循證醫(yī)學(xué)教學(xué)課件：第二章 提出臨床需要解決的問題

1、第二章 提出臨床需要解決的問題 （一）確定需要解決的問題 1、問題的來源 （1）診斷問題 怎樣基于準(zhǔn)確度、精確度、可接受性、費(fèi)用及安全性等因素來選擇和解釋診斷試驗(yàn)，以便確定或排除某種診斷。 （2）病因問題 就具體某個(gè)患者而言，引起該病的原因可能有哪些？ （3）預(yù)后問題 怎樣估計(jì)病人可能的病程和預(yù)測(cè)可能的結(jié)局？ （4）治療問題 怎樣為患者選擇“利”大于“弊”并價(jià)有所值的治療方法？ （5）預(yù)防問題 怎樣通過識(shí)別和糾正危險(xiǎn)因素來減少疾病的發(fā)生及通過篩查來早期診斷，達(dá)到一、二級(jí)預(yù)防的目的？ 2、問題的分類 （1）背景問題（background questions） 是關(guān)于疾病的一般性知識(shí)。如病因（包括

2、生物、心理、社會(huì)因素等）、病理、病生等方面的問題。 （2）前景問題（foreground questions） 是關(guān)于處理、治療病人的專門知識(shí)問題，有時(shí)也涉及到與治療及預(yù)后有關(guān)的生理、心理及社會(huì)因素等方面的問題。“背景”問題 對(duì)一種疾病的一般知識(shí)提出問題 包括兩個(gè)基本成分 1、一個(gè)問題詞根（誰、什么、何處、何時(shí)、怎樣為何）加上一個(gè)動(dòng)詞 2、一種疾病或疾病的一個(gè)方面問題的構(gòu)建 例如：“我患的是什么?。俊薄拔以趺磿?huì)得這種?。俊薄盀槭裁匆鸢l(fā)熱？”等等。 前景問題（foreground questions） 對(duì)處理病人的特殊知識(shí)提出問題 需要考慮四大要素： P病人或人群（Patient/Popula

3、tion） I干預(yù)（Intervention） C比較干預(yù)（Comparison intervention） O臨床結(jié)局（Outcomes）PICO模式Patient/PopulationOutcomeIntervention/ExposureComparison臨床問題的組成PICO對(duì)無法手術(shù)切除的NSCLC對(duì)有后腹膜淋巴結(jié)轉(zhuǎn)移的肝癌患者放療基礎(chǔ)上進(jìn)行化療放射治療相比單純的放療相比化療改善生存率?能否改善病人的生存質(zhì)量食道癌的高危對(duì)象維生素礦物質(zhì)空白對(duì)照減低食道癌的發(fā)生率提出臨床問題: ask案例1: 皮膚感染 一個(gè)28歲男性，在過去8個(gè)月中反復(fù)發(fā)生癤病，應(yīng)用過幾個(gè)療程的抗生素。 能否預(yù)防復(fù)

4、發(fā)?組織問題（PICO) Population ：人群 復(fù)發(fā)性皮膚感染的病人Indicator (intervention, test, etc)：干預(yù) 預(yù)防性的抗生素治療Comparison：對(duì)照 對(duì)照不治療Outcome：結(jié)果 降低復(fù)發(fā)率?案 例 2： 一個(gè)64歲男性肥胖病人，曾嘗試過 無數(shù)減肥方法。看到報(bào)紙上有關(guān) “瘦身夾克” Chitosan（聚氨基葡萄糖）. 他問你的建議。 PICOPICO 問 題 Population 肥胖病人（ obes* OR overweight ) Indicator chitosan 治療 Comparison 對(duì)照安慰劑 Outcome 體重下降(de

