Another important classification of a CDSS is based on the timing of its use. Physicians use these systems at point of care to help them as they are dealing with a patient, with the timing of use being either pre-diagnosis, during diagnosis, or post diagnosis. Pre-diagnosis CDSS systems are used to help the physician prepare the diagnoses. CDSS used during diagnosis help review and filter the physician's preliminary diagnostic choices to improve their final results. Post-diagnosis CDSS systems are used to mine data to derive connections between patients and their past medical history and clinical research to predict future events. As of 2012 it has been claimed that decision support will begin to replace clinicians in common tasks in the future.