Absolutely!
Monday, June 29, 2009
Not many things in this world are absolute.This phrase tends to resonate increasingly as I progress further through medical training; I find myself more and more using terms such as likely, unlikely, often, rarely, common and usual.
A professor, in the first few weeks of Med, lecturing our class said "Medicine is about the odds, the chances. If you know the odds, if you know what's likely, what's common, most of the time, you'll be right."
The Prof went on to discuss Bayes' Theorem, Pre- and Post- test likelihood and associated matter. In retrospect, that lecture, given to half a class of exhausted MBBSI students, at 3pm on a Friday all quite overwhelmed with knowledge, was a washout, only because, unlike the Hotel California, we were not "programmed to receive."
Deeper into the Rabbit Hole, it becomes apparent every day the importance of understanding Bayesian theory at a deeper level is essential to Good Clinical Practice, as is an acknowledgment that nothing is absolute. Indeed, we are taught the value of data analysis, and develop the skills to establish what is likely, or unlikely.
Today I attended a lecture about 'Troponinitis', that is, the differential diagnoses for elevated TnI. After the lecture, Lt TriN offered a 'three line' summary, thus;
- Troponins are highly sensitive for cardiac muscle damage.
- Troponins, whilst specific for cardiac muscle damage, do not specify a cause of damage.
- Always consider the pre- and post- test probability of a range of diagnoses.
An important lesson here is that Point 3 can only be satisfied with a knowledge the causes of elevated Troponin. For a good list, check out the paper by Korff et al, mentioned below.
As I've said, few things are absolute. It's a brave physician who'll respond to a clinical question with a jovial Absolutely! Sure, some diagnoses reveal themselves incontrovertibly, but not all. For the rest, the physician might diagnose an disease, or recommend a specific treatment, but remember, they're playing the odds. They have a list in their head (or on paper) of Differential Diagnoses, and one or two is most likely. Perhaps, in the words of Bergson;
Reference: Korff S, Katus H A, and Giannitsis E; Differential diagnosis of elevated troponins; Heart 92: 987-993.
As I've said, few things are absolute. It's a brave physician who'll respond to a clinical question with a jovial Absolutely! Sure, some diagnoses reveal themselves incontrovertibly, but not all. For the rest, the physician might diagnose an disease, or recommend a specific treatment, but remember, they're playing the odds. They have a list in their head (or on paper) of Differential Diagnoses, and one or two is most likely. Perhaps, in the words of Bergson;
An absolute can only be given in an intuition, while all the rest has to do with analysis.
Reference: Korff S, Katus H A, and Giannitsis E; Differential diagnosis of elevated troponins; Heart 92: 987-993.
