Access Database Design for Clinical Research Studies October

Access Database Design for Clinical Research Studies October 17, 2003 Paul A. Harris Julie Mc. Farlane GCRC Research Skills Workshop

Clinical Database Design n Task #1 – Determine the discrete measurement types and the times of occurrence (1 hour + ? ) n Excel is a great tool to perform this 1 st cut view of the data as your final product should be a grid AND if possible, the vertical axis can be used later to actually create the Access tables.

Time Discrete Msmts Note units and examples given whenever possible Drugs are Difficult to Capture (Dose/ Type/Start/Stop) Same Measurement Frequency 1 Time Per Study or Patient In a one-time study, we can group these with the Demographic Information to reduce tables (ie one-to-one table relationships aren’t that helpful.

Clinical Database Design Task #2 – Ask Questions 1) Who/what/where – This will help you think of where the database file should be stored, security, interface, etc. (JM – 1 user; JM office – network server) n Who will enter data? , Where will data be entered? , Will more than one person need to add data? , Where will data be stored? , Who will need to access the data and when? (JM entering data / NB access periodic – cannot see server) 2) What sorts of questions will you try to answer with the database – this will help in designing tables and queries (Does ACE Inhibitor correlate with decrease in AFIB? Initially blinded – pharmacy to give key later by vial label number) n Will we need real-time query tools? Will we need the final numbers packaged in a certain way? (Individual measurement groups and/or individual measurements – all to Excel file)

Clinical Database Design Task #3 – Table Structure Use information gained in the Excel exercise and in the question and answer session to determine the optimum table design structure. Work on paper before committing time to programming. If the Excel file is in good shape, you can often manipulate and import rather than typing in Access. After setting up tables, always set up formal relationships between tables to enforce referential integrity. If possible, write queries to repackage and ask questions about your data before going on – this will ensure you have a table design that will eventually work (use dummy data for this exercise)

Clinical Database Design Task #3 – Table Structure Think about final user interface. Does the table structure look appropriate? Do all tables have a unique (primary key) field? Is it logical? If not, add a tablename_id autonumber field. You really strive to never design a table that doesn’t have a unique field. Are all tables related through a primary/foreign key relationship? You should be able to start at the lowest data table and work back to high level details following foreign/primary key links if table relationships are properly set up (think one to many relationships).

Clinical Database Design Real-World Exercise Look at the example spreadsheet and think about table structures for this project. Demographics (include one-shot msmts unless this data will be one set of a larger group of data). The study number or patient MRN is a logical choice for PK here. Most measurements that are not one-shot in this study are repeated with sufficient frequency that we might think about dumping all data in one other table. The PK choice here is not as obvious, but we could perhaps combine the study number with an underscore and a time code (visit number) to assure we don’t add the same data for the same patient.

Clinical Database Design Real-World Demonstration

Clinical Database Design Real-World Demonstration Rework Excel File into sheets for each table with field names and values. This should really be done only after 2 -3 cuts at Excel file, screening form and flow sheets. Import sheets for demographics and study measurements into Access. Clean and check results. Set up relationships.

Clinical Database Design User Interface Your goals in designing a user interface should be: 1) Provide an intuitive interface for users that matches the logical workflow process. Help those poor overworked souls do their jobs. 2) Completely protect your database from inappropriate data entry. Guide the process of data entry. Don’t let those misfits put garbage into this application.