Relative risk reduction (RRR) tells you by how much the treatment reduced the risk of bad outcomes relative to the control group who did not have the treatment. In the previous example, the relative risk reduction of fever and rash in the group of the children on the intervention was 40 per cent (1 – 0.6 = 0.4 or 40 per cent).

nnt = 1/arr。 NNT是指在评价治疗或预防疾病措施的研究中，用某种方法（药物、疫苗等）处理某人群（疾病、健康人群等）时，获得1例有利结局或者防止1例不良结局时，所需要的人数。

Relative risk reduction (RRR) compares the probability of an event occurring in two groups by showing the proportionate reduction in probability. The relative risk reduction formula is the following: Alternatively, use the following formula with RR to obtain the same results:

In epidemiology, the relative risk reduction (RRR) or efficacy is the relative decrease in the risk of an adverse event in the exposed group compared to an unexposed group. It is computed as ( I u − I e ) / I u {\displaystyle (I_{u}-I_{e})/I_{u}} , where I e {\displaystyle I_{e}} is the incidence in the exposed group, and I u {\displaystyle I ...

Absolute Risk Reduction (ARR) is the change in risk in the 2 groups and its inverse is the Number Needed to Treat (NNT). Patient expected event rate (PEER) is the expected rate of events in a patient received no treatment or conventional treatment. The Z-test for Odds Ratio shows whether the exposure affect the odds of outcome.

RR=40%/80%=0.5。 (表1) 表1. 两种药物治疗不同心脏病疾病的试验结果. 对于A药和B药，两个试验的RR都是0.5。 我们可以说“A药可以使室性心律失常患者的死亡率下降50%；B药也可以使急性心肌梗死患者的死亡率下降50%”。 上面的描述中，我们实际上使用了相对危险度降低（Relative Risk Reduction, RRR）的概念。 （表2） RRR=（对照组事件发生率 - 试验组事件发生率）*100% / 对照组事件发生率. 表2. 两种药物治疗不同心脏病疾病的试验. 那么，“A药可以使患者的死亡率 …

2023年2月22日 · nnt = 1/arr。 NNT是指在评价治疗或预防疾病措施的研究中，用某种方法（药物、疫苗等）处理某人群（疾病、健康人群等）时，获得1例有利结局或者防止1例不良结局时，所需要的人数。

ARR is the difference in the event rate between treatment group and control groups. The number needed to treat (NNT) is the number of patients who need to be treated in order to prevent one additional bad outcome (i.e. the number of patients that need to be treated for one to benefit compared with a control in a clinical trial).

2021年11月9日 · The recent controversy about vaccines approved for emergency use against COVID-19 has elicited much discussion regarding Relative Risk Reduction (RRR) and Absolute Risk Reduction (ARR). In broad terms, the ARR compares the overall outcomes of one event versus another; how much is the overall probability of an outcome reduced or increased?

Absolute Risk Reduction (ARR) and Relative Risk Reduction (RRR) are both measures used in clinical trials to assess the effectiveness of a treatment or intervention. ARR calculates the difference in risk between the control group and the treatment group, providing a more straightforward interpretation of the treatment's impact on reducing the ...