Assessing sleep and pain among adults with myalgic encephalomyelitis/chronic fatigue syndrome: psychometric evaluation of the PROMIS® sleep and pain short forms.

PURPOSE: To evaluate the psychometric properties of the patient-reported outcome measurement information system® (PROMIS) short forms for assessing sleep disturbance, sleep-related impairment, pain interference, and pain behavior, among adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). METHODS: Data came from the Multi-Site ME/CFS study conducted between 2012 and 2020 at seven ME/CFS specialty clinics across the USA. Baseline and follow-up data from ME/CFS and healthy control (HC) groups were used to examine ceiling/floor effects, internal consistency reliability, differential item functioning (DIF), known-groups validity, and responsiveness. RESULTS: A total of 945 participants completed the baseline assessment (602 ME/CFS and 338 HC) and 441 ME/CFS also completed the follow-up. The baseline mean T-scores of PROMIS sleep and pain measures ranged from 57.68 to 62.40, about one standard deviation above the national norm (T-score = 50). All four measures showed high internal consistency (ω = 0.92 to 0.97) and no substantial floor/ceiling effects. No DIF was detected by age or sex. Known-groups comparisons among ME/CFS groups with low, medium, and high functional impairment showed significant small-sized differences in scores (η2 = 0.01 to 0.05) for the two sleep measures and small-to-medium-sized differences (η2 = 0.01 to 0.15) for the two pain measures. ME/CFS participants had significantly worse scores than HC (η2 = 0.35 to 0.45) for all four measures. Given the non-interventional nature of the study, responsiveness was evaluated as sensitivity to change over time and the pain interference measure showed an acceptable sensitivity. CONCLUSION: The PROMIS sleep and pain measures demonstrated satisfactory psychometric properties supporting their use in ME/CFS research and clinical practice.

Effectiveness of an ACT-based rehabilitation program for the treatment of chronic fatigue: Results from a 12-months longitudinal study.

Acceptance and Commitment Therapy (ACT) is potentially effective for treating chronic fatigue. Given the paucity of studies on this topic, we aimed to assess long-term trajectories of primary (fatigue, quality of life and functional abilities) and secondary outcomes (anxious and depressive symptoms) of an ACT-based rehabilitation program for patients with chronic fatigue. Further, we examined if changes in potential process variables (psychological inflexibility, metacognitive beliefs, and cognitive and behavioral responses to symptoms) during ACT predicted change in all outcomes across follow-up. One-hundred ninety-five workers on sick leave (mean age: 43.61 ± 9.33 years; 80.5% females) with a diagnosis of chronic fatigue were enrolled in a manualized, 3.5-week intensive return-to-work rehabilitation program based on ACT. All completed a battery of questionnaires at pre-, post-treatment, 6 and 12 months follow-up. We found significant longitudinal changes in most primary and secondary outcomes from pre- up to 12 months follow-up. All process variables significantly decreased from pre- up to 12 months follow-up, and pre-to-post changes in fear avoidance beliefs were most often associated with a greater change in outcomes across follow-up. Depressive symptomatology showed a similar trajectory of change to fatigue, meaning that scores were correlated at each time point and tended to converge over time. This suggests that both symptoms influence each other substantially over a year following the treatment. Concluding, results lend support to the effectiveness of an ACT-based rehabilitation program for patients with chronic fatigue and provide preliminary evidence for the role of process variables and depressive symptomatology on subsequent change in outcomes.

Cognitive factors are associated with disability and pain, but not fatigue among physiotherapy attendees with persistent pain and fatigue.

