tion because of the infant brain’s particular plasticity, that is, its ability to mold or shape itself to accommodate to damage in one area with new growth and connections to other areas to achieve the same function (Johnston et al., 2001; Luciana, 2003). Studies of long-term outcomes are still important to determine whether such accommodation compromises other neurodevelopmental processes as the child matures.

Although the wording is slightly different in documents on drugs and devices, a child is regarded as an individual between the ages of 2 and 11 (FDA, 1994, unpaged; ICH, 2000; FDA, 2004p). For certain conditions and medical products, differences within this age group in cognitive and emotional development may be significant, particularly with respect to the use of medical devices that normally require user set-up steps, user programming, or other patient-initiated control. What is well beyond the capabilities of a 3-year-old may be quite manageable for a 10-year-old. Physiologic differences within the 2-to-11 age group also may be important. For example, younger children whose bones heal more quickly may be safely treated for femoral fractures using a body cast, whereas children aged 6 to 12, who heal more slowly, may benefit from surgical treatment that requires a shorter period of incapacitation (see discussion of titanium nails below).

For drugs and devices, FDA documents differ on the age range for adolescents. For drugs, the range is ages 12 to 15 (“up to age 16”) (FDA, 1994, unpaged). For medical devices, however, the upper end of the range is age 20 (or “up to the age of 21”) (FDA, 2004p, p. 4). In specifying this broader range, the guidance on medical devices states: “Given the scope of medical devices and the impact that a device could have on a growing adolescent, as well as the effect growth could have on the device, we believe that including the upper age limit identified above may be useful for some devices and device clinical trials” (FDA, 2004p, p. 4). No specific instances are cited. The guidance also notes that “the descriptions are somewhat arbitrary and that, in fact, the subject’s weight, body size, physiological development, neurological development, and neuromuscular coordination may often be more appropriate indicators than chronological age” (FDA, 2004p, pp. 4–5).3

3  

The National Institutes of Health (NIH) policy statement on the inclusion of children in research also applies to “individuals under the age of 21 years” (NIH, 1998, unpaged). NIH requires research proposals to describe the rationale for including or excluding particular age groups in studies. The statement notes that the definition differs from the regulations of the Department of Health and Human Services governing children’s participation in federally conducted, supported, or regulated research. Under these regulations, state law on the age of majority governs decisions about whether the regulations apply, and nearly all states specify age 18 as the age of majority. Under NIH policy, an 18-year-old would be an adult for consent purposes (under state law) but a child for study inclusion purposes. The policy statement was developed in response to language in House and Senate Appropriations Committee reports for fiscal year 1996 that noted the need for the more widespread inclusion of children in research (NIH, 1998).



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