5、crease weight OR kilogram*)問題1：抗凝劑對(duì)腦卒中病人有效嗎？問題2：抗凝劑與不用抗凝劑相比能改善急性缺血性腦卒中病人的臨床預(yù)后嗎？干預(yù)措施病人類型干預(yù)措施對(duì)照措施病人類型臨床結(jié)局（二）查找最佳證據(jù) 檢索文獻(xiàn)資料（三）嚴(yán)格評(píng)價(jià)臨床研究證據(jù)結(jié)果是什么?結(jié)果是不是真實(shí)? 這些結(jié)果能否應(yīng)用于我們的病?（臨床價(jià)值與適用性） （四）綜合分析證據(jù)，并用于臨床決策 用最佳證據(jù)指導(dǎo)臨床決策需要整合臨床醫(yī)生的實(shí)踐經(jīng)驗(yàn)和技能以及病人的的具體情況和期望。 （五）后效評(píng)價(jià)決策效果，不斷提高臨床決策水平和質(zhì)量 1、后效評(píng)價(jià)的含義 用循證醫(yī)學(xué)的后效評(píng)價(jià)是指對(duì)應(yīng)用循證醫(yī)學(xué)的理念從事醫(yī)療活動(dòng)后的結(jié)果

6、進(jìn)行評(píng)價(jià)，即評(píng)價(jià)解決患者具體臨床問題后的結(jié)果。 2、后效評(píng)價(jià)的內(nèi)容提出問題尋找證據(jù)評(píng)價(jià)證據(jù)應(yīng)用證據(jù)后效評(píng)價(jià)循證醫(yī)學(xué)實(shí)踐的結(jié)果再評(píng)價(jià)問題的組成，以及是否反映了臨床實(shí)際再評(píng)價(jià)各種標(biāo)準(zhǔn)的真實(shí)性、可靠性和實(shí)用性再評(píng)價(jià)證據(jù)在實(shí)際患者中的應(yīng)用若不盡滿意，則應(yīng)再評(píng)價(jià)再評(píng)價(jià)檢索策略的準(zhǔn)確性和全面性 循證醫(yī)學(xué)實(shí)踐舉例： 冠心病所致的急性心肌梗死（AMI）是心血管病的危重疾患，其病死率可達(dá)10%以上。如何提高臨床療效，降低病死率，改善患者的預(yù)后，是臨床醫(yī)生和患者極其關(guān)注的問題。近年來從急性心肌梗死的發(fā)病機(jī)制角度，臨床應(yīng)用鏈激酶作溶栓療法進(jìn)行了大量的治療性研究。那么，根據(jù)不同的研究結(jié)果，能夠證明這一療法有效嗎？ 1

7、、提出問題 應(yīng)用鏈激酶對(duì)急性心肌梗死患者進(jìn)行溶栓治療，能夠降低其病死率嗎？ 2、文獻(xiàn)檢索 根據(jù)上述臨床問題，確定檢索文獻(xiàn)的關(guān)鍵詞： 急性心肌梗死溶栓療法；RCT臨床試驗(yàn)（并限定單個(gè)RCT含AMI1 000例） 共檢索到9篇文獻(xiàn)，總病例為58 600例。 3、嚴(yán)格評(píng)價(jià)文獻(xiàn) 運(yùn)用臨床流行病學(xué)及循證醫(yī)學(xué)有關(guān)治療性研究證據(jù)的嚴(yán)格評(píng)價(jià)標(biāo)準(zhǔn)，對(duì)這9篇文獻(xiàn)進(jìn)行嚴(yán)格質(zhì)量評(píng)價(jià)，并在此基礎(chǔ)上進(jìn)行系統(tǒng)評(píng)價(jià)，得出如下結(jié)論： （1）溶栓療法治療AMI的總體效果：如下表18（95%CI 3%23%）1.911.5對(duì)照組56 （95%CI 43%77%）9.6試驗(yàn)組救活一例需治療病例數(shù)相對(duì)病死降低率(%)絕對(duì)病死降低率(%