OBJECTIVES: Most research exploring the relationship between cognitive factors and pain, disability and fatigue in patients with persistent pain/fatigue has been performed in multi disciplinary environments. It is unclear whether these associations are consistent in other contexts. This study therefore aimed to establish the relationships between these factors in patients with persistent pain/fatigue referred for physiotherapy treatment. DESIGN: Cross-sectional observational study assessing the association between cognitive factors (self-efficacy and catastrophizing) and levels of pain, disability, mental fatigue and physical fatigue in patients with persistent pain/fatigue disorders. Data were analysed using regression analyses. SETTING: Two out-patient physiotherapy departments, Manchester, UK. PARTICIPANTS: 166 patients with persistent pain and fatigue disorders chronic widespread pain, fibromyalgia and chronic fatigue syndrome/myalgic encephalopathy). MAIN OUTCOME MEASURES: Disability was assessed using the Fibromyalgia Impact Questionnaire, whilst mental and physical fatigue were assessed with the sub-scales of the Chalder Fatigue Scale. Pain intensity was measured with a Numeric Pain Rating Scale, self-efficacy with the Chronic Pain Self-efficacy Questionnaire and catastrophizing with the Pain Catastrophizing Scale. RESULTS: Cognitive factors were significantly associated with pain (self-efficacy beliefs ß=-0.30, P<0.05; catastrophizing ß=0.24, P<0.05) and disability (self-efficacy beliefs ß=-0.62, P<0.05), but not fatigue. CONCLUSIONS: Similar associations were observed in patients referred to physiotherapy as to those observed in patients treated in multi disciplinary clinical environments. Self-efficacy beliefs appear to be particularly strong determinants of disability, but exert a lesser influence over pain or fatigue. Targeting self-efficacy may be an effective method to reduce disability in patients with persistent pain and fatigue disorders.

Guided graded Exercise Self-help for chronic fatigue syndrome: patient experiences and perceptions.

Purpose: This study explored patient experiences of Guided graded Exercise Self-help (GES) delivered as part of a randomised controlled trial for people with chronic fatigue syndrome/myalgic encephalomyelitis. The trial found that GES was better than specialist medical care at reducing fatigue and improving physical functioning.Methods: Semi-structured interviews were conducted with patients reporting improvement (n = 9) and deterioration (n = 10), and analysis involved thematic "constant comparison."Results: The improved group described more facilitators to doing GES, and were more likely to describe high levels of self-motivation, whereas the deteriorated group described more barriers to GES (including worse exacerbation of symptoms after GES, greater interference from comorbid conditions, and obstacles to GES in their lives), and had been ill for longer. Having the capacity to do GES was important; of note, those with relatively lower levels of functioning sometimes had more time and space in their lives to support their GES engagement. We identified an important "indeterminate phase" early on, in which participants did not initially improve.Conclusions: GES may be improved by targeting those most likely to improve, and teaching about the indeterminate phase.Implications for rehabilitationUsing the Guided Exercise Self-help booklet alone is unlikely to be sufficient to support patients through Guided Exercise Self-help successfully.Additional guidance from skilled physiotherapists/health professionals who demonstrate an understanding of what it is like to cope with chronic fatigue syndrome/myalgic encephalomyelitis is also important.Those using Guided Exercise Self-help may need additional support through a commonly experienced "indeterminate phase" - an initial phase in the programme where few benefits, along with various challenges associated with increasing activity, are experienced.Individuals who have been ill with chronic fatigue syndrome/myalgic encephalomyelitis for a relatively longer period of time and/or have additional comorbid conditions may benefit from more bespoke therapies with greater health professionals input, delivered by appropriate therapists.

Psychometric properties of the PROMIS® Fatigue Short Form 7a among adults with myalgic encephalomyelitis/chronic fatigue syndrome.

PURPOSE: To evaluate the psychometric properties of the Patient-Reported Outcome Measurement Information System® Fatigue Short Form 7a (PROMIS F-SF) among people with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). METHODS: Analyses were conducted using data from the Multi-Site Clinical Assessment of ME/CFS study, which recruited participants from seven ME/CFS specialty clinics across the US. Baseline and follow-up data from ME/CFS participants and healthy controls were used. Ceiling/Floor effects, internal consistency reliability, differential item functioning (DIF), known-groups validity, and responsiveness were examined. RESULTS: The final sample comprised 549 ME/CFS participants at baseline, 386 of whom also had follow-up. At baseline, the sample mean of PROMIS F-SF T-score was 68.6 (US general population mean T-score of 50 and standard deviation of 10). The PROMIS F-SF demonstrated good internal consistency reliability (Cronbach's α = 0.84) and minimal floor/ceiling effects. No DIF was detected by age or sex for any item. This instrument also showed good known-groups validity with medium-to-large effect sizes (η2 = 0.08-0.69), with a monotonic increase of the fatigue T-score across ME/CFS participant groups with low, medium, and high functional impairment as measured by three different variables (p < 0.01), and with significantly higher fatigue T-scores among ME/CFS participants than healthy controls (p < 0.0001). Acceptable responsiveness was found with small-to-medium effect sizes (Guyatt's Responsiveness Statistic = 0.28-0.54). CONCLUSIONS: Study findings support the reliability and validity of PROMIS F-SF as a measure of fatigue for ME/CFS and lend support to the drug development tool submission for qualifying this measure to evaluate therapeutic effect in ME/CFS clinical trials.

