1. A clinical data management system comprising: a plurality of staging databases comprising clinical study level staging databases and pooled cross-study databases storing clinical data, study metadata, study properties, and clinical reference tables; a plurality of distributed digital data processing servers configured to import and adapt source data from disparate clinical site sources into the staging databases at refresh intervals of uniform frequency, wherein the distributed digital data processing servers capture and maintain an audit trail of source data imported into the staging databases; user interfaces and external system interfaces comprising a plurality of input modules for enabling a user of the system to input one or more study-specific changes to data model standards and mapsets and a plurality of delivery and visualization modules configured for reporting and displaying processed clinical study data mapped into the staging databases; and a study data mapper that maintains a plurality of data models comprising a study metadata model, a clinical data model, a discrepancy data model, and a reporting support data model, wherein the study data mapper is configured to: map data from the staging databases into the data models, and map data from the data models into data delivery databases, wherein the data models act as consistent core data structures of data across said disparate clinical site sources, said consistent core data structures allowing for study-specific additions but not allowing for destructive changes to core variables or tables; perform said mapping into the data models by using metadata defining the data models for transforming data from each staging database to one or more data models according to one or more mapsets, wherein each mapset specifies how data for a clinical study is to be transformed into a standard set of target tables; electronically transmit data from one or more staging databases into the clinical data models, wherein each table of the clinical data models includes a primary key and a surrogate key, in which the primary key defines the uniqueness of a record within a table; determine the compliance of the clinical data model with clinical data model standards; electronically transmit non-compliant data into the discrepancy data model; and add unique identifiers to data model tables to identify change deltas; add original code and decode values to data model tables; add data status flags to the data models to assist status and query management; and insert a source reference field into said data models to provide traceability from said clinical site sources to the data models.