Measuring inconsistency in meta-analyses

1.     X², p<0.05 為異質性研究, p>0.05 為同質性研究

2.     I², 以%表示, I²=0 為同質性研究， I²>50%(0.5) 為異質性研究，不適合做統合分析；<0.25為輕度異質性研究，0.25-0.5為中度異質性研究。較被人所用。

3.     Tau² or τ² ， Tau² =0 為同質性研究(the fixed effect)，Tau² >0.1為異質性研究(random-effects meta-analysis for variance)

Case control study 評讀等級

依據 US Agency for Health Care Policy and Research Classification(AHCPR, 1992)

Case control study(病例對照分析)(又稱為retrospective study) - 被歸為 III 等級。
(等級依序為Ia, Ib, IIa, IIb, III, IV)


依據Oxford Centre for Evidence-based medicine Levels of Evidence(May, 2001)


Case control study(病例對照分析)(又稱為retrospective study) - 被歸為 IV等級。
(等級依序為Ia, Ib, Ic, IIa, IIb, IIc, IIIa, IIIb,  IV, V)

醫學文獻評讀、方法、等級介紹 and Jadad quality scoring

Jadad quality scoring

總分5分，大於等於3分為值得參考的文章。

Jadad 分數表

評估項目	分數	說明
1.是否隨機分派（randomized）	2	詳細說明如何進行隨機分派方式且正確
	1	提及採隨機分派，但未說明方式
	0	未採隨機方式如類實驗法
2.是否雙盲實驗（double- blind）	2	具體說明如何進行雙盲實驗，且被認為恰當
	1	提及採雙盲實驗，但未說明如何進行
	0	使用單盲或未採盲化
3.對失聯及退出樣本的追蹤	1	清楚說明個案退出及失聯原因
（withdrawals & drop-out）	0	未說明個案退出及失聯原因

資料來源：

Moher D, Jadad A. R., & Tugwell. P. ( 1996). Assessing the quality of randomized controlled trials. Current issues and future directions. International Journal Technology Assessment in Health Care. 12(2), 195-208.

Relative risk (相對事件發生率,相對危險比) and Relative odds(又稱為odds ratio)

	事件(event)發生	無事件發生	總和
E(實驗組)	1       a	b      19	20
C(控制組)	4       c	d      16	20
總和	5     a+c	b+d    35	40

Relative risk (相對事件發生率,相對危險比, risk ratio)，即實驗組的事件發生率與控制組事件發生率相比(對照比例)。

Relative odds(又稱為odds ratio)，即實驗組發生事件的勝算與控制組發生事件的勝算相比。

EER(experiment event rate, 實驗組的事件發生率)= a/a+b=1/1+19=0.05

CER(control event rate, 控制組事件發生率)= c /c+d=4/4+16=0.2

Experiment event odds(實驗組發生事件的勝算)= a/b=1/19=0.053

Control event odds(控制組發生事件的勝算)= c/d=4/16=0.25

RR(Relative risk, risk ratio)=EER/CER=0.05/0.2=1/4, 及實驗組發生事件的比率(或風險)是控制組的1/4或25%

當RR=1表示實驗組事件發生率與控制組相同，或表示實驗組危險發生率與控制組相同。當RR>1，表示實驗組事件發生率較控制組大，或表示實驗組危險發生率較控制組大。當RR<1，表示實驗組事件發生率較控制組小，或表示實驗組危險發生率較控制組小。同時還要看95%CI，若信賴區間的數值含1，表示兩組事件發生率或危險發生率有部分相同，若95%CI數值不含1且區間數值大於1，則表示實驗組事件發生率或危險發生率大於控制組。反之95%CI數值不含1且區間數值小於1，則表示實驗組事件發生率或危險發生率小於控制組。

Odds ratio(勝算比)= experiment event odds/ control event odds=( a/b)/( c/d)= ad/bc=(1*16)/(4*19)=0.21

當OR=1表示實驗組事件事件發生(或危險)勝算與控制組相同，或表示實驗組危險發生率與控制組相同。當OR>1，表示實驗組事件發生(或危險)勝算較控制組大，或表示實驗組危險勝算較控制組大。當OR<1，表示實驗組事件發生(或危險)勝算較控制組小。同時還要看95%CI，若信賴區間的數值含1，表示兩組事件事件發生(或危險)勝算有部分相同，若95%CI數值不含1且區間數值大於1，則表示實驗組事件事件發生(或危險)勝算大於控制組。反之95%CI數值不含1且區間數值小於1，則表示實驗組事件事件發生(或危險)勝算小於控制組。

RRR(Relative risk reduction) 相對危險度減少百分比=(CER-EER)/CER

※    要注意有可能RRR值一樣，但是CER和EER卻差異很大，因此不可單看RRR。

ARR(absolute risk reduction) 絕對危險度減少百分比= CER-EER>0

ARR的倒數則代表為NNT(number needed to treat, 治療多少病人數有一人獲益)，NNT愈小愈好。

ARI(absolute risk increase) 絕對危險度增加百分比= CER-EER<0

ARI的倒數則代表為NNH(number needed to harm, 治療多少病人數會造成一人傷害)，NNH愈大愈好。

	Example 1: risk reduction			Example 2: risk increase
	Experimental group (E)	Control group (C)	Total	(E)	(C)
Events (E)	EE = 15	CE = 100	115	EE = 75	CE = 100
Non-events (N)	EN = 135	CN = 150	285	EN = 75	CN = 150
Total subjects (S)	ES = EE + EN = 150	CS = CE + CN = 250	400	ES = 150	CS = 250
Event rate (ER)	EER = EE / ES = 0.1, or 10%	CER = CE / CS = 0.4, or 40%	N/A	EER = 0.5 (50%)	CER = 0.4 (40%)

