What is ESTIMATED Relative Risk (ERR)?

Estimated Relative Risk refers to a statistical measure used to compare the risk of a certain event occurring in two different groups, particularly when working with observational data where true relative risk cannot be calculated directly as it would be in a randomized controlled trial. It’s an estimate derived from observational data, typically from cohort or case-control studies. Key Points About Estimated Relative Risk: Definition: It’s the estimated ratio of the probability of the event occurring in the exposed group to the probability of the event occurring in the non-exposed (or control) group. Calculation in Cohort Studies: In cohort studies, estimated relative risk is often calculated as the incidence rate (or risk) of the event in the exposed group divided by the incidence rate in the non-exposed group. Use in Case-Control Studies: In case-control studies, where incidence rates cannot be directly calculated, the odds ratio is often used as an estimate of relative risk, especially when the outcome is rare. Interpretation: An estimated relative risk greater than 1 suggests a higher risk of the event in the exposed group compared to the control group, while a value less than 1 suggests a lower risk. Confidence Intervals: It’s important to calculate confidence intervals for the estimated relative risk to understand the precision of the estimate. Limitations: The accuracy of the estimated relative risk can be affected by biases and confounders in the study design, especially in observational studies. Adjustments: Statistical adjustments (like stratification or multivariable analysis) are often used to control for potential confounding variables. Conclusion: The estimated relative risk is a crucial concept in epidemiology and medical research, providing insights into the association between exposures and outcomes. However, it’s essential to interpret it within the context of the study’s design and the potential for bias and confounding factors. Problem: What would be the absolute and relative risk reduction if the incidence of heart attack was 2% in the intervention group and 7% in the control group? A prospective study recruited 10,000 smokers and 10,000 non-smokers aged 30 to 39 and followed them for 20 years. The cases of throat cancer are shown in this table. no Cancer Cancer Relative Frequency(%) Smokers 9800 200 2.0% Non-Smokers 9950 50 0.5% What is the estimated relative risk of throat cancer for smokers vs. non-smokers?