A clinical decision support system (CDSS) includes a CDSS module (20) comprising a digital processing device (10) configured to store patient data (34) and a clinical guideline (22). The clinical guideline comprises connected nodes representing clinical workflow events, actions, or decisions, wherein contiguous groups of the nodes are grouped into care phases (40). The CDSS module is configured to associate patient data with patient care phases selected from the care phases of the clinical guideline, and determine patient care phase time intervals for the patient care phases based on acquisition date information for the patient data associated with the patient care phases. The selected patient care phase may be a care phase associated with a clinical guideline node associated with the new patient data, or may be a patient care phase that is consistent with the acquisition date for the new patient data.