=284), or 10 mg/day (n=283) or matching placebo (n=278) for 14 weeks. The primary efficacy outcomes were the weekly mean pain score and the Fibromyalgia Impact Questionnaire (FIQ) total score at week 14. Secondary efficacy measures included scores for the Patient's Global Impression of Change (PGIC) scale, the Global Fatigue Index (GFI), and the 36-item Short-Form health survey (SF-36; physical function scale only) at week 14. The safety profile of esreboxetine was evaluated based on adverse events and other safety measures.

RESULTS

Patients receiving all dosages of esreboxetine demonstrated statistically significant improvements in the pain score (P≤0.025), the FIQ score (P≤0.023), and the PGIC score (P≤0.007) compared with patients in the placebo group. Additionally, patients receiving esreboxetine at dosages of 4 mg/day and 8 mg/day showed statistically significant improvements in the GFI score compared with those receiving placebo (P=0.001). No significant differences in SF-36 physical function scores were observed between patients receiving esreboxetine (any dosage) and those receiving placebo. Adverse events were mostly mild to moderate in severity; insomnia, constipation, dry mouth, nausea, dizziness, hot flush, headache, hyperhidrosis, and palpitations were reported most frequently.

CONCLUSION

Esreboxetine was generally well tolerated and was associated with significant improvements in pain, FIQ, PGIC, and fatigue scores compared with placebo. The lack of a dose-response relationship in both the efficacy and safety analyses suggests that esreboxetine at a dosage of 4 mg/day would offer clinical benefit with the least risk of drug exposure.

Burden of illness and treatment patterns for patients with fibromyalgia

OBJECTIVE

  This study was designed to describe burden of illness and treatment patterns, and to examine the patient, physician, and care factors associated with the treatment choices of individuals receiving new prescriptions for fibromyalgia (FM).

DESIGN

  This is a baseline assessment of the Real-World Examination of Fibromyalgia: Longitudinal Evaluation of Costs and Treatments (REFLECTIONS), a prospective observational study. Baseline data (including a physician survey, a patient visit form, and computer-assisted telephone interviews) were collected from July 2008 through May 2010 in 58 care settings in the United States, including Puerto Rico.

RESULTS

  Patients (N = 1,700) were mostly female (94.6%) and white (82.9%). Mean age was 50.4 years and mean duration of illness was 5.6 years. Mean Fibromyalgia Impact Questionnaire total score was 54.4 (range 0-80), and Brief Pain Inventory average pain severity level was 5.5 (range 0-10). Patients reported high annual health care use and numerous work limitations related to FM. Patients were taking 182 unique types of medications prescribed for FM, including duloxetine (26.8%), nonsteroidal anti-inflammatory drugs (26.6%), pregabalin (24.5%), opioids (24.2%), tramadol (15.3%), benzodiazepines (15.2%), cyclobenzaprine (12.9%), milnacipran (8.9%), and others. Most patients took more than one medication concurrently (77.8%). Type of current medications used was most strongly associated with medication history and physician specialty.

CONCLUSIONS

  Burden of illness was high for patients with FM, and treatment patterns were highly variable. Importantly, the treatments with the most evidence to support their use were not always the most frequently chosen.

A review of duloxetine 60 mg once-daily dosing for the management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic osteoarthritis pain and low back pain

BACKGROUND

Duloxetine is a selective dual neuronal serotonin (5-Hydroxytryptamine, 5-HT) and norepinephrine reuptake inhibitor (SSNRI). It is indicated in the United States for treatment of major depressive disorder (MDD), generalized anxiety disorder (GAD), and several chronic pain conditions, including management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic osteoarthritis (OA) pain and chronic low back pain (LBP). Its use for antidepressant and anxiolytic actions has been extensively reviewed previously. We here review the evidence for the efficacy of 60 mg once-daily dosing of duloxetine for chronic pain conditions.

METHOD

The literature was searched for clinical trials in humans conducted in the past 10 years involving duloxetine.

RESULTS

There were 199 results in the initial search. Studies not in the English language were excluded. We then included only studies of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain (OA and LBP). Studies of painful symptoms reported in mental health studies were excluded. This resulted in 32 studies. Articles that did not include a 60 mg/day daily dose as a study arm were excluded. This resulted in 30 studies, broken down as follows: 12 for diabetic peripheral neuropathy, 9 for fibromyalgia, 6 for LBP, and 3 for OA pain.

