1. Clinical Reasoning Skills STEPP Course ST1;2014 Peter Macfarlane

2. intellectual process; leading to a ‘working diagnosis’ & management- discussion some puzzles

3. sound medical principle;.. ‘diagnosis precedes treatment’.....right diagnosis...right treatment...no diagnosis/wrong diagnosis;..! APLS/emergency approach vs classical history/examination/formulation/?Ix/progress

4. Hx /Ex...the medical student approach, exhaustive data..but no idea what it means!) then; hypothesis/analytical/deductive approach mental shortcuts (heuristics) then iterative diagnosis approach...’I know what’s going on here;...series of closed questions to check this....

5. pattern recognition; ‘ducks’ quick: like recognizing a friend slower: patterns/clusters Stepwise ‘rule outs’; used to exclude ‘don’t miss’ diagnoses probabilistic reasoning; ‘zebras’ ‘informal’; e.g.-age -duration illness -’red flags’

6. ‘formal’ probabilistic reasoning the Bayesian approach Sensitivity Specificity Positive predictive value Negative predictive value know the 2X2 table

8. SpP IN : SnN OUT :

9. SpP IN : test(or Sx/Sg) with high Specificity performance, Positive result is a good ‘rule IN’ SnN OUT : test (or Sx/Sg) with high Sensitivity performance, Negative result is a good ‘rule OUT’ #

10. investigations...beware of pitfalls. -’paralysis by analysis’ - treat the child not the numbers -always question whether you know what the test result means (values,pos,neg), before you start. -’sometimes the best thing to do for the patient (child) is to spare them the misery of a useless intervention ’

11. keep it simple; Occam’s Razor (1 diagnosis), but learn how to juggle complex multiple problems.. Test of treatment Test of time, beware pressure to act.... ‘don’t just do something, stand there!’ if no diagnosis- keep an open mind, think aloud and get advice (foster ethos of 2 nd opinion) abandon the ‘diagnosis’ when things don’t go to plan When the diagnosis is ‘obvious’ ; avoid premature closure; always ask ‘what else could this be?’.......... think beyond the obvious; avoid the cognitive trap recognize your own biases #

12. Test of Treatment ‘first do no harm’, Test of Treatment rarely leads to robust diagnosis; nearly always better to use ‘test of time’ (except in critical illness). lots of confounders....

13. ‘treatment’ trial apparent effect TPFP uncertainno apparent effect or worse TNFN ?

14. trial of treatment confounders False positives placebo spontaneous improvement/remission natural fluctuation in disease process False negatives side effects wrong drug/dose/duration natural fluctuation in disease process drug resistant disease variant

15. ways to improve test of treatment establish the baseline agree the end point objective measurement if possible; if not reduce ‘subjectivity’ keep everything else the same careful thought about drug selection, dose route, duration Use the ‘3 step protocol’; multiple trials of n=1 #

16. Questions?