Predictors of fatigue in rheumatoid arthritis

People with RA commonly experience fatigue. Fatigue is a key contributor to increased clinical care costs, primary care consultations and employment loss. Despite this, our understanding of the prognostic of factors of poor fatigue outcomes is lacking and fatigue is poorly managed. Examining longitudinal predictors of fatigue can identify both individuals ‘at risk’ of poor prognosis, and candidate mechanisms that are worthy of greater inspection. This review discusses the factors most commonly investigated as being implicated in the prognosis of RA fatigue. The available data appears to implicate generic factors such as pain, mental health, disability and sleep as consistent predictors of fatigue outcome, while the role of disease activity and inflammation seems less clear. However, the existing data are not without methodological limitations and there have been no specific studies primarily designed to investigate the inflammatory biomarkers of fatigue. Future studies are required to more comprehensively and robustly determine the mechanisms of fatigue.

O15 Maintaining musculoskeletal health: a randomised controlled trial of cognitive behaviour therapy among people at high risk of developing chronic widespread pain

Background

Cognitive behaviour therapy (CBT) is effective in the management of fibromyalgia (and its characteristic feature chronic widespread pain (CWP). CBT is recommended in all recent major fibromyalgia management guidelines. From large-scale epidemiological studies, prediction models are available which identify groups at high-risk of developing CWP. We now test whether it is possible to prevent onset of CWP and/or change factors associated with its onset.

Methods

A randomised controlled trial of CBT delivered by telephone plus usual care (tCBT) was tested against usual care alone (UC). Eligible adults aged at least 25 years were identified by a survey of persons registered with sixteen general practices across Scotland. Respondents reporting regional pain (not CWP) for which they had recently consulted their GP and at least 2 items from a previously validated ‘high risk’ profile (Somatic Symptom Scale, Sleep Problem Scale, Illness Behaviour Scale) were invited to participate. tCBT was delivered across 6 sessions over 8 weeks with booster sessions 3 and 6 months after treatment start. Primary outcome was CWP at 12 months. Secondary outcomes were risk profile measures: fatigue (Chalder Fatigue Scale), Patient Global Impression of Change (PGIC: 7 categories), psychological distress (General Health Questionnaire) and quality of life (EQ-5D-5L) also at 12 months. Analysis used logistic, ordinal logistic or linear regression depending on outcome variable type; expressed as an effect size with 95% confidence interval.

Results

1,002 people were randomised, with equal numbers assigned to each arm of the trial: 59% of participants were female, with a median age of 59 (range 25-91) years. 66% of tCBT participants completed treatment and 83% of all participants provided follow-up data at 12 months. There was no difference in the proportion with CWP at 12 months (tCBT 18.0% v. UC 17.5%). There were improvements (all favouring tCBT) in Illness Behaviour Score (mean difference (md) -0.83; -1.55,-0.11), Sleep Problem Scale (md -0.90; -1.45,-0.36), psychological distress (Odds Ratio (OR) per category 0.65; 0.50, 0.85), EQ-5D-5L (md 0.024; 0.009, 0.039), Chalder Fatigue Scale (md -1.05; -1.66,-0.44) and PGIC (OR per category 0.51;0.39,0.67). Specifically 30.2% of those receiving tCBT reported their health as much or very much better, compared to 17.3% of those receiving UC.

Conclusion

This first-ever large-scale trial of prevention, aimed at persons at high risk, has shown tCBT does not change the likelihood of CWP onset but does improve the underlying risk profile for developing the condition as well as improving distress , fatigue and quality of life. Those receiving tCBT were, 12 months later, significantly more like to consider their health was better. This trial provides evidence for extending the group of people considered to benefit from CBT.

Disclosures

G.J. Macfarlane None. M. Beasley None. N. Scott None. P. McNamee None. J. McBeth None. G. Prescott None. G.T. Jones None. P. Hannaford None. N. Basu None. P. Keeley None. K. Lovell None.