CONCLUSIONS

The studies reviewed report that duloxetine 60 mg once-daily dosing is an effective option for the management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic OA pain and chronic LBP. As these pains are often comorbid with MDD or GAD, duloxetine might possess the pharmacologic properties to be a versatile agent able to address several symptoms in these patients. With adequate attention to FDA prescribing guidance regarding safety and drug-drug interactions, duloxetine 60 mg once-daily dosing appears to be an effective option in the appropriate pain patient population.

A framework for fibromyalgia management for primary care providers

Fibromyalgia is a chronic widespread pain disorder commonly associated with comorbid symptoms, including fatigue and nonrestorative sleep. As in the management of other chronic medical disorders, the approach for fibromyalgia management follows core principles of comprehensive assessment, education, goal setting, multimodal treatment including pharmacological (eg, pregabalin, duloxetine, milnacipran) and nonpharmacological therapies (eg, physical activity, behavioral therapy, sleep hygiene, education), and regular education and monitoring of treatment response and progress. Based on these core management principles, this review presents a framework for primary care providers through which they can develop a patient-centered treatment program for patients with fibromyalgia. This proactive and systematic treatment approach encourages ongoing education and patient self-management and is designed for use in the primary care setting.

Electroconvulsive therapy in patients with depression and fibromyalgia

The effect of electroconvulsive therapy (ECT) on depression and other symptoms of fibromyalgia was studied in a prospective 3-month trial in 13 patients with fibromyalgia and concomitant depression. All the patients met the DSM-IV diagnostic criteria for Major Depressive Disorder and fulfilled the American College of Rheumatology diagnostic criteria for fibromyalgia. The Montgomery and Asberg Depression Rating Scale (MADRS) and the clinical global impression scale (CGI) were used to assess the severity of depression and the clinical change of the patients. The fibromyalgia impact questionnaire (FIQ) was used to evaluate the severity of the fibromyalgia symptoms. The intensity of pain was evaluated using a 6-point scale (0=no pain, 5=very severe pain), and tender point palpation. All assessments were performed at baseline and at follow-up visits, which took place one week, one month and three months after ECT. There was a significant improvement in depression after ECT according to MADRS. Using CGI, six patients were much or very much improved, while four patients were minimally improved and three patients had no change. There was significant improvement in four out of ten FIQ item scores, "feel good", "fatigue", "anxiety" and "depression". No significant change was found in the FIQ item scores "physical function", "pain", "stiffness" and "morning tiredness" or number of tender points and self-reported pain. We conclude that ECT is a safe and effective treatment for depression in fibromyalgia patients, but has no effect on the pain or other physical symptoms of these patients.

Validation of a Finnish version of the Fibromyalgia Impact Questionnaire (Finn-FIQ)