8、)病死率(%)組別 （2）溶栓療法治療AMI分層分析的治療效果：在該系統(tǒng)評(píng)價(jià)中，將AMI病例心電圖具急性損傷ST段變化及伴室內(nèi)阻滯兩個(gè)亞組的治療結(jié)果統(tǒng)計(jì)分析如下表：25AMI伴室內(nèi)阻滯組21AMI伴急性ST抬高組相對(duì)病死降低率(%)組別 （3）溶栓療法治療AMI的時(shí)相效應(yīng)結(jié)果： 該系統(tǒng)評(píng)價(jià)分析AMI發(fā)作后接受溶栓治療，對(duì)降低病死率的時(shí)相效應(yīng)作了具體分析，結(jié)果顯示，如果晚治1小時(shí)，就會(huì)丟失生還率1.60.6；其中AMI發(fā)作在6小時(shí)內(nèi)接受溶栓療法者效果為最好，12小時(shí)后則療效差。 4、指導(dǎo)臨床決策 上述結(jié)果提示： （1）AMI患者應(yīng)用溶栓療法對(duì)降低該病病死率具有一定的臨床價(jià)值； （2）AMI發(fā)作6

9、小時(shí)內(nèi)接受溶栓療法比晚用效果為好； （3）AMI伴有心電圖ST抬高以及伴有室內(nèi)阻滯者療效相對(duì)更好； 這些證據(jù)需聯(lián)系患者的具體臨床特點(diǎn)參考應(yīng)用。 5、在EBM實(shí)踐中驗(yàn)證其效果，提高認(rèn)識(shí)第三章 研究證據(jù)的分類、分級(jí)與推薦一. 研究證據(jù)的分類原始研究證據(jù) 指直接在受試者中進(jìn)行單個(gè)有關(guān)病因、診斷、預(yù)防、治療和預(yù)后等試驗(yàn)研究所獲得的第一手?jǐn)?shù)據(jù)，進(jìn)行統(tǒng)計(jì)學(xué)處理、分析、總結(jié)后得出的結(jié)論。2. 二次研究證據(jù) 指盡可能全面收集某一問題的全部原始研究證據(jù)，進(jìn)行嚴(yán)格評(píng)價(jià)、整合、分析、總結(jié)后所得出的綜合結(jié)論，是對(duì)多個(gè)原始研究證據(jù)再加個(gè)后得到的證據(jù)。 系統(tǒng)評(píng)價(jià) 臨床決策分析 臨床證據(jù)手冊(cè) 衛(wèi)生技術(shù)評(píng)估 臨床實(shí)踐指南 二

10、、證據(jù)分級(jí)與推薦牛津大學(xué)循證醫(yī)學(xué)中心標(biāo)準(zhǔn)GRADE標(biāo)準(zhǔn) 循證醫(yī)學(xué)證據(jù)的分級(jí)水平及依據(jù) 推薦分級(jí) 證據(jù)水平 治療、預(yù)防、病因的證據(jù) A 1a RCTs的系統(tǒng)綜述。 1b 單項(xiàng)RCT（95%Cl較窄）。 1c 滿足全或無結(jié)果。即必須滿足下列要求：（1） 用 傳 統(tǒng)方法治療患者全部殘廢或失敗， 用新療法有部分 患者存活或治愈；（2）用傳統(tǒng)方法治療，許多患者死 亡或治療失敗，用新療法無一死亡或失敗。 B 2a 隊(duì)列研究的系統(tǒng)綜述。 2b 單項(xiàng)隊(duì)列研究（包括質(zhì)量較差的RCT） 2c 結(jié)局研究。 3a 病例對(duì)照研究的系統(tǒng)綜述。 3b 單項(xiàng)病例對(duì)照研究。 C 4 系列病例分析及質(zhì)量較差的病例對(duì)照研究。 D

11、5 沒有分析評(píng)價(jià)的專家意見。GRADE系統(tǒng)簡介GRADE（Grading of Recommendations Assessment, Development and Evaluation）是由2000年建立的GRADE工作組提出的一套評(píng)級(jí)系統(tǒng)。GRADE系統(tǒng)使用易于理解的方式評(píng)價(jià)證據(jù)質(zhì)量和推薦等級(jí)，目前已被世界衛(wèi)生組織（WHO）、Cochrane協(xié)作網(wǎng)等一批著名機(jī)構(gòu)所采用。證據(jù)質(zhì)量（GRADEpro）為達(dá)到透明和簡化的目標(biāo)， GRADE系統(tǒng)將證據(jù)質(zhì)量分為高、 中、 低、 極低 4 級(jí)。一些使用GRADE系統(tǒng)的組織甚至把低和極低歸為一級(jí)。推薦等級(jí)使用GRADE系統(tǒng)時(shí)，指南小組用“強(qiáng)推薦”表示他

