Right truncation and data on time-to-onset of adverse drug reactions from spontaneous reporting databases. Some patients who were exposed to the drug and who will eventually develop the adverse drug reaction may do it after the time of analysis. Here, in these hypothetical examples, the patient on the top line is included in the database because he experienced the adverse drug reaction before the time of analysis, i.e. x
1 ≤ t
1. The patient on the bottom line is not included in the database because he has not yet experienced the adverse drug reaction, i.e. , when data are analyzed.