Background and purpose Fibromyalgia (FM) is a chronic pain syndrome, which affects up to 5% of the general population. The aetiology of FM is unclear. The lack of specific diagnostic laboratory tests or imaging options combined with the severe burden on both patients and society caused by the FM syndrome demands the development of valid instruments able to measure the current health status of the FM patients. The Fibromyalgia Impact Questionnaire (FIQ) is the most widely used of these instruments. Our objective was to translate the Fibromyalgia Impact Questionnaire (FIQ) into Finnish and evaluate its validity in Finnish speaking FM patients. Methods FIQ was translated by two bilingual researchers into the Finnish version (Finn-FIQ) and linked to the categories of International Classification of Functioning, Disability and Health (ICF). Finn-FIQ was administered to 162 patients who had prior fibromyalgia diagnoses M79.0 according to ICD-10 year 2006 version. They also filled in the Health Assessment Questionnaire (HAQ), the Rand 36-item Health Survey (RAND-36), the Beck Depression Inventory IA (BDIIA), the Chronic Pain Acceptance Questionnaire (CPAQ), the International Physical Activity Questionnaire Short Form (IPAQ), and they assessed their general well-being on a 0-100 mm visual analogue scale while attending a clinical check-up visit. Internal consistency was estimated according to Cronbach's alpha internal consistency. An exploratory factor analysis was performed to identify related items and to show construct validity. Correlation coefficients were calculated by the Spearman method. Results From the 162 participants 153 were female and 9 male, 119 (73%) had an active job or were students, 21 (13%) were unemployed, 16 (10%) were retired and 6 (4%) were on sick leave. The mean age was 47 years. The internal consistency value (95% CI) was 0.90 for the overall Finn-FIQ. The factor analysis performed for construct analysis showed that Finn-FIQ was loaded on 4 factors. These factors were loaded on components of ICF and explained 69% of total variance. Significant correlations were obtained between patients own assessments of general well-being and Finn-FIQ total score (r = 0.64 [95% CI 0.53-0.73]) and also between Finn-FIQ total score and HAQ total score (r = 0.56 [95% CI 0.44-0.66]). Finn-FIQ questions had significant correlations with RAND-36 domains. Conclusion Finn-FIQ is a valid and feasible instrument to mirror the functioning of FM patients according to its internal consistency, correlation to general well-being, convergent validity and response rate. It covers the main components of the ICF framework hence reflecting the whole spectrum of functioning. Implications In our study Finn-FIQ was proven as a valid instrument with Finnish speaking FM patients. Original FIQ and other validated translations have already confirmed their place in fibromyalgia research. After this study Finnish fibromyalgia research can be included in those using the best-known instrument in validated form and native language. Current study showed also Finn-FIQ's ability to measure functioning of the FM patients, and it had good applicability among Finnish speaking patients. Therefore it can be recommended also for monitoring individual FM patients and their functioning for example during different treatment trials.

Development and testing of the fibromyalgia diagnostic screen for primary care

BACKGROUND

The Fibromyalgia Diagnostic Screen was developed for use by primary care clinicians to assist in the diagnostic evaluation of fibromyalgia, a disorder that predominantly affects women.

METHODS

The screen was designed to have a patient-completed questionnaire and a clinician-completed section, which included a brief physical examination pertinent to the differential diagnosis of fibromyalgia. The items in the questionnaire were based on patient focus groups and clinician and patient Delphi exercises, which resulted in a ranking of the most common and troublesome fibromyalgia symptoms. One hundred new chronic pain patients (pain > 30 days) and their primary care physicians completed the screen. The patients were grouped as fibromyalgia or nonfibromyalgia by an independent fibromyalgia specialist, who was blind to screen responses. Logistic regression was used to model the probability of fibromyalgia as a function of physician-reported and patient-reported variables. Best subset regression was used to identify a subset of symptoms that were summed to form a single measure. Receiver operating characteristic (ROC) analysis was then used to select thresholds for continuous variables. The symptom and clinical variables were combined to create candidate prediction rules that were compared in terms of sensitivity and specificity to select the best criterion.

RESULTS

Two final models were selected based on overall accuracy in predicting fibromyalgia: one used the patient-reported questionnaire only, and the other added a subset of the physical examination items to this patient questionnaire.

CONCLUSION

A patient-reported questionnaire with or without a brief physical examination may improve identification of fibromyalgia patients in primary care settings.

Gabapentin and pregabalin in the treatment of fibromyalgia: a systematic review and a meta-analysis

WHAT IS KNOWN AND OBJECTIVES

Fibromyalgia (FBM) is a common chronic pain disorder affecting up to 2% of the general population. Current treatment options are mostly symptom-based and limited both in efficacy and number. Two promising alternatives are gabapentin (GP) and pregabalin (PB). We aimed to estimate the efficacy and safety/tolerability of the two compounds in FBM through a systematic review and a meta-analysis of relevant randomized double-blind placebo-controlled (RCT) were performed.

DATA SOURCES, EXTRACTION AND ANALYSIS

A literature search was conducted through MEDLINE, EMBASE, Cochrane CENTRAL and the reference lists of relevant studies. Responders to treatment (>30% reduction in mean pain score) and dropouts due to lack of efficacy were used as primary outcome measures. Dropout rates and incidence of common adverse outcomes were also investigated. Four RCTs, reporting data on 2040 patients, were reviewed and three of them using PG were included in the meta-analysis.