Defining and measuring recovery from myalgic encephalomyelitis and chronic fatigue syndrome: the physician perspective.

PURPOSE: To inform an operationalised definition of recovery from myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) for research and practice. Without a consensus on defining and measuring recovery, there will continue to be controversy amongst researchers, clinicians, and patients when interpreting treatment outcomes. METHOD: This study explores physicians' views on recovery from ME and CFS. We conducted semi-structured interviews with 10 physician participants who are experts in the ME and CFS field. Our deductive thematic analysis, using a realist perspective, provided a framework for differentiating recovery and significant improvement. RESULTS: Physicians conceptualised recovery as complete symptom remission and a return to premorbid functioning (adjusted for with age), whereas they viewed significant improvement as a substantial reduction in symptoms with considerable functional gains, where patients may operate in daily life but still must cope or be treated. CONCLUSIONS: Our findings provide recommendations and approaches for measuring: daily functioning, symptomatology, quality of life, and physical functioning. Implications for rehabilitation Physicians viewed recovery as complete symptom remission and a return to premorbid functioning (adjusted for with age). Recovery from myalgic encephalomyelitis and chronic fatigue syndrome should be viewed as multidimensional, considering patients' daily life, psychosocial functioning, and overall physical functioning. These findings can improve practitioner-client interactions, as they provide recommendations for measuring recovery in research and practice.

Energy envelope maintenance among patients with myalgic encephalomyelitis and chronic fatigue syndrome: Implications of limited energy reserves.

OBJECTIVE: The Energy Envelope Theory of myalgic encephalomyelitis and chronic fatigue syndrome postulates that individuals with myalgic encephalomyelitis and chronic fatigue syndrome may experience some increase in functioning if their level of exertion consistently remains within the limits of their available energy. Findings of several studies support this theory; however, the current study is the first to explore how an individual's initial level of available energy may influence the relation between energy envelope maintenance and level of functioning. METHOD: The functioning, activity, and symptomatology of six groups of individuals with myalgic encephalomyelitis and chronic fatigue syndrome were compared. Groups were created based upon level of available energy (higher or lower) and energy envelope adherence (underextended, within, overextended). RESULTS: Results indicate that, as expected, individuals with myalgic encephalomyelitis and chronic fatigue syndrome who had higher available energy also had better functioning than individuals with lower available energy; however, this relation was less pronounced for individuals who were overexerting themselves. DISCUSSION: These results are consistent with the Energy Envelope Theory, and they suggest that overexertion was particularly impactful for individuals with higher levels of available energy.

Home-based family focused rehabilitation for adolescents with severe Chronic Fatigue Syndrome.

AIMS:: The purpose of this article is to describe and evaluate a home based, family focused rehabilitative approach for severely affected housebound adolescents with Chronic Fatigue Syndrome (CFS). The main aims were to facilitate a return to school, improve physical functioning, reduce fatigue and assess any adverse effects of the intervention. METHODS:: Six housebound adolescents aged 11-18, diagnosed with CFS by a paediatrician, were assessed and treated at home by an experienced cognitive behaviour therapist. Outcomes were assessed 12 months after discharge from treatment. RESULTS:: At 12 months follow-up all patients had returned to either school or college, and physical functioning had improved in most of the patients. Fatigue had reduced in some. No adverse effects of the intervention were reported. CONCLUSION:: Severely affected adolescents with CFS showed improved physical functioning and social adjustment after a home-based rehabilitative approach. Although several patients showed improvements in physical functioning, they did not all show substantial improvements in fatigue. At this crucial stage of development, it is important to offer young people and their parents hope by stating that improvement is possible.

