Loeb S, Vonesh EF, Metter EJ, Carter HB, Gann PH, and Catalona WJ.
“What is the true number-needed-to-screen and treat to save a life with prostate-specific antigen (PSA) testing?”
Journal of Clinical Oncology January 2011; 29: 464.
Link: http://www.ncbi.nlm.nih.gov/pubmed/21189374
Although number needed to screen (NNS) and number needed to treat (NNT) are useful statistics to assess the benefits and harms of an intervention, in a survival study setting such as the European Randomized Study of Screening for Prostate Cancer (ERSPC), NNS and NNT are time specific, and reporting values at one time point may lead to misinterpretation of results. We developed a model predicting that the NNS in this trial would decrease from 837 at year 10 to 503 at year 12, and NNT would decrease from 29 to 18.