The Permutation Distancing Test for dependent single-case observational AB-phase design data: A Monte Carlo simulation study.

The Permutation Distancing Test (PDT) is a nonparametric test for evaluating treatment effects in dependent single-case observational design (SCOD) AB-phase data without linear trends. Monte Carlo methods were used to estimate the PDT power and type I error rate, and to compare them to those of the Single-Case Randomization Test (SCRT) assuming a randomly determined intervention point and the traditional permutation test assuming full exchangeability. Data were simulated without linear trends for five treatment effect levels (- 2, - 1, 0, 1, 2), five autocorrelation levels (0, .15, .30, .45, .60), and four observation number levels (30, 60, 90, 120). The power was calculated multiple times for all combinations of factor levels each generating 1000 replications. With 30 observations, the PDT showed sufficient power (≥ 80%) to detect medium treatment effects up to autocorrelation ≤ .45. Using 60 observations, the PDT showed sufficient power to detect medium treatment effects regardless of autocorrelation. With ≥ 90 observations, the PDT could also detect small treatment effects up to autocorrelation ≤ .30. With 30 observations, the type I error rate was 5-7%. With 60 observations and more, the type I error rate was ≤ 5% with autocorrelation < .60. The PDT outperformed the SCRT regarding power, particularly with a small number of observations. The PDT outperformed the traditional permutation test regarding type I error rate control, especially when autocorrelation increased. In conclusion, the PDT is a useful and promising nonparametric test to evaluate treatment effects in dependent SCOD AB-phase data without linear trends.

Individual outcomes after tailored versus generic self-management strategies for persistent fatigue in youth with a fatigue syndrome or rheumatic condition: A multiple single-case study.

OBJECTIVE: To examine individual outcomes after tailored lifestyle (PROfeel) or generic dietary advice as self-management intervention for persistent fatigue in adolescents and young adults with a chronic condition, to compare participants who did and did not benefit and to explore changes to factors in the biopsychosocial model of fatigue after PROfeel. METHOD: A multiple single-case AB-phase design was embedded in a randomized crossover trial (N = 45). Intensive longitudinal data (ILD) on outcomes 'fatigue severity', 'self-efficacy' and 'quality of life' (QoL) were collected through weekly smartphone measurement for 20 weeks. ILD on biopsychosocial factors were collected through experience sampling methodology for 28 days pre-post first intervention. Baseline characteristics were compared with t-tests and chi-square tests. Permutation distancing tests were used to assess change over time in all ILD. RESULTS: Regarding weekly measurements, nineteen participants (42.22%) showed small to large positive outcomes (drange = .05 to 2.59), mostly after PROfeel. Eleven participants (24.44%) showed small to moderate negative outcomes (drange = -.02 to -2.46), mostly after dietary advice. Fatigue severity improved most, followed by self-efficacy. Participants who benefitted showed higher QoL levels and lower fatigue and pain levels compared with others at baseline (all p < .02). When positive outcomes were observed after PROfeel, typically ≥1 biopsychosocial factor had been targeted successfully. CONCLUSION: Self-management advice has more potential when tailored to individual characteristics, including the biopsychosocial model of fatigue. PROfeel appears particularly useful as fatigue intervention for individuals with relatively less severe symptoms.

Targeting persistent fatigue with tailored versus generic self-management strategies in adolescents and young adults with a fatigue syndrome or rheumatic condition: A randomized crossover trial.

OBJECTIVES: To evaluate the use of two self-management intervention strategies for persistent fatigue in adolescents and young adults with a fatigue syndrome or rheumatic condition. DESIGN: A randomized crossover trial administering tailored lifestyle advice and generic dietary advice, each 12 weeks, with a four-week washout period between. METHODS: Sixty participants (aged 12-29) were included. Tailoring was achieved through the PROfeel method. Dietary guidelines were conceptualized by the Netherlands Nutrition Centre. Questionnaires were used pre-post-interventions to measure primary outcome 'fatigue severity' (Checklist Individual Strength-8) and secondary outcomes 'self-efficacy' (Self-Efficacy Scale-28) and 'quality of life' (QoL) (Paediatric Quality of Life Inventory 4.0). Feasibility and adherence were self-rated on a scale of 1 to 10 (low to high). Linear mixed modelling was used to assess change over time, compare strategy effectiveness and study the impact of intervention order. RESULTS: Fatigue severity, self-efficacy and QoL regarding 'physical' and 'emotional' functioning improved significantly over time (all p < .015). The average improvement of the two QoL subscales was clinically relevant, as was the fatigue improvement in 20 out of 46 participants who completed the trial and 5 dropouts. The interventions were equally effective, and intervention order did not impact the improvement level (prange = .242-.984). The self-management strategies received similar feasibility (M = 6.45, SD = 1.91) and adherence (M = 7.67, SD = 1.67) ratings. CONCLUSIONS: As small to clinically relevant improvements were observed, self-management strategies might be particularly useful to bridge waiting time for guided treatments such as Cognitive Behavioural Therapy.

Dynamic modeling of experience sampling methodology data reveals large heterogeneity in biopsychosocial factors associated with persistent fatigue in young people living with a chronic condition.

