The magnetic resonance imaging 'rule of five': predicting the occurrence of relapse

In this study from the US, the researchers evaluated the ‘rule of five’ which recommends that subjects exhibiting at least five lesions over the baseline be referred for closer monitoring which has been used as an informal safety criterion with limited evaluation. Based on this the study was to determine the best threshold for the rule and to demonstrate its predictive validity for determining the risk of further relapses for MS trials.

Using patient data from a phase II clinical trial, the researchers used logistic regression modelling. They used rate ratios and receiver operating characteristics curves to determine the predictive validity. They found that the best definition of a threshold constituted five lesions over the baseline. 35% of patients broke this and therefore increased the odds on an imminent relapse by a factor of 3.2. Overall, having five or more lesions from baseline was found to be a significant predictor of an imminent relapse.

Authors: Morgan CJ, Ranjan A

Source: Mult Scler. 2013 Apr 23. [Epub ahead of print]

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