O25 Quantifying and predicting the effect of anti-TNF therapy on axSpA-related fatigue: results from the BSRBR-AS registry and meta-analysis

Background

Fatigue represents a critical priority among patients with axial spondyloarthritis (axSpA). Its effective management is a major unmet clinical need. Existing studies indicate that anti-TNF therapy may reduce fatigue levels, although any effect has yet to be definitively quantified. Moreover, predictors of any such improvements have not been studied.

Methods

The British Society for Rheumatology Register in Axial Spondyloarthritis (BSRBR-AS) prospectively recruited axSpA patients across 83 centres in the UK. Changes in fatigue levels (measured using the Chalder Fatigue Scale (0-33)) over 1 year were compared between those starting anti-TNF therapy at the time of recruitment and those not. Differences between treatment groups were adjusted using propensity score matching. Results were combined with other studies in a meta-analysis to calculate pooled estimates. Then, among those BSRBR-AS anti-TNF commencers with clinically relevant fatigue, baseline predictors of response were investigated.

Results

Of the 998 BSRBR-AS recruits with complete fatigue outcome data, 310 were anti-TNF commencers and 688 were not. At 1 year follow-up, the former group reported a mean change in fatigue of -2.6 (95% CI -4.1, -1.9) points while the latter reported a mean worsening of fatigue by 0.2 points. Following propensity score adjustment, those commencing anti-TNF therapy reduced fatigue by 3.0 points compared to those not 95% CI (-4.1-1.9). In the meta-analysis, including 1109 subjects across 5 observational studies and trials, treatment with anti-TNF therapy resulted in a significant improvement in fatigue (SMD 0.36, 95% CI 0.15-1.56). Of those BSRBR-AS recruits commencing anti-TNF, n = 205 (66%) reported clinically significant fatigue at baseline of whom n = 139 (68%) experienced a clinically relevant improvement in their fatigue at 1 year. Poor sleep quality at baseline was predictive of fatigue improvement.

Conclusion

Anti TNF therapy results in a significant but modest reduction in fatigue amongst axSpA patients, with those reporting poor sleep quality most likely to report improvement. Effective management will likely require additional, possibly non-pharmacological, approaches.

Disclosures

J. Shim None. L. Dean None. M. Karabayas None. G. Jones None. G. Macfarlane None. N. Basu None.

Top down or bottom up? An observational investigation of improvement in fibromyalgia symptoms following hip and knee replacement

OBJECTIVES

Many patients with osteoarthritis have comorbid symptoms of FM, but it is unknown how these symptoms respond to surgical procedures that address nociceptive input in the periphery, such as total joint replacement. Here we explore differences in clinical characteristics between patients whose FM symptoms do and do not improve following total hip or knee replacement.

METHODS

Participants were 150 patients undergoing knee or hip replacement who had a minimum FM survey score of 4 or greater prior to surgery. The top tertile of patients experiencing the most improvement in FM symptoms at month 6 were categorized as 'Improve' (n = 48) while the bottom two tertiles were categorized as 'Worsen/Same' (n = 102). Baseline symptom characteristics were compared between groups, as well as improvement in overall pain severity, surgical pain severity and physical function at 6 months.

RESULTS

The Worsen/Same group had higher levels of fatigue, depression and surgical site pain at baseline (all P < 0.05). Additionally, they improved less on overall pain severity and physical functioning 6 months after surgery (both P < 0.05).

CONCLUSION

Most patients derive significant benefit in improvement of comorbid FM symptoms following total joint replacement, but a substantial proportion do not. Understanding the neurobiological basis for these different trajectories may help inform clinical judgment and improve patient care.

