Transcript Therapies

Evidence Based Medicine
Critical Appraisal
高雄榮民總醫院
臨床訓練中心 實證醫學組
徐圭璋 [email protected]
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
for Evidence-based Medicine Levels of Evidence
(May 2001)
Level
Therapy
1a
系統性回顧 Systematic review (分析數個隨機臨床對照試驗,
其結果均類似)
1b
設計良好, 結果精確之隨機臨床對照試驗
1c
All or none
2a
系統性回顧 (分析數個世代研究, 其結果均類似)
2b
世代研究 Cohort study;設計粗糙之隨機臨床對照試驗
2c
“Outcomes” Research; Ecological studies
3a
系統性回顧 (分析數個病例-對照研究, 其結果均類似)
3b
病例 - 對照研究 Case-control study
4
某家醫院的十年經驗; 設計不良之世代研究 及病例 - 對照研究
5
未經考證之專家個人意見, 基礎研究, 細胞實驗, 生理實驗, 動
物實驗…的結果
高雄榮總 實證醫學組
http://www.cebm.net/index.aspx?o=1157
http://www.phru.nhs.uk/Pages/PHD/resources.htm
GATE Frame: 5 PECOT components
4.Outcomes
+
1. Participants
-
2. Exposure Gp
3. Comparison
5. Time
GATE a general appraisal tool for epidemiology
http://www.health.auckland.ac.nz/comhealth/epiq/epiq.htm
高雄榮總 實證醫學組
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.
A. Are the results of the study
valid?
Screening questions
1. 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 questions
3. 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 controlgroup 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 questions
1. 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 questions
3. 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?
高雄榮總 實證醫學組
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?
高雄榮總 實證醫學組
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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