Equation	Variable	Abbr.	Example 1	Example 2
CER − EER	>0: absolute risk reduction	ARR	(−)0.3, or (−)30%	N/A
	<0: absolute risk increase	ARI	N/A	0.1, or 10%
(CER − EER) / CER	> 0: relative risk reduction	RRR	(−)0.75, or (−)75%	N/A
	< 0: relative risk increase	RRI	N/A	0.25, or 25%
1 / (CER − EER)	>0: number needed to treat	NNT	(−)3.33	N/A
	< 0: number needed to harm	NNH	N/A	10
EER / CER	relative risk	RR	0.25	1.25
(EE / EN) / (CE / CN)	odds ratio	OR	0.167	1.5
EER − CER	attributable risk	AR	(−)0.30, or (−)30%	0.1, or 10%
(RR − 1) / RR	attributable risk percent	ARP	N/A	20%
1 − RR (or 1 − OR)	preventive fraction	PF	0.75, or 75%	N/A

Revised from http://en.wikipedia.org/wiki/Absolute_risk_reduction

PubMed 醫學期刊文獻資料庫之搜尋簡介

Epworth Sleepiness Scale

0 = no chance of dozing

1 = slight chance of dozing

2 = moderate chance of dozing

3 = high chance of dozing

SITUATION	CHANCE OF DOZING
Sitting and reading	____________
Watching TV	____________
Sitting inactive in a public place (e.g a theater or a meeting)	____________
As a passenger in a car for an hour without a break	____________
Lying down to rest in the afternoon when circumstances permit	____________
Sitting and talking to someone	____________
Sitting quietly after a lunch without alcohol	____________
In a car, while stopped for a few minutes in traffic	____________

THE EPWORTH SLEEPINESS SCALE KEY

1 - 6	Congratulations, you are getting enough sleep!
7 - 8	Your score is average
9 and up	Seek the advice of a sleep specialist without delay

http://www.stanford.edu/~dement/epworth.html

期刊報告-101.5-陳清文

CPAP for the Metabolic Syndrome in Patients with Obstructive Sleep Apnea

Surendra K. Sharma, Swastik Agrawal, Deepak Damodaran, Vishnubhatla Sreenivas, Tamilarasu Kadhiravan, Ramakrishnan Lakshmy, Priya Jagia, and Atin Kumar

NEJM 2011,365,24：2277-2286

Abstr act

Background

Obstructive sleep apnea is associated with an increased prevalence of the metabolic syndrome and its components. It is unclear whether treatment of obstructive sleep apnea syndrome with continuous positive airway pressure (CPAP) would modify these outcomes.

Methods

In our double-blind, placebo-controlled trial(RCT), we randomly assigned patients with obstructive sleep apnea syndrome to undergo 3 months of therapeutic CPAP followed by 3 months of sham CPAP, or vice versa, with a washout period of 1 month in between. Before and after each intervention, we obtained measurements of anthropometric variables, blood pressure, fasting blood glucose levels, insulin resistance (with the use of homeostasis model assessment), fasting blood lipid profile, glycated hemoglobin levels, carotid intima–media thickness(CIMT), and visceral fat. The metabolic syndrome was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria, with Asian cutoff values for abdominal obesity.

Results

A total of 86 patients completed the study, 75 (87%) of whom had the metabolic syndrome. CPAP treatment (vs. sham CPAP) was associated with significant mean decreases in systolic blood pressure (3.9 mm Hg; 95% confidence interval [CI], 1.4 to 6.4; P = 0.001), diastolic blood pressure (2.5 mm Hg; 95% CI, 0.9 to 4.1; P < 0.001), serum total cholesterol (13.3 mg per deciliter; 95% CI, 5.3 to 21.3; P = 0.005), non–high density lipoprotein cholesterol (13.3 mg per deciliter; 95% CI, 4.8 to 21.8; P = 0.009), low-density lipoprotein cholesterol (9.6 mg per deciliter; 95% CI, 2.5 to 16.7; P = 0.008), triglycerides (18.7 mg per deciliter; 95% CI, 4.3 to 41.6; P = 0.02), and glycated hemoglobin (0.2%; 95% CI, 0.1 to 0.4; P = 0.003). The frequency of the metabolic syndrome was reduced after CPAP therapy (reversal found in 11 of 86 patients [13%] undergoing CPAP therapy vs. 1 of 86 [1%] undergoing sham CPAP). Accelerated hypertension developed 1 patient receiving CPAP therapy first, intolerance to CPAP developed in 2 others, and another patient declined to continue sham CPAP. Conclusions

In patients with moderate-to-severe obstructive sleep apnea syndrome, 3 months of CPAP therapy lowers blood pressure and partially reverses metabolic abnormalities.

1. OSA(OBSTRUCTIVE SLEEP APNEA)在美國的盛行率，男性為24%，女性為9%；在北印度的盛行率，男性為13.7%，女性為3.8%。


2. MS新陳代謝症候群(METABOLIC SYNDROME)是心血管疾病的危險因子，和OSA相關，有OSA的病人其MS的盛行率為74%-85%，無OSA的病人其MS的盛行率為37%-41%。


3. OSA是高血壓和insulin抗性的獨立危險因子。


4. AHI(apnea-hypopnea index)=Apnea次數(flow cessation)+hypopnea次數(partial flow obstruction)

mild 5≦AHI<15
moderate  15≦AHI<30
severe 30 ≦ AHI