12、們確信相關(guān)的干預(yù)措施利大于弊。用“弱推薦”表示干預(yù)措施有可能利大于弊，但他們把握不大。GRADE中的證據(jù)質(zhì)量和推薦等級(jí)符號(hào)字母/數(shù)字證據(jù)質(zhì)量 高質(zhì)量A 中等質(zhì)量B 低質(zhì)量C 極低質(zhì)量D決定證據(jù)質(zhì)量的因素可能降低證據(jù)質(zhì)量的因素研究的局限性結(jié)果不一致間接證據(jù)精確度不夠發(fā)表偏倚可能增加證據(jù)質(zhì)量的因素效應(yīng)值很大可能的混雜因素會(huì)降低療效劑量-效應(yīng)關(guān)系研究設(shè)計(jì)與證據(jù)質(zhì)量高：為不降級(jí)的隨機(jī)試驗(yàn)和升 2 級(jí)的觀察性研究； 中：為降級(jí)的隨機(jī)試驗(yàn)和升 1 級(jí)的觀察性研究； 低：降 2 級(jí)的隨機(jī)試驗(yàn)和沒有升降級(jí)的觀察性研究； 非常低：降3級(jí)的隨機(jī)試驗(yàn)、 降1級(jí)的觀察性研究、 病例分析/病例報(bào)告。這些局限性包括（RC

13、Ts）隱藏分組缺失盲法缺失（特別是結(jié)局指標(biāo)為主觀性指標(biāo)且對(duì)其的評(píng)估極易受偏倚影響時(shí)）失訪過多未進(jìn)行意向性分析、觀察到療效就過早終止試驗(yàn)或未報(bào)道結(jié)果（通常是未觀察到療效的一些研究）結(jié)果不一致（ Inconsistency）Inconsistency may arise from differences in:populations (e.g. drugs may have larger relative effects in sicker populations) interventions (e.g. larger effects with higher drug doses) outcome

14、s (e.g. diminishing treatment effect with time)差異可能源于人群（如藥物對(duì)重癥人群的療效可能相對(duì)顯著）、干預(yù)措施（如較高藥物劑量會(huì)使療效更顯著）或結(jié)局指標(biāo)（如隨時(shí)間推移療效降低）。間接證據(jù)（ Indirectness)There are two types of indirectness:1. Indirect comparison2. Indirect populationinterventioncomparatoroutcome精確度不夠（Imprecision ）當(dāng)研究納入的患者和觀察事件相對(duì)較少而致可信區(qū)間較寬時(shí)，指南小組將降低該研究的證據(jù)

15、質(zhì)量。A threshold rule-of-thumb valueTotal number of events is less than 300（dichotomous）Total population size is less than 400（continuous）發(fā)表偏倚（ Publication bias ）Publication bias arises when investigators fail to report studies they have undertaken (typically those that show no effect). Methods to det

16、ect the possibility of publication bias in systematic reviews exist, although authors of the reviews and guideline panels must often guess about the likelihood of publication bias. A prototypical situation that should elicit suspicion of publication bias occurs when published evidence is limited to

17、a small number of trials, all of which are showing benefits of the studied intervention.若研究者未能發(fā)表研究（通常是陰性結(jié)果的研究）時(shí)，證據(jù)質(zhì)量亦會(huì)減弱。典型情況是當(dāng)公開的證據(jù)僅局限于少數(shù)試驗(yàn)而這些試驗(yàn)全部由企業(yè)贊助，此時(shí)不得不質(zhì)疑存在發(fā)表偏倚。Funnel Plot第四章 研究證據(jù)來源與檢索 醫(yī)學(xué)索引在線(Medline) 其中PubMed最常用, 其網(wǎng)址為: /PubMed/ 中國生物醫(yī)學(xué)文獻(xiàn)數(shù)據(jù)庫 中國循證醫(yī)學(xué)/Cochrance中心臨床研究數(shù)據(jù)庫 網(wǎng)址為: Cochrance圖書館(CL) 網(wǎng)址為:

