Traditional methods for analysing clinical and epidemiological data have focused on the first occurrence of the outcome or event being measured. These methods can be unsuitable for analysing recurring events because a first event may signal another one; that is, recurrent events are not independent of each other.

A new study focused on recurring events in CTC's multicentre trial, LIPID, which had shown that lipid lowering with a statin prevented a coronary event. We investigated recurrent events and whether risk factors were different for first and recurrent events. A semiparametric proportional-hazards model and a parametric conditional model were both found to be useful tools for exploring the biological cardiovascular process. The analysis also showed that the study drug, pravastatin, prevented first and second cardiovasacular events to a similar degree.