1. A computer-implemented method for processing a personal health record (PHR) including a plurality of events each having a time stamp, the method comprising: creating a plurality of event-concept pairs by mapping each of the plurality of events in the PHR to a corresponding health concept among a plurality of health concepts; assigning to each of the plurality of event-concept pairs the time stamp of the event corresponding to the event-concept pair; identifying associations among the plurality of event-concept pairs, wherein the plurality of health concepts are categorized into a plurality of categories, wherein identifying associations involves referencing a database of stored information specifying associations between health concepts among the plurality of health concepts, wherein at least some of the specified associations are between health concepts that are in different categories in the plurality of categories, and wherein the plurality of categories are medical tests, diseases, symptoms, medications, and treatments; identifying an associative subset of event-concept pairs among the plurality of event-concept pairs, wherein the associative subset includes those events in the PHR that are either associated with a header concept or are associated with another event within the associative subset, and wherein the associated subset includes health concepts that are in different categories of the plurality of categories; and linking a plurality of members of the associative subset of event-concept pairs to form a thread, wherein the thread presents a relationship among the plurality of members of the associative subset of event-concept pairs, wherein creating, assigning, identifying associations, and linking are performed by a computer system.