Survivorship Bias in MECFS Treatment
Here's how survivorship bias works:
Planes come back from war with bullet holes in them.
Naive engineers analyze planes that come back and reinforce the parts with holes.
No additional planes come back.
Smart engineer points out "The bullet holes are where the planes were hit and survived. The planes that went down got hit where there are no bullet holes."
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Now let's see it in MECFS...
Patients come to the doctor with MECFS symptoms
Doctor prescribes CBT and GET
Only the patients without MECFS remain able to attend the clinic after treatment.
Doctor sees only patients without MECFS come back and assumes that therefore the treatment worked for the people with MECFS. But they don't see that all the patients with MECFS never came back to the clinic because they became too sick!
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So no matter how many patients are harmed the GP will learn that GET and CBT works! This is survivorship bias at work.*
*The only other group to return will be patients who do not follow instructions and instead listen to their bodies. Thus the stereotype of MECFS patients as "unreasonable" and "non-compliant"
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Other myths perpetuated by this phenomenon:
MECFS is always actually POTS (Because POTS patients will benefit from treatment)
MECFS and Fibro are the same thing
(Because effective treatment for fibro like SNRIs keeps patients coming back)
My ______ therapy cures everyone who doesn't give up on it
(Because everyone it failed or made worse is labeled as "giving up")
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Medicine has a tendency to assume that patients not coming back is a good thing. This is normally reasonable. If you go to the doctor for an acute issue and they give you a treatment that works, the end. You don't generally go back to say "thanks doc that really fixed me up I'm all good now." You just go on to live your life.
But for patients with chronic issues not coming back is different. If a patient with incurable chronic pain or chronic fatigue never visits your clinic again after 1 session it probably doesn't mean you cured their incurable disease. It means you didn't provide enough treatment value for them to return. Or worse, it means you made them too sick to even attend your clinic again.
When doctors falsely equate patients not returning with good outcomes regardless of the condition being treated they are falling victim to survivorship bias. They may in fact be drawing conclusions about their treatment from a tiny minority of patients for which it worked when the vast majority of patients were in fact drastically harmed.
The 2015 ME Association study showed this to be the case where 74% of patients declined under Graded Excercise Therapy. However, most clinics offering GET will tell you they have incredibly high recovery rates among their "long term patients". They aren't lying. It's just that their "long-term patients" aren't the ones with severe PEM. Those patients likely didn't make it past 1 or 2 sessions.
It is time to kill the myth of the non-compliant patient and teach survivorship bias in chronic illness management to med school students everywhere.
