Data Warehouse Case Study Essay

History of the CDR When the project began in 199596, the CDR, initially referred to as the clinical research info menial, was intended to support and enhance clinical research at the University of Virginia by providing clinicians, students, and researchers with direct, rapid access to retrospective clinical and administrative patient role information. Re? ecting this intent, the system was funded by the School of Medicine and ho social occasiond in the Academic Computing Health Sciences group, which is distinct from the medical centers IT group. With considerable assistance and cooperation from info owners and stewards, legacy data from several different sources were irritated into a single relational database and periodically updated. Authorized users accessed the CDR through a standard Web browser and viewed or downloaded data to their personalized computers for further analysis.Initially, accent mark was placed on getting the CDR running as quickly as possible and with a min imum of resources consequently, extensive transformation of data to an enterprise data model was not performed. The CDR project team consists of 2. 53. 0 FTEs (full-time equivalents) one developer, one developer-database administrator, and portions of analyst, clinician, and administrative FTEs. To date, the costs of developing and operating the CDR have been approximately $200,000 per year, underwritten by the School of Medicine.Over the course of the project, there have been signi? cant enhancements to the user interface, incorporation of additional data sources, and the development of an integrated data model. There has overly been increasing interest in using the CDR to serve a broader audience than researchers and to support management and administrative exploitsto meet the challenge of providing a way for bothone with a need to knowat every level of the organizationaccess to accurate and timely data necessary to support effective decision making, clinical research, and att end improvement.In the atomic number 18a of education, the CDR has become a core teaching resource for the part of Health Evaluation Sciences masters program and for the School of Nursing. Students use the CDR to understand and master informatics issues such as data capture, vocabularies, and coding, as well as to perform Case instruction A Data Warehouse for an Academic Medical Center 167 exploratory analyses of healthcare questions. Starting in Spring 2001, the CDR will also be introduced into the universitys undergraduate medical curriculum. System Description Following is a brief overview of the CDR application as it exists at the University of Virginia.System Architecture. The CDR is a relational data storage warehouse that resides on a Dell PowerEdge 1300 (Dual Intel 400MHz processors, 512MB RAM) running the Linux operating system and Sybase 11. 9. 1 relational database management system. For storage, the system uses a Dell Powervault 201S 236GB RAID Disk Array. As of Octo ber 2000, the database contained 23GB of information about 5. 4 million patient visits (16GB visit data, 7GB testing groundoratory results). Data loading into Sybase is achieved using custom Practical Extraction and Report terminology (Perl) programs. CDR Contents. The CDR currently draws data from four independent systems (see Table 1).In addition, a number of derived values (for example, number of days to next inpatient visit, number of multiplication a diagnostic code is used in various settings) are computed to provide summary information for selected data elements. Data from each of these source systems are integrated into the CDRs data model. In addition to the current contents listed in Table 1, users and the CDR project team have identi? ed additional data elements that might be incorporated Table 1. Contents of the CDR Type of Data Inpatient, outpatient visits Source of Data Shared Medical Systems DescriptionPatient registration and demographic data, diagnoses, procedures , unit and census information, billing transactions, including medications, costs, charges, reimbursement, insurance information Physician billing transactions from inpatient and outpatient visits, diagnoses, and procedures science laboratory test results Available Dates Jul 1993Jun 2000 Professional billing Laboratory results Cardiac surgery IDX billing system HL-7 messages from SunQuest Lab System Cardiac surgery outcomes data (de? ned by Society of Thoracic Surgeons Oct 1992Jun 2000 Jan 1996Jun 2000 Clinical details for pectoral surgery casesJul 1993Jun 2000 168 Einbinder, Scully, Pates, Schubart, Reynolds into the CDR, including microbiology results, discharge summaries (and other narrative data), outpatient prescribing information, order entry details, and tumor registry information. As of October 2000, we have just ? nished incorporating death registry data from the Virginia Department of Health into the CDR. These data will provide our users with direct access to more compr ehensive mortality outcomes data than are contained in local information systems, which loosely are restricted to an in-hospital death indicator.User Interface. The user interface runs in a standard Web browser and consists of a data dictionary, a parade of common gateway interface (CGI) programs implemented using the C programming language, and JavaScriptenabled HTML pages. Structured query language (SQL) statements are generated automatically in solvent to point-and-click actions by the user, enabling submission of ad hoc queries without prior knowledge of SQL. The SQL queries are sent to the CGI programs that query the database and return results in dynamically created HTML pages.The entire process is controlled by the contents of the data dictionary, which is used to format SQL results, set up HTML links for data drill-down, and provide on-line help. Data may be downloaded immediately into Microsoft Excel or another analysis tool on the users workstation. Query Formulation. Mo st CDR users use the Guided Query function to retrieve data. This process involves three steps 1. De? ne a population of interest by setting conditions, for example, date ranges, diagnostic codes, physician identi? ers, service locations, and lab test codes or values. 2.Submit the query, specifying how much data the CDR should return (all matching data or a speci? ed number of rows). 3. After the CDR returns the population of interest, use the Report Menu to explore various attributes of the population on a case-by-case or group level. Custom reports can also be de? ned, and the results of any report can be downloaded into Microsoft Excel, Access, or other analysis tool. Generally, the query process requires several iterations to modify the population conditions or report options. In addition, browse the data may help the user generate ideas for additional queries.We believe that it is helpful for end users to go through this query process themselvesto directly subscribe to the dat a. However, many users, especially those with a pressing need for data for a meeting, report, or grant, prefer to use CDR team members as intermediaries or analysts. To date, we have seek to meet this preference, but as query volume increases, our ability to provide data in a timely manner may fall off. Security. A steering committee of clinicians guided the initial development of the CDR and established policies for its utilization and access. Only authorized users may log onto the CDR.To protect con? dentiality, all patient and physician identifying information has been partitioned into a secure Case Study A Data Warehouse for an Academic Medical Center 169 database. Translation from or to disguised identi? ers to or from actual identi? ers is possible but requires a written request and appropriate approval (for example, from a supervisor or the human investigations committee). All data transmitted from the database server to the users browser are encrypted using the secure Nets cape Web server, and all accesses to the database are logged.In addition, CDR access is restricted to personal computers that are part of the Virginia. edu domain or that are authenticated by the universitys proxy server. Evaluation Understanding user needs is the basis for ameliorate the CDR to enable users to retrieve the data independently and to increase engagement of the CDR at our institution. Thus, assessing the value of the CDRhow well we meet our users needs and how we might increase our user basehas been an important activity that has helped guide planning for changes and enhancements and for allocation of our limited resources.Efforts to evaluate the CDR have included several approaches Monitoring user population and usage patterns Administering a CDR user survey Tracking queries submitted to the CDR and performing follow-up telephone interviews Usage Statistics. Voluntary usage of an IS resource is an important measure of its value and of user satisfaction. 5 Howeve r, usage of a data warehouse is likely to be quite different than for other types of information resources, such as clinical information systems. A clinical system is likely to be used many times per day a data warehouse may be used sporadically.Thus, although we proctor system usage as a measure of the CDRs value, we believe that frequency of usage cannot be viewed in isolation in assessing the success of a data warehouse. Since the CDR went live, more than 300 individuals have requested and obtained logon IDs. As of September 30, 2000, 213 individuals had logged on and submitted at least one query. This number does not include usage by CDR project team members and does not re? ect analyses performed by team members for end users. Figure 1 shows the cumulative number of active users (those who submitted a query) and demonstrates a linear growth pattern.