Evidence Based MedicineCritical Appraisal

高雄榮民總醫院臨床訓練中心 實證醫學組徐圭璋 kchsu@vghks.gov.tw

高雄榮總 實證醫學組

實證醫學五步驟 提出問題 (Question formulation) 搜尋證據 (Evidence search)

嚴格判讀 (Critical appraisal) 恰當運用 (Evidence application) 評估結果 (Outcome evaluation)

高雄榮總 實證醫學組

問題 住院醫師林玲玲對主治醫師的醫囑有所疑問，於是努力搜尋文獻， 終於找到幾篇論文，但是其中結論各有不同，而且也的文章感覺好像不太可信，又有的不太適用，因為沒有人教過她如何嚴謹地評讀論文，所以她實在不知道該怎麼辦。

高雄榮總 實證醫學組

答案？ 看是哪一本期刊？ 看屬哪一個國家？ 看從哪一個醫院？ 看自哪一個作者？ 還要看什麼？

高雄榮總 實證醫學組

嚴格判讀 (Critical appraisal)

信度 (reliability) 效度 (validity) 重要性 (importance) 實際運用之可能 (applicability)

高雄榮總 實證醫學組

Oxford Center Oxford Center for Evidence-based Medicine Levels of Evidence for Evidence-based Medicine Levels of Evidence (May 2001)(May 2001)

LevelLevel TherapyTherapy

11aa 系統性回顧 系統性回顧 Systematic review Systematic review (( 分析數個隨機臨床對照試分析數個隨機臨床對照試驗驗 , , 其結果均類似其結果均類似 ))

11bb 設計良好設計良好 , , 結果精確之隨機臨床對照試驗結果精確之隨機臨床對照試驗11cc All or noneAll or none

22aa 系統性回顧 系統性回顧 (( 分析數個世代研究分析數個世代研究 , , 其結果均類似其結果均類似 ))22bb 世代研究 世代研究 Cohort studyCohort study;; 設計粗糙之隨機臨床對照試驗設計粗糙之隨機臨床對照試驗22cc ““ Outcomes” Research; Ecological studiesOutcomes” Research; Ecological studies

33aa 系統性回顧 系統性回顧 (( 分析數個病例分析數個病例 -- 對照研究對照研究 , , 其結果均類似其結果均類似 ))33bb 病例 病例 - - 對照研究 對照研究 Case-control studyCase-control study

44 某家醫院的十年經驗某家醫院的十年經驗 ; ; 設計不良之世代研究 及病例 設計不良之世代研究 及病例 - - 對照研對照研究究

55 未經考證之專家個人意見未經考證之專家個人意見 , , 基礎研究基礎研究 , , 細胞實驗細胞實驗 , , 生理實驗生理實驗 , , 動物實驗…的結果動物實驗…的結果

http://www.cebm.net/index.aspx?o=1157

http://www.phru.nhs.uk/Pages/PHD/resources.htm

高雄榮總 實證醫學組

2. Exposure Gp

3. Comparison

5. Time

4.Outcomes+ -

1. Participants

GATE Frame: 5 PECOT components

GATE a general appraisal tool for epidemiologyhttp://www.health.auckland.ac.nz/comhealth/epiq/epiq.htm

10 questions to help you make sense of randomised controlled trials

The 10 questions are adapted from Guyatt GH, Sackett DL, and Cook DJ, Users’ guides to the medical literature. II. How to use an article about therapy or prevention. JAMA 1993; 270 (21): 2598-2601 and JAMA 1994; 271(1): 59-63

© Public Health Resource Unit, England (2006). All rights reserved.

高雄榮總 實證醫學組

A. Are the results of the study valid?Screening questions1. Did the study ask a clearly-focused

question? Consider if the question is “focused” in

terms of : the population the intervention the outcomes

高雄榮總 實證醫學組

2. Was this a randomised controlled trial (RCT)?

Consider: why this study was carried out as an RCT if this was the right research approach for the

question being asked

Is it worth continuing?

高雄榮總 實證醫學組

Detailed questions3. Were participants appropriately allocated to intervention

and control groups? Consider:

how participants were allocated to intervention and control groups. Was the process truly random?

whether the method of allocation was described. Stratification, blocked etc?

how the randomisation schedule was generated and how a participant was allocated to a study group

if the groups were well balanced. if there were differences reported that might have explained any

outcome(s) (confounding)

高雄榮總 實證醫學組

4. Were participants, staff and study personnel ‘blind’ to participants’ study group?

Consider: the fact that blinding is not always possible if every effort was made to achieve blinding if you think if matters in this study the fact that we are looking for ‘observer bias’

高雄榮總 實證醫學組

5. Were all of the participants who entered the trial accounted for at its conclusion?

Consider: if any intervention-group participants got a control-

group option or vice versa (cross-over?) if all participants were followed up in each study group

(was there loss-to-follow-up?) if all the participants’ outcomes were analysed by the

groups to which they were originally allocated (intention-to-treat analysis)

what additional information would you liked to have seen to make you feel better about this

高雄榮總 實證醫學組

6. Were the participants in all groups followed up and data collected in the same way?

Consider: if, for example, they were reviewed at the same

time intervals and if they received the same amount of attention from researchers and health workers. Any differences may introduce performance bias.

