期刊報告-101.8-廖文慧


Early use of noninvasive positive pressure ventilation for acute lung injury: A multicenter randomized controlled trial

Objective: Noninvasive positive pressure ventilation is beneficial for patients with acute respiratory failure. However, its possible benefit for patients with acute lung injury (200 mm Hg <PaO2/FIO2 <300 mm Hg) remains unclear. Our aim was to assess the safety and efficacy of noninvasive positive pressure ventilation for patients with acute lung injury and compare this with high-concentration oxygen therapy.

Design: A multicentered randomized controlled trial.

Setting: Ten multipurpose intensive care units.

Patients: Forty patients who fulfilled the criteria for acute lung injury were included in this study.

Interventions: Patients were randomly allocated to receive either noninvasive positive pressure ventilation (noninvasive positive pressure ventilation group) or high-concentration oxygen therapy through a Venturi mask (control group).

Measurements and Main Results: Twenty-one patients were assigned to the noninvasive positive pressure ventilation group and 19 were in the control group. At study entry, the patients’ characteristics in the two groups were similar. Noninvasive positive pressure ventilation application decreased the respiratory rate and improved PaO2/FIO2 with time. The proportion of patients requiring intubation and the actual number of intubations in the noninvasive positive pressure ventilation group were significantly less than in the control group (one of 21 vs. seven of 19; p=.02, and one of 21 vs. four of 19; p = .04, respectively). Noninvasive positive pressure ventilation showed a trend for reducing inhospital mortality (one of 21 vs. five of 19; p = .09). The total number of organ failures in the noninvasive positive pressure ventilation group was significantly lower than in the control group (three vs. 14; p < .001).

Conclusions: Noninvasive positive pressure ventilation is safe for selected patients with acute lung injury. However, a larger randomized trial with need for intubation and mortality as the outcomes of interest is required. (Crit Care Med 2012; 40: 455–460)

KEY WORDS: acute lung injury; acute respiratory distress syndrome; endotracheal intubation; noninvasive positive pressure ventilation; randomized controlled trial

無插管病人的意識評估可用Glasgow coma scale; 插管病人可用此The Kelly-Matthay scale來評估病人的意識狀態。

Source from: Kelly BJ, Matthay MA: Prevalence and severity of neurologic dysfunction in critically ill patients. Influence on need for continued mechanical ventilation. Chest 1993; 104:1818–1824.

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