at the bedside evidence based medicine stephen r. hayden, md department of emergency medicine ucsd...

At the Bedside

Evidence Based Medicine

Stephen R. Hayden, MDDepartment of Emergency

MedicineUCSD Medical Center, San

Diego

Teaching

The best teaching is taught by patients themselves 

Sir William Osler

EBM at the Bedside

At the bedside, use history and physical exam elements for teaching EBM

Take an item of history or physical exam and think of it as a “diagnostic test”

Presence or absence of a clinical finding changes the probability of disease

EBM at the Bedside Opportunity to discuss many EBM concepts Test properties of clinical exam parameters

Precision (kappa) of clinical examination Accuracy (likelihood ratios, PPV, NPV)

Moving from pretest to post test probability Quantifies the utility of diagnostic tests

Example

How often do you see a case of chest pain in the emergency department?

How precise are clinical findings in chest pain patients?

Interrater reliability (Kappa)

Precision of Clinical Features

Clinical Feature Kappa

Chest pain radiates to L arm

0.89

Pain in substernal location 0.74

Pain described as pressure 0.57

Pain described as sharp 0.30

Pain with movement 0.27

Hickan DH, et al. J Chronic Dis. 1985;38:91-100

Precision of Physical Findings

Physical signs of heart failure in MI

Gadsboll N. European Heart J. 1989;10:1017-1028

Clinical Feature Kappa

Dyspnea 0.62 - 0.75

Neck vein distension 0.31 – 0.51

Dependent edema 0.27 – 0.64

Third heart sound 0.14 – 0.37

Rales 0.12 – 0.31

How accurate are clinical findings in chest pain patients?

Accuracy of Clinical Features

Clinical Feature Positive LR (CI)

Radiation to left armRadiation to right shoulderRadiation to both L and R arm

2.3 (1.7-3.1)2.9 (1.4-6.0)7.1 (3.6-14.2)

Third heart sound 3.2 (1.6-6.5)

Hypotension 3.1(1.8-5.2)

Diaphoresis 2.0 (1.9-2.2)

Nausea or vomiting 1.9 (1.7-2.3)

Past history of MI 1.5-3.0Panju AA, et al. JAMA. 1998;280:1256-1263

Accuracy of Clinical Features

Clinical Feature Negative LR (CI)

Pleuritic chest pain 0.2 (0.2-0.3)

Chest pain sharp or stabbing

0.3 (0.2-0.5)

Positional chest pain 0.3 (0.2-0.4)

Chest pain reproduced by palpation

0.2 - 0.4

Panju AA, et al. JAMA. 1998;280:1256-1263

Can this really be done in a busy ED?

EBM at the Bedside

Don’t attempt to answer all possible questions for every patient

Pick one clinical finding relevant to a individual patient

Choose cases you see frequently in ED

EBM at the Bedside

Requires advance preparation Have Kappa’s, likelihood ratios

with you on index cards, palm pilot, workstation

Need rapid access to high quality evidence

Medcalc3000.com

http://pbrain.hypermart.net/medrules.html

(Freeware)

BestBets.org

Analgesia and Abdominal Pain

http://nhscrd.york.ac.uk/darehp.htm

ACP Journal Club

How do you find articles relating to the precision and accuracy of the H&P?

Search Tips

Add specific terms to search strategy

“Physical examination” “Medical history taking” “Sensitivity” or “specificity” “Clinical assessment” “Observer variation” “Interrater reliability”

MI Reference

Panju AA, et al. Is this patient having a myocardial infarction? JAMA. 1998;280:1256-1263

Summary

Reviewed how to take EBM to the bedside Identifying elements of the H&P as “tests” Describing precision and accuracy of H&P Preparing in advance / bedside tools Rapid access to pre-appraised resources

“I desire no other epitaph than the statement that I taught medical

students in the wards, as I regard this by far the most useful and

important work I have been called upon to do.” Sir William Osler

Farewell Address, 1905