Evidence-Based Pediatrics for the Real World:

Reading, Reflecting, and ‘Rithmetic

Bud Wiedermann, MD, MAProfessor of Pediatrics, George

Washington UniversityAttending in Infectious Diseases,

Children’s National Medical CenterWashington, DC

Faculty Disclosure

My spouse and I have not had any relevant financial relationships during the past 12 months.

Educational Need/Practice Gap

• The Problem– EBM = “empiricist quackery”?– Barriers of busy practice, volume of new

information

• The Solution– Demystify EBM– Relax, you don’t need to read

everything!

When you walk out of here, you will be able to….

• Restate clinical conundrums as answerable questions

• Effectively and efficiently find answers to clinical conundrums

• Relate p values, likelihood ratios, and number needed to treat to real-world, practical pediatric practice.

Reading

‘Rithmetic

Reflecting

Reading Has 2 Components

Reflection Has 3 Components

•In action•On action•For action

‘Rithmetic Has Too Many Components!

• Frequentists vs. Bayesians

• Number needed to treat

• Likelihood Ratios

Time for a Case

Caitlyn is a 22 month-old girl, previously healthy except for minor, self-limited viral illnesses who presents with a 36 hour history of fussiness, occasional tugging at her left ear, and fever to touch. Exam reveals a slightly fussy infant with a temperature of 38.7 C, left middle ear effusion, and a slightly bulging, erythematous TM.

Do You Have a Question?

•Background–Any recent textbook

–MD Consult–Up-to-Date–Etc.

•Foreground–PubMed–Up-to-Date?–Dynamed?–Google?

“If they can get you asking the wrong questions, they don't have to worry about answers.”

-Thomas Pynchon

Take a Shortcut!

PICO

Another Caveat About Reading the Literature

• Don’t forget to browse!– How do you know what you need to

know?– Curiosity kills cats, not physicians!

• Primary sources– NEJM, JAMA, BMJ– Pediatrics

• Pediatrics in Review

• AAP Grand Rounds

• Evidence-Based Child Health

If You Find a Good One, Ask Yourself ….

• Could Caitlyn have been included in the study?

• If not, is she close enough that can I still use some of the results?– If yes, read the Methods and Results

sections (not the abstract or conclusions)

– If no, put it aside for another time (or not)

Rx of AOM In Children < 2 yo

• Inclusion criteria– AOM Severity of Symptoms Score >3

(Pediatr Infect Dis J 2009;28:9-12)– Presence of middle ear effusion– Moderate or marked bulging of TM, or

slight bulging with either otalgia or marked erythema of membrane

• RCT – high dose amox/clav vs. placebo

NEJM 2011; 364:105-15

Clinical Failure Higher in Placebo Group (‘Rithmetic)

Visit Day

Antibiotic Placebo p NNT

4-5 4% 23% <0.001 5

10-12 16% 51% <0.001 3

NNT: What is it Good For?(Absolutely Nothing?)

• I, like most physicians, don’t do a good job of explaining risk to patients and families

• The second part of Reading– Read Your Patients– Understand Their Values

• NNT = 5 with the right side of your brain

J Gen Intern Med 2008; 23:2117-2124

Health Psychol 2009;28:21-216

BMJ 2003; 327:745-748.

Risk Characterization Theater

Rifkin and Bower (2007). The Illusion of Certainty. New York, Springer.

If You Can’t Draw….…. Foster Insight

Which of these works better for communicating single event probabilities?

You have a 30% chance of a side effect from this drug.

Three out of every 10 patients have a side effect from this drug.

BMJ 2003;327:741-744.

4/1000 women >40 yo who do not undergo breast cancer screening die of breast cancer, vs. 3/1000 of those who

do.

Mammography reduces breast cancer by 25%.

In every 1000 women who undergo screening one will be saved from dying of breast cancer.

To prevent one death from breast cancer, 1000 women need to undergo screening

for 10 years.

Accuracy of Pneumatic Otoscopy (More ‘Rithmetic)

• Sensitivity 87%• Specificity 89%• Is that good enough?

– If yes, what is it good for?– If no, why not?

• What do sensitivity and specificity mean to you?

Arch Dis Child 1992; 146:433-435

Playing the Horses (Odds)

• LR+ = sens/(1-spec)= 0.87/0.11 = 7.9

• LR- = (1-sens)/spec=0.11/0.89 = 0.12

Reflecting

• Our individual experiences are a form of evidence.

• Subject to errors– Pretest probability– Strength of evidence

BMJ 2002;324:729-732.

Availability

• We overestimate frequency of vivid or easily recalled events.

• This is why we love zebras!

Representativeness

• Judging how similar a case is to a prototype

• Usually overestimates probability

• … and its pal, Anchoring

…. And more

• Wrong decisions based on:– How detailed the description is

(Support Theory)– Order that the data are presented

(later data=more weight)– Tendency to overestimate

probability of serious but treatable diseases

Other ResourcesOtitis Media

• NEJM 2011;364:116-126.• Management of Acute Otitis Media:

Update. Evidence Report/Technology Assessment No. 198. RAND/AHRQ, November 2010. http://www.ahrq.gov/clinic/tp/otitisuptp.htm(Warning: 207 pages)

Other ResourcesEBM

• University of Alberta– http://www.ebm.med.ualberta.ca/

• University of Oxford– http://www.cebm.net/

• JAMA Users’ Guides– http://pubs.ama-assn.org/misc/usersguid

es.dtl

Questions?

bwiederm@cnmc.org