K - 4 Scenario Prognosis.ppt

7/28/2019 K - 4 Scenario Prognosis.ppt

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Scenario:

You see a 70 year old man in an outpatientclinical 3 months after he has been dischargedfrom your service with a cerebral infarctionstroke. He is in sinus rhythm, has mild residual

left-sided weakness but is otherwise well. Hisonly medication is aspirin and he has noallergies. He recently saw an article on the BMJwebsite describing the risk of seizure after acerebral infarction and is concerned that this willhappen to him.

Please try to answer the question as best as youcan!


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2

Task

Read it and decide:

Whether it answers your question.

If so, what that answer is.

What you will tell the patient

EBM WAYVALIDITY

IMPORTANCE

APPLICABILITY


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3

EBM Process

Patient

Encounter

Formulating the

Clinical Question

Searching the

Evidence

Appraising the

Evidence

Diagnosis

Therapy

PrognosisEtiology

Patient

Intervention

Comparison

Outcome

Hierarchy of evidence

Pre appraised resources

Drawing conclusion

That impact on practice

DOE

POE

(Lang, 2000)


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4

PICO

P I C O


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5

PICO

P I C OPatients with

a history of

cerebralinfarct stroke

Risk of

seizure

within 5years

Keyword: stroke, seizure

Formulating questions:

IN patients with a history of cerebral infarct stroke, what is the risk of

seizure within 5 years?


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Epileptic seizures after a first

stroke: the Oxford shire

community stroke project

John Burn et all, BMJ 1997;3715: 1582-

Example : an article of prognostic test, entitle :


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Background: Cerebrovasculer disease is an important cause of

epilepsy, particularly in elderly people. When seizures complicate a clinical stroke they have a

devastating effect on morale and further impair an

already compromised quality of life.

Precise estimates of the risk of developing epilepsywould be helpful not only to patients but also to those

who give advice on returning to work or driving.

Objectives: To describe the immediate and long term risk of epileptic

seizures after a first ever stroke


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Study Design:

Cohort study following up stroke survivors for 2 to 6.5

years; comparison with age specific incidence rates of

epileptic seizures in the general population.

Setting: Community based stroke register

Subjects: 675 patients with a first stroke, followed up for

a minimum of 2 years

Main outcome measures: occurrence of single and

recurrent seizures


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Table 3 Cumulative actuarial risks (95% confidence intervals) of experiencing a

seizure after stroke by type of first stroke (19 patients with a history of prestroke

seizures were excluded)

Time

after

stroke

Cerebral

infarction

Primary

intracerebral

haemorrhage

Subarachnoid

haemorrhageTotal

1 year 4.2 (2.2 to 6.2) 19.9 (1.5 to 38.3) 22.0 (2.6 to 41.8) 5.7 (3.5 to 7.9)

2 years 6.7 (4.1 to 9.3) 19.9 (1.5 to 38.3) 27.8 (5.3 to 50.7) 8.2 (5.4 to 11.0)

3 years

7.4 (4.0 to

10.8) 26.1 (2.2 to 50.0) 34.3 (8.0 to 62.0) 9.5 (5.8 to 13.2)

4 years

8.6 (4.5 to

12.7) 26.1 (1.3 to 50.9) 34.3 (2.0 to 68.1) 10.5 (6.0 to 15.0)

5 years

9.7 (3.7 to

15.7) 26.1 (0 to 54.8) 34.3 (0 to 100) 11.5 (4.8 to 18.2)


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Was a defined, representative sample

of patients assembled at a common

(usually early) point in the course of

their disease?

Yes - from a common point but unsure

how GPs decided which stroke

patients should be admitted to hospital

Was patient follow-up sufficiently long

and complete?

Yes-minimum of 2 years and up to 6.5

years

Were objective outcome criteria

applied in a "blind" fashion?

Patients were asked at follow-up if

they had a seizure and were then

assessed by a study neurologist

(unsure if neurologist was blinded)

If subgroups with different prognoses

are identified, was there adjustmentfor important prognostic factors?

looked at different stroke types,

previous history of stroke

Was there validation in an

independent group ("test-set") of

patients?

NO (there was no pre study intention)

Are the result valid?


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Are the valid results of the prognosis study

important?

How likely are the outcomes overtime?

4.2% over one year

How precise are the prognostic

estimates?

95% confidence interval

2.63 to 5.77

Calculation:N = 545

P = 4.2 %

SE = 0.042 x (1-0.042)

545

= 0.008

= 0.8 %

95% CI = 4.2% (1.96 x 0.8%)

= 4.2%

1.57%= 2.63 to 5.77


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Can you apply this valid, important evidence about

prognosis in caring for your patient?

Were the study patients similar to

your own?

YES

Will this evidence make a clinically

important impact on your conclusions

about what to offer or tell your patient?

YES

Documents

K - 4 Scenario Prognosis.ppt