The entire life cycle of a device, from development to clinical trials to market entry, differs significantly from that of a drug. The evolution of a device is often incremental. As experience with the device is gained, modifications can be made both before and after the product is marketed. This iterative process is often done in collaboration with innovative surgeons and other specialists.
The premarket testing of devices via clinical trials is distinctly different from drug trials. Drug trials generally involve large numbers of participants, as safety and efficacy must be demonstrated prior to approval. Device trials are more limited in scope. They require skilled clinicians in order to achieve the best results, and this can reduce the number of participants. Moreover, most device trials cannot be blind, as sham surgery or the use of a placebo device are unacceptable practices.
The immediate impact of a device on the body is more evident than that of a drug. Effects are often observed within hours or days. Therefore, the risks are "front-loaded" and device efficacy is more easily measured. When registries are maintained it is possible to track longer term use and outcomes of a medical device. Postmarket surveillance of drugs is difficult due to variables in prescribing, patient adherence, and use in combination with other medicines.
Product lifespan is another key area of divergence between drugs and devices. A pharmaceutical can be on the market for decades. Estimates suggest that the majority of devices currently on the market are only two years old, while most of the others are no more than five years old. (4. Outlook for Medical Technology Innovation—Report 1: The State of the Industry. Falls Church, VA: The Lewin Group, 2001:19).
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