Long-term maintenance of response across multiple fibromyalgia symptom domains in a randomized withdrawal study of pregabalin

An evidence-based review of pregabalin for the treatment of fibromyalgia

OBJECTIVES

Pregabalin, an α2-δ agonist, is approved for the treatment of fibromyalgia (FM) in the United States, Japan, and 37 other countries. The purpose of this article was to provide an in-depth, evidence-based summary of pregabalin for FM as demonstrated in randomized, placebo-controlled clinical studies, including open-label extensions, meta-analyses, combination studies and post-hoc analyses of clinical study data.

METHODS

PubMed was searched using the term "pregabalin AND fibromyalgia" and the Cochrane Library with the term "pregabalin". Both searches were conducted on 2 March 2017 with no other date limits set.

RESULTS

Eleven randomized, double-blind, placebo-controlled clinical studies were identified including parallel group, two-way crossover and randomized withdrawal designs. One was a neuroimaging study. Five open-label extensions were also identified. Evidence of efficacy was demonstrated across the studies identified with significant and clinically relevant improvements in pain, sleep quality and patient status. The safety and tolerability profile of pregabalin is consistent across all the studies identified, including in adolescents, with dizziness and somnolence the most common adverse events reported. These efficacy and safety data are supported by meta-analyses (13 studies). Pregabalin in combination with other pharmacotherapies (7 studies) is also efficacious. Post-hoc analyses have demonstrated the onset of pregabalin efficacy as early as 1-2 days after starting treatment, examined the effect of pregabalin on other aspects of sleep beyond quality, and shown it is effective irrespective of the presence of a wide variety of patient demographic and clinical characteristics.

CONCLUSIONS

Pregabalin is a treatment option for FM; its clinical utility has been comprehensively demonstrated.

Multidimensional daily diary of fatigue-fibromyalgia-17 items (MDF-fibro-17): part 2 psychometric evaluation in fibromyalgia patients

Background

The Multidimensional Daily Diary of Fatigue-Fibromyalgia-17 instrument (MDF-Fibro-17) has been developed for use in fibromyalgia (FM) clinical studies and includes 5 domains: Global Fatigue Experience, Cognitive Fatigue, Physical Fatigue, Motivation, and Impact on Function. Psychometric properties of the MDF-Fibro-17 needed to demonstrate the appropriateness of using this instrument in clinical studies are presented.

Methods

Psychometric analyses were conducted to evaluate the factor structure, reliability, validity, and responsiveness of the MDF-Fibro-17 using data from a Phase 2 clinical study of FM patients (N = 381). Confirmatory factor analyses (CFA) were performed to ensure understanding of the multidimensional domain structure, and a secondary factor analysis of the domains examined the appropriateness of calculating a total score in addition to domain scores. Longitudinal psychometric analyses (test-retest reliability and responder analysis) were also conducted on the data from Baseline to Week 6.

Results

The CFA supported the 17-item, 5 domain structure of this instrument as the best fit of the data: comparative fit index (CFI) and non-normed fit index (NNFI) were 0.997 and 0.992 respectively, standardized root mean square residual (SRMR) was 0.010 and the root mean square error of approximation (RMSEA) was 0.06. In addition, total score (CFI and NNFI both 0.95) met required standards. For the total and 5 domain scores, reliability and validity data were acceptable: test-retest and internal consistency were above 0.9; correlations were as expected with the Global Fatigue Index (GFI) (0.62-0.75), Fibromyalgia Impact Questionnaire (FIQ) Total (0.59–0.71), and 36-Item Short Form Health Survey (SF-36) vitality (VT) (0.43–0.53); and discrimination was shown using quintile scores for the GFI, FIQ Total, and Pain Numeric Rating Scale (NRS) quartiles. In addition, sensitivity to change was demonstrated with an overall mean responder score of -2.59 using anchor-based methods.

