Mechanisms are provided for caching patient information in a variable list and using the variable list to evaluate patient rules. The mechanisms generate a patient registry comprising a plurality of patient registry records, each patient registry record being associated with a corresponding patient and comprising personal and medical information about the corresponding patient. The mechanisms compile at least one variable list for an input variable of one or more clinical rules. The variable list comprises a plurality of instances of personal and medical information from the plurality of sources that are associated with the variable. The mechanisms also process at least one clinical rule in the one or more clinical rules that references the variable as a criteria for evaluating the at least one clinical rule, based on the variable list associated with the variable to determine if the criteria is satisfied by one or more instances.