A novel 4-dimensional live-cell imaging system to study leukocyte-endothelial dynamics in ANCA-associated vasculitis

Neutrophils, monocytes and the endothelium are critical to ANCA-associated vasculitis (AAV) pathogenesis. This study aimed to develop a 4-dimensional (4D) live-cell imaging system that would enable investigation of spatial and temporal dynamics of these cells in health and disease. We further aimed to validate this system using autologous donor serum from AAV patients and polyclonal ANCA IgG, as well as exploring its potential in the pre-clinical testing of putative therapeutic compounds. Neutrophils and monocytes were isolated from peripheral venous blood of AAV patients or healthy controls and co-incubated on an endothelial monolayer in the presence of autologous serum. Alternatively, polyclonal ANCA IgG was used, following TNF-α priming, and imaged in 4-dimensions for 3 h using a spinning disc confocal microscope. Volocity 6.3^® analysis software was used for quantification of leukocyte dynamics. The use of autologous serum resulted in increased neutrophil degranulation (p = .002), transmigration (p = .0096) and monocyte transcellular transmigration (p = .0013) in AAV patients. Polyclonal MPO-ANCA IgG induced neutrophil degranulation (p < .001) in this system. C5aR1 antagonism reduced neutrophil degranulation (p < .0002). We have developed a novel 4D in vitro system that allows accurate quantification of multiple neutrophil- and monocyte-endothelial interactions in AAV in a single assay. This system has the potential to highlight dynamics key to pathophysiology of disease, as well investigating the impact of potential therapeutics on these functions.

Inflammation and the Central Nervous System in Inflammatory Rheumatic Disease

PURPOSE OF REVIEW

To review how peripheral inflammation in rheumatic disease influences the central nervous system. We consider recent studies of rheumatic disease that employ functional and structural neuroimaging in the context of inflammation, as well as recent studies considering how immunosuppressive therapy is associated with changes in brain function and structure.

RECENT FINDINGS

The most compelling evidence thus far comes from studies of rheumatoid arthritis and indicates that higher levels of inflammation are associated with changes in cognitive, affective, and pain-processing brain regions, some of which may be rectified by anti-inflammatory treatment. Comorbid symptoms such as widespread pain and fatigue may also be associated with these changes. Inflammation may be associated with compensatory activation of brain regions to offset structural changes. This emerging line of evidence suggests that communication between the brain and immune system are an important and underappreciated aspect of inflammatory rheumatic disease.

Association of Inflammation With Pronociceptive Brain Connections in Rheumatoid Arthritis Patients With Concomitant Fibromyalgia

OBJECTIVE

Rheumatoid arthritis (RA) patients with concomitant fibromyalgia (FM) exhibit alterations in brain connectivity synonymous with central sensitization. This study was undertaken to investigate how peripheral inflammation, the principal nociceptive stimulus in RA, interacts with brain connectivity in RA patients with FM.

METHODS

RA patients with concomitant FM and those without FM (FM+ and FM-, respectively; n = 27 per group) underwent functional connectivity magnetic resonance imaging. Seed-to-whole-brain functional connectivity analyses were conducted using seeds from the left mid/posterior insula and left inferior parietal lobule (IPL), which are regions that have been previously linked to FM symptoms and inflammation, respectively. The association between functional connectivity and erythrocyte sedimentation rate (ESR) was assessed in each group separately, followed by post hoc analyses to test for interaction effects. Cluster-level, family-wise error (FWE) rates were considered significant if the P value was less than 0.05.

RESULTS

The group of RA patients with FM and those without FM did not differ by age, sex, or ESR (P > 0.2). In FM+ RA patients, increased functional connectivity of the insula-left IPL, left IPL-dorsal anterior cingulate, and left IPL-medial prefrontal cortex regions correlated with higher levels of ESR (all FWE-corrected P < 0.05). Post hoc interaction analyses largely confirmed the relationship between ESR and connectivity changes as FM scores increased.

CONCLUSION

We report the first neurobiologic evidence that FM in RA may be linked to peripheral inflammation via pronociceptive patterns of brain connectivity. In patients with such "bottom-up" pain centralization, concomitant symptoms may partially respond to antiinflammatory treatments.