RESULTS

Pregabalin at a dose of 600, 450 and 300 mg per day is effective in FBM compared to placebo (NNT: 7, upper 95% CI: 12, 450 mg). A number of adverse events (AE), such as dizziness, somnolence, dry mouth, weight gain, peripheral oedema, is consistently associated with treatment at any dose and could lead one out of four patients to quit treatment (NNH: 6, lower 95% CI: 4, 600 mg). Indirect comparison meta-analysis suggests that PB at a dose of 450 mg per day could result in more responders than at 300 mg, but this result needs to be interpreted with caution as there were no significant differences between 600 and 300 mg or between 600 and 450 mg. Data on GP is limited.

WHAT IS NEW AND CONCLUSIONS

The analysis indicates that PB at a dose of 450 mg per day is most likely effective in treating FBM, although AE are not negligible. Further evidence is necessary for more conclusive inferences.

Health outcomes and costs among employees with fibromyalgia treated with pregabalin vs. standard of care

OBJECTIVE

To compare comorbidities, drug use, benefit costs, absences, medication persistence/adherence between employees with fibromyalgia initiating treatment with pregabalin (PGB) vs. antidepressant Standard of Care ([SOC] amitriptyline, duloxetine, or venlafaxine).

METHODS

Retrospective study of 240 adults initiating PGB or SOC after 7/1/2007. Multivariate regression models on propensity-score-matched cohorts compared postindex costs, absences, and adherence between cohorts.

RESULTS

Pregabalin users had significantly more preindex muscle pain and dizziness and less depression than SOC (each P < 0.05). Use of some non-PBG/SOC drugs differed. No differences were found in total medical, drug, or absenteeism cost. PGB had more sick leave (9.8 vs. 6.8 days, P = 0.04), but other absence types were similar. All adherence metrics were nonsignificantly greater for PGB vs. SOC.

CONCLUSION

Despite several comorbidity and drug use differences, most employee benefit outcomes and adherence did not differ between the cohorts.

Fibromyalgia syndrome and depressive symptoms: comorbidity and clinical correlates

OBJECTIVE

Fibromyalgia is characterized by chronic widespread musculoskeletal pain and higher pain perception in specific anatomic sites called tender points. Fibromyalgia is frequently associated with psychiatric symptoms, like depression and anxiety; indeed some authors have argued about the possibility to classify this syndrome into affective spectrum disorder. Few studies have analyzed the impact of depressive symptoms on pain threshold. This research is aimed at evaluating the prevalence and the clinical correlates of depressive symptoms in fibromyalgic patients, and investigating their impact on pain perception and quality of life.

METHODS

Outpatients between 18 and 75 years with diagnosis of fibromyalgia according to the criteria of the American College of Rheumatology have been included. All subjects have been evaluated with the following rating scales: HAM-D; VAS (to quantify pain); a visual analogical scale to evaluate quality of life; and Paykel's List of Recent Life Events.

RESULTS

Thirty subjects have been recruited. Most patients (83.3%) had clinically significant depressive symptoms as indicated by a HAM-D score >7. Depressive symptoms are associated with higher pain perception, worse quality of life and more severe life events.

CONCLUSION

The presence of depressive symptoms is associated with a great impairment in patients with fibromyalgia syndrome: indeed the psychiatric comorbidity lowers pain threshold and worsens the quality of life of our patients. Future studies should be conducted in order to identify the individual factors, e.g. stress or inflammatory processes, which drive the association between depression and higher severity of fibromyalgia syndrome.

Duloxetine in the treatment of chronic pain due to fibromyalgia and diabetic neuropathy

Duloxetine is a serotonin-norepinephrine reuptake inhibitor approved by the US Food and Drug Administration for the treatment of fibromyalgia and painful diabetic neuropathy at doses of 60 mg daily. Duloxetine has been shown to significantly improve the symptoms of chronic pain associated with these disorders, as measured by the Fibromyalgia Impact Questionnaire, Brief Pain Inventory scores, the Clinical Global Impressions Scale, and other various outcome measures in several placebo-controlled, randomized, double-blind, multicenter studies. Symptom improvement generally began within the first few weeks, and continued for the duration of the study. In addition, the efficacy of duloxetine was found to be due to direct effects on pain symptoms rather than secondary to improvements in depression or anxiety. Adverse events including nausea, constipation, dry mouth, and insomnia, were mild and transient and occurred at relatively low rates. In conclusion, duloxetine, a selective inhibitor for the serotonin and norepinephrine transporters, is efficacious in the treatment of chronic pain associated with fibromyalgia or diabetic neuropathy, and has a predictable tolerability profile, with adverse events generally being mild to moderate.

