實證醫學 2010-07-09 GS 謝閔傑

實證醫學的 5 個步驟 步驟1: 形成臨床問題 步驟2: 尋找証據 步驟3: 嚴謹評估証據 步驟4: 臨床應用 步驟5: 評估效果

步驟1: 形成臨床問題 Type of Questions (1) Background questions (2) Foreground questions Developing Answerable Question

Background questions Q: General information about the most common and serious side effects of stavudine. Evidence source: Current drug information compendia

Background Questions Two essential components: A question about (Who、What、Where、 When、Why or How) A disease, symptom, test, or therapy

For examples: Background Questions Who is at highest risk for contrast-induced nephropathy [disease]? When should clinicians consider adding a second or third antihypertensive drug [therapy] to a patient’s regimen? What role does insulin play in polycystic ovary syndrome [disease]?

Foreground Questions PICO A question root P代表 patient 或者 problem “is”, “do” or “does” PICO P代表 patient 或者 problem I 代表 intervention 通常為診斷 (diagnostic) 或者是治療 (treatment) C代表 comparisons (comparative intervention) O代表 outcome

Foreground Questions In patients with recent myocardial infarction and left ventricular dysfunction [patient/problem], is valsartan [intervention] superior to captopril [comparative intervention] for preventing cardiovascular-related mortality [outcome]? In patients excessively anticoagulated with warfarin [patient/problem], does oral vitamin K [intervention] work as well as intravenous vitamin K [comparative intervention] to reduce INR to safe levels [outcome]?

Foreground Questions For women in their third trimester of pregnancy who are traveling to a malaria-endemic area [patient/problem], does mefloquine [intervention] cause fetal harm [outcome]? In patients with coronary artery disease [patient/problem], do low-dose folic acid supplements [intervention] reduce the rate of cardiovascular events [outcome]?

步驟1: 形成臨床問題 建議以 PICO 的方式形成問題 P: Patient I: Intervention C: Comparison O: Outcome

步驟1: 形成臨床問題 舉例 Sepsis 病患使用 activated protein C (APC) 治療是否會降低死亡率？ P: Patient – Sepsis 病患 I: Intervention – 使用 APC 治療 C: Comparison – 不使用 APC 治療 O: Outcome – 死亡率

步驟2: 尋找證據 醫學資料庫檢索 MEDLINE Best Evidence Cochrane Database of Systematic Reviews EBM Reviews Therapeutics Local Holdings Articles in English Diagnosis Systematic Reviews Research on Human Subjects Prognosis Protocols Latest Update Etiology New Reviews

步驟2: 尋找證據 以 Medline 為例 以 Key word, Text word 查尋 Map to medical subject headings (MeSH) And, Or, And Not 功能: 可交集或聯集 Key word 限制功能: Limited to (年代,英文,Randomized controlled trial)

步驟3: 嚴謹評估證據 Critical Appraisal VALIDITY RELIABILITY APPLICABILITY

The Evidence Pyramid

[A] 1a 1b 1c [B] 2a 2b 2c 3a 3b [C] 4 [D] 5 Grade of Recommendation Level of Evidence Therapy [A] 1a Systemic review of RCTs 1b Single RCT 1c ‘All-or-none’ [B] 2a Systemic review of cohort studies 2b Cohort study or poor RCT 2c ‘Outcomes’ research 3a Systemic review of case-control studies 3b Case-control study [C] 4 Case series [D] 5 Expert opinion, physiology, bench research

步驟3: 嚴謹評估證據 – Statistics and EBM Index 敏感度（sensitivity）、特異度（specificity）、概似比（likelihood ratio）、檢測前機率（pre-test probability）、檢測後機率（post-test probability） ARR (Absolute risk reduction) = EER (Experimental Event Rate) - CER (Control Event Rate)、 Number needed to treat, NNT=1/ARR （增加一位病患得到某種處置好處所需的治療病人數）、相對危險度減少百分比（relative risk reduction，RRR） 絕對危險度增加百分比（absolute risk increase，ARI）= EER (Experimental Event Rate) - CER (Control Event Rate)、 Number needed to harm, NNH=1/ARI（增加一位受試者罹患某種醫源性傷害的治療病人數） 相對危險 (Relative risk)、勝算 (Odds)、勝算比 (Odds ratio) 、信賴區間(confidence interval)

步驟4: 臨床應用 應用於臨床病患 應以effective, efficiency, equality 的理念應用於病人 最終結果想法(the end result idea)的理想 制定醫療政策 Agent for Healthcare Research and Quality (AHRQ) in USA

步驟5: 評估效果 Can the results be applied to my patient care? Are the benefits worth the harms and costs?

結論 步驟1: 形成臨床問題 步驟2: 尋找証據 步驟3: 嚴謹評估証據 步驟4: 臨床應用 步驟5: 評估效果 P: Patient I: Intervention C: Comparison O: Outcome 步驟2: 尋找証據 步驟3: 嚴謹評估証據 步驟4: 臨床應用 步驟5: 評估效果

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