Diagnosis by meds
May 2, 2010 6:01 AM   Subscribe

Is there a general term for a medical diagnosis "you have disease X" mainly because you responded to treatment T?

I associate this mostly with mental issues where science has not yet fingered a cause; no physical damage, no bacterium, no antibody indicators, no genetic correlation. But hey, she improved markedly after taking Zoloft, ergo, she must have clinical depression.
posted by gregoreo to Science & Nature (17 answers total) 1 user marked this as a favorite
I don't know of a term for this, but it's not just mental health - if someone has a high probability of having asthma you give them an inhaler (beta-2 agonist), and if they respond to that they have asthma.
posted by Coobeastie at 6:16 AM on May 2, 2010

I don't think it's an actual, you know, term, but it's an empirical approach?
posted by gaspode at 6:59 AM on May 2, 2010 [2 favorites]

I don't know if there's a term either, but my doctor diagnosed my migraines that way: Triptans made the headache go away, so it's a migraine.
posted by amf at 7:22 AM on May 2, 2010

In fact, you don't (in general) know that Patient has X because T cured Patient. What you know is T cures X and T cured Patient. That doesn't necessarily imply that Patient had X; only that whatever Patient had was (also) cured by T. To know that Patient had X in this case, you'd have to also know that T cures only X. (But since the point was to cure patient, in the short run, the difference doesn't matter -- "matter", in this case, meaning that knowing the difference wouldn't change any decisions).
posted by TruncatedTiller at 8:02 AM on May 2, 2010

In distinguishing between bipolar disorder and schizophrenia, if it responds positively to lithium, it's bipolar disorder. That is called differential diagnosis.

At least that's what I was taught in college ten years ago.
posted by fiercecupcake at 8:17 AM on May 2, 2010

Sort of close is diagnosis of exclusion.
posted by dogmom at 9:37 AM on May 2, 2010

Differential diagnosis just means that there is something that differentiates between the two- it doesn't necessarily have to be meds. What you're describing is a diagnosis of exclusion. The problem is likely that they have to put some sort of diagnosis on your chart to get you insurance coverage, so depression was their best guess in that scenario. It doesn't mean that they actually believe the person has depression.
posted by emilyd22222 at 9:50 AM on May 2, 2010

I don't think it has an official name, but I've always thought of it as the House approach. He tends to order treatment to see if the patient will respond, without knowing what's actually wrong with the patient, in about 3/4 of the episodes.
posted by vytae at 10:29 AM on May 2, 2010

Since we learn so much from television medical shows, I'm going to chime in with "differential diagnosis."
posted by radioamy at 11:03 AM on May 2, 2010

"Empirical diagnosis" is the droid term you're looking for.
posted by neuron at 1:09 PM on May 2, 2010

Once you see a patient you sometimes establish a diagnosis on the basis of signs, symptoms and general physical examination. This is often known as a preliminary diagnosis or a working diagnosis. It can also be called an empircal diagnosis if you do not have a 'smoking gun' (e.g. a positive culture of a bug that might be causing an infection). At this stage you should also form a list of differential diagnosis which are all possible diagnoses if your working diagnosis turns out to be incorrect after further investigation.

I dont think there is an exact name of process you have mentioned and it is a pratice which is discouraged because of associated risks and in many cases where the drug affects the symptoms rather that the underlying cause then it may not even work. However, there are similar practices such as a 'provocative test' where a small dose of muscle relaxant is given to someone who may be suspected of having myasthinia gravis. If correct, the patient suffers from profound muscle weakness.
posted by london302 at 1:35 PM on May 2, 2010

Empirical. When my previous doc would try a treatment (low hazard) to see if it worked and resolved the diagnosis, he called it the empirical approach.
posted by theora55 at 3:28 PM on May 2, 2010

A list of differential diagnoses is more often refined by further testing, not trial and error treatment. Every patient that walks in the office gets a differential diagnosis. You have a cough? I'm thinking asthma, pneumonia, COPD, Upper respiratory tract infection, etc. That's a differential diagnosis.
posted by alygator at 6:09 PM on May 2, 2010

Empirical: Based on experience and observation, rather than systematic logic. Experienced physicians often use empirical reasoning to make diagnoses, based on having seen many cases over the years. Less-experienced physicians are more likely to use diagnostic guides and manuals. In practice, both approaches (if properly applied) will usually come up with the same diagnosis.
posted by london302 at 2:29 AM on May 3, 2010

Theora55, is partially right. His doctor arrived at an empirical diagnosis but that was the bit before he gave him a medicine. Once he took the medicine and got better his empirical diagnosis was confirmed. So the first bit was empirical diagnosis but I think we are struggling to find the name of the second bit.
posted by london302 at 2:32 AM on May 3, 2010

London302, that's exactly what I was seeking, thanks. "Empirical diagnosis" as suggested here and in what I've read considers raw symptoms plus easy correlations such as ancestral history. I was focusing though on the next stage of diagnosis that considers response to a treatment. The terms "provocative tests" and "differential diagnoses" sound close to what I had in mind, but suggest a proper experiment.

I am particularly concerned for a couple of acquaintances for whom a "diagnosis by meds" gave happy results on the first shot. No controls. No differential tests. Hmf, placebo effect might account for improvements! So could coincidence. I hoped there might be a standard cautionary qualification for a "diagnosis by meds" or by other treatment.
posted by gregoreo at 1:11 PM on May 3, 2010

Gregoreo, I am glad you found at least a part of what you were looking for. If it is any consolation "diagnosis by meds" is actively discouraged in most civilised countries but it is hard to police this in the 'family practice' setting.

This does not apply to the examples you have shared above but there are cases when the choice is actually between a relatively low cost and safe medicine or a battrey of unpleasant and expensive tests purely in order to demonstrate the disease (not the best example but I would take a few days of Losec than to get a tube shoved into my stomach to establish a diagnosis of GERD).
posted by london302 at 12:00 PM on May 4, 2010

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