A pilot randomized controlled trial of the Yoga of Awareness program in the management of fibromyalgia

A mounting body of literature recommends that treatment for fibromyalgia (FM) encompass medications, exercise and improvement of coping skills. However, there is a significant gap in determining an effective counterpart to pharmacotherapy that incorporates both exercise and coping. The aim of this randomized controlled trial was to evaluate the effects of a comprehensive yoga intervention on FM symptoms and coping. A sample of 53 female FM patients were randomized to the 8-week Yoga of Awareness program (gentle poses, meditation, breathing exercises, yoga-based coping instructions, group discussions) or to wait-listed standard care. Data were analyzed by intention to treat. At post-treatment, women assigned to the yoga program showed significantly greater improvements on standardized measures of FM symptoms and functioning, including pain, fatigue, and mood, and in pain catastrophizing, acceptance, and other coping strategies. This pilot study provides promising support for the potential benefits of a yoga program for women with FM.

Pregabalin in treatment-refractory fibromyalgia

Context:

Fibromyalgia is a chronic musculoskeletal pain disorder. The pain can be intractable and may not respond to commonly-used treatments, such as tricyclic antidepressants and opioids.

Objectives:

To evaluate pregabalin response in the subset of patients with fibromyalgia whose pain had been judged refractory to other treatments.

Methods:

Patients had previously participated in a controlled trial of pregabalin and had moderate to severe pain despite treatment with gabapentin, a tricyclic antidepressant, and a third medication (e.g., other anticonvulsants, opioid, selective serotonin reuptake inhibitors, tramadol). Flexible-dose pregabalin 150-600 mg/day was added for 3-month treatment cycles, each followed by 3- to 28-day pregabalin “drug holiday” that lasted until a relapse occurred. Pain intensity was measured using the visual analogue scale of the Short-Form McGill Pain Questionnaire completed at baseline, the end of each 3-month treatment period and at the relapse visit. Analysis was at 15 months (after 5 cycles).

Results:

In total, 25 patients were included and 19 completed the 15-month analysis period. At baseline, 88% were receiving ≥1 pain medication. Pregabalin 150-600 mg/day was associated with statistically significant, clinically meaningful pain reduction during each treatment cycle. Pain quickly returned to baseline levels during the “drug holidays” in a median time of 2-4 days. Somnolence (n=5) and dizziness (n=4) were the most common adverse events.

Conclusions:

These results suggest that pregabalin may be beneficial in patients with fibromyalgia who have had an unsatisfactory response to treatment with other medications.

Fatigue in fibromyalgia: a conceptual model informed by patient interviews

Background

Fatigue is increasingly recognized as an important symptom in fibromyalgia (FM). Unknown however is how fatigue is experienced by individuals in the context of FM. We conducted qualitative research in order to better understand aspects of fatigue that might be unique to FM as well as the impact it has on patients' lives. The data obtained informed the development of a conceptual model of fatigue in FM.

Methods

Open-ended interviews were conducted with 40 individuals with FM (US [n = 20], Germany [n = 10] and France [n = 10]). Transcripts were analyzed using qualitative methods based upon grounded theory to identify key themes and concepts.

Results

Participants were mostly female (70%) with a mean age of 48.7 years (range: 25-79). Thirty-one individuals (i.e., 77.5%) spontaneously described experiencing tiredness/lack of energy/fatigue due to FM. Participants discussed FM fatigue as being more severe, constant/persistent and unpredictable than normal tiredness. The conceptual model depicts the key elements of fatigue in FM from a patient perspective. This includes: an overwhelming feeling of tiredness (n = 17, 42.5%), not relieved by resting/sleeping (n = 15, 37.5%), not proportional to effort exerted (n = 25, 62.5%), associated with a feeling of weakness/heaviness (n = 20, 50%), interferes with motivation (n = 22, 55%), interferes with desired activities (n = 27, 67.5%), prolongs tasks (n = 15, 37.5%), and makes it difficult to concentrate (n = 21, 52.5%), think clearly (n = 12, 30%) or remember things (n = 9, 22.5%).

Conclusion

The majority of individuals with FM who participated in this study experience fatigue and describe it as more severe than normal tiredness.

