Description
Veterans Health Information Systems and
Technology Architecture, VistA, is an integrated system
of software applications that directly supports patient
care at Veterans Health Administration (VHA) healthcare
facilities. VistA operates under the auspices of the
VHA Office of Information.
It connects VHA facilities' workstations and PCs with
nationally mandated and locally adapted software applications
that are accessed by end users through a graphical user
interface known as the Computerized Patient Record System
(CPRS).
Each VistA application generates at least one data file.
Within these files are the clinical, administrative,
and computer infrastructure-related data that support
day-to-day operations and contain patients' medical and
healthcare utilization histories, including data on demographics,
episodes of care, medicines, practitioner information,
diagnoses, procedures, etc. All patients treated at VA
Medical Centers are included in the files, which are
updated continuously at the point of care or as part
of administrative processes. Data are entered into VistA
by way of manual entry, bar codes, and automated instrumentation.
Some data are derived from central financial, personnel
and operational systems and distributed to local facilities'
VistA files.
VistA is the source of data for many VHA datasets or
databases of interest to researchers, for example:
• VHA Medical SAS ® Datasets
• VHA Decision Support System (DSS) National
Data Extracts
• Pharmacy Benefits Management (PBM) data
• VISN data warehouses
National and VISN-level databases that include VistA
data elements have well developed procedures for research
access. Before attempting local VistA access, investigators
will want to consider whether or not the national data
sources can meet their data needs. For summary information
about VA data sources, see the VIReC Web-based "Toolkit
for New Users of VA Data."
VistA History
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VistA evolved from the Decentralized Hospital Computer
Program (DHCP), the VHA's first electronic information
system, adopted in the 1980s. DHCP is still the core
of the health information system in individual medical
centers. To acknowledge the increasing technological
complexity of the VHA medical centers' information systems,
the name VistA was introduced in 1996. In 1997, the Computerized
Patient Record System (CPRS) graphic interface was introduced.
For clinicians, CPRS dramatically improves the ease of
recording clinical details and provides easy access to
patient charts. More historical details are available
in "VistA-U.S. Department of Veterans Affairs national-scale
HIS" by S.H. Brown, M.J. Lincoln, P.J. Groen, and
R.M. Kolodner [Int J Med Inf. 2003 Mar;69(2-3):135-56,
PMID 12810119 ].
The first guide for users of electronic VHA databases,
the Department of Veterans Affairs Databases Resources
Guide, was a five-volume set produced by Martha
Beattie, Ph.D., Ralph W. Swindle, Ph.D., Lynn A. Tomko,
B.A. and other authors. The set, known as the "Blue
Books," was produced with the support of Service
Directed Research project #91-009, awarded to Ralph Swindle
by the VA Health Services Research and Development Service.
Volume 5 of that set covers DHCP files. VistA has grown
in size and complexity, but the "Blue Books" still
hold valuable information regarding gaining access to
VA healthcare utilization data.
VistA Future
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VistA is in the midst of modernization, progressing
into an enterprise-wide information system based on Oracle,
Linux and Java. The goal of VistA modernization is to
move from an encounter-centric to a more patient-centric
information system. One benefit of the conversion, particularly
for data-driven decision making, will be more, and easier
access to, national stores of clinical data.
The keystone of the new system will be the Health Data
Repository (HDR). The HDR will be a national databank
for standardized, patient-specific clinical data. When
the HDR begins operations in 2005, clinical data that
are now dispersed over 128 individual VistA sites will
be aggregated in a central repository. VistA will more
rigorously enforce data standardization so that it will
be compliant with emerging healthcare data management
practices. Local variations will be "mapped" to
the standards so that historical data can be properly
represented to the HDR. Each patient's records will be
stored as a true longitudinal healthcare record.
Not every element of patient records will be stored
at the HDR. Registration, enrollment, and eligibility
data will be housed in a separate database, as will financial
data. Images like those produced by cardiology and radiology
tests will be stored locally, not sent to the HDR, though
the potential for a central repository of images is still
being considered. Nevertheless, the HDR will greatly
increase the amount of nationally compiled clinical data
available for analysis. For more on the future of VA
health information management, see the VHA Office of
Information's Health e Vet Web
page.
