When looking for factors that predict the future recurrence of a past health outcome, many studies are done poorly. Ideally, studies that seek to identify such predictive factors should enrol participants at a consistent point in the inception of their disease.

For example, in a prognostic cohort study looking at recurrence of low back pain, participants could be enrolled at the end of their first episode of back pain and followed to see when their next episode of low back pain occurs. The same study could also identify factors that predict the likelihood of recurrence of the low back pain.