18、 雜志 循證醫(yī)學(xué)雜志（英） 提供臨床醫(yī)學(xué)最佳證據(jù)，為二次發(fā)表的文獻(xiàn)摘要并加以專家評(píng)述。 網(wǎng)址：http:cemb.jrzox.ac.uk 美國內(nèi)科醫(yī)師學(xué)院雜志俱樂部 循證護(hù)理雜志 循證衛(wèi)生保健雜志Clinical Evidence 由美國內(nèi)科醫(yī)學(xué)會(huì)和英國醫(yī)學(xué)雜志聯(lián)合主編的最佳研究證據(jù)集。網(wǎng)址：http:/products/clinicalevidence.cfmEBM 常用的中文數(shù)據(jù)庫中國知網(wǎng)： 萬方數(shù)據(jù)： 中文科技期刊數(shù)據(jù)庫： 中國生物醫(yī)學(xué)文獻(xiàn)數(shù)據(jù)庫(CBM)中國醫(yī)院數(shù)字圖書館： 院內(nèi)網(wǎng)址：58網(wǎng)址: 循證醫(yī)學(xué)的網(wǎng)絡(luò)資源 教育部循證醫(yī)學(xué)網(wǎng)上合作中心： /教育部循證醫(yī)學(xué)網(wǎng)上合作中心中山大學(xué)分中

19、心：（廣州中心） / 教育部循證醫(yī)學(xué)網(wǎng)上合作中心中醫(yī)循證中心：（北京中心） /循證醫(yī)學(xué)在線 EBM /循證醫(yī)學(xué) - 網(wǎng)絡(luò)資源Cochrane協(xié)作網(wǎng)： Cochrane圖書館 Sumsearch網(wǎng)站(/searchform4.htm) TRIP Database 網(wǎng)站 Doctors Desk (英國國家保健服務(wù)系統(tǒng)) http:/drsdesk.sghms.ac.uk 研究證據(jù)的檢索PICO 策略檢索詞的正確選擇 主題詞檢索 關(guān)鍵詞檢索循證醫(yī)學(xué)實(shí)踐舉例病例: 男性，45歲，有慢性乙肝史15年 因“乏力、腹脹、少尿2周”入院。 初步診斷: 慢性乙肝，肝硬化 胃鏡發(fā)現(xiàn)“食管靜脈中度曲張” 。提出問

20、題： 食管靜脈曲張首次破裂出血的危險(xiǎn)性有多少？ 什么預(yù)防措施最好？尋找證據(jù)： 檢索了中國醫(yī)院數(shù)字圖書館， Cochrane圖書館，EMbace, PubMed等電子信息資源。 關(guān)鍵詞: 門脈高壓，食管靜脈曲張，預(yù)防措施 “portal hypertension” “esophageal variceal bleeding”, “medical and surgical prevention”. 結(jié) 果：(1) 首次出血危險(xiǎn)性（既往無出血史者）: 破裂出血的發(fā)生率- 4.4% 首次出血的病死率- 25%-50% 首次出血的危險(xiǎn)因子(risk factors)- 肝功能損害程度 曲張靜脈的大小 內(nèi)

21、鏡下存在紅色特征 肝靜脈壓力梯度值(HVPG) 1.6kPa(12mmHg) (2) 預(yù)防首次出血的臨床隨機(jī)對(duì)照試驗(yàn) 分流手術(shù)與無特殊治療間的比較: 不理想 Meta-分析（4項(xiàng)RCT）: 出血的發(fā)生率明顯降低(OR 0.31)， 但生存率降低, 病死率提高(OR1.6)。慢性或復(fù)發(fā)性腦病明顯增加(OR2.0) 硬化劑治療與無特殊治療間的比較 : 無結(jié)果 Meta-分析（ 20項(xiàng)臨床試驗(yàn)）： 各研究在治療指征和控制出血及死亡的療效方面存在明顯的異源性.曲張靜脈套扎術(shù)與無特殊治療的比較 : 好 最新Meta-分析（ 5項(xiàng)臨床試驗(yàn)）: 首次出血 的OR( 95CI) 為0.36 (0.260.50

