| Contamination | Some patients in the control arm of a trial may receive the intervention under study; this is referred to as contamination. A man in the control arm of a study of PSA testing may request the test from his GP if, for example, he hears about it from a friend in the intervention arm. |
| Flagging | A list of the individuals in a research study is sent to a registry. The records for those individuals are identified in the registry, and those records are “flagged” with the name of the study. Whenever events (death, cancer diagnosis) are added to the registry, study staff can be informed when events are added to a record flagged as being in their study. |
| Misattribution bias | Where a man’s underlying cause of death is not clear, previous diagnoses may be influential. So if a man had received a diagnosis of localised prostate cancer, this may be assumed to be the primary tumour when there are doubts about this after death. |
| MREC | Multi-centre Research Ethics Committee |
| PIAG | Patient Information Advisory Group |