RLO: Numbers needed to treat (NNT) and numbers needed to harm (NNH)



Title/link Description
Relative Risk Reduction and Absolute Risk Reduction (RLO) This RLO considers how to measure and interpret the magnitude of effect in clinical trial results using relative risk reduction (RRR) and absolute risk reduction (ARR).
Determining the clinical importance of trial results (RLO) Demonstrates how to interpret and use clinical trial data (ARR, RRR, NNT, NNH, and confidence intervals) in practice.
Surrogate Outcomes (RLO) Considers the type of evidence which should be used when making decisions about patient care.
Sensitivity and Specificity (RLO) Explains how diagnostic test accuracy is described by the terms sensitivity and specificity. Sensitivity describes the accuracy of the test in detecting disease. Specificity describes the accuracy of the test in detecting health.
Confidence Intervals (RLO) Defines the term 'confidence intervals' and demonstrates how they can be used to determine the significance and range of possible sizes of a treatment effect.
Barratt A et al. Tips for learners of evidence-based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to treat. CMAJ 2004;171 (4):353-358  
Watt E, Burrell A. Implementing NNTs. Volume 1, number 7 available at www.evidence-based-medicine.co.uk  



RLO Transcript (Rich Text Format 45kb)