are specified in the report because the scope of the task includes health conditions and behaviors that are unique to this age group. The age break in defining adolescent up to age 18 in this report is influenced by the age breaks currently associated with Medicaid data systems. Yet such definitions are frequently arbitrary. An earlier National Research Council (NRC) and Institute of Medicine (IOM) report Adolescent Health Services: Missing Opportunities (IOM and NRC, 2009a) described adolescence as a time of major transitions in which youth develop relational and behavioral skills and patterns that continue into adulthood and that critically impact future life experiences and outcomes. In earlier decades, adolescence was thought to begin with biological processes, namely the onset of puberty (generally around ages 12 or 13) and to end with the assumption of the social roles of an adult, such as the completion of education, the beginning of full-time employment, and the formation of relationships such as marriage and parenthood. In practice, multiple age breaks are used to define adolescence, such as the variations associated with the legal age of driving, underage drinking, military recruitment, voting, and so forth. Most of these eligibility criteria are determined by local customs or federal and state regulations that are not informed by the science of adolescent development.
The 2009 NRC and IOM report observed that adolescence is a theoretical construct that continues to evolve in response to historical events, cultural context, and biological changes. Disagreement persists among health care researchers, experts in adolescent health and development, practitioners, and policy makers on the specific age ranges associated with the terms children and adolescents. The lower range of adolescence has