The importance of a research case definition

Abstract:

All scientific activities with diseases rely on the selection of reliable and valid case definitions in order to accurately estimate prevalence rates, to identify biological markers, and to understand the outcomes of treatment trials. The failure to develop a consensus on which research case definition to use for defining Myalgic Encephalomyelitis (ME) and chronic fatigue syndrome (CFS) has had negative consequences for the scientific and patient community.

If case definition criteria inappropriately select patients with symptoms due to primary affective disorders, other fatiguing medical conditions, burnout, or over-committed lifestyle issues, the scientific consequences are serious. For example, a case definition that is too broad would include individuals with other illnesses and conditions, complicating the tasks of estimating prevalence rates or identifying effective treatment programs.

A consensus on a research case definition and its operationalization and assessment would enable investigators to select more homogenous samples that could expedite the identification of valid biological markers, and consequently reduce misperceptions regarding the role of psychogenic versus biomedical factors. Our editorial reviews the implications of previous research and clinical case definitions in CFS and ME domains.

Source: Leonard A. Jason, Pamela A. Fox & Kristen D. Gleason. The importance of a research case definition.  Fatigue: Biomedicine, Health & Behavior. Pages 1-7 | Received 01 Aug 2017, Accepted 04 Oct 2017, Published online: 12 Oct 2017.    http://www.tandfonline.com/doi/abs/10.1080/21641846.2018.1389336?journalCode=rftg20 

Psychometric properties and factor structure of a shortened version of the Cognitive Behavioural Responses Questionnaire (CBRQ)

Abstract:

OBJECTIVE: Symptoms of chronic fatigue syndrome (CFS) can be perpetuated by cognitive and behavioural responses to the illness. We aimed to determine the factor structure, reliability and validity of the 40-item Cognitive Behavioural Responses Questionnaire (CBRQ) using data gathered from CFS patients. We also propose a short version CBRQ for greater clinical utility.

METHODS: The psychometric analysis was performed on datasets drawn from two sources: a clinical service for CFS patients (N=576) and the PACE randomised controlled trial (RCT) of CFS treatments (N=640). An exploratory factor analysis (EFA) was conducted on the clinical dataset and a confirmatory factor analysis (CFA) was performed on the RCT dataset. Using these results, a short version of the CBRQ was proposed. Reliability, metric invariance across age and sex, and construct validity were assessed.

RESULTS: The EFA (relative Chi-square 2.52; RMSEA 0.051; CFI 0.964; TLI 0.942) and CFA (relative Chi-square 4.029; RMSEA 0.069; CFI 0.901; TLI 0.892) revealed that eight factor models fitted the data well. Satisfactory Cronbach’s alpha values were obtained for the final subscales (≥0.76). The shortened CBRQ was obtained by removing items that cross-loaded onto other factors and/or were the lowest loading items in each factor. The shortened CBRQ contained 18 items which had high factor loadings, good face-validity and reliability (Cronbach’s alpha 0.67-0.88).

CONCLUSIONS: The CBRQ, long and short versions, are reliable and valid scales for measuring cognitive and behavioural responses of patients with CFS. Further research is needed to examine the utility of the CBRQ in other long-term conditions.

Source: Ryan EG, Vitoratou S, Goldsmith KA, Chalder T. Psychometric properties and factor structure of a shortened version of the Cognitive Behavioural Responses Questionnaire (CBRQ). Psychosom Med. 2017 Oct 10. doi: 10.1097/PSY.0000000000000536. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/29023262

Grey and white matter differences in Chronic Fatigue Syndrome – A voxel-based morphometry study

Abstract:

OBJECTIVE: Investigate global and regional grey and white matter volumes in patients with Chronic Fatigue Syndrome (CFS) using magnetic resonance imaging (MRI) and recent voxel-based morphometry (VBM) methods.

METHODS: Forty-two patients with CFS and thirty healthy volunteers were scanned on a 3-Tesla MRI scanner. Anatomical MRI scans were segmented, normalized and submitted to a VBM analysis using randomisation methods. Group differences were identified in overall segment volumes and voxel-wise in spatially normalized grey matter (GM) and white matter (WM) segments.

RESULTS: Accounting for total intracranial volume, patients had larger GM volume and lower WM volume. The voxel-wise analysis showed increased GM volume in several structures including the amygdala and insula in the patient group. Reductions in WM volume in the patient group were seen primarily in the midbrain, pons and right temporal lobe.

CONCLUSION: Elevated GM volume in CFS is seen in areas related to processing of interoceptive signals and stress. Reduced WM volume in the patient group partially supports earlier findings of WM abnormalities in regions of the midbrain and brainstem.

Source: Finkelmeyer A, He J, Maclachlan L, Watson S, Gallagher P, Newton JL, Blamire AM. Grey and white matter differences in Chronic Fatigue Syndrome – A voxel-based morphometry study. Neuroimage Clin. 2017 Sep 28;17:24-30. doi: 10.1016/j.nicl.2017.09.024. ECollection 2018. https://www.ncbi.nlm.nih.gov/pubmed/29021956

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

Abstract:

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.

Source: Andrew R. Devendorf, Carly T. Jackson, Madison Sunnquist & Leonard A. Jason. Defining and measuring recovery from myalgic encephalomyelitis and chronic fatigue syndrome: the physician perspective. Disability and Rehabilitation. Published online: 05 Oct 2017