A computer apparatus to assist diagnosis of a patient including: a memory storing instructions for execution and an output for results of a processor that provides a patient builder and a vertex filter. Where the builder inputs patient data including historical clinical； and open data, and to create a patient clinical object, PCO, graph； and a full patient graph PCOs for each patient. The filter includes: a context builder to build a domain based on a specification and open data； a context-based vertex filter ranking vertices in the full patient graph based on domain affiliation, retaining any vertices with high domain affiliation； and computing a similarity between the patient PCO and other PCOs in the full patient graph using the retained vertices； and a patient ranker ranks the PCOs according to t similarity Where the output lists patients similar to the patient to suggest patient diagnoses.
