循证医学教学.ppt

Five Steps of EBM A. Finding problems in clinical practice B. Searching for the best evidence C. Appraising and analyzing the acquired evidence D. Applying the evidence to direct the diagnosis, therapy and prognosis of diseases E. Appraising the outcomes Question Question: Question of ◆ patients： ◆Intervention: ◆Comparison: ◆Outcome: Search Key word: Database: Clinical evidence： Cochrane Library： Medline： 评价证据（ctitical appraisal）的基本内容 证据的真实性（validity） 证据的重要性（important） 证据的实用性（application） 证据的真实性评价 真实性Validity 真实性Validity 2、Was the randomization concealed? 随机表隐匿 充分隐藏的方法： 中心随机 药房随机 事先统一编号的同样容器 现场随机（计算机随机） 连续编号，密封的，不透明的信封 其他远离病人入组地点的一些随机方法来 判断，保证产生随机方案者不管理随机方案 真实性Validity 3、Were the groups similar at the start of the trial? ⑴ yes ⑵ No, adjusted for the baseline variables？ 真实性Validity 4、Was follow-up of patients sufficiently long and complete? 确定应根据研究目的、疾病性质等相应的医学理论知识来决定。 1. Withdraw less than 20% 2.at a mean of ？years. 真实性Validity 5、Were all patients analyzed in the groups to which they were? A.效力分析（efficacy analysis）只考虑完成了指定治疗的病人进行比较，改变了原先RCT分组指定的治疗内容的患者，夸大了治疗措施的效果。 B.实际治疗分析（treatment received analysis）或解释试验（Expianatory trials）分析仅是简单的队列研究两组的可比性可能较差。 C.意愿治疗分析（intension-to-treat analysis,ITT）保留随机化分配的优点防止预后较差的病人在最后分析中被排除出去 两组可比性好，结论更可靠。 真实性Validity 6、Were patients, clinicians, and study personnel kept blind to treatment? it was a double-blind placebo-controlled trial？ 真实性Validity 7、Were groups treated equally, apart from the experimental therapy? 随机 双盲 基线 隐藏 随访 完全 治疗一致 重要性Important 1、What is the magnitude of the treatment effect? 1、What is the magnitude of the treatment effect? 新的评价治疗研究的指标 相对危险度(RR，relative risk ) 相对危险降低率(RRR，relative risk reduction) 绝对危险降低率(ARR，absolute risk reduction) NNT：挽救一个病人免于发生某种临床事件，需 要治疗具有此类危险的病人数（NNT， number needed to treat）