The Visit-Data Warehouse: Enabling Novel Secondary Use of Health Information
Exchange Data
Authors: Fleischman William , Lowry Tina , Shapiro Jason 
Published: December 2014

Introduction/Objectives: Health Information Exchange (HIE) efforts face challenges
with data quality and performance, and this becomes especially problematic when data is
leveraged for uses beyond primary clinical use. We describe a secondary data
infrastructure focusing on patient-encounter, nonclinical data that was built on top of
a functioning HIE platform to support novel secondary data uses and prevent potentially
negative impacts these uses might have otherwise had on HIE system
performance.Background: HIE efforts have generally formed for the primary clinical use
of individual clinical providers searching for data on individual patients under their
care, but many secondary uses have been proposed and are being piloted to support care
management, quality improvement, and public health.Description of the HIE and Base
Infrastructure: This infrastructure review describes a module built into the Healthix
HIE. Healthix, based in the New York metropolitan region, comprises 107 participating
organizations with 29,946 acute-care beds in 383 facilities, and includes more than 9.2
million unique patients. The primary infrastructure is based on the InterSystems
proprietary Caché data model distributed across servers in multiple locations, and uses
a master patient index to link individual patients’ records across multiple sites. We
built a parallel platform, the “visit data warehouse,” of patient encounter data
(demographics, date, time, and type of visit) using a relational database model to allow
accessibility using standard database tools and flexibility for developing secondary
data use cases. These four secondary use cases include the following: (1) tracking
encounter-based metrics in a newly established geriatric emergency department (ED), (2)
creating a dashboard to provide a visual display as well as a tabular output of
near-real-time de-identified encounter data from the data warehouse, (3) tracking
frequent ED users as part of a regional-approach to case management intervention, and
(4) improving an existing quality improvement program that analyzes patients with return
visits to EDs within 72 hours of discharge.Results/Lessons Learned: Setting up a
separate, near-real-time, encounters-based relational database to complement an HIE
built on a hierarchical database is feasible, and may be necessary to support many
secondary uses of HIE data. As of November 2014, the visit-data warehouse (VDW) built by
Healthix is undergoing technical validation testing and updates on an hourly basis. We
had to address data integrity issues with both nonstandard and missing HL7 messages
because of varied HL7 implementation across the HIE. Also, given our HIEs federated
structure, some sites expressed concerns regarding data centralization for the VDW. An
established and stable HIE governance structure was critical in overcoming this initial
reluctance.Conclusions: As secondary use of HIE data becomes more prevalent, it may be
increasingly necessary to build separate infrastructure to support secondary use without
compromising performance. More research is needed to determine optimal ways of building
such infrastructure and validating its use for secondary purposes.