Conclusion

The MDF-Fibro-17 reliably measures 5 domains of FM-related fatigue and psychometric evaluation confirms that this measure meets or exceeds each of the predefined acceptable thresholds for evidence of reliability, validity, and responsiveness to changes in clinical status. This suggests that the MDF-Fibro-17 is an appropriate and responsive measure of FM-related fatigue in clinical studies.

Pregabalin for pain in fibromyalgia in adults

BACKGROUND

This review updates part of an earlier Cochrane review on 'Pregabalin for acute and chronic pain in adults' (Moore 2009), and considers only fibromyalgia pain.Antiepileptic drugs have been used in pain management since the 1960s. Pregabalin is an antiepileptic drug also used in management of chronic pain conditions, including fibromyalgia. Pain response with pregabalin is associated with major benefits for other symptoms, and improved quality of life and function in people with chronic painful conditions.

OBJECTIVES

To assess the analgesic efficacy and adverse events of pregabalin for pain in fibromyalgia in adults, compared with placebo or any active comparator.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE for randomised controlled trials from inception to May 2009 for the original review and to 16 March 2016 for this update. We also searched the reference lists of retrieved studies and reviews, and online clinical trial registries.

SELECTION CRITERIA

We included randomised, double-blind trials of eight weeks' duration or longer, comparing pregabalin with placebo or another active treatment for relief of pain in fibromyalgia, and reporting on the analgesic effect of pregabalin, with subjective pain assessment by the participant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with moderate pain relief (at least 30% pain relief over baseline or much or very much improved on Patient Global Impression of Change scale (PGIC)) or substantial pain relief (at least 50% pain relief over baseline or very much improved on PGIC). Where pooled analysis was possible, we used dichotomous data to calculate risk ratio and number needed to treat (NNT), using standard methods. We assessed the quality of the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created 'Summary of findings' tables.

MAIN RESULTS

Our searches identified two new published studies with classic design, and one new published study with an enriched enrolment randomised withdrawal (EERW) design.We included eight studies. Five (3283 participants) had a classic design in which participants were randomised at the start of the study to pregabalin (150, 300, 450, or 600 mg daily) or placebo, with assessment after 8 to 13 weeks of stable treatment. No studies included active comparators. Studies had low risk of bias, except that the last observation carried forward (LOCF) imputation method used in analyses of the primary outcomes could overestimate treatment effect.Pregabalin increased the number of participants experiencing substantial benefit (at least 50% pain intensity reduction after 12 or 13 weeks' stable treatment (450 mg: RR 1.8, 95% CI 1.4 to 2.1, 1874 participants, 5 studies, high quality evidence)). Substantial benefit with pregabalin 300 to 600 mg was experienced by about 14% of participants with placebo, but about 9% more with pregabalin 300 to 600 mg (22% to 24%) (high quality evidence). Pregabalin increased the number of participants experiencing moderate benefit (at least 30% pain intensity reduction after 12 or 13 weeks' stable treatment) (450 mg: RR 1.5, 95% CI (1.3 to 1.7), 1874 participants, 5 studies, high quality evidence). Moderate benefit with pregabalin 300 to 600 mg was experienced by about 28% of participants with placebo, but about 11% more with pregabalin 300 to 600 mg (39% to 43%) (high quality evidence). A similar magnitude of effect was found using PGIC of 'very much improved' and 'much or very much improved'. NNTs for these outcomes ranged between 7 and 14 (high quality evidence).A small study (177 participants) compared nightly with twice-daily pregabalin, and concluded there was no difference in effect.Two studies (1492 participants began initial dose titration, 687 participants randomised) had an EERW design in which those with good pain relief after titration were randomised, double blind, to continuing the effective dose (300 to 600 mg pregabalin daily) or a short down-titration to placebo for 13 or 26 weeks. We calculated the outcome of maintained therapeutic response (MTR) without withdrawal, equivalent to a moderate benefit. Of those randomised, 40% had MTR with pregabalin and 20% with placebo (high quality evidence). The NNT was 5, but normalised to the starting population tested it was 12. About 10% of the initial population would have achieved the MTR outcome, similar to the result from studies of classic design. MTR had no imputation concerns.The majority (70% to 90%) of participants in all treatment groups experienced adverse events. Specific adverse events were more common with pregabalin than placebo, in particular dizziness, somnolence, weight gain, and peripheral oedema, with number needed to harm of 3.7, 7.4, 18, and 19 respectively for all doses combined (high quality evidence). Serious adverse events did not differ between active treatment groups and placebo (very low quality evidence). Withdrawals for any reason were more common with pregabalin than placebo only with the 600 mg dose in studies of classic design. Withdrawals due to adverse events were about 10% higher with pregabalin than placebo, but withdrawals due to lack of efficacy were about 6% lower (high quality evidence).