Selected elements of VistA clinical data, extracted
nationally, have recently become available from another
new source, the Financial and Clinical Data Marts (FCDM)
. VISN 16 is working with the VISN Support Service Center
to create and maintain the FCDM. The marts are enterprise-wide
relational databases with access to online analytical
processing tools for statistical analysis. DSS National
Data Extracts of Laboratory, Radiology and Pharmacy data
are the FCDM's first offering.
VistA provides a wealth of patient-level healthcare
utilization information about users of the nation's largest
integrated healthcare system. Like other administrative
databases, however, VistA files are organized to promote
patient care and facility management rather than research
analysis.
VistA files include information on all persons treated
at a VA Medical Center, across the full spectrum of inpatient
and outpatient care provided at that facility, and they
provide the most clinical detail of any VA database.
A limited set of data elements is extracted from all
VA facilities and merged to form national datasets, but
local facility VistA data files are still the only source
for most clinical, administrative and financial data.
Within the VistA system, each active patient is assigned
an Integration Control Number (ICN) as a unique identifier.
Investigators who find it necessary to access multiple
VistA files for data may find the ICN to be useful, along
with Social Security number, for linkage of local VistA
files. (ICN does not appear in national data extracts.)
Limitations
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The decentralized structure of the VistA system creates
challenges for data users. VistA files are maintained
locally, at the VA medical facilities or VISNs where
they are generated. Permission for access must be granted
by each facility included in an analysis. Access to identifiable,
patient-level data must also be approved by each local
Institutional Review Board (IRB). For multi-site studies,
gaining access can be a complex, time-consuming process.
Not all data elements necessary to an investigation
may be available from the same file. Furthermore, some
may exist only as text, not in a convenient, computable
format. In addition, some leeway exists for local modifications
in VistA software by local Information Resources Management
Services (IRMs). That is, some modules of software packages
may not apply at all sites and others may be customized
to suit local user expectations. Certain clinical data,
notably results from cardiac and other imaging tests,
may be created and stored outside of VistA and the software
applications used to create the images can vary from
site to site. Menus within software packages vary from
one VA site to another, complicating communication with
technical staffs. Because of procedural differences,
a data element may have a different meaning at one site
than it does at another. Fortunately, local variations
in VistA architecture are decreasing. Investigators will
nevertheless want to thoroughly explore and become familiar
with their data.
The complexity of and the site-to-site variations in
VistA files make local technical assistance a necessity.
Local IRM personnel, however, carry the burden of administering
and maintaining the local system, so locating technical
personnel available for a commitment to research can
be a challenge.
As with all healthcare utilization data, the application
of VistA data to healthcare policy questions requires
caution in interpretation. For example, the validity
of using administrative codes such as ICD-9-CM and CPT-4
codes to represent the clinical status of patients has
itself become the subject of inquiry. (See “Administrative
Databases and Outcomes Assessment: An Overview of Issues
and Potential Utility” by Sanjay K. Gandhi et al.
[J Managed Care Pharm 1999: 215-222, http://www.amcp.org/data/jmcp/JMCP=05_06_99.PDF]).
For a discussion of the accuracy of diagnostic coding
in general, see “Measuring Diagnoses: ICD Code
Accuracy” by Kimberly J. O'Malley, PhD et al. [Health
Services Research, Oct 2005;40(5):1620-1639, PMID:
16178999]. Documentation available from the Vista
Documentation Library for each of VistA's software
packages can provide clues to the context in which elements
are entered into the database. Invaluable consultations
with other VA data users on the best interpretation of
VA data are available through the HSRData
listserv.
More information on the utility of VistA data for research
can be found in the VIReC monograph, " VIReC
Insights: Veterans Health Information Systems and Technology
Architecture (VistA) as a Research Tool  .
Data
Quality
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When analyzing any healthcare claims or utilization
data, the question must always be asked whether the data
are sufficiently accurate and consistent to support analysis.
The Health Data and Informatics Program of the VHA's
Office of Information promotes VistA data quality, fostering
best practices for assuring uniformity of policy and
practice, but few studies have been designed specifically
to investigate the reliability and validity of VA data.
Articles from several studies that utilized VistA data
in their analyses mention some evidence of the validity
or reliability observed in the data. A discussion of
factors affecting VA data quality is included in VIReC's Research
User Guides to the Inpatient and Outpatient Medical
SAS Datasets.
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