医学研究设计简介

56 100
b+d a+b+ c+d =1.36
104 96 200 RR=(60/100) / (44/100)
RR=(a/(a+b)) / (c/(c+d))
2013/7/27
Department of Medical Research, Chimei Medical Center
13
RR(Relative Risk, Rate Ratio)

Cases:

一或多個醫院中就醫的所有病例 整個社區或團體族群的所有病例 整個社區 醫院其他病人 病人親屬 病人的同學、同事、鄰居
Department of Medical Research, Chimei Medical Center

Control:



2013/7/27
16
Case-Control Study-Advantage
obesity
Mark Elwood. Critical Appraisal of Epidemiological Studies and Clinical Trails. 2nd Edition.
2013/7/27 Department of Medical Research, Chimei Medical Center
smoking
Mark Elwood. Critical Appraisal of Epidemiological Studies and Clinical Trails. 2nd Edition.
2013/7/27 Department of Medical Research, Chimei Medical Center
2013/7/27
18
Case-Control Study-disadvantage



Exposure status需要靠過去的紀錄或回 憶 bias：recall bias, selection bias 不容易研究多重疾病事件，且疾病事件 的時序性不易建立 Control group不好選 Confounding effect
Department of Medical Research, Chimei Medical Center
2013/7/27
11
Cohort Study - disadvantage


前瞻性研究，費時、昂貴 不適於研究稀有或潛伏期夠長的疾病 若是retrospective cohort study，需要有 過去exposure status的紀錄 Loss of follow up可能影響效度
Department of Medical Research, Chimei Medical Center
2013/7/27
19
OR (Odds Ratio)
MI Smk smk a c a+c odds1=a/b odds2=c/d MI b d a+b c+d MI MI
smk
smk
30
15 45
Department of Medical Research, Chimei Medical Center
26
RCT
Cross-Over Design
Treatment A Treatment B
Outcome 1
Recruited samples
Randomization
Treatment B
Now! exposed gr. diseased gr. Recruited samples
Non-exposed gr.
2013/7/27
Nondiseased gr.
Department of Medical Research, Chimei Medical Center
15
Selection of study subject
醫學研究設計簡介
醫學研究部 研究暨統計諮詢室 呂瑾立
科學的思考方式

演譯法 歸納法 猜測與否證- Karl Popper
我們雖然無法證明某個假說為真，卻可以經由不斷地 否證，除去錯誤的假說，如此留下來的假說比較可能 趨近為真。
2013/7/27
Department of Medical Research, Chimei Medical Center
2013/7/27
9
Cohort study
(concurrent cohort study)
Now!
(retrospective cohort study)
Now!
exposed gr. Recruited samples
diseased gr.
Non-exposed gr.
2013/7/27
Nondiseased gr.
OR (Odds Ratio)

0<=OR<∞ 0<=OR<1, protection factor OR=1, no effect OR>1, risk factor
2013/7/27
Department of Medical Research, Chimei Medical Center



一致性 不能用機會解釋 沒有其他干擾因素 合理性 相關強度、相關的特定程度、劑量效應關係、 生物學上的贊同性
Department of Medical Research, Chimei Medical Center

參考條件—

2013/7/27
5
Confounding effect
exposure outcome
200 230
350 365 550 595
b+d a+b+ c+d
OR=30× 350 / 200× 15 =3.5
Department of Medical Research, Chimei Medical Center
Odds Ratio=odds1/odds2=ad/bc
2013/7/27
20
7
The association between O.C. use and MI - underestimation
Oral contraceptive use
—
O.C. users are less obese than non-users
Myocardial infarction
+ Obesity increases the risk of myocardial infarction
association
association
Confounding factor
Mark Elwood. Critical Appraisal of Epidemiological Studies and Clinical Trails. 2nd Edition.
2013/7/27 Department of Medical Research, Chimei Medical Center

簡單便宜 容易推廣到參考族群
2013/7/27
Department of Medical Research, Chimei Medical Center
23
Cross-Sectional Studydisadvantage


頂多建立相關(association),無法推論因 果關係（causal-effect relationship） 注意 selective survival bias Confounding effect
10
Department of Medical Research, Chimei Medical Center
Cohort study - advantages




適於研究rare exposure 可直接觀察exposed 和non-exposed group的疾病發生率 可觀察多重健康事件事件發生的時序性、 先後次序 Eligibility criteria和outcome assessments可以標準化 比RCT的行政作業簡單、便宜
2013/7/27
Department of Medical Research, Chimei Medical Center
12
RR(Relative Risk, Rate Ratio)
MI O.C. O.C. a c a+c MI b d a+b c+d MI MI
O.C.
O.C.
60
44
40 100
21
Cross-sectional study
exposed gr. diseased gr.
Non-exposed gr.
Nondiseased gr.
2013/7/27
Department of Medical Research, Chimei Medical Center
22
Cross-Sectional StudyAdvantage

較適用於研究稀有或潛伏期長的疾病 較快得到結果，較便宜 保留探討多種致病因子的可能性
2013/7/27
Department of Medical Research, Chimei Medical Center
17
Matching- 控制干擾因子的一種方法

Frequency matching
8
常見的研究設計法

觀察性研究法



Case series study 世代研究法(cohort study) 病例對照研究(case control study) 斷代研究法(cross-sectional study)

試驗性研究法


社區試驗法 臨床試驗法
Department of Medical Research, Chimei Medical Center
吸煙者之肺癌死亡率為 不吸煙者之10倍
研究設計 測量的台灣男 子中，吸煙者 與不吸煙者的 肺癌死亡率
流行病學方法論，p 11。第三版。王榮德著 2013/7/27 Department of Medical Research, Chimei Medical Center
4
因果關係的判定標準

必要條件—時序性 次要條件—

0<=RR<∞ 0<=RR<1, protection 源自文库actor RR=1, no effect RR>1, risk factor
2013/7/27
Department of Medical Research, Chimei Medical Center
14
Case-control study
2013/7/27
Department of Medical Research, Chimei Medical Center
24
Clinical Trial
RCT(Randomized controlled trial)

Parallel design Cross-Over design
2013/7/27

要有整個族群的資料 找符合條件裡頭最接近病例的人 Cases是陸續收案時

Individual matching


先考慮age, gender, race，避免 overmatching
Department of Medical Research, Chimei Medical Center
6
The association between O.C. use and MI - overestimation
Oral contraceptive use
+
O.C. users smoke more heavily than non users
Myocardial infarction
+ Smokers, irrespective of O.C. use, have a higher infarction than nonsmokers
2
提出假說 演繹 歸納
推論出小前提
估計或檢定分析結 果得到研究摘要
研究設計並 進行測量
流行病學方法論，p 11。第三版。王榮德著 2013/7/27 Department of Medical Research, Chimei Medical Center
3
吸煙導致肺癌 演繹 歸納
台灣的男子吸煙者 比不吸煙者易得肺 癌
Department of Medical Research, Chimei Medical Center
25
RCT
Parallel Design
Treatment A Recruited samples Outcome 1
Randomization
Treatment B
Outcome 2
2013/7/27