AUTHORS' CONCLUSIONS

Pregabalin 300 to 600 mg produces a major reduction in pain intensity over 12 to 26 weeks with tolerable adverse events for a small proportion of people (about 10% more than placebo) with moderate or severe pain due to fibromyalgia. The degree of pain relief is known to be accompanied by improvements in other symptoms, quality of life, and function. These results are similar to other effective medicines in fibromyalgia (milnacipran, duloxetine).

Clinical utility, safety, and efficacy of pregabalin in the treatment of fibromyalgia

Fibromyalgia is a chronic debilitating medical syndrome with limited therapeutic options. Pregabalin, an anticonvulsant and α-2-Δ subunit receptor ligand, is one of the anchor drugs approved by the US Food and Drug Administration for the treatment of fibromyalgia. The drug has shown clinically meaningful benefits across multiple symptom domains of fibromyalgia. Efficacy of pregabalin in fibromyalgia pain has been evaluated in at least five high-quality randomized trials, two long-term extension studies, a meta-analysis, a Cochrane database systematic review, and several post hoc analyses. These studies also hint towards a meaningful benefit on sleep, functioning, quality of life, and work productivity. Side effects of pregabalin, although common, are mild to moderate in intensity. They are noted early during therapy, improve or disappear with dose reduction, and are not usually life- or organ threatening. In most patients, tolerance develops to the most common side effects, dizziness, and somnolence, with time. With close clinical monitoring at initiation or dose titration, pregabalin can be effectively used in primary care setting. Pregabalin is cost saving with long-term use and its cost-effectiveness profile is comparable, if not better, to that of other drugs used in fibromyalgia. In the present era of limited therapeutic options, pregabalin undoubtedly retains its role as one of cardinal drugs used in the treatment of fibromyalgia. This review intends to discuss the clinical utility of pregabalin in the management of fibromyalgia with a focus on efficacy, safety, and cost-effectiveness.

Deconstructing chronic low back pain in the older adult--Step by step evidence and expert-based recommendations for evaluation and treatment part III: Fibromyalgia syndrome

OBJECTIVE

To present the third in a series of articles designed to deconstruct chronic low back pain (CLBP) in older adults. The series presents CLBP as a syndrome, a final common pathway for the expression of multiple contributors rather than a disease localized exclusively to the lumbosacral spine. Each article addresses one of 12 important contributors to pain and disability in older adults with CLBP. This article focuses on fibromyalgia syndrome (FMS).

METHODS

A modified Delphi approach was used to create the evaluation and treatment algorithm, the table discussing the rationale behind each of the algorithm components, and the stepped-care drug recommendations. The team involved in the creation of these materials consisted of a principal investigator, a 5-member content expert panel, and a 9-member primary care panel. The evaluation and treatment recommendations were based on availability of medications and other resources within the Veterans Health Administration (VHA) facilities. However, non-VHA panelists were also involved in the development of these materials, which can be applied to both VA and civilian settings. The illustrative clinical case was taken from the clinical practice of the principal investigator.

RESULTS

Following expert consultations and a review of the literature, we developed an evaluation and treatment algorithm with supporting materials to aid in the care of older adults with CLBP who have concomitant FMS. A case is presented that demonstrates the complexity of pain evaluation and management in older patients with CLBP and concomitant FMS.

CONCLUSIONS

Recognition of FMS as a common contributor to CLBP in older adults and initiating treatment targeting both FMS and CLBP may lead to improved outcomes in pain and disability.

