Dear Sirs.

I am working with the  R packages Hmisc and PredictABEL to make NRI estimates from my Cox models with and without a specific biomarker.
According to Pencina et al (Statistics in Medicine 2010, DOI: 0.1002/sim.4085 ), a continuous/non-categorical NRI (NRI>0) is to be used when there are no obvious reason to categorize risk, such as the risk of future cardiovascular events in patients with established cardiovascular disease.

My question is therefore: Which value(s) are to be used in the calculation of continuous NRI from the output in Hmisc or in PredictABEL? Does continuous NRI equal total NRI in the output?



Yours sincerely

Gard Frodahl T. Svingen
PhD student
the University of Bergen
Bergen, Norway


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