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Table 6 Glossary

From: Multivariable risk prediction can greatly enhance the statistical power of clinical trial subgroup analysis

Risk-Benefit Prediction Model – Same as a Risk Prediction Model except factors that predict benefit of a specific treatment and those that predict harm from the treatment are also included.

Control Event Rate (CER) – Rate of bad outcomes in the control group.46

Pre-treatment risk – Risk of bad outcomes in the absence of treatment. In a clinical trial, pre-treatment risk is equivalent to the true control event rate (CER).

Experimental Event Rate (EER) – Rate of bad outcomes in the intervention group. 46

Relative Risk Reduction (RRR) – The proportional reduction in the rate of bad events between experiment (experimental event rate [EER]) and control (control event rate [CER]) patients in a trial, calculated as |EER – CER|/CER. 46

Absolute Risk Reduction (ARR) – The absolute arithmetic difference in event rates, |EER – CER|. 46

Number Needed to Treat (NNT) – The number of patients who need to be treated to prevent 1 additional bad outcome; calculated as 1/ARR.

  1. Risk Prediction Model – Predicting overall risk based upon combining information from multiple risk factors. Prediction models can be presented as full regression prediction model (such as predicted probability of death using APACHE), as a simple risk index (such as predicting birth outcomes using a 10 point APGAR score) or condensed into risk categories (low, medium, high peri-operative risk).
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BMC Medical Research Methodology

ISSN: 1471-2288

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