Time to improvement of pain and sleep quality in clinical trials of pregabalin for the treatment of fibromyalgia

OBJECTIVE

To determine the time to immediate and sustained clinical improvement in pain and sleep quality with pregabalin in patients with fibromyalgia.

DESIGN

A post hoc analysis of four 8- to 14-week phase 2-3, placebo-controlled trials of fixed-dose pregabalin (150-600 mg/day) for fibromyalgia, comprising 12 pregabalin and four placebo treatment arms.

PATIENTS

A total of 2,747 patients with fibromyalgia, aged 18-82 years.

METHODS

Pain and sleep quality scores, recorded daily on 11-point numeric rating scales (NRSs), were analyzed to determine time to immediate improvement with pregabalin, defined as the first of ≥2 consecutive days when the mean NRS score was significantly lower for pregabalin vs placebo in those treatment arms with a significant improvement at endpoint, and time to sustained clinical improvement with pregabalin, defined as a ≥1-point reduction of the baseline NRS score of patient responders who had a ≥30% improvement on the pain NRS, sleep NRS, or Fibromyalgia Impact Questionnaire (FIQ) from baseline to endpoint, or who reported "much improved" or "very much improved" on the Patient Global Impression of Change (PGIC) at endpoint.

RESULTS

Significant improvements in pain and sleep quality scores at endpoint vs placebo were seen in 8/12 and 11/12 pregabalin treatment arms, respectively (P < 0.05). In these arms, time to immediate improvements in pain or sleep occurred by day 1 or 2. Time to sustained clinical improvement occurred significantly earlier in pain, sleep, PGIC, and FIQ responders (P < 0.02) with pregabalin vs placebo.

CONCLUSIONS

Both immediate and sustained clinical improvements in pain and sleep quality occurred faster with pregabalin vs placebo.

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.

Pregabalin in neuropathic pain: evidences and possible mechanisms

Pregabalin is an antagonist of voltage gated Ca2+ channels and specifically binds to alpha-2-delta subunit to produce antiepileptic and analgesic actions. It successfully alleviates the symptoms of various types of neuropathic pain and presents itself as a first line therapeutic agent with remarkable safety and efficacy. Preclinical studies in various animal models of neuropathic pain have shown its effectiveness in treating the symptoms like allodynia and hyperalgesia. Clinical studies in different age groups and in different types of neuropathic pain (peripheral diabetic neuropathy, fibromyalgia, post-herpetic neuralgia, cancer chemotherapy-induced neuropathic pain) have projected it as the most effective agent either as monotherapy or in combined regimens in terms of cost effectiveness, tolerability and overall improvement in neuropathic pain states. Preclinical studies employing pregabalin in different neuropathic pain models have explored various molecular targets and the signaling systems including Ca2+ channel-mediated neurotransmitter release, activation of excitatory amino acid transporters (EAATs), potassium channels and inhibition of pathways involving inflammatory mediators. The present review summarizes the important aspects of pregabalin as analgesic in preclinical and clinical studies as well as focuses on the possible mechanisms.

Pregabalin: latest safety evidence and clinical implications for the management of neuropathic pain

Used mainly for the management of neuropathic pain, pregabalin is a gabapentinoid or anticonvulsant that was initially developed as an antiepileptic agent. After more than a decade of experience with pregabalin, experience and studies have shown that the adverse effect profile of pregabalin is well tolerated for the management of neuropathic pain and other conditions. Its use is associated with benign central nervous system and systemic adverse effects, and there are very limited metabolic, idiosyncratic or known teratogenic adverse effects. Along with its efficacy in particular neuropathic pain conditions, pregabalin's safety led it to be one of the first pharmacotherapies considered for the management of neuropathic pain. This review discusses the use of pregabalin as well as its potential adverse effects, including the most commonly noted features of sedation, dizziness, peripheral edema and dry mouth. Although other adverse effects may occur, these appear to be uncommon. The review also discusses the clinical implications of pregabalin's use for the clinician.