Among the most important resources for research are databases and registries of health experience. Some are highly specialized but not very large; some are broad and enormous. Some are maintained only for research; some are primarily maintained for administrative or other purposes but are available for research. They may be organized by illness (leprosy...), by exposure (oral contraceptives...), by mode of intervention (kidney transplant...), by general healthcare experience (nursing home stay...), or by population (residents of Saskatchewan).
Perhaps the largest collection of health databases in the world is the set of U.S. "Medicare" database systems, which every year processes the records of over 600 million reimbursement claims. (Medicare is the Federal health insurance program for people age 65 and over, people with serious disabilities, and people suffering from serious kidney disease.) The Medicare databases, which are managed by the Health Care Financing Administration (HCFA), contain enrollment and eligibility data, claims for payment, data on the ways healthcare services are used, and many specialized data (such as on end-stage renal disease).36
Much very useful research is performed on HCFA data, which as collected is personally identifiable. Public-use files are made available in which, HCFA certifies, "all identifiers have been encrypted, ranged, or blanked." For research projects which meet the criteria for release of identifiable data, HCFA supplies data under Release Agreements pursuant to "routine uses" announced under the Privacy Act. The protections are strict. (See page 59 regarding the Privacy Act, and page 68 regarding conditions on use of Medicare data.)
"Medicaid" databases also are important research resources. (Medicaid programs are regimes under which the States pay for basic health care for low-income, blind, or otherwise disadvantaged people, using joint Federal–State funds.) Like Medicare data, Medicaid data are administrative and billing records.
Although the data may not be of highest quality and are not fully standardized nationally, they nonetheless provide large amounts of diverse information about health and health care about millions of patients "in the real world." Sophisticated computer programs allow searching for data on patient age and sex, diagnoses, use of medicines and medical procedures, costs, and other factors. Researchers are allowed access to the data under restrictive conditions.37
Health databases useful for research are maintained in many places.38 In Europe, just to mention a few examples to suggest their variety, they include the 30 Regional Centers of the French Pharmacovigilance System, the Danish Psychiatric Central Register, the Crohn's Disease Register for the Brussels region, and the Prescription Event Monitoring System run by the Drug Safety Research Unit in Southampton. All of these hold personally identifiable data, as they must.
(36) U.S. Health Care Financing Administration, Bureau of Data Management and Strategy, Data Users Reference Guide (HCFA, Baltimore, Maryland, September 1995), and Overview of Health Care Financing Administration Data: Resource Guide (HCFA, Baltimore, Maryland, April 1996).
(37) Jeffrey L. Carson and Brian L. Strom, "Medicaid databases," pp. 199–216 of Brian L. Strom, editor,Pharmacoepidemiology, Second Edition (John Wiley & Sons, Chichester and New York, 1994).
(38) Several hundred databases were surveyed and described in a series of International Drug Benefit/Risk Data Resource Handbooks(covering North America, Europe, Japan, Australia, and New Zealand) prepared under the auspices of the International Medical Benefit/Risk Foundation, Geneva. Information on the Handbooks can be obtained from Dr. Judith K. Jones, The Degge Group, Ltd., 1616 North Fort Meyer Drive, Arlington, Virginia 22209-3109.