It is important to understand that the 56% less fractures is the relative risk reduction (RRR). The control group had a 0.5% chance of having a hip fracture and treatment group a 0.2% chance of having a hip fracture. The absolute risk reduction (ARR) is only 0.3%.
Full Answer
What is the relative risk reduction (RRR)?
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.
What is the RR of a treatment with a bad outcome?
In this hypothetical case, the RR is 0.6 (12 per cent ÷ 20 per cent = 0.6). When a treatment has an RRgreater than 1, the riskof a bad outcomeis increased by the treatment; when the RR is less than 1, the risk of a bad outcome is decreased, meaning that the treatment is likely to do good.
What does RR of 1 mean in clinical trials?
For example, when the RR is 2.0 the chance of a bad outcome is twice as likely to occur with the treatment as without it, whereas an RR of 0.5 means that the chance of a bad outcome is twice as likely to occur without the intervention. When the RR is exactly 1, the risk is unchanged.
What does it mean when the RRR is negative?
The difference between the wrong result in the experimental group and the control group is relative risk reduction. With this formula, if the RRR is coming to be negative, that means the treatment has increased the risk of the outcome because of EER with greater than CER.
What does it mean when RRR relative risk reduction is equal to 25%?
The relative risk reduction is the difference in event rates between two groups, expressed as a proportion of the event rate in the untreated group. For example, if 20% of patients die with treatment A, and 15% die with treatment B, the relative risk reduction is 25%.
What does a relative risk of 0.25 mean?
Similarly a risk ratio of 0.25 is interpreted as the probability of an event with treatment being one-quarter of that without treatment. This may be expressed alternatively by saying that treatment decreases the risk of events by 100 × (1 –RR)% = 75%.
How do you calculate RRR from RR?
The RR = (8/1000) / (10/1000) = 0.8 making the RRR = (1-0.8/1)=0.2 or 20%. Although this sounds impressive, the absolute risk reduction is only 0.01-0.008=. 002 or 0.2%. Thus the NNT is 1/0.002=500 patients....Toolkit.YesNoNot Exposed109901 more row
What is RRR in risk assessment?
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.
What does a relative risk of 0.3 mean?
An RR that is less than 1.00 means that the risk is lower in the exposed sample. An RR that is greater than 1.00 means that the risk is increased in the exposed sample. 3. An RR of, say, 0.3 can be expressed in plain English in many ways.
What does a risk ratio of 0.5 mean?
An odds ratio of 0.5 would mean that the exposed group has half, or 50%, of the odds of developing disease as the unexposed group. In other words, the exposure is protective against disease.
How do you calculate RRR or ARR?
If a person's AR of stroke, estimated from his age and other risk factors, is 0.25 without treatment but falls to 0.20 with treatment, the ARR is 25% – 20% = 5%. The RRR is (25% – 20%) / 25% = 20%. The NNT is 1 / 0.05 = 20.
What is RRR in pharmacy?
Prof. Mary Ferrill explains how to calculate RR, RRR (Relative RIsk Reduction), ARR (Absolute Risk Reduction), and NNT/NNH. She starts this video with a table about the exposure and outcome for treatments.
What does a relative risk of 1.5 mean?
What relative risk tells us. A relative risk that is greater than 1.0 shows that there is an increased risk among the people in Group A. • This means if the relative risk was 1.5, people in Group A would be 50% more likely than people in all other groups to die from a cause.
What is RRR in clinical trials?
Relative risk reduction for trial 1 The relative risk reduction (RRR), represents the difference in event rates expressed relative to (or proportionally of) the control event rate. It is usually expressed as a percentage.
What does a negative RRR mean?
Negative value: Absolute Risk Increase. ** For Relative Risk Reduction (RRR): Positive value: Relative Risk Reduction. Negative value: Relative Risk Increase.
What does a relative risk of 1.6 mean?
The odds ratio (OR) is the odds of an event in an experimental group relative to that in a control group. An RR or OR of 1.00 indicates that the risk is comparable in the two groups. A value greater than 1.00 indicates increased risk; a value lower than 1.00 indicates decreased risk.
What does a relative risk less than 1 mean?
A relative risk of one implies there is no difference of the event if the exposure has or has not occurred. If the relative risk is greater than 1, then the event is more likely to occur if there was exposure. If the relative risk is less than 1, then the event is less likely to occur if there was exposure.
What does a relative risk of 2.5 mean?
This means that. those in the control group were 2.5 times more likely to die than those in the treatment group. The relative risk is interpreted in terms of the risk of the group in the numerator.
What does risk ratio less than 1 mean?
decreased riskA risk ratio greater than 1.0 indicates an increased risk for the group in the numerator, usually the exposed group. A risk ratio less than 1.0 indicates a decreased risk for the exposed group, indicating that perhaps exposure actually protects against disease occurrence.
How do you interpret relative risk ratio?
A relative risk or odds ratio greater than one indicates an exposure to be harmful, while a value less than one indicates a protective effect. RR = 1.2 means exposed people are 20% more likely to be diseased, RR = 1.4 means 40% more likely. OR = 1.2 means that the odds of disease is 20% higher in exposed people.
What is relative risk?
Mathematically, it is the expressed as the incidence rate of the outcome in the exposed group,
What does RR 1 mean?
RR = 1 means that exposure does not affect the outcome. RR < 1 means that the risk of the outcome is decreased by the exposure, which can be called a "protective factor". RR > 1 means that the risk of the outcome is increased by the exposure.
Why is odds ratio used in case control?
In practice the odds ratio is commonly used for case-control studies, as the relative risk cannot be estimated. In fact, the odds ratio has much more common use in statistics, since logistic regression, often associated with clinical trials, works with the log of the odds ratio, not relative risk.
Is apixaban a risk factor?
In this case, apixaban is considered to be a protective factor rather than a risk factor because it is associated with causing a reduced risk of disease. Assuming the causal effect between the exposure and the outcome, values of RR can be interpreted as follows: RR = 1 means that exposure does not affect the outcome.
What is risk in statistics?
Unlike risk in lay terms, which is generally associated with a bad event, risk in statistical terms refers simply to the probability (usually statistical probability) that an event will occur, whether it be a good or a bad event.
Is RRR constant or variable?
RRR is usually constant across a range of absolute risks. But the ARR is higher and the NNT lower in people with higher absolute risks. If a person’s AR of stroke, estimated from his age and other risk factors, is 0.25 without treatment but falls to 0.20 with treatment, the ARR is 25% – 20% = 5%. The RRR is (25% – 20%) / 25% = 20%.