Sunday, August 13, 2017

The Heartbreak of Psoriais - Guilt by Association

I was asked this week for an informal opinion by someone who was advised by his dermatologist to take a biologic medicine for psoriasis.   Now, my knowledge of this disorder is barely skin deep, yet knowledge alone will not set you free in the murky world of medicine.  Knowing something is not as significant as knowing when to do something.

Can guacamole really cause cancer?  Read on.

Biologic medicines, which have surpassed in frequency the nearly omnipresent TV ads for erectile dysfunction, are expensive medications that have risks of serious, albeit uncommon, side effects.  And, unlike chemotherapy for cancer, which has a finite course, biologic medicines are administered forever, that is without a clear stopping point. 

The individual who questioned me was not suffering from insufferable psoriasis and was satisfied with the conventional topical treatments he has been using for years.  His dermatologist offered the biologic in an effort to reduce his risk of heart disease.  Let me try to explain.

If you GOOGLE psoriasis and heart disease, you will find a surfeit of hits claiming some kind of connection between the two conditions. However, if you GOOGLE any two items on any subject, you are likely to hit upon some ‘connection’.   I just randomly GOOGLED guacamole and cancer and sure enough, there is a 'connection'!  Presumably, the dermatologist accepted the psoriasis-cardiac connection to be one of causality, meaning that psoriais can cause heart disease.  Extrapolating beyond this FAKE NEWS, he assumed that treating the psoriasis would mitigate the risk of an adverse cardiac event.   It is exactly this false reasoning that so often gets patients into trouble.  The logic of the intervention seems sound, but it is entirely specious.

The facts are here that there is no proof that psoriasis causes heart disease.  Clearly then, it makes no sense to treat the skin condition hoping to prevent a complication for which there is no proof that psoriasis causes.  Psoriasis may be associated with or linked to heart disease, which understandably suggests to an ordinary patient that there is a strong connection where Condition A causes Condition B.  I address this fallacy several times each week when I am asked if heartburn medications cause hip fractures or dementia.  They are associated with these complications in a statistical sense, but have not been shown to cause the complications.

Say I publish a study showing that tall individuals are associated with high blood pressure.  This does not mean that height is responsible or that we should hope that our children remain short.

Do you think that this blog is associated with astute and discerning readers?   If so, can I write next week that reading the Whistleblower blog is powerful brain food?


  1. Interesting and Factual post. Thank you. Too often, and especially if the patient suffers with chronic illness, too many cooks in the kitchen spoil the broth. And with too many 'opinions' not based on fact ~ everyone concerned suffers. Conversely, often times, too many facts are bypassed and ignored because they cannot (For whatever reason) be seen under a microscope or seen (Or was overlooked) on an MRI or CT scan. Sometimes treatment is not based on factual or known/proven scientific evidence, but opinionated, maybe exhausted, doctors provide the patient with a specific treatment because they googled it? ...if I'm making any sense to you?

  2. I love the example of guacamole and cancer. I see this "associated with" nonsense multiple times per weeks in various "medical" news feeds. You can find a chart of such associations at A couple of my favorites:

    Total revenue generated by arcades is associated with computer science doctorates awarded in the US.


    Number of sociology doctorates awarded in US is associated with deaths caused by anticoagulants.

  3. @Joseph - Excellent comments! So much absurdity to sort through to try and reach the truth.