药学英语药学英语 (32).ppt

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1、 Unit Eleven Drug Safety and EfficacyPart four Balancing Benefits and Adverse Effects 治疗益处与不良反应相权衡治疗益处与不良反应相权衡vWhether a drug is indicated depends on the balance of its benefits and harms.vIn making such judgements,clinicians often consider factors that are somewhat subjective,such as personal exper

2、ience,anecdotes nkdts 轶事,peer practices,and expert opinions.v是否使用某种药物取决于对其利弊的权衡。v临床医生在做出这种判断时，其经常考虑的因素多少有些主观，诸如个人经验、典型案例、同行惯例与专家意见。vThe number needed to treat(NNT)is a less subjective accounting of the likely benefits of a drug(or any other intervention).vNNT is the number of patients who need to be

3、 treated for one patient to benefit.vFor example,consider a drug that decreases mortality of a certain disease from 10%to 5%,an absolute risk reduction of 5%(1 in 20).v需需治治数数(NNT)在计算药物(或其他治疗干预)的可能益处时主观性较小。v需治数指的是为使一个患者受益需要治疗的患者的数量。v例如，考虑一种药物能将某种疾病的死亡率从10降低至5，绝对风险降低5(即20人中1个)。vThat means that of 100

4、patients,90 would live even without treatment,and thus would not benefit from the drug.vAlso 5 of the 100 patients will die even though they take the drug and thus also do not benefit.v这意味着100例患者中，90人即使没有接受治疗也能生存，因此不会从该药中受益。v这100名患者中有5名尽管服用了药物依然会死亡，因此也不会从该药中受益。vOnly 5 of the 100 patients(1 in 20)ben

5、efit from taking the drug;thus,20 need to be treated for 1 to benefit,and the NNT is 20.vNNT can be simply calculated as the inverse of the absolute risk reduction,if the absolute risk reduction is 5%(0.05),the NNT=1/0.05=20.vNNT can be calculated for adverse effects also,in which case it is sometim

6、es called the number needed to harm(NNH).v100例中仅有5人(20:1)受益于服用药物。因此，需要治疗20人才能使一人获益，故需治数为20。v需治数亦可由绝对风险降低值的倒数计算得知。如绝对风险降低5(0.05)，那么需治数=1/0.05=20。v需治数亦可用于计算不良反应，在这种情况下，它有时被称为不良事件所需人数(出现伤害时的经治人数，NNH)。vImportantly,NNT is based on changes in absolute risk;it cannot be calculated from changes in relative

7、risk.vRelative risk is the proportional difference between two risk levels.vFor example,a drug that decreases mortality from 10%to 5%decreases absolute mortality by 5%but decreases relative mortality by 50%(i.e.,a 5%death rate indicates 50%fewer deaths than a 10%death rate).v重要的是，需治数是基于绝绝对对风风险险的变化，它

8、不能根据相相对对风风险险的变化来计算。v相对风险是比较两个风险水平的比例差值。例如，一种药物将10的死亡率降至5，其绝对死亡率降低5，但相对死亡率降低50(意即5的死亡率与10的死亡率相比预示死亡人数减少50)。vMost often,benefits are reported in the literature as relative risk reductions because these make a drug look more effective than the absolute risk reductions(in the previous example,a 50%reduc

9、tion in mortality sounds much better than a 5%reduction).v文献报道治疗益处时通常报告相对风险的降低，因为这样做比采用绝对风险的降低会使药物看起来显得更有效(在上一示例中，死亡率减少50%听起来比减少5%感觉好得多)。vIn contrast,adverse effects are usually reported as absolute risk increases because they make a drug appear safer.vFor example,if a drug increases the incidence of bleeding from 0.1%to 1%,the increase is more likely to be reported as 0.9%than 1000%.v相反，不良反应通常报告为绝对风险的增加，因为这会使药物看起来显得更安全。v例如，如果一种药物会使出血发生率从0.1增加到1，这种增加很可能被报告为0.9而不是1000。