高雄榮總 實證醫學組

7. Did the study have enough participants to minimise the play of chance?

Consider: if there is a power calculation. This will

estimate how many participants are needed to be reasonably sure of finding something important (if it really exists and for a given level of uncertainty about the final result).

高雄榮總 實證醫學組

B. What are the results?

8. How are the results presented and what is the main result?

Consider: if, for example, the results are presented as a proportion

of people experiencing an outcome, such as risks, or as a measurement, such as mean or median differences, or as survival curves and hazards

how large this size of result is and how meaningful it is how you would sum up the bottom-line result of the

trial in one sentence

高雄榮總 實證醫學組

9. How precise are these results? Consider:

if the result is precise enough to make a decision

if a confidence interval were reported. Would your decision about whether or not to use this intervention be the same at the upper confidence limit as at the lower confidence limit?

if a p-value is reported where confidence intervals are unavailable

高雄榮總 實證醫學組

C. Will the results help locally?

10. Were all important outcomes considered so the results can be applied?

Consider whether: the people included in the trial could be

different from your population in ways that would produce different results

your local setting differs much from that of the trial

you can provide the same treatment in your setting

高雄榮總 實證醫學組

Consider outcomes from the point of view of the: individual policy maker and professionals family/carers wider community

Consider whether: any benefit reported outweighs any harm and/or cost. If this

information is not reported can it be filled from elsewhere? policy or practice should change as a result of the evidence

contained in this trial

高雄榮總 實證醫學組

Systematic Reviews

All relevant studies identified? Quality of studies assessed? Combination of studies reasonable?

高雄榮總 實證醫學組

10 questions to help you make sense of systematic reviews

高雄榮總 實證醫學組

A. Is the study valid?

Screening questions1. Did the study ask a clearly-focused

question? Consider if the question is “focused” in

terms of : the population studied the intervention given or exposure the outcomes considered

高雄榮總 實證醫學組

2. Did the review include the right type of study?

Consider: Address the review’s question Have an appropriate study design

Is it worth continuing?

高雄榮總 實證醫學組

Detailed questions3. Did the reviewers try to identify all relevant

studies? Consider:

which bibliographic databases were used if there was follow-up from reference lists if there was personal contact with experts if the reviewers searched for unpublished studies if the reviewers searched for non-English-language

studies

高雄榮總 實證醫學組

4. Did the reviewers assess the quality of the included studies?

Consider: if a clear, pre-determined strategy was used to

determine which studies were included. Look for:

- a scoring system

- more than one assessor

高雄榮總 實證醫學組

B. What are the results?

5. If the results of the studies have been combined, was it reasonable to do so?

Consider whether: the results of each study are clearly displayed the results were similar from study to study (look for tests of heterogeneity) the reasons for any variations in results are discussed

高雄榮總 實證醫學組

6. How are the results presented and what is the main result?

Consider: how the results are expressed (e.g. odds ratio,

relative risk, etc.) how large this size of result is and how

meaningful it is How you would sum up the bottom-line result

of the review in one sentence

高雄榮總 實證醫學組

7. How precise are these results? Consider:

if a confidence interval were reported. Would your decision about whether or not to use this intervention be the same at the upper confidence limit as at the lower confidence limit?

if a p-value is reported where confidence interval are unavailable

高雄榮總 實證醫學組

8. Can the results be applied to the local population?

Consider whether: the population sample covered by the review

could be different from your population in ways that would produce different results

your local setting differs much from that of the review

you can provide the same intervention in you setting

高雄榮總 實證醫學組

9. Were all important outcomes considered? Consider outcomes from the point of view

of the: Individual policy makers and professionals Family/carers Wider community

高雄榮總 實證醫學組

C. Will the results help locally?

10. Should policy or practice change as a result of the evidence contained in this review?

Consider: whether any benefit reported outweighs any

harm and/or cost. If this information is not reported can it be filled in from elsewhere?

高雄榮總 實證醫學組

Consider outcomes from the point of view of the: individual policy maker and professionals family/carers wider community

Consider whether: any benefit reported outweighs any harm and/or cost. If

this information is not reported can it be filled from elsewhere?

policy or practice should change as a result of the evidence contained in this trial

高雄榮總 實證醫學組

Qualitative Research

Research design appropriate? Recruitment strategy appropriate? Data collected justified? Researcher-participants relationship

considered? Ethical issues considered? Data analysis rigorous?

高雄榮總 實證醫學組

Cohort Study

Cohort recruitment acceptable? Exposure accurately measured? Outcome accurately measured? All important confounding factors

identified and considered in design and analysis?

高雄榮總 實證醫學組

Case Control Study

Cases recruitment acceptable? Controls selection acceptable? Exposure accurately measured? Confounding factors identified and

considered in design and analysis?

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Diagnostic Test Study

All participants get the diagnostic test and the standard reference?

Results of the test of interest influenced by the results of the reference standard?

Disease status of the tested population clearly described?

Methods for the test described in detail?

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Economic Evaluations

All resources and health outcomes identified, measured accurately and valued credibly?

Consequences for different times adjusted? Incremental analysis of the consequences

and cost of alternatives performed? Sensitivity analysis adequate?

高雄榮總 實證醫學組

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