Network structure of functional somatic symptoms, 2024, Fischer et al

Network structure of functional somatic symptoms
https://www.sciencedirect.com/science/article/pii/S0022399924003805

Results
The final network had a relatively small number of edges, with small (46.5 %) or small- to medium-sized (47.1 %) correlations. Ten communities were identified: and cognitive problems/fatigue/depression, sensory problems, facial pain, head/neck/upper back pain, dizziness/nausea, throat pain/problems with swallowing, chest pain, widespread pain, abdominal pain/problems with digestion, and genital pain. The highest node strength in the network was found for the symptoms “tired”, “down, depressed, or hopeless”, and “tired after minimal exertion”.

Conclusions
The network analyses pointed to ten distinct groups of moderately associated symptoms in individuals with FSS. Fatigue and depression emerged as important symptoms connecting groups. Future studies should test whether (transdiagnostic) interventions specifically targeting these symptoms are particularly potent in alleviating FSS.

 

Full abstract.

Highlights

• The network structure of functional somatic symptoms (FSS) was estimated.
• Ten communities (i.e., groups of symptoms) emerged.
• Central symptoms connecting FSS were fatigue and depression.
• In addition, bridge symptoms connecting FSS and depression were identified.
• These included fatigue, balance, nausea, and pain/discomfort during digestion.

Abstract

Objective
The overlap among functional somatic syndromes (FSS) is substantial, which is why various empirical attempts at an improved understanding of related symptoms have been undertaken. Network analyses are particularly valuable from a clinical point of view, since they focus on the extent to which symptoms expression is co-dependent. The aim of this study was to provide the first estimation of the network structure of symptoms in 17 FSS.

Methods
N = 3054 young adults participated in an online survey. The Questionnaire on Functional Somatic Syndromes (FSSQ) was used to diagnose FSS and to assess related symptoms. The Patient Health Questionnaire (PHQ-9) was used to assess (comorbid) depression. Various R packages were used for network analysis, which yielded correlations between symptoms (edges), symptom groups (communities), and measures of centrality for individual symptoms (e.g., node strength).

Results
The final network had a relatively small number of edges, with small (46.5 %) or small- to medium-sized (47.1 %) correlations. Ten communities were identified: and cognitive problems/fatigue/depression, sensory problems, facial pain, head/neck/upper back pain, dizziness/nausea, throat pain/problems with swallowing, chest pain, widespread pain, abdominal pain/problems with digestion, and genital pain. The highest node strength in the network was found for the symptoms “tired”, “down, depressed, or hopeless”, and “tired after minimal exertion”.

Conclusions
The network analyses pointed to ten distinct groups of moderately associated symptoms in individuals with FSS. Fatigue and depression emerged as important symptoms connecting groups. Future studies should test whether (transdiagnostic) interventions specifically targeting these symptoms are particularly potent in alleviating FSS.

 

If I understand this correctly, they did a bunch of graph math using questionnaires of symptoms, moods and other stuff, to find that people report those symptoms. So they basically identified the symptoms that patients report using a convoluted process. Somewhat. Genius stuff.

The conclusion is bizarre. They lump together a bunch of health issues unified by factors independent of the symptoms themselves, or the patients, rather it is medicine's lack of understanding that unifies them, then ponder if, and this has been done to death already, having lumped them together, perhaps they could transdiagnostically (i.e. generically) treat them specifically.

Unfortunately they used two useless questionnaires in the form of some psychosomatic questionnaire and the PHQ-9, which asks mainly generic questions where anyone ill without support would rate highly.

Just swinging randomly at things and shouting how they're hitting stuff very specifically, as they always intended to.

 

Introduction

Medically unexplained symptoms or functional somatic symptoms are highly abundant in the general population [1] as well as in primary [2] and secondary healthcare settings [3]. In specific constellations, they have received labels such as “chronic fatigue syndrome” [4], “fibromyalgia” [5], and “irritable bowel syndrome” [6], which can be found as exclusionary diagnoses in various somatic disease chapters within the International Classification of Diseases [ICD; 7]. However, the overlap among at least some of these functional somatic syndromes (FSS) is substantial [8, 9]. This has led some researchers to question the necessity of several distinct FSS [10], of which at least 17 have been described in the literature [11].

 

"In brief, N=3,054 young adults residing in Switzerland were recruited via college and university mailing lists between 2009 and 2010 and participated in an online survey on functional somatic syndromes. Mean age was 24.6 ± 5.6 years, 2,042 (73.4%) of the participants were women and 812 (26.6%) were men. In total, n=289 individuals fulfilled research diagnostic criteria for at least one of 17 FSS, including chronic fatigue syndrome, fibromyalgia, and irritable bowel syndrome "

Fukuda was used to diagnose "CFS".

 

Should be as yet medically unexplained .When their entire attitude is not to spend any effort into finding an explanation for persistent symptoms the rank amateurs will carry on invading this space since they have to bear no consequences for gross incompetence or outright fraud.

 

This kind of network analysis is a bit outside my experience, but a few comments:

I think a bit greater caution is needed in reporting the findings given both the small edge weights and the fact that multiple centrality measures are below cut-off. The network analysis alone can't establish predictive relationships and they group together very broad categories ("tiredness", "pain") without differentiating out (say) acute vs sporadic/intermittent vs chronic pain. I don't think there's great value in aggregating symptoms into communities in this way.

The cohort (n=3054) was recruited "via college and university mailing lists between 2009 and 2010 and participated in an online survey" (original paper using this dataset can be found here); being of younger and more educated adults, it is not representative of the general population. The authors say that 289 individuals (9.5%) met "research diagnostic criteria for at least one of 17 FSS", but there was no clinical evaluation; this is how they did it:

They go on to say:

Reference 47 is the Larun et al Cochrane exercise therapy review and reference 49 is the Price et al Cochrane CBT review.

Also, despite the use of "post-exertional malaise" once, the authors then consistently use "post-exertional tiredness", indicating that they don't understand the symptom.