Patient Registries 101

Basic concepts about patient registries

Patient registry
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A patient registry (aka clinical registry) is an organized system that uses observational methods to collect data for assessment of outcomes in a defined patient population. Although registries contain information about individual patients, they are not the same as electronic health records. Patient registries allow users to understand a well-defined health issue of a population. 


Common reasons for using a patient registry are:

  • Monitor health status of defined populations
  • Facilitate disease management, such as by identifying patients with warning signs
  • Understand variations in treatment and outcomes 
  • Observe the natural history of a disease
  • Evaluate clinical effectiveness or cost effectiveness of health care products and services
  • Measure quality of health care
  • Monitor safety or harm
  • Public health surveillance

Patient Populations

Registries are classified according to the common characteristics shared by the patients in the registry.

  • Disease registries include patients with the same disease (e.g. diabetes). Registries exist now for common medical conditions as well as rare ones.
  • Health services registries are defined by patients who have had the same procedure (e.g. hernia surgery), hospitalization, or other clinical encounter
  • Product registries track patients who have been exposed to a certain drug, vaccine, or medical device


    A patient registry can exist in any format. A stack of index cards could serve as a very simple registry. These days registries are more commonly organized on electronic spreadsheets or complex online databases.


    Registries vary broadly in scope, ranging from a few hundred patients to millions.

    Examples of different sized registries include:

    • A group of rheumatologists sets up a registry to measure the degree to which they are managing 200 patients with rheumatoid arthritis according to evidence-based recommendations.
    • Kaiser Permanente's asthma registry tracks asthma-related emergency department visits and hospitalizations among 42,000 patients in Colorado.
    • The Cystic Fibrosis Foundation established a cystic fibrosis registry to track the health of more than 27,000 people with cystic fibrosis in the U.S.
    • Some countries with single-payer national health insurance systems, such as Denmark and Sweden, maintain national patient registries

    Registries can share data with each other. For example, a hospital maintains a registry of patients treated for breast cancer and shares that information with the state registries, which in turn sends the data to a national cancer registry. 

    Data Elements

    A patient registry does not contain all known health information about the patients. The data elements included in the registry are defined and chosen in order to support the main purpose of the registry.

    For example, a registry for heart disease patients would focus on medications, diagnostic tests, procedures, and comorbid conditions related to heart disease.

    A registry includes primary and/or secondary data. Primary data are collected for the purposes of the registry itself. Secondary data are those that were first collected for other purposes but are later made available to the registry. Secondary data can come from different sources. Clinical data, such as height, weight, blood pressure, and chronic diseases would be available from outpatient electronic health records. Information about hospital admissions or medication refills may need to come from claims databases. Data can be supplied to registries by clinical information systems, trained personnel (registrars), or directly by the patients themselves. 


    Gliklich RE, Dreyer NA, editors. Registries for Evaluating Patient Outcomes: A User's Guide. 2nd edition. Rockville (MD): Agency for Healthcare Research and Quality (US); 2010 Sep. Accessed on May 22, 2014

    Centers for Disease Control and Prevention. How Cancer Registries Work. Accessed on May 22, 2014

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