OBJECTIVE: To evaluate associations between self-reported biopsychosocial factors and persistent fatigue with dynamic single-case networks. METHODS: 31 persistently fatigued adolescents and young adults with various chronic conditions (aged 12 to 29 years) completed 28 days of Experience Sampling Methodology (ESM) with five prompts per day. ESM surveys consisted of eight generic and up to seven personalized biopsychosocial factors. Residual Dynamic Structural Equation Modeling (RDSEM) was used to analyze the data and derive dynamic single-case networks, controlling for circadian cycle effects, weekend effects, and low-frequency trends. Networks included contemporaneous and cross-lagged associations between biopsychosocial factors and fatigue. Network associations were selected for evaluation if both significant (α < 0.025) and relevant (ß ≥ 0.20). RESULTS: Participants chose 42 different biopsychosocial factors as personalized ESM items. In total, 154 fatigue associations with biopsychosocial factors were found. Most associations were contemporaneous (67.5%). Between chronic condition groups, no significant differences were observed in the associations. There were large inter-individual differences in which biopsychosocial factors were associated with fatigue. Contemporaneous and cross-lagged associations with fatigue varied widely in direction and strength. CONCLUSIONS: The heterogeneity found in biopsychosocial factors associated with fatigue underlines that persistent fatigue stems from a complex interplay between biopsychosocial factors. The present findings support the need for personalized treatment of persistent fatigue. Discussing the dynamic networks with the participant can be a promising step towards tailored treatment. TRIAL REGISTRATION: No. NL8789 (http://www.trialregister.nl).

Paediatric short fatigue questionnaire, a 4-item fatigue questionnaire for children.

OBJECTIVE: To investigate whether a paediatric Short Fatigue Questionnaire (pSFQ) assesses a valid construct for subjective fatigue, to assess its psychometric properties and provide a cut-off score for severe fatigue in children. METHODS: The pSFQ consists of 4 items from the Checklist Individual Strength-8 (CIS-8). Data of previous studies using the CIS-8 were used to assess the pSFQ in healthy children (n = 316), children with chronic fatigue syndrome (n = 173), and children with a chronic disease (n = 442). All children were 12-18 years old. Confirmatory factor analysis (CFA) was performed, followed by Cronbach alpha's to investigate internal consistency, and Spearman's correlations to assess construct validity. With ROC analysis, we determined a cut-off score for severe fatigue and provide normative data on the pSFQ for children with and without a chronic disease. RESULTS: CFA confirmed a one-factor model in the pSFQ representing subjective fatigue. Cronbach's alpha ranged from good to excellent (0.84-0.94), as did construct validity (-0.76 and - 0.87 for correlation with two other fatigue measurements). ROC analysis delivered a cut-off score of ≥21, with a sensitivity of 93.9% and specificity of 96.2% for severe fatigue. Normative data for children with and without a chronic disease showed similar patterns compared to other fatigue questionnaires. CONCLUSION: The pSFQ is a practical and reliable screening instrument for severe fatigue in children with and without a chronic disease, and effectively reduces the questionnaire length with 50% compared to the conventional CIS-8.

Identifying disrupted biological factors and patient-tailored interventions for chronic fatigue in adolescents and young adults with Q-Fever Fatigue Syndrome, Chronic Fatigue Syndrome and Juvenile Idiopathic Arthritis (QFS-study): study protocol for a randomized controlled trial with single-subject experimental case series design.

BACKGROUND: Chronic fatigue with a debilitating effect on daily life is a frequently reported symptom among adolescents and young adults with a history of Q-fever infection (QFS). Persisting fatigue after infection may have a biological origin with psychological and social factors contributing to the disease phenotype. This is consistent with the biopsychosocial framework, which considers fatigue to be the result of a complex interaction between biological, psychological, and social factors. In line, similar manifestations of chronic fatigue are observed in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) and juvenile idiopathic arthritis (JIA). Cognitive behavioral therapy is often recommended as treatment for chronic fatigue, considering its effectiveness on the group level. However, not everybody benefits on the individual level. More treatment success at the individual level might be achieved with patient-tailored treatments that incorporate the biopsychosocial framework. METHODS: In addition to biological assessments of blood, stool, saliva, and hair, the QFS-study consists of a randomized controlled trial (RCT) in which a single-subject experimental case series (N=1) design will be implemented using Experience Sampling Methodology in fatigued adolescents and young adults with QFS, CFS/ME, and JIA (aged 12-29). With the RCT design, the effectiveness of patient-tailored PROfeel lifestyle advices will be compared against generic dietary advices in reducing fatigue severity at the group level. Pre-post analyses will be conducted to determine relevance of intervention order. By means of the N=1 design, effectiveness of both advices will be measured at the individual level. DISCUSSION: The QFS-study is a comprehensive study exploring disrupted biological factors and patient-tailored lifestyle advices as intervention in adolescent and young adults with QFS and similar manifestations of chronic fatigue. Practical or operational issues are expected during the study, but can be overcome through innovative study design, statistical approaches, and recruitment strategies. Ultimately, the study aims to contribute to biological research and (personalized) treatment in QFS and similar manifestations of chronic fatigue. TRIAL REGISTRATION: Trial NL8789 . Registered July 21, 2020.