ness of a device. This report uses the term postmarket studies or postmarket study commitments to refer collectively to condition-of-approval studies and Section 522 studies that are ordered after a device enters the market.

Some postmarket studies continue to follow individuals who participated in the clinical trials or other studies that were used to support an application for FDA approval or clearance of a medical device.6 Other postmarket studies involve registries of new patients. A registry is a system for collecting information about a class of individuals or patients who have in common a disease, injury, condition, medical procedure or product, or similar characteristic. The term registry is sometimes used narrowly to refer to the database itself and sometimes more broadly to refer to analyses and studies based on registry information. For the latter, this report generally refers to registry studies or registry-based studies.

A major tool of FDA postmarket surveillance is an adverse event reporting system for collecting and analyzing information about product failures or harms related to or potentially related to medical products. For medical devices, the emphasis is on the reporting of device failures and malfunctions and device-related deaths or serious injuries. As discussed in Chapters 3 and 4, the primary FDA program of adverse event reporting for medical products, MedWatch, relies on passive surveillance; that is, it awaits reports that manufacturers, health care facilities, health care professionals, and others decide to submit. In addition, FDA has created the Medical Device Safety Network (MedSun, formerly known as the Medical Product Surveillance Network), a pilot program that involves selected hospitals and nursing homes). This program includes some elements of active surveillance, for example, a request that all or some participating institutions collect information on a specific problem or event.

In addition to surveillance undertaken or directed by FDA, manufacturers for implanted devices such as pacemakers and defibrillators conduct active surveillance of these products. Health care providers, some state governments, accrediting groups, and various other private organizations also have surveillance programs for identifying patient safety problems, although medical devices usually do not figure prominently in these programs.

Certain activities to build additional knowledge about the safety or effectiveness of a marketed medical device—for example, some clinical tri-


A guidance document on clinical trials involving medical devices cites this definition of clinical trial: “a prospective study comparing the effect and value of intervention(s) against a control in human subjects” (Friedman et al., 1985; cited in FDA, 1996c). Many clinical studies used to support FDA approval of medical devices do not have prospective control groups. Chapter 6 and Appendix D discuss research strategies and issues.

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