Flexible dosed duloxetine in the treatment of fibromyalgia: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To investigate the efficacy of flexible dose duloxetine 60-120 mg/day on changes in fibromyalgia (FM) symptoms assessed by the Patient Global Impression of Improvement (PGI-I) scale.

METHODS

Outpatients ≥ 18 years of age who met American College of Rheumatology criteria for FM, and had ≥ 4 score on the Brief Pain Inventory (BPI) average pain item, were randomized to duloxetine (n = 263) or placebo (n = 267) for 24 week double-blind treatment (primary endpoint at Week 12). Key secondary measures included BPI average pain severity, patient-rated scales assessing mood, anxiety, pain, sleep, and stiffness, Clinical Global Impression of Severity (CGI-S), Multidimensional Fatigue Inventory, Cognitive and Physical Functioning Questionnaire, Beck Depression Inventory (BDI), Beck Anxiety Inventory, and Medical Outcome Study Short-Form Health Survey (SF-36).

RESULTS

At Week 12, duloxetine-treated patients reported significantly greater global improvement with mean PGI-I scores of 2.8 compared to 3.4 in the placebo group (p < 0.001). Significantly more duloxetine- versus placebo-treated patients (57% vs 32%; p < 0.001) reported feeling "much" or "very much better" (PGI-I score ≤ 2). There was significantly greater improvement with duloxetine versus placebo treatment in BPI average pain severity, mood (including BDI total), anxiety (patient-rated only), stiffness, CGI-S, fatigue, all SF-36 domains (except role-physical and physical component summary), and being less bothered by pain or sleep difficulties. Treatment-emergent adverse events occurring significantly more frequently with duloxetine included: nausea, headache, constipation, dry mouth, dizziness, diarrhea, and hyperhidrosis.

CONCLUSION

Treatment with duloxetine 60, 90, and 120 mg/day was associated with feeling much better, pain reduction, being less bothered by sleep difficulties, and improvement in mood, stiffness, fatigue and functioning. (Clinical trial registry NCT00673452).

The pathophysiology, diagnosis and treatment of fibromyalgia

Research in fibromyalgia has increased understanding of the possible genetic and environmental factors that could be involved in the etiology of fibromyalgia. There is now substantial evidence for augmentation of central pain processing in fibromyalgia. Because the clinical presentation of fibromyalgia is heterogeneous, treatment recommendations must be individualized for each patient. The rapid growth of trials in fibromyalgia in recent years has resulted in new evidence-based approaches to pharmacological and nonpharmacological treatment.

Role and rationale for the use of milnacipran in the management of fibromyalgia

Fibromyalgia (FM) is a complex syndrome characterized by chronic widespread musculoskeletal pain which is often accompanied by multiple other symptoms, including fatigue, sleep disturbances, decreased physical functioning, and dyscognition. Due to these multiple symptoms, as well as high rates of comorbidity with other related disorders, patients with FM often report a reduced quality of life. Although the pathophysiology of FM is not completely understood, patients with FM experience pain differently from the general population, most likely due to dysfunctional pain processing in the central nervous system leading to both hyperalgesia and allodynia. In many patients with FM, this aberrant pain processing, or central sensitization, appears to involve decreased pain inhibition within the spinal tract, which is mediated by descending pathways that utilize serotonin, norepinephrine, and other neurotransmitters. The reduced serotonin and norepinephrine levels observed in patients with FM suggest that medications which increase the levels of these neurotransmitters, such as serotonin and norepinephrine reuptake inhibitors (SNRIs), may have clinically beneficial effects in FM and other chronic pain conditions. Milnacipran is an SNRI that has been approved for the management of FM. In clinical trials, treatment with milnacipran for up to 1 year has been found to improve the pain and other symptoms of FM. Because FM is characterized by multiple symptoms that all contribute to the decreased quality of life and ability to function, the milnacipran pivotal trials implemented responder analyses. These utilized a single composite endpoint to identify the proportion of patients who reported simultaneous and clinically significant improvements in pain, global disease status, and physical function. Other domains assessed during the milnacipran trials include fatigue, multidimensional functioning, mood, sleep quality, and patient-reported dyscognition. This review article provides information intended to help clinicians make informed decisions about the use of milnacipran in the clinical management of patients with FM. It draws primarily on results from 2 of the pivotal clinical trials that formed the basis of approval of milnacipran in the United States by the Food and Drug Administration.

