All Lines Is the Right Approach: Selecting Patient Lines of Therapy for an External Comparator Arm.

Summary: Imagine you are testing a new medicine but only have a group of people taking it, with no "control" group for comparison. To figure out if the medicine works, scientists look at past medical records to build a matching control group. But patients often try many different treatments (called "lines of therapy") over time. Which one should scientists pick to compare?

This study tested four ways to choose. They found that using all the times a patient was eligible for a treatment works best. Picking just the last or a random time gave wrong answers. Using "all lines" gives the fairest and most accurate results.