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# Why odds ratio can estimate risk ratio

Why Odds Ratio Can Estimate Risk Ratio: A Comprehensive Review

Understanding the relationship between odds ratio and risk ratio is crucial in various fields, especially in epidemiology and medical research. This article aims to provide a clear and concise explanation of why odds ratio can estimate risk ratio effectively. By highlighting the positive aspects and benefits of this estimation method, we will explore the conditions under which odds ratio can be used to estimate risk ratio accurately.

I. Understanding Odds Ratio and Risk Ratio:

1. Definition of Odds Ratio:

• Odds ratio is a statistical measure that compares the odds of an event occurring in one group to the odds of it occurring in another group.
• It is commonly used in case-control studies and logistic regression analysis.
2. Definition of Risk Ratio:

• Risk ratio, also known as relative risk, compares the probability of an event occurring in one group to the probability of it occurring in another group.
• It is commonly used in cohort studies and clinical trials.

II. Positive Aspects of Estimating Risk Ratio using Odds Ratio:

1. Practicality:

• Odds ratio can be easily calculated using data from case-control studies, where the prevalence of the outcome is known.
• Risk ratio, on the other hand, requires data from
When the risks (or odds) in the two groups being compared are both small (say less than 20%) then the odds will approximate to the risks and the odds ratio will approximate to the relative risk.

## Can you convert odds ratio to risk ratio?

The simplest way to ensure that the interpretation is correct is to first convert the odds into a risk. For example, when the odds are 1:10, or 0.1, one person will have the event for every 10 who do not, and, using the formula, the risk of the event is 0.1/(1+0.1) = 0.091.

## Can you use odds ratio to estimate the risk ratio if this is a case-control study?

Key Concept: In a study that is designed and conducted as a case-control study, you cannot calculate incidence. Therefore, you cannot calculate risk ratio or risk difference. You can only calculate an odds ratio. However, in certain situations a case-control study is the only feasible study design.

## Would you say that your odds ratio is an accurate approximation of the risk ratio?

As a result, risks, rates, risk ratios or rate ratios cannot be calculated from the typical case-control study. However, you can calculate an odds ratio and interpret it as an approximation of the risk ratio, particularly when the disease is uncommon in the population.

## When an odds ratio is used to estimate the relative risk quizlet?

When can OR be used to estimate RR? The odds ratio always approximates the relative risk if the disease is frequent. In a cohort study of obesity and myocardial infarction, the odds ratio was calculated to be 4.5 while the relative risk was 2.5.

## Can odds ratio and relative risk be the same?

When the outcome is rare (typically <10%), the value of OR is not too different from that of RR, and the two can be used interchangeably irrespective of whether the risk is lower [Table 3b] or higher [Table 3c] in the exposed group as compared to the unexposed.

## Is relative risk the same as rate ratio?

Risk ratio: ratio of the risk of an event in one group (exposure or intervention) to that in another group (control). So it depends on your definitions of rate and risk. The term "relative risk" is sometimes used as a synonym for risk ratio, and rate ratio is one of the relative risk measures too.

#### In what case will the relative risk be similar to the odds ratio?

If the study outcome is rare among those exposed (Table 1), then A will be small relative to B, so the risk (A/[A + B]) will be close to the odds (A/B). Similarly, if the outcome is rare among those not exposed, then C will be small relative to D and [C/(C + D)] will be close to (C/D).

#### Is odds ratio a relative measure of association?

Odds ratios (OR) are commonly reported in the medical literature as the measure of association between exposure and outcome. However, it is relative risk that people more intuitively understand as a measure of association.

#### Should relative risk and odds ratio be the same?

For example: “The odds ratio is approximately the same as the relative risk if the outcome of interest is rare. For common events, however, they can be quite different.”3 How close is “approximately the same,” how uncommon does an event have to be to qualify as “rare,” and how different is “quite different”?

#### What is the difference between odds ratio and relative risk in meta analysis?

The risk ratio (RR, or relative risk) is the ratio of the risk of an event in the two groups, whereas the odds ratio (OR) is the ratio of the odds of an event (see Box 6.4. a). For both measures a value of 1 indicates that the estimated effects are the same for both interventions.

#### What is the difference between odds ratio and relative risk reddit?

I understand that odds ratio is the ratio is the odds of two groups (ie positive outcomes/negative outcomes), where as relative risk is the ratio of risk of two groups (ie positive outcomes/all outcomes).

#### Why do we use odds ratio over relative risk?

When the outcome is not rare in the population, if the odds ratio is used to estimate the relative risk it will overstate the effect of the treatment on the outcome measure. The odds ratio will be greater than the relative risk if the relative risk is greater than one and less than the relative risk otherwise.

#### How do you calculate odds ratio and relative risk?

Thus the odds ratio is (a/b) / (c/d) which simplifies to ad/bc. This is compared to the relative risk which is (a / (a+b)) / (c / (c+d)). If the disease condition (event) is rare, then the odds ratio and relative risk may be comparable, but the odds ratio will overestimate the risk if the disease is more common.