Milnacipran: A New Treatment for Fibromyalgia Syndrome

Objective:

To review the pharmacology, efficacy, and tolerability of milnacipran, a dual serotonin-norepinephrine reuptake inhibitor (SNRI), in the treatment of symptoms of fibromyalgia syndrome and associated fibromyalgia pain.

Data Sources:

English-language articles were obtained via searches of MEDLINE (1950-January 2010), EMBASE (1980-January 2010), and International Pharmaceutical Abstracts (1970-January 2010), using the key words milnacipran, fibromyalgia, serotonin-norepinephrine reuptake inhibitors, F 2207, and pain management. Bibliographies of selected articles were used to identify additional sources.

Study Selection and Data Extraction:

Available published articles reporting the results of human studies of milnacipran were reviewed for inclusion in this article. Additional information regarding pharmacology, adverse events, contraindications, and precautions was obtained from the manufacturer's prescribing information.

Data Synthesis:

Milnacipran is a dual SNRI approved for the treatment of fibromyalgia symptoms and pain. Milnacipran is well absorbed upon oral administration, has limited first-pass elimination, has a short halflife, and is not metabolized by the cytochrome P450 enzyme group. Phase 3 clinical trials evaluating the efficacy of milnacipran demonstrated a 10–20% higher composite response rate compared with placebo in the treatment of fibromyalgia symptoms and associated pain when milnacipran was given in doses of 100–200 mg/day. Significant improvements in physical functioning, fatigue, cognition, and mental health were also noted. Milnacipran appears to have fewer anticholinergic, sedative, and cardiovascular adverse effects compared with other pharmacologic treatments of fibromyalgia. Nausea was the most commonly reported adverse event.

Conclusions:

Milnacipran is an effective treatment for the symptoms of fibromyalgia syndrome and associated pain. Additional studies are needed to assess comparative effectiveness with that of other pharmacologic treatments of fibromyalgia syndrome, long-term efficacy, and safety.

A patient survey of the impact of fibromyalgia and the journey to diagnosis

BACKGROUND

Fibromyalgia is a painful, debilitating illness with a prevalence of 0.5-5.0% that affects women more than men. It has been shown that the diagnosis of fibromyalgia is associated with improved patient satisfaction and reduced healthcare utilization. This survey examined the patient journey to having their condition diagnosed and studied the impact of the condition on their life.

METHODS

A questionnaire survey of 800 patients with fibromyalgia and 1622 physicians in 6 European countries, Mexico and South Korea. Patients were recruited via their physician.

RESULTS

Over half the patients (61%) were aged 36-59 years, 84% were women, and the mean time since experiencing fibromyalgia symptoms was 6.5 years. Patients had experienced multiple fibromyalgia symptoms (mean of 7.3 out of 14), with pain, fatigue, sleeping problems and concentration difficulties being the most commonly reported. Most patients rated their chronic widespread pain as moderate or severe and fibromyalgia symptoms were on average "fairly" to "very" disruptive, and had a "moderate" to "strong" impact on patients' lives. 22% were unable to work and 25% were not able to work all the time because of their fibromyalgia. Patients waited on average almost a year after experiencing symptoms before presenting to a physician, and it took an average of 2.3 years and presenting to 3.7 different physicians before receiving a diagnosis of fibromyalgia. Patients rated receiving a diagnosis as somewhat difficult on average and had difficulties communicating their symptoms to the physician. Over one third (35%) felt their chronic widespread pain was not well managed by their current treatment.

CONCLUSIONS

This survey provides further evidence that fibromyalgia is characterized by multiple symptoms and has a notable impact on quality of life and function. The diagnosis of fibromyalgia is delayed. Patients wait a significant period of time before presenting to a physician, adding to the prolonged time to diagnosis. Patients typically present with a multitude of symptoms, all resulting in a delay in diagnosis and eventual management. Helping clinicians to diagnose and manage patients with fibromyalgia should benefit both patients and funders of healthcare.

Toward characterization and definition of fibromyalgia severity

Background

There are no standard criteria for defining or assessing severity of fibromyalgia (FM) as a condition as fibromyalgia is associated with multiple symptom domains. The objective of this study was to evaluate whether patient self-reported severity of FM is associated with severity of pain and sleep interference and the presence of core co-morbidities.

