Clinical data is a staple resource for most health and medical research. Clinical data is either collected during the course of ongoing patient care or as part of a formal clinical trial program. Clinical data falls into six major types:

• Electronic health records
• Administrative data
• Claims data
• Patient / Disease registries
• Health surveys
• Clinical trials data

See boxes below for examples of each major type.

The purest type of electronic clinical data which is obtained at the point of care at a medical facility, hospital, clinic or practice. Often referred to as the electronic medical record (EMR), the EMR is generally not available to outside researchers. The data collected includes administrative and demographic information, diagnosis, treatment, prescription drugs, laboratory tests, physiologic monitoring data, hospitalization, patient insurance, etc.

Individual organizations such as hospitals or health systems may provide access to internal staff.  Larger collaborations, such as the NIH Collaboratory Distributed Research Network provides mediated or collaborative access to clinical data repositories by eligible researchers.  Additionally, the UW De-identified Clinical Data Repository (DCDR) and the Stanford Center for Clinical Informatics allow for initial cohort identification.

Often associated with electronic health records, these are primarily hospital discharge data reported to a government agency like AHRQ.

Claims data describe the billable interactions (insurance claims) between insured patients and the healthcare delivery system. Claims data falls into four general categories: inpatient, outpatient, pharmacy, and enrollment. The sources of claims data can be obtained from the government (e.g., Medicare) and/or commercial health firms (e.g., United HealthCare).

Disease registries are clinical information systems that track a narrow range of key data for certain chronic conditions such as Alzheimer's Disease, cancer, diabetes, heart disease, and asthma. Registries often provide critical information for managing patient conditions.

In order to provide an accurate evaluation of the population health, national surveys of the most common chronic conditions are generally conducted to provide prevalence estimates. National surveys are one of the few types of data collected specifically for research purposes, thus making it more widely accessible.  

Clinical research data may be available through national or discipline-specific organizations.  Level of access is likely restricted but available through proper channels.

Proprietary research data may also be available through individual agreements with private companies.