Spurious Claims For The Impact of Transdiagnostic CBT on Persistent Physical Symptoms 

 

In a just published study James et al (2022) extol the virtues of their transdiagnostic CBT therapy (plus standard medical care) for Persistent Physical Symptoms.
s. In an earlier study  these authors found no difference in outcome at 52 weeks follow up on the Work and Social Adjustment Scale (WSAS: the declared primary outcome measure) between those undergoing the transdiagnostic CBT plus standard medical care and those having the latter alone. Not to be outdone they have gone on a fishing expedition in their latest paper  James et al (2022) and focus on two secondary outcome measures, WSAS score at the end of active treatment  and the PHQ-15 score at 52 weeks, claiming that there was a significant difference between the transdiagnostic CBT  and standard medical care using both these secondary measures.

 This looks a little fishy as they are the originators of the treatment. No mention of the need for independent replication of their findings. Further the comparison group was standard medical care, but this design does not control for attention or the presentation of a credible treatment rationale. Scepticism seems in order. This intensifies when the outcome measures used are considered.

The WSAS (Mundt et al 2002) was designed to assess the impact of mental health on functioning in 5 domains work, home management, social leisure activities, private leisure activities and close relationships. As such there is clear separation between the causal agent (mental health) and effect (functioning). In the initial validation study the WSAS was administered to a sample of depressed patients and a sample of OCD patients, the WSAS scores correlated with the severity of each disorder.  

Mental Health can affect one’s ability to do certain day-to-day tasks in their lives. Please read each item below and respond based on how much your mental health impairs your ability to carry out the activity. 

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If however the term ‘mental health’ in the above table is replaced with “Persistent Physical Symptoms’ the distinction between causal agent and effect is lost. Consider, a person who is terminally ill with cancer or a progressive neurological disorder, they would likely score high in each domain. But it would not be anticipated that any psychological intervention is going to attenuate their physical symptoms, because there is a fusion of physical symptoms and impairment. [In the original validation study the term ‘disorder’ was used because they were known to have either depression or OCD].

The burden of proof is on those who would reword the WSAS so that it related to PPS to demonstrate a meaningful distinction between say fibromyalgia and impairment in functioning or irritable bowel syndrome and functioning or between chronic fatigue syndrome and functioning. The WSAS was not validated for PPS  but that has not stopped James et al (2022) using it as their primary outcome measure in their study of transdiagnotic CBT for PPS compared to standard medical care.

 

The PHQ-15 is a measure of symptom severity and is rated on a 3- point Likert scale. This brief validated measure looks at a range of symptoms and asks patients to report to what extent their symptoms bothered them in the past four weeks. The PHQ-15 contains 15 items and the total score can range from 0 to 30 where a higher score indicates greater symptom severity (Kroenke et al., 2010). The items include several related to pain, (stomach pain, back pain, pain in arms and legs or other joints, headaches, chest pain), fatigue, as well as other symp- toms related to the different systems of the body i.e. shortness of breath, dizziness, bowel symptoms.

But there is no clear mechanism by which a psychological intervention impacts such an array of symptoms. The authors considered 9 possible mediating variables (7 of which were cognitive), but only 2, catastrophising and symptom focusing appeared operative (Type 2 error). Suggesting that the supposed mediating variables may be chance findings. One of the suggested variables related to depression (PHQ-9) and the other anxiety (GAD-7) but for the supposed cognitive mediation model evinced by James et al (2022), they cannot be mediators, depression is known to covary with WSAS as such it cannot be an explanatory variable.

Assessment in the study is entirely by self-report measures but the authors totally ignore that they are subject to demand characteristics e.g wanting to please the therapist by reporting improvement or to convince oneself that time has not been wasted. It would have been more meaningful for an independent assessor to ask since ‘x’ have you felt the same, a little better, a little worse, much better, much worse.  

James et al (2022) justify their transdiagnostic therapy on the basis that ‘people with different PPS share some cognitive and behavioural responses to symptoms, including catastrophising, symptom focusing, fear avoidance beliefs, avoidance behaviour and lack of acceptance (Deary, Chalder, & Sharpe, 2007)’. This is a sweeping statement certainly catastrophising and avoidance behaviour have been implicated in the development of chronic pain, but this is not to say that they are germane to the category of PPS (MUS). The use of the term ‘some’ makes the Deary, Chalder, & Sharpe, 2007 model incapable of falsification.

 

The  term PPS as used byJames et al (2022), is a smokescreen for the construct Medically Unexplained Symptoms whose validity Keith Geraghty and I have challenged.

Dr Mike Scott

 

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