Many kinds of medical data, such as image data, alphanumeric data, and physiological signal data, are controlled, interpreted, and archived at a hospital. Alphanumeric data are usually stored in hospital databases and consist of details such as the patient’s biodata, lab test results, medical histories, and doctors’ notes.
Image data include copies of X-rays, magnetic resonance imaging (MRI) scans, computerized tomography (CT) scans, and ultrasound images. Physiological data are also kept, such as recordings of the electrocardiogram (ECG), electroencephalogram (EEG), electromyogram (EMG), and blood pressure readings.
Medical data can be stored in many forms, such as binary data, which consist of simple yes/no or male/female-type answers, and categorical data, which contain answers from many options. For example, regarding a cardiac drug, the categories could be calcium channel blocker, beta blocker, or antiarrhythmic agent.
Integer data may involve blood pressure readings, whereas continuous data consist of real-value measurements. Image data are composed of pixels that can be easily stored as TIFF, JPEG, or BMP file types for future analysis and diagnosis.
Medical records have increased in size as databases of quantitative data continually grow.
Computer databases for medical records have been around for the last 40 years, beginning with the first database, COSTAR (Computer-Based Medical Record System). Since then, other large databases have followed, such as PROMIS (Problem-Oriented Medical Information System) at the University of Vermont during the 1970s.
The Arthritis, Rheumatism, and Aging Medical Information System (ARAMIS), developed at Stanford University in 1972, was also based on the PROMIS structure but was designed to collect time-oriented data to record a patient’s recovery progress. Continued developments in technology since then have now allowed medical records to be made accessible online and to be carried around on personal digital assistants (PDAs) or smart cards.