Related Experiment Video
Updated: Jun 23, 2026
05:37
An R-Based Landscape Validation of a Competing Risk Model
Published on: September 16, 2022
Relative risk, absolute risk and number needed to treat: basic concepts
1Centro de Estudos de Medicina Baseada na Evidência, Faculdade de Medicina de Lisboa, Lisboa, Portugal. avc@fm.ul.pt
Summary
This paper introduces key concepts for analyzing medical literature, explaining relative risk reduction (RRR), absolute risk reduction (ARR), and number needed to treat (NNT) for evaluating therapeutic interventions.
Area of Science:
- Medical research methodology
- Clinical trial analysis
- Evidence-based medicine
Background:
- Therapeutic intervention benefits are typically assessed via clinical trials.
- Clinical trials compare experimental groups to control groups (placebo or active agents).
- Measures of association like RRR, ARR, and NNT quantify benefits and harms.
Purpose of the Study:
- To introduce fundamental concepts for analyzing medical literature.
- To explain relative risk reduction (RRR), absolute risk reduction (ARR), and number needed to treat (NNT).
- To empower readers to critically evaluate medical literature and inform decision-making.
Main Methods:
- Explanation of basic methodological concepts in medical literature analysis.
- Utilizing published studies to illustrate concepts.
- Focus on relative risk reduction (RRR), absolute risk reduction (ARR), and number needed to treat (NNT).
Main Results:
- Provides a clear understanding of RRR, ARR, and NNT.
- Demonstrates how these measures are used in clinical trial interpretation.
- Establishes a foundation for critical appraisal of medical research.
Conclusions:
- Understanding RRR, ARR, and NNT is crucial for interpreting clinical trial results.
- This foundational knowledge enables informed decision-making based on medical literature.
- This paper serves as an introductory guide to essential statistical concepts in medicine.
Related Concept Videos
01:12Relative Risk
Relative risk (RR) is a statistical measure commonly used in epidemiology to compare the likelihood of a particular event occurring between two groups. This metric is important for evaluating the relationship between exposure to a specific risk factor and the probability of a particular outcome. It plays a crucial role in medical research, public health studies, and risk assessment. Relative risk quantifies how much more (or less) likely an event is to occur in an exposed group compared to an...
01:23Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches
Biopharmaceutical studies constitute a vital field aiming to enhance drug delivery methods and refine therapeutic approaches, drawing upon diverse interdisciplinary knowledge. In research methodologies, the choice between controlled and non-controlled studies significantly influences the study's reliability and accuracy.
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast, controlled...
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast, controlled...
01:09Odds Ratio
The odds ratio (OR) is a statistical measure used extensively in epidemiology and research to quantify the strength of association between exposure and outcome across different groups. Unlike relative risk, which compares the probabilities of an event occurring, the odds ratio compares the odds of an event occurring in the exposed group to the odds of it occurring in the unexposed group. The odds, in this context, are calculated as the probability of the event happening divided by the...
01:12Hazard Ratio
The hazard ratio (HR) is a widely used measure in clinical trials to compare the risk of events, such as death or disease recurrence, between two groups over time. It reflects the ratio of hazard rates—the instantaneous risk of the event occurring—between a treatment group and a control group. This measure provides valuable insights into the relative effectiveness of a treatment by assessing how the risk of an event differs between the two groups.
For example, in a clinical trial evaluating a...
For example, in a clinical trial evaluating a...
01:49Probability Laws
Overview
01:11Hazard Rate
The hazard rate, also known as the hazard function or failure rate, is a statistical measure used to describe the instantaneous rate at which an event occurs, given that the event has not yet happened. From a probabilistic perspective, it represents the likelihood that a subject will experience the event in a very small time interval, conditional on surviving up to the beginning of that interval. In terms of frequency, the hazard rate can be viewed as the ratio of the number of events to the...