Clinical Scenario

Step 1: Ask an answerable clinical question--P. I. C. O.

Patient / Problem : Intervention / Exposure:

Comparison: Outcome:

PICOQuestion:

• Patient / Problem : • Intervention / Exposure: • Comparison: • Outcome:

Step 2: Effective searches for the best Evidence

搜尋策略的設計表 SEARCH STRATEGY DESIGN TABLE

　　主要詞彙 Primary Term

同義字 Synonym 1 同義字 Synonym 2

P OR OR AND

I OR OR AND

C OR OR AND

O OR OR AND

實際搜尋 ACTUAL SEARCHES

Cochrane 搜尋　　　　　　　　　　　 文獻數　　　　　　　　　　　　

PubMed 搜尋 文獻數　　　　　　　　　　　　

Step 3: Critically appraise that evidence for its validity and

importance

A. 此一有害原因的研究的結果能令人信服嗎 ?Are the results of this harm study

valid?

1. 實驗組與對照組除了對治療的曝露有別外 , 其他方面是否皆相似 ?Were there clearly defined groups of patients, similar in

all important ways other than exposure to the treatment or other cause?

本文獻： □ Yes □No □Unclear評論 Comment ：

2. 實驗組與對照組的評量方法是否相同 ? Were treatments/ exposures and clinical outcomes measured in the same ways in both groups (was the assessment of outcomes either

objective or blinded to exposure)?

本文獻： □ Yes □No □Unclear評論 Comment ：

3. 追蹤夠久夠完整嗎 ? Was the follows-up of study patients complete

and long enough?本文獻： □ Yes □No □Unclear評論 Comment ：

4. 因果關係夠明確嗎 ? Do the results satisfy some “diagnostic tests for

causation”?a) 曝露在發作之前嗎 ? Is it clear that the exposure preceded

the onset of the outcome?b) 與劑量具有相關斜度嗎 ? Is there a dose-response gradient?c) 從”去曝露 -- 再曝露”的研究上有正面證據嗎 ? Is there positive evidence from a

“dechallenge-rechallenge” study?d) 因果關係具有生物學上的意義嗎 ? Does the association make biological

sense (in terms of pathophysiology, etc.)?

 

本文獻： □ Yes □No □Unclear評論 Comment ：

B. 此一有害原因的研究的結果夠重要嗎 ? Are the valid results from this harm

study important?

5. What is the magnitude of the association between the exposure and outcome?

• In a randomized trial or cohort study: relative risk (RR) = [a/(a + b)]/[c/(c + d)]. NNH = 1/ [a/(a + b) − c/(c + d)] = 1 /│1-RR│x PEER • In a case-control study: relative odds (OR) = ad/bc (RR can’t be calculated because the investigator selects the people with the outcomes (rather than those with the exposure) and we can’t calculate the “incidence”) • if OR <1: NNH = if OR >1: NNH = where PEER is the patient expected event rate (the adverse event rate among individuals who are not exposed to the putative cause).

6. What is the precision of the estimate of the association between the exposure and

the outcome? (CI: confidence interval)• We might not want to label an OR from

a case–control study as impressive unless it is >4 for minor adverse events, and we’d set this value at progressively lower levels as the severity of the adverse event increases.

• There is less potential bias in cohort studies and therefore we might regard a relative risk of >3 as convincing for more severe adverse events)

C. 此一令人信服且結果重要的研究的會改變我們對病患的治療嗎 ? Should these valid, potentially

important results change the treatment of our patient?

7. 我們的病患與研究中收錄的病患有明顯不同 ? Is our patient so different from those included in

the study that its results don’t apply?本文獻： □ Yes □No □Unclear評論 Comment ：

8. 此項治療對我們的病患潛在的危害為何 ? 潛在的益處的為何 ?

What is our patient’s risk of the adverse event? What is our patient’s potential benefit from the therapy?

本文獻： □ Yes □No □Unclear評論 Comment ：

9. 病人對治療的喜惡與期望為何 ?What are our patient’s preferences, condemns and

expectations from this treatment?

10. 有其他治療方法嗎 ? What alternative treatments are available?