Biopsychosocial predictors and trajectories of work participation after transdiagnostic occupational rehabilitation of participants with mental and somatic disorders: a cohort study.

BACKGROUND: Group-based transdiagnostic occupational rehabilitation programs including participants with mental and somatic disorders have emerged in clinical practice. Knowledge is sparse on subsequent participation in competitive work. This study aimed to investigate trajectories for (re)entry to work for predefined subgroups in a diagnostically heterogeneous sample of sick-listed participants after completing occupational rehabilitation. METHODS: A cohort of 212 participants aged 18-69 on long-term sick leave (> 8 weeks) with chronic pain, chronic fatigue and/or common mental disorders was followed for one year after completing a 3½-week rehabilitation intervention based on Acceptance and Commitment Therapy. Self-reported, clinical and registry data were used to study the associations between predefined biopsychosocial predictors and trajectories for (re)entry to competitive work (≥ 1 day per week on average over 8 weeks). Generalized estimating equations analysis was used to investigate trajectories. RESULTS: For all biopsychosocial subgroups (re)entry to work increased over time. Baseline employment, partial sick leave and higher expectation of return to work (RTW) predicted higher probability of having (re)entered work at any given time after discharge. The odds of increasing reentry over time (statistical interaction with time) was weaker for the group receiving the benefit work assessment allowance compared with those receiving sickness benefit (OR = 0.92, p = 0.048) or for those on partial sick leave compared with full sick leave (OR 0.77, p < 0.001), but higher for those who at baseline had reported having a poor economy versus not (OR 1.16, p = 0.010) or reduced emotional functioning compared with not (OR 1.11, p = 0.012). Health factors did not differentiate substantially between trajectories. CONCLUSIONS: Work participation after completing a transdiagnostic occupational rehabilitation intervention was investigated. Individual and system factors related to work differentiated trajectories for (re)entry to work, while individual health factors did not. Having a mental disorder did not indicate a worse prognosis for (re)entry to work following the intervention. Future trials within occupational rehabilitation are recommended to pivot their focus to work-related factors, and to lesser extent target diagnostic group.

Activity pacing: moving beyond taking breaks and slowing down.

This brief communication responds to the paper by Jeong and Cho (Qual Life Res 26(4):903-911, 2017) that has described activity pacing in limited terms of adjusting activities through going at a slower rate and taking breaks. Activity pacing was reported as not involving goal setting, in comparison to other strategies for long-term conditions such as Acceptance and Commitment Therapy. This brief communication aims to challenge this limited perception of activity pacing in light of numerous studies that recognise pacing to be a more complex strategy. Pacing is considered to be a multifaceted coping strategy, including broad themes of not only adjusting activities, but also planning activities, having consistent activity levels, acceptance of current abilities and gradually increasing activities, and one that includes goal setting as a key facet. It is essential that pacing is both defined and measured as a multifaceted strategy in order to assess the outcomes of pacing, and for meaningful comparisons with other strategies regarding efficacy for the management of long-term conditions.

Clinical and cost-effectiveness of the Lightning Process in addition to specialist medical care for paediatric chronic fatigue syndrome: randomised controlled trial.

OBJECTIVE: Investigate the effectiveness and cost-effectiveness of the Lightning Process (LP) in addition to specialist medical care (SMC) compared with SMC alone, for children with chronic fatigue syndrome (CFS)/myalgic encephalitis (ME). DESIGN: Pragmatic randomised controlled open trial. Participants were randomly assigned to SMC or SMC+LP. Randomisation was minimised by age and gender. SETTING: Specialist paediatric CFS/ME service. PATIENTS: 12-18 year olds with mild/moderate CFS/ME. MAIN OUTCOME MEASURES: The primary outcome was the the 36-Item Short-Form Health Survey Physical Function Subscale (SF-36-PFS) at 6 months. Secondary outcomes included pain, anxiety, depression, school attendance and cost-effectiveness from a health service perspective at 3, 6 and 12 months. RESULTS: We recruited 100 participants, of whom 51 were randomised to SMC+LP. Data from 81 participants were analysed at 6 months. Physical function (SF-36-PFS) was better in those allocated SMC+LP (adjusted difference in means 12.5(95% CI 4.5 to 20.5), p=0.003) and this improved further at 12 months (15.1 (5.8 to 24.4), p=0.002). At 6 months, fatigue and anxiety were reduced, and at 12 months, fatigue, anxiety, depression and school attendance had improved in the SMC+LP arm. Results were similar following multiple imputation. SMC+LP was probably more cost-effective in the multiple imputation dataset (difference in means in net monetary benefit at 12 months £1474(95% CI £111 to £2836), p=0.034) but not for complete cases. CONCLUSION: The LP is effective and is probably cost-effective when provided in addition to SMC for mild/moderately affected adolescents with CFS/ME. TRIAL REGISTRATION NUMBER: ISRCTN81456207.

