The Rationale for This Poll: Uncovering the Etiology of ME/CFS
I'd just like to explain why I am interested in fielding questions about the co-morbid conditions of ME/CFS. These reason is that a questionnaire on these co-morbid conditions can help get an idea of whether they are playing a causal role in ME/CFS or not, as I now explain.
A co-morbid condition of a disease is one which is statistically found more often in patients with the disease than in healthy controls.
When you have a co-morbid condition linked to a disease, logically there are three possible explanations for why that co-morbid condition is more prevalent in patients with the disease. These three possibilities are as follows:
(1) The co-morbid condition predisposes towards getting the disease. That is, the co-morbid condition plays a causal role in the disease, and has some tendency to precipitate the disease, so that is why statistically you often see the co-morbid condition accompanying the disease.
(2) The disease predisposes towards getting the co-morbid condition. That is, the disease plays a causal role in the co-morbid condition, and has some tendency to precipitate the co-morbid condition, so that is why statistically you often see the co-morbid condition accompanying the disease.
(3) The co-morbid condition does not cause the disease, and the disease does not cause the co-morbid condition. However, a third independent factor causes both the disease and the co-morbid condition, and that is why statistically the co-morbid condition and the disease often appear together, because a this third factor tends to cause both of them.
How can we use these three possibilities to undercover the causes of a disease like ME/CFS? Well, consider this:
• If (1) is the case, then you'd expect the co-morbid condition to arise before you get the disease.
• If (2) is the case, then you'd expect the co-morbid condition to arise after you get the disease.
• If (3) is the case, then the co-morbid condition could equally arise before or after you got the disease, since a third factor is the cause of both disease and co-morbid condition.
So for this poll, the question to ask is whether each co-morbid condition arose before or after an individual developed ME/CFS. If it arose before, then it suggests the co-morbid condition was actually playing a causal role in the ME/CFS. If it arose after, then it suggests that the co-morbid condition was just a result of ME/CFS, but did not actually play a part in causing ME/CFS.
So for example, the fact that irritable bowel syndrome (IBS) is a known co-morbid condition of ME/CFS, and the fact the poll at the moment shows 27% of people said they had IBS before developing ME/CFS hints that IBS may well be a causal factor in ME/CFS.
One mistake I did make in this poll was not including an option for when IBS and the other co-morbid conditions appeared in people only after they developed ME/CFS (a situation which would suggest that IBS does not play a causal role in ME/CFS, but rather that it is caused by ME/CFS). So this poll is logically flawed, because for each of the co-morbid conditions, the poll should have had two available answers, one answer option for when the condition appeared before you got ME/CFS, and another answer option for when it appeared after you got ME/CFS.
I should really consider setting up another poll along the same lines, as unfortunately the logic of this one is not quite right, inasfar as my objective of uncovering the causes behind ME/CFS is concerned.
The only other confounding consideration in the above logic is the possibility that (3) might be true, in which case, you cannot derive any etiological information from whether a co-morbid condition arises before or after the development of ME/CFS. So even if the poll is set up correctly, the etiological conclusions of this poll would only be valid if we assume that (3) is not the case.