Letters2 February 2010
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    We applaud Cook and Ridker (1) for their clear discussion of reclassification measures and recent developments in judging the incremental value of a biomarker for prediction of outcome. A key area of application is in cardiovascular disease, in which the time horizon is typically 10 years. One important problem recognized by Cook and Ridker is that not all persons will have follow-up completed until 10 years. Kaplan–Meier curves and Cox regression analysis were introduced long ago to deal with such censored observations. Reclassification measures, such as the net reclassification index (NRI) (2), have been proposed for binary ...


    • 1. Cook NRRidker PMAdvances in measuring the effect of individual predictors of cardiovascular risk: the role of reclassification measures. Ann Intern Med2009;150:795-802. [PMID: 19487714] LinkGoogle Scholar
    • 2. Pencina MJ, D'Agostino RB Sr, D'Agostino RB Jr, Vasan RS. Evaluating the added predictive ability of a new marker: from area under the ROC curve to reclassification and beyond. Stat Med. 2008;27:157-72; discussion 207-12. [PMID: 17569110] Google Scholar
    • 3. Viallon VRagusa SClavel-Chapelon FBénichou JHow to evaluate the calibration of a disease risk prediction tool. Stat Med2009;28:901-16. [PMID: 19156698] CrossrefMedlineGoogle Scholar
    • 4. Pepe MSFeng ZGu JWComments on ‘Evaluating the added predictive ability of a new marker: From area under the ROC curve to reclassification and beyond’ by M. J. Pencina et al., Statistics in Medicine (DOI: 10.1002/sim.2929). Stat Med2008;27:173-81. [PMID: 17671958] CrossrefMedlineGoogle Scholar