## FAQ

What does an odds ratio of 2.5 mean?
For example, OR = 2.50 could be interpreted as the first group having “150% greater odds than” or “2.5 times the odds of” the second group.
What is the formula for the odds ratio of risk?
The simplest way to ensure that the interpretation is correct is to first convert the odds into a risk. For example, when the odds are 1:10, or 0.1, one person will have the event for every 10 who do not, and, using the formula, the risk of the event is 0.1/(1+0.1) = 0.091.
How do you know when to use relative risk vs odds ratio?
The relative risk (also known as risk ratio [RR]) is the ratio of risk of an event in one group (e.g., exposed group) versus the risk of the event in the other group (e.g., nonexposed group). The odds ratio (OR) is the ratio of odds of an event in one group versus the odds of the event in the other group.
What is the difference between odds ratio and mean difference?
Examples include odds ratios (which compare the odds of an event between two groups) and mean differences (which compare mean values between two groups). Effect measures can broadly be divided into ratio measures and difference measures (sometimes also called relative and absolute measures, respectively).
What is the difference between risk ratio and risk difference?
A risk ratio is the probability (or risk) of an outcome in one group divided by the probability in another, whereas the risk difference is the probability of an outcome in one group minus the probability in another.
Do you use odds ratio OR relative risk in case-control study?
Key Concept: In a study that is designed and conducted as a case-control study, you cannot calculate incidence. Therefore, you cannot calculate risk ratio or risk difference. You can only calculate an odds ratio. However, in certain situations a case-control study is the only feasible study design.
What is the relationship between risk ratio and rate ratio?
Rate ratio: ratio of the rate of an event in one group (exposure or intervention) to that in another group (control). Risk ratio: ratio of the risk of an event in one group (exposure or intervention) to that in another group (control).

## Why odds ratio can estimate risk ratio

 What is the relationship between the terms relative risk and association? Frequently, the term "relative risk" is used to encompass all of these. These relative measures give an indication of the "strength of association." How do you decide between odds ratio and relative risk? The relative risk (also known as risk ratio [RR]) is the ratio of risk of an event in one group (e.g., exposed group) versus the risk of the event in the other group (e.g., nonexposed group). The odds ratio (OR) is the ratio of odds of an event in one group versus the odds of the event in the other group. What is the difference between rate ratio and odds ratio? The normally used odds ratio from a classical case-control study measures the association between genotype and being diseased. In comparison, under incidence density sampling, the incidence rate ratio measures the association between genotype and becoming diseased. What is the difference between odds ratio and correlation? At first glance, odds ratio analysis and correlation analysis seem to answer similar questions, however they differ in the type of outcomes each seeks to analyze. Odds ratio analysis looks at discrete, or binary outcomes, whereas correlation analysis examines continuous outcomes. How do you know when to use odds ratio? When is it used? Odds ratios are used to compare the relative odds of the occurrence of the outcome of interest (e.g. disease or disorder), given exposure to the variable of interest (e.g. health characteristic, aspect of medical history). How can you determine whether an odds ratio OR relative risk is statistically significant using a confidence interval? If the RR, OR, or HR = 1, or the confidence interval (CI) = 1, then there is no statistically significant difference between treatment and control groups. If the RR/OR/HR >1, and the CI does not include 1, events are significantly more likely in the treatment than the control group. Can you calculate risk ratio from odds ratio? The simplest way to ensure that the interpretation is correct is to first convert the odds into a risk. For example, when the odds are 1:10, or 0.1, one person will have the event for every 10 who do not, and, using the formula, the risk of the event is 0.1/(1+0.1) = 0.091.
• Is odds ratio a direct measure of risk?
• Odds ratios (OR) are commonly reported in the medical literature as the measure of association between exposure and outcome. However, it is relative risk that people more intuitively understand as a measure of association. Relative risk can be directly determined in a cohort study by calculating a risk ratio (RR).
• Why is the odds ratio quite different from the risk ratio?
• The relative risk (also known as risk ratio [RR]) is the ratio of risk of an event in one group (e.g., exposed group) versus the risk of the event in the other group (e.g., nonexposed group). The odds ratio (OR) is the ratio of odds of an event in one group versus the odds of the event in the other group.
• Why is the odds ratio an indirect measure of risk?
• In case control studies the odds ratio (OR) is the measure of the association between the frequency of an exposure and the frequency of an outcome. The OR is an indirect measure of risk in case control studies because incidence rates cannot be calculated.
• Should I use odds ratio OR relative risk?
• Odds ratios (OR) are commonly reported in the medical literature as the measure of association between exposure and outcome. However, it is relative risk that people more intuitively understand as a measure of association. Relative risk can be directly determined in a cohort study by calculating a risk ratio (RR).
• Do you use odds ratio OR relative risk in case control study?
• Key Concept: In a study that is designed and conducted as a case-control study, you cannot calculate incidence. Therefore, you cannot calculate risk ratio or risk difference. You can only calculate an odds ratio. However, in certain situations a case-control study is the only feasible study design.
• When should relative risk be used?
• Relative Risk (RR) is often used when the study involves comparing the likelihood, or chance, of an event occurring between two groups. Relative Risk is considered a descriptive statistic, not an inferential statistic; as it does not determine statistical significance.

February 8, 2024
February 8, 2024
February 8, 2024