I recently read the long-term follow-up results from the NLST lung cancer screening trial, which got me thinking about how trial results can change over time as the initial benefits of an intervention wear off. To explore this idea, I created a simple simulation to show how the efficacy signal can get diluted as more years of data are added. In the original NLST study, screening with chest CTs showed clear benefits for lung cancer survival after 3 years, but after 12 years of follow-up, the difference in survival between the screened and unscreened groups was no longer statistically significant. My simulation used a toy example with a blood sugar-lowering medication to demonstrate how this can happen.
See the full details on Google Colab: link