22、) ，NNT 為4.1。受體阻滯劑治療與無特殊治療的比較：好 Meta-分析（ 9項(xiàng)臨床試驗(yàn) ）: 排除1項(xiàng)異質(zhì)性研究后，減少出血的OR 0.54(0.390.74) ，NNT：11。死亡率降低的 OR 0.75( 0.571.06) 。嚴(yán)格評(píng)價(jià)證據(jù)： 用治療性實(shí)驗(yàn)研究的質(zhì)量評(píng)價(jià)標(biāo)準(zhǔn)對(duì)上述研究進(jìn)行評(píng)價(jià)，結(jié)果是文章的真實(shí)性和可靠性都很好。應(yīng)用證據(jù)： 這個(gè)研究納入的患者與該患者相似。醫(yī)師將這些最新研究結(jié)果告知患者后，患者感到很滿意。防止初次出血的發(fā)生（結(jié)論）：1.受體阻滯劑: 首選: 便宜，簡單，防止胃黏膜出血。2.曲張靜脈套扎術(shù): 安全的治療,受體阻滯劑禁忌證或不能耐受患者的替代措施。3.分流手

23、術(shù): 預(yù)防出血，但增加病死率和肝性腦病。4.硬化劑治療: 療效較差，費(fèi)用昂貴,有潛在危險(xiǎn)性。Case example: Using EBM as a support1. The patientPauline is a new patient who recently moved to the area to be closer to her son and his family. She is 67 years old and has a history of congestive heart failure brought on by several myocardial infarctio

24、ns. She has been hospitalized twice within the last 6 months for worsening of heart failure. At the present time she remains in normal sinus rhythm. She is extremely diligent about taking her medications (enalapril, aspirin and simvastatin) and wants desperately to stay out of the hospital. She live

25、s alone with several cats.You think she should also be taking digoxin but you are not certain if this will help keep her out of the hospital. You decide to research this question before her next visit. Pauline2. Focusing the question-PICO It is to take the identified problem and construct a question

26、 that is relevant to the case and is phrased in such a way as to facilitate finding an answer. This is called constructing a well built clinical question. Patient or problem-PHow would you describe a group of patients similar to yours? What are the most important characteristics of the patient? This

27、 may include the primary problem, disease, or co-existing conditions. Sometimes the sex, age or race of a patient might be relevant to the diagnosis or treatment of a disease. Intervention -IWhich main intervention, prognostic factor, or exposure are you considering? What do you want to do for the p

28、atient? Prescribe a drug? Order a test? Order surgery? What factor may influence the prognosis of the patient? Age? Co-existing problems? What was the patient exposed to? Cigarette smoke? Patient / Problemcongestive heart failure, elderlyInterventiondigoxin Companone, placebo Outcomeprimary: reduce

29、need for hospitalization; secondary: reduce mortality Comparison-CWhat is the main alternative to compare with the intervention? Are you trying to decide between two drugs, a drug and no medication or placebo, or two diagnostic tests? Your clinical question does not always need a specific comparison

30、. Outcomes-OWhat can you hope to accomplish, measure, improve or affect? What are you trying to do for the patient? Relieve or eliminate the symptoms? Reduce the number of adverse events? Improve function or test scores? The structure of the question might look like this: Patient / Problemcongestive

31、 heart failure, elderlyInterventiondigoxin Comparison, if anynone, placebo Outcomeprimary: reduce need for hospitalization; secondary: reduce mortalityFor our patient, the clinical question might be: In elderly patients with congestive heart failure, is digoxin effective in reducing the need for reh

32、ospitalization? It is a therapy question and the best evidence would be a randomized controlled clinical trial. 3. the literature search The practice of Evidence-based Medicine advocates that clinicians search the published literature to find answers to their clinical questions. There are literally

33、millions of published reports, journal articles, correspondence and studies available to clinicians. Choosing the best resource to search is an important decision. Select a resource 8000 articles published per day30 Kg of guidelines per family dactor25,000 biomedical journals in print1500 medical ar

