Letter to the editor:
Loades, M. E., Rimes, K., Lievesley, K., Ali, S., & Chalder, T. (2019). Cognitive and behavioural responses to symptoms in adolescents with chronic fatigue syndrome: A case-control study nested within a cohort. Clinical Child Psychology Psychiatry. Advance online publication. doi:10.1177/1359104519835583
Loades, Rimes, Lievesley, Ali and Chalder (2019) report that unhelpful cognitive and behavioural responses to symptoms appear to be particularly prominent in adolescents with chronic fatigue syndrome (CFS). Their method to determine unhelpful responses, however, could be questioned.
Catastrophizing, for example, was assessed by how much participants agreed with statements such as ‘my illness is awful and I feel that it overwhelms me’ (Ryan, Vitoratou, Goldsmith, & Chalder, 2018). Descriptions such as these might reflect the severity of symptoms rather than the patient’s response to them. This is particularly relevant as the control group consisted of asthma patients who were less disabled than patients with CFS. Asthma patients had approximately half the score on the Chalder Fatigue Questionnaire and almost 40 points more on the Short-Form 36-item Physical Functioning Scale than patients with CFS. Anyone familiar with these scales will realize the enormous disparity in health reflected by such figures. Consequently, a direct comparison of cognitive and behavioural responses to symptoms might be misleading.
A study that did control for fatigue severity found that CFS patients showed lower levels of catastrophizing, damage beliefs and symptom focusing than patients with autoimmune rheumatic diseases (Ali, Matcham, Irving, & Chalder, 2017). In the hierarchical linear regression model by Loades et al. (2019), all of the cognitive and behavioural responses measured, explained less than 8% of the variance of fatigue at follow-up when baseline factors such as mood and fatigue were accounted for. This is contrary to the view that catastrophizing and symptom focusing are central in driving disability in CFS.
The assessment of fear avoidance is even more problematic as it is based on agreement with statements such as ‘physical activity makes my symptoms worse’ (Ryan et al., 2018). The experience of physical activity making symptoms worse is considered to be the hallmark symptom of CFS, often referred to as post-exertional malaise (Institute of Medicine, The National Academies Press, 2015). Consequently, one would expect most if not all CFS patients agree with this statement.
The National Institute for Health and Clinical Excellence (NICE) guideline, used to select
participants in the study by Loades et al., instructs clinicians to reconsider the diagnosis of CFS if patients do not experience post-exertional malaise (National Institute for Health and Care Excellence, 2007). I would therefore recommend modifying the assessment of fear avoidance in patients with CFS. Otherwise one risks measuring patients’ symptoms and mislabelling them as maladaptive cognitive responses.
Finally, Loades et al. suggest that all-or-nothing, boom-and-bust behaviour patterns exacerbate CFS symptoms in a self-perpetuating cycle. Two large studies, a Dutch (Van der Werf, Prins, Corresponding author: Vercoulen, van der Meer, & Bleijenberg 2000) and Belgian (Meeus et al., 2011) one, have tested this hypothesis using objective outcomes. Patients and healthy controls were instructed to wear an actimeter on several consecutive days to monitor their activity. Both studies found no difference in day-today fluctuations in the activity pattern between CFS patients and controls. Consequently, the view that boom-and-bust patterns of activity are perpetuating symptoms in CFS patients is unfounded.
Read full letter and references
Importantly, aspects of the biological basis of the ongoing disease have been revealed over the last 2-3 years that promise new leads towards an effective clinical diagnostic test that may have a general application.