The Longitudinal Course of Fatigue in Antineutrophil Cytoplasmic Antibody-associated Vasculitis

OBJECTIVE

Fatigue is common and burdensome in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). This study aimed to understand how fatigue changes over time following treatment initiation and to determine whether individuals with the poorest prognosis can be robustly identified.

METHODS

One hundred forty-nine patients with AAV and new-onset disease recruited to 2 clinical trials (RITUXVAS and MYCYC) were followed for 18 months. Fatigue was measured at baseline and 6-month intervals using the vitality domain of the Medical Outcomes Study Short Form-36 quality of life questionnaire and compared to a cohort of 470 controls. Group-based trajectory modeling (GBTM) determined trajectories of the symptom to which baseline characteristics and ongoing fatigue scores were compared.

RESULTS

Fatigue levels at diagnosis were worse in patients than controls [median (interquartile range; IQR) 30 (10-48) vs 70 (55-80); p < 0.001], with 46% of patients reporting severe fatigue. Fatigue improved after 6 months of treatment but remained worse than in controls (p < 0.001). GBTM revealed varied trajectories of fatigue: low fatigue stable (n = 23), moderate baseline fatigue improvers (n = 29), high baseline fatigue improvers (n = 61), and stable baseline high fatigue (n = 37). Participants who followed stable high fatigue trajectories had lower vasculitis activity compared to improvers, but no other demographic or clinical variables differed.

CONCLUSION

This study longitudinally measured fatigue levels in patients with AAV. Although most patients improved following treatment, an important subgroup of patients reported persistently high levels of fatigue that did not change. Few clinical or laboratory markers distinguished these patients, suggesting alternative interventions specific for fatigue are required. [clinicaltrialsregister.eu, RITUXVAS EudraCT number: 2005-003610-15; MYCYC EudraCT number: 2006-001663-33].

Advances in Therapies and Imaging for Systemic Vasculitis

Vasculitis is a systemic disease characterized by immune-mediated injury of blood vessels. Current treatments for vasculitis, such as glucocorticoids and alkylating agents, are associated with significant side effects. Furthermore, the management of both small and large vessel vasculitis is challenging because of a lack of robust markers of disease activity. Recent research has advanced our understanding of the pathogenesis of both small and large vessel vasculitis, and this has led to the development of novel biologic therapies capable of targeting key cytokine and cellular effectors of the inflammatory cascade. In parallel, a diverse range of imaging modalities with the potential to monitor vessel inflammation are emerging. Continued expansion of combined structural and molecular imaging using positron emission tomography with computed tomography or magnetic resonance imaging may soon provide reliable longitudinal tracking of vascular inflammation. In addition, the emergence of radiotracers able to assess macrophage activation and immune checkpoint activity represents an exciting new frontier in imaging vascular inflammation. In the near future, these advances will allow more precise imaging of disease activity enabling clinicians to offer more targeted and individualized patient management.

Functional and structural magnetic resonance imaging correlates of fatigue in patients with rheumatoid arthritis

Objectives

Fatigue is a major burden among patients with RA, yet is poorly understood. We sought to conduct the first imaging study to investigate the neurobiological correlates of fatigue in RA and to improve upon the methodological limitations of previous neuroimaging studies that have investigated this symptom in other populations.

Methods

Chronically fatigued RA patients were clinically characterized before undertaking a combined functional and structural mode MRI brain scan. The functional sequences were acquired during a fatigue-evoking task, then network-to-whole-brain analyses were undertaken. The structural analyses employed voxel-based morphometry in order to quantify regional grey matter volume. The scan was repeated 6 months later to test reproducibility.

Results

Fifty-four participants attended both scans [n = 41 female; baseline mean (s.d.) age 54.94 (11.41) years]. A number of significant functional and structural neural imaging correlates of fatigue were identified. Notably, patients who reported higher levels of fatigue demonstrated higher levels of functional connectivity between the Dorsal Attention Network and medial prefrontal gyri, a finding that was reproduced in the repeat scans. Structurally, greater putamen grey matter volumes significantly correlated with greater levels of fatigue.

Conclusion

Fatigue in RA is associated with functional and structural MRI changes in the brain. The newly identified and reproduced neural imaging correlates provide a basis for future targeting and stratification of this key patient priority.

Intravenous pulse methylprednisolone for induction of remission in severe ANCA associated Vasculitis: a multi-center retrospective cohort study

Background

Intravenous pulse methylprednisolone (MP) is commonly included in the management of severe ANCA associated vasculitis (AAV) despite limited evidence of benefit. We aimed to evaluate outcomes in patients who had, or had not received MP, along with standard therapy for remission induction in severe AAV.

Methods

We retrospectively studied 114 consecutive patients from five centres in Europe and the United States with a new diagnosis of severe AAV (creatinine > 500 μmol/L or dialysis dependency) and that received standard therapy (plasma exchange, cyclophosphamide and high-dose oral corticosteroids) for remission induction with or without pulse MP between 2000 and 2013. We evaluated survival, renal recovery, relapses, and adverse events over the first 12 months.

Results

Fifty-two patients received pulse MP in addition to standard therapy compared to 62 patients that did not. There was no difference in survival, renal recovery or relapses. Treatment with MP associated with higher risk of infection during the first 3 months (hazard ratio (HR) 2.7, 95%CI [1.4–5.3], p = 0.004) and higher incidence of diabetes (HR 6.33 [1.94–20.63], p = 0.002), after adjustment for confounding factors.

Conclusions

The results of this study suggest that addition of pulse intravenous MP to standard therapy for remission induction in severe AAV may not confer clinical benefit and may be associated with more episodes of infection and higher incidence of diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1226-0) contains supplementary material, which is available to authorized users.

Protocol for a multicentre randomised controlled parallel-group trial to compare the effectiveness of remotely delivered cognitive-behavioural and graded exercise interventions with usual care alone to lessen the impact of fatigue in inflammatory rheumatic diseases (LIFT)

INTRODUCTION

Fatigue remains pervasive, disabling and challenging to manage across all inflammatory rheumatic diseases (IRDs). Non-pharmacological interventions, specifically cognitive-behavioural approaches (CBAs) and graded exercise programmes designed to support and increase exercise, are valuable treatments which help patients with IRD to manage their fatigue. Yet, healthcare systems have encountered substantial barriers to the implementation of these therapeutic options. Lessening the Impact of Fatigue in Inflammatory Rheumatic Diseases: a Randomised Trial (LIFT) is designed to give insights into the effectiveness of a remotely delivered standardised intervention for a range of patients with IRD. It will also enable the exploration of putative moderating factors which may allow for the future triage of patients and to investigate the precise mediators of treatment effect in IRD-related fatigue.

METHODS AND ANALYSIS

LIFT is a pragmatic, multicentre, three-arm randomised, controlled trial, which will test whether adapted CBA and personalised exercise programme interventions can individually reduce the impact and severity of fatigue. This will be conducted with up to 375 eligible patients diagnosed with IRD and interventions will be delivered by rheumatology healthcare professionals, using the telephone or internet-based audio/video calls.

ETHICS APPROVAL AND DISSEMINATION

Ethical approval has been granted by Wales REC 7 (17/WA/0065). Results of this study will be disseminated through presentation at scientific conferences and in scientific journal. A lay summary of the results will be sent to participants.

TRIAL REGISTRATION NUMBER

NCT03248518; Pre-results.

Development of a person-centered conceptual model of perceived fatigability

PURPOSE

Perceived fatigability, reflective of changes in fatigue intensity in the context of activity, has emerged as a potentially important clinical outcome and quality of life indicator. Unfortunately, the nature of perceived fatigability is not well characterized. The aim of this study is to define the characteristics of fatigability through the development of a conceptual model informed by input from key stakeholders who experience fatigability, including the general population, individuals with multiple sclerosis (MS), and individuals with fibromyalgia (FM).

METHODS

Thirteen focus groups were conducted with 101 participants; five groups with n = 44 individuals representing the general population, four groups with n = 26 individuals with MS, and four groups with n = 31 individuals with FM. Focus group data were qualitatively analyzed to identify major themes in the participants' characterizations of perceived fatigability.

RESULTS

Seven major themes were identified: general fatigability, physical fatigability, mental fatigability, emotional fatigability, moderators of fatigability, proactive and reactive behaviors, and temporal aspects of fatigability. Relative to those in the general sample, FM or MS groups more often described experiencing fatigue as a result of cognitive activity, use of proactive behaviors to manage fatigability, and sensory stimulation as exacerbating fatigability.

CONCLUSIONS

Fatigability is the complex and dynamic process of the development of physical, mental, and/or emotional fatigue. Trait- and state-like biological, psychological, social, and environmental moderators contribute to tremendous variability in fatigability (both between and within-person variability). Future research to further characterize fatigability across populations, test treatments for fatigability, and develop new measures of this construct are greatly needed.

Sensory sensitivity and symptom severity represent unique dimensions of chronic pain: a MAPP Research Network study

Chronic overlapping pain conditions (COPCs) are characterized by aberrant central nervous system processing of pain. This "centralized pain" phenotype has been described using a large and diverse set of symptom domains, including the spatial distribution of pain, pain intensity, fatigue, mood imbalances, cognitive dysfunction, altered somatic sensations, and hypersensitivity to external stimuli. Here, we used 3 cohorts, including patients with urologic chronic pelvic pain syndrome, a mixed pain cohort with other COPCs, and healthy individuals (total n = 1039) from the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network to explore the factor structure of symptoms of centralized pain. Using exploratory and confirmatory factor analysis, we identified 2 general factors in all 3 cohorts, one characterized by a broad increased sensitivity to internal somatic sensations,environmental stimuli, and diffuse pain, termed Generalized Sensory Sensitivity, and one characterized by constitutional symptoms-Sleep, Pain, Affect, Cognition, Energy (SPACE). Longitudinal analyses in the urologic chronic pelvic pain syndrome cohort found the same 2-factor structure at month 6 and 1 year, suggesting that the 2-factor structure is reproducible over time. In secondary analyses, we found that Generalized Sensory Sensitivity particularly is associated with the presence of comorbid COPCs, whereas SPACE shows modest associations with measures of disability and urinary symptoms. These factors may represent an important and distinct continuum of symptoms that are indicative of the centralized pain phenotype at high levels. Future research of COPCs should accommodate the measurement of each factor.

Prognosis and future developments in vasculitis

The prognosis of ANCA-associated vasculitis has been transformed in recent years. Once it was a set of invariably acute and fatal conditions, but these disorders are currently considered to be chronic diseases. This change is largely attributable to earlier diagnosis and the careful application of immunotherapeutics. However, patients still experience premature mortality, relapse, comorbid ill health and poor quality of life. Mortality rates in large-vessel vasculitis are not comparable; however, morbidity and poor patient outcomes prevail. Toxicity secondary to glucocorticoids represents a common driver of poor outcomes across systemic vasculitis. The main thrust of future treatment strategies is to reduce if not eliminate exposure to these agents.