34、ticles onto Medline per daySearching primary resourcesTypes of study -original research,reports of experiments(eg surveys,observational studies,randomized controlled trials) Large databases such as MEDLINE will give you access to the primary literature. Secondary resources such as ACP Journal Club,

35、POEMS, Clinical Inquiries, and Clinical Evidence, will provide you with an assessment of the original study. The Cochrane Library provides access to systematic reviews which help summarize the results from a number of studies.Where and how to find them? Databases MEDLINE Produced by the U.S. Nationa

36、l Library of Medicine, the MEDLINE database contains over 11 million references to journal articles in life sciences with a concentration on biomedicine. MEDLINE is available free of charge, via PubMed, from the National Library of Medicine. It is also available for a fee from several providers incl

37、uding Ovid Technologies and Aries Knowledge Finder. Access PubMed at: The Cochrane Library The Cochrane Library consists of several electronic databases: Cochrane Database of Systematic Reviews (Cochrane Reviews) provides access to regularly updated, systematic reviews, maintained by the various Coc

38、hrane Review Groups.Database of Abstracts of Reviews of Effects (DARE)Cochrane Central Register of Controlled Trials Cochrane Database of Methodology Reviews For more information see Cochrane Library at /reviews/clibintro.htm Formulate the strategy Step 1: Search each important concept separately. Y

39、ou want to be sure it found the appropriate MeSH Terms and Text Words. PubMed attempts to map your term to an appropriate Medical Subject Heading (MeSH) Step 2: Combine the separate sets of articles Step 3: Limit the results to the appropriate publication type, language and human Review the results4

40、.There are three basic questions that need to be answered for every type of study: Are the results of the study valid? What are the results? Will the results help in caring for my patient?1. Randomization: Was the assignment of patients to treatment randomized?Yes No 2. Patient follow-up: Were all p

41、atients who entered the trial properly accounted and attributed for at its conclusion? Yes No 3. Analysis of patients: Were patients analyzed in the groups to which they were randomized? Yes No Are the results of the study valid? 4. Blinding: Were patients, health workers, and study personnel blind

42、to treatment? Yes No 5. Baseline characteristics of patients: Were groups similar at the start of the trial? Yes No 6. Treatments: Aside from the experimental intervention, were the groups treated equally? Yes No Conclusions: Digoxin did not affect mortality but reduced hospitalizations in patients

43、with heart failure and normal sinus rhythm.Outcomes: Outcome Digoxin Placebo RRR ARR NNT Mortality 34.8% 35.1% nonsignificant p=0.08 Total hospitalization 64.3% 67.1% 4.1% 2.8% 36 hospitalization for CHF 27% 35% 23% 8% 13 hospitalization for CV causes 49.9% 54.4% 8.3% 4.5% 22 5. Return to the patien

44、t - integrate that evidence with clinical expertise, patient preferences and apply it to practiceThe study population appears to be similar enough to Pauline that we can consider the results applicable to her case. The results of this study indicate that digoxin can reduce the need for hospitalizati

45、ons in patients with heart failure and normal sinus rhythm. Digoxin may be an appropriate therapy to help keep Pauline at home and out of the hospital. However, if Pauline elects to be treated with digoxin, there will be a need to monitor therapy, draw frequent drug levels, and hold the risk of toxi

46、city. For Pauline, these issues may be offset by the possible benefit of avoidance of hospitalization. 6. Self-evaluationEvaluate your performance with this patientTake a moment to reflect on how well you were able to conduct the steps in the EBM Process. EBM CycleGENERATE THE QUESTIONCONDUCT THE SE

47、ARCHAPPRAISE DIRECTNESSAPPRAISE VALIDTYAPPRAISE RESULTSAPPRAISEAPPLICABILITYINDIVIDUALIZERESULTSCase 1: Therapy for Strep Throat The Patient1. Start with the patient - a clinical problem or question arises out of the care of the patient.Henry is an active 5 year old boy. His mother brought him in fo

48、r a check-up because Henry has had a fever and a sore throat for several days. You suspect Strep and take a throat culture. The standard treatment for Streptococcal Pharyngitis is oral Penicillin three times a day. However, for Henry and his mother, you are concerned about compliance and the expense of