Methods

We recruited individuals ≥ 18 years of age with a clinician-confirmed diagnosis of FM ≥ 3 months and a current pain rating >2 on a 0-10 numeric rating scale (NRS). Patients completed a questionnaire by mail in which they self-rated their FM severity (very mild, mild, moderate, and severe), their current pain severity and extent of sleep interference (NRS; mild, 0-3; moderate, 4-6, severe, 7-10), and provided information (yes/no) on the presence of core comorbidities (symptoms of depression, anxiety, sleep problems, back pain, neck pain) and medication use for FM. The core symptoms of FM were stratified to assist with patient characterization. Analysis of variance (ANOVA) was used to explore the relationship between self-reported FM severity and continuous variables (pain severity and sleep interference), and Mantel-Haenszel chi-square analysis was used to evaluate the trend in the proportions of patients reporting use of medications and core symptoms of FM by severity of FM. To complement patient-reported FM severity and to understand physicians' perspectives, a survey was performed among 28 physician specialists (rheumatology, neurology, anesthesiology/pain management, family practice, internal medicine, and psychiatry) to determine what they assessed when evaluating FM severity in clinical practice.

Results

The population (N = 129) of FM patients was predominantly female (89.1%), with a mean age of 49.4 ± 11.0 years, and 81.4% reported duration ≥ 2 years. Self-reported FM severity was moderate/severe in 86.0% of patients; mean current pain score was 6.40 ± 2.19 (moderate), and mean sleep interference score was 7.28 ± 2.23 (severe). Greater FM severity was significantly associated with higher levels of current pain and sleep interference (p < 0.0001), the proportion of patients reporting FM medication use (p = 0.0001), and the presence of core comorbidities (p < 0.05). Pain, functional disability, and fatigue severity were ranked as the top three criteria by the highest proportion of physicians when evaluating FM severity.

Conclusion

With higher self-reported FM severity, patients have greater pain and sleep interference as well as increased frequency of core comorbidities. Further investigation into understanding FM severity is warranted.

Burden of fibromyalgia and comparisons with osteoarthritis in the workforce

OBJECTIVES

To calculate the fibromyalgia (FM) burden of illness (BOI) from the employer perspective and to compare annual prevalence, work output, absence, and health benefit costs of employees with FM versus osteoarthritis (OA).

METHODS

Retrospective regression model analysis comparing objective work output, total health benefit (health care, prescription drug, sick leave, disability, workers' compensation) costs, and absence days for FM, versus OA and NoFM cohorts, while controlling for differences in patient characteristics.

RESULTS

FM prevalence was 0.73%; OA 0.90%. Total health benefit costs for FM were $8452 versus $11,253 (P < 0.0001) for OA and $4013 (P < 0.0001) for NoFM, with BOI = $4439. Total absence days were 16.8 versus 19.8 (P < 0.0001) and 6.4 (P < 0.0001), respectively. FM had significantly lower annual work output than NoFM (19.5%, P = 0.003) but comparable with OA.

CONCLUSION

FM places a significant cost, absence, and productivity burden on employers.

Milnacipran: beyond a role of antidepressant

Milnacipran is a serotonin and norepinephrine reuptake inhibitor (SNRI) with negligible effects on any presynaptic or postsynaptic receptors. Milnacipran has unique pharmacokinetic and pharmacodynamic characteristics that distinguish it from the other marketed serotonin and norepinephrine reuptake inhibitors, venlafaxine, desvenlafaxine, and duloxetine such as equipotent serotonin and norepinephrine reuptake inhibition and a linear dose-concentration trend at therapeutic doses. The half-life of milnacipran is approximately 8 hours. In addition, milnacipran does not inhibit the cytochrome P 450 system, indicating minimal propensity for drug-drug interactions. The antidepressant efficacy of milnacipran has been clearly established in a number of randomized, double-blind, placebo-controlled clinical trials, and it has been widely used for treating major depressive disorder. Moreover, evidence suggests that milnacipran is effective and tolerable in the treatment of fibromyalgia and may have usefulness for fatigue and anxiety symptoms. The current paper reviews researches conducted to date that is relevant to the efficacy, tolerability, and mechanism of action of milnacipran in the treatment of depression, fibromyalgia, and other psychiatric syndromes. Future directions of research are also identified.