Neural Indicators of Fatigue in Chronic Diseases: A Systematic Review of MRI Studies

While fatigue is prevalent in chronic diseases, the neural mechanisms underlying this symptom remain unknown. Magnetic resonance imaging (MRI) has the potential to enable us to characterize this symptom. The aim of this review was to gather and appraise the current literature on MRI studies of fatigue in chronic diseases. We systematically searched the following databases: MedLine, PsycInfo, Embase and Scopus (inception to April 2016). We selected studies according to a predefined inclusion and exclusion criteria. We assessed the quality of the studies and conducted descriptive statistical analyses. We identified 26 studies of varying design and quality. Structural and functional MRI, alongside diffusion tensor imaging (DTI) and functional connectivity (FC) studies, identified significant brain indicators of fatigue. The most common regions were the frontal lobe, parietal lobe, limbic system and basal ganglia. Longitudinal studies offered more precise and reliable analysis. Brain structures found to be related to fatigue were highly heterogeneous, not only between diseases, but also for different studies of the same disease. Given the different designs, methodologies and variable results, we conclude that there are currently no well-defined brain indicators of fatigue in chronic diseases.

A multi-modal MRI study of the central response to inflammation in rheumatoid arthritis

It is unknown how chronic inflammation impacts the brain. Here, we examined whether higher levels of peripheral inflammation were associated with brain connectivity and structure in 54 rheumatoid arthritis patients using functional and structural MRI. We show that higher levels of inflammation are associated with more positive connections between the inferior parietal lobule (IPL), medial prefrontal cortex, and multiple brain networks, as well as reduced IPL grey matter, and that these patterns of connectivity predicted fatigue, pain and cognitive dysfunction. At a second scan 6 months later, some of the same patterns of connectivity were again associated with higher peripheral inflammation. A graph theoretical analysis of whole-brain functional connectivity revealed a pattern of connections spanning 49 regions, including the IPL and medial frontal cortex, that are associated with peripheral inflammation. These regions may play a critical role in transducing peripheral inflammatory signals to the central changes seen in rheumatoid arthritis.

Many diseases, such as rheumatoid arthritis, are characterized by a chronic inflammatory state, but it is not clear whether or how this affects the brain. Here, the authors show that the severity of on-going inflammation predicts altered functional brain connectivity in people with rheumatoid arthritis.

Fatigue independently predicts different work disability dimensions in etanercept-treated rheumatoid arthritis and ankylosing spondylitis patients

Background

Work disability remains a significant problem in ankylosing spondylitis (AS) and rheumatoid arthritis (RA), despite biological therapy. This study aimed to test the hypothesis that the prevalent symptom of fatigue longitudinally predicts work disability among RA and AS patients commencing etanercept.

Methods

Two observational studies, comprising RA and AS etanercept commencers, respectively, were analysed. Both provided data on work disability over 1 year and a comprehensive set of putative predictors, including fatigue. A series of repeated measures models were conducted, including baseline variables, visit (6/12 months), and the interaction between visit and each of the explanatory variables.

Results

A total of 1003 AS and 1747 RA patients were assessed. For AS, fatigue was significantly associated with presenteeism (linear mixed model coefficient 3.75, 95% confidence interval (CI) 2.14 to 5.36) and activity impairment (2.62, 1.26 to 3.98), but not with work productivity loss (1.81, −0.40 to 4.02) or absenteeism (generalised linear mixed model odds ratio (OR) 1.18, 95% CI 0.92 to 1.51). In RA, fatigue was associated with presenteeism (coefficient 3.44, 95% CI 2.17 to 4.70), activity impairment (1.52, 0.79 to 2.26), work productivity loss (4.16, 2.47 to 5.85), and absenteeism (OR 1.23, 95% CI 1.02 to 1.49). The lack of significant interactions between fatigue and visit supported a consistent effect of baseline fatigue over time.

Conclusions

Among patients beginning etanercept therapy, fatigue has a significant and independent effect on absenteeism, presenteeism, productivity loss, and activity impairment for RA patients and a significant but dimension-selective effect on work disability among AS patients.

Trial registration

ClinicalTrials.gov, NCT00544557. Registered on 16 October 2007. ClinicalTrials.gov, NCT00488475. Registered on 20 June 2006.