Tutorial: The practical application of longitudinal structural equation mediation models in clinical trials.

The study of mediation of treatment effects, or how treatments work, is important to understanding and improving psychological and behavioral treatments, but applications often focus on mediators and outcomes measured at a single time point. Such cross-sectional analyses do not respect the implied temporal ordering that mediation suggests. Clinical trials of treatments often provide repeated measures of outcomes and, increasingly, of mediators as well. Repeated measurements allow the application of various types of longitudinal structural equation mediation models. These provide flexibility in modeling, including the ability to incorporate some types of measurement error and unmeasured confounding that can strengthen the robustness of findings. The usual approach is to identify the most theoretically plausible model and apply that model. In the absence of clear theory, we put forward the option of fitting a few theoretically plausible models, providing a type of sensitivity analysis for the mediation hypothesis. In this tutorial, we outline how to fit several longitudinal mediation models, including simplex, latent growth and latent change models. This will allow readers to learn about one type of model that is of interest, or about several alternative models, so that they can take this sensitivity approach. We use the Pacing, Graded Activity, and Cognitive Behavioral Therapy: A Randomized Evaluation (PACE) trial of rehabilitative treatments for chronic fatigue syndrome (ISRCTN 54285094) as a motivating example and describe how to fit and interpret various longitudinal mediation models using simulated data similar to those in the PACE trial. The simulated data set and Mplus code and output are provided. (PsycINFO Database Record

Economic evaluation of multidisciplinary rehabilitation treatment versus cognitive behavioural therapy for patients with chronic fatigue syndrome: A randomized controlled trial.

BACKGROUND: A multi-centre RCT has shown that multidisciplinary rehabilitation treatment (MRT) is more effective in reducing fatigue over the long-term in comparison with cognitive behavioural therapy (CBT) for patients with chronic fatigue syndrome (CFS), but evidence on its cost-effectiveness is lacking. AIM: To compare the cost-effectiveness of MRT versus CBT for patients with CFS from a societal perspective. METHODS: A multi-centre randomized controlled trial comparing MRT with CBT was conducted among 122 patients with CFS diagnosed using the 1994 criteria of the Centers for Disease Control and Prevention and aged between 18 and 60 years. The societal costs (healthcare costs, patient and family costs, and costs for loss of productivity), fatigue severity, quality of life, quality-adjusted life-year (QALY), and cost-effectiveness ratios (ICERs) were measured over a follow-up period of one year. The main outcome of the cost-effectiveness analysis was fatigue measured by the Checklist Individual Strength (CIS). The main outcome of the cost-utility analysis was the QALY based on the EuroQol-5D-3L utilities. Sensitivity analyses were performed, and uncertainty was calculated using the cost-effectiveness acceptability curves and cost-effectiveness planes. RESULTS: The data of 109 patients (57 MRT and 52 CBT) were analyzed. MRT was significantly more effective in reducing fatigue at 52 weeks. The mean difference in QALY between the treatments was not significant (0.09, 95% CI: -0.02 to 0.19). The total societal costs were significantly higher for patients allocated to MRT (a difference of €5,389, 95% CI: 2,488 to 8,091). MRT has a high probability of being the most cost effective, using fatigue as the primary outcome. The ICER is €856 per unit of the CIS fatigue subscale. The results of the cost-utility analysis, using the QALY, indicate that the CBT had a higher likelihood of being more cost-effective. CONCLUSIONS: The probability of being more cost-effective is higher for MRT when using fatigue as primary outcome variable. Using QALY as the primary outcome, CBT has the highest probability of being more cost-effective. TRIAL REGISTRATION: ISRCTN77567702.

Processes in acceptance and commitment therapy and the rehabilitation of chronic fatigue.

Acceptance and commitment therapy (ACT) has never been tested for patients with chronic fatigue. We aimed to test if a 3.5-week ACT rehabilitation program for patients with chronic fatigue improved quality of life (QoL), fatigue, and psychological flexibility. Further, to test if improvements in QoL and fatigue were associated with improvement in psychological flexibility, and if psychological flexibility explained variance above and beyond maladaptive cognitions typically targeted in CBT for fatigue. Patients (n = 140) who had been on sick leave > 8 weeks due to chronic fatigue received a 3.5-week non-controlled inpatient rehabilitation program based on ACT. A physician and a psychologist examined the patients, assessing medication use and SCID-I diagnoses. Patients completed questionnaires about somatic complaints, psychological complaints, and maladaptive cognitions before and after treatment. At post-treatment, patients reported improved QoL (p < 0.001; g = 1.07) and less fatigue (p < 0.001; g = 1.08), but not increased psychological flexibility (p = 0.6). Changes in psychological flexibility was associated with improved QoL, but not fatigue, in hierarchical regression analyses. When adjusting for other cognitions, changes in fear-avoidance cognitions and all-or-nothing thoughts, but not psychological flexibility, were associated with improved QoL and fatigue. The ACT-based treatment improved QoL and reduced fatigue for patients with chronic fatigue with large effect sizes. Improvement was associated with a reduction in fear-avoidance cognitions and all-or-nothing thoughts, but not psychological flexibility.

Heart rate variability biofeedback therapy and graded exercise training in management of chronic fatigue syndrome: An exploratory pilot study.

OBJECTIVE: Chronic fatigue syndrome (CFS) is characterised by persistent fatigue, exhaustion, and several physical complaints. Research has shown cognitive behavioural therapy (CBT) and graded exercise training (GET) to be the most effective treatments. In a first step we aimed to assess the efficacy of heart rate variability biofeedback therapy (HRV-BF) as a treatment method comprising cognitive and behavioural strategies and GET in the pilot trial. In a second step we aimed to compare both interventions with regard to specific parameters. METHODS: The study was conducted in an outpatient treatment setting. A total of 28 women with CFS (50.3±9.3years) were randomly assigned to receive either eight sessions of HRV-BF or GET. The primary outcome was fatigue severity. Secondary outcomes were mental and physical quality of life and depression. Data were collected before and after the intervention as well as at a 5-month follow-up. RESULTS: General fatigue improved significantly after both HRV-BF and GET. Specific cognitive components of fatigue, mental quality of life, and depression improved significantly after HRV-BF only. Physical quality of life improved significantly after GET. There were significant differences between groups regarding mental quality of life and depression favouring HRV-BF. CONCLUSION: Both interventions reduce fatigue. HRV-BF seems to have additional effects on components of mental health, including depression, whereas GET seems to emphasise components of physical health. These data offer implications for further research on combining HRV-BF and GET in patients with CFS. TRIAL REGISTRATION: The described trial has been registered at the International Clinical Trials Registry Platform following the number DRKS00005445.

Activity Pacing is Associated With Better and Worse Symptoms for Patients With Long-term Conditions.

BACKGROUND: Activity pacing has been associated with both improved and worsened symptoms, and its role in reducing disability among patients with long-term conditions has been questioned. However, existing studies have measured pacing according to unidimensional subscales, and therefore the empirical evidence for pacing as a multifaceted construct remains unclear. We have developed a 26-item Activity Pacing Questionnaire (APQ-26) for chronic pain/fatigue containing 5 themes of pacing: activity adjustment, activity consistency, activity progression, activity planning, and activity acceptance. OBJECTIVE: To assess the associations between the 5 APQ-26 pacing themes and symptoms of pain, physical fatigue, depression, avoidance, and physical function. METHODS: Cross-sectional questionnaire study design. Data analyzed using multiple regression. PARTICIPANTS: A total of 257 adult patients with diagnoses of chronic low back pain, chronic widespread pain, fibromyalgia, and chronic fatigue syndrome/myalgic encephalomyelitis. RESULTS: Hierarchical multiple regression showed that activity adjustment was significantly associated with increased physical fatigue, depression, and avoidance, but decreased physical function (all Ps≤0.030). Activity consistency was associated with decreased pain, physical fatigue, depression, and avoidance, but increased physical function (all Ps≤0.003). Activity planning was associated with reduced physical fatigue (Ps=0.025) and activity acceptance was associated with increased avoidance (Ps=0.036). CONCLUSIONS: Some APQ-26 pacing themes were associated with worse symptoms and others with symptom improvement. Specifically, pacing themes involving adjusting/reducing activities were associated with worse symptoms, whereas pacing themes involving undertaking consistent activities were associated with improved symptoms. Future study will explore the causality of these associations to add clarification regarding the effects of pacing on patients' symptoms.

The utility of patient-reported outcome measures among patients with myalgic encephalomyelitis/chronic fatigue syndrome.

PURPOSE: Debilitating fatigue is a core symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS); however, the utility of patient-reported symptom outcome measures of fatigue for ME/CFS patients is problematic due to ceiling effects and issues with reliability and validity. We sought to evaluate the performance of three patient-reported symptom measures in a sample of ME/CFS patients and matched controls. METHODS: Two hundred and forty ME/CFS patients and 88 age, sex, race, and zip code matched controls participated in the study. Participants completed the Multidimensional Fatigue Inventory-20, DePaul Symptom Questionnaire, and RAND SF-36. RESULTS: The general and physical fatigue subscales on Multidimensional Fatigue Inventory-20, as well as the role of physical health on the RAND SF-36, demonstrated questionable or unacceptable internal consistency and problematic ceiling effects. The DePaul Symptom Questionnaire demonstrated excellent internal reliability, and less than 5 % of participants were at the ceiling on each subscale. The post-exertional malaise subscale on the DePaul Symptom Questionnaire demonstrated excellent clinical utility as it was able to differentiate between ME/CFS patients and controls (OR 1.23, p < .001) and predicted ceiling effects on other patient-reported outcome subscales. A score of 20 on the post-exertional malaise subscale of the DePaul Symptom Questionnaire optimally differentiated between patients and controls. CONCLUSIONS: Significant ceiling effects and concerns with reliability and validity were observed among Multidimensional Fatigue Inventory-20 and RAND SF-36 subscales for ME/CFS patients. The DePaul Symptom Questionnaire addresses a number of concerns typically identified when using patient-reported outcome measures with ME/CFS patients; however, an improved multidimensional patient-reported outcome tool for measuring ME/CFS-related symptoms is warranted.

Treatment expectations influence the outcome of multidisciplinary rehabilitation treatment in patients with CFS.

OBJECTIVE: To improve the effectiveness of treatment in patients with chronic fatigue syndrome it is worthwhile studying factors influencing outcomes. The aims of this study were (1) to assess the association of expectancy and credibility on treatment outcomes, and (2) to identify baseline variables associated with treatment expectancy and credibility. METHODS: 122 patients were included in a randomized controlled trial of whom 60 received cognitive behavioural therapy (CBT) and 62 multidisciplinary rehabilitation treatment (MRT). Expectancy and credibility were measured with the credibility and expectancy questionnaire. Outcomes of treatment, fatigue, and quality of life (QoL), were measured at baseline and post-treatment. Multiple linear regressions were performed to analyse associations. RESULTS: In explaining fatigue and the physical component of the QoL, the effect of expectancy was significant for MRT, whereas in CBT no such associations were found. The main effect of expectancy on the mental component of QoL was not significant. For credibility, the overall effect on fatigue and the physical component of QoL was not significant. In explaining the mental component of QoL, the interaction between treatment and credibility was significant. However, the effects within each group were not significant. In the regression model with expectancy as dependent variable, only treatment centre appeared significantly associated. In explaining credibility, treatment centre, treatment allocation and depression contributed significantly. CONCLUSIONS: For clinical practice it seems important to check the expectations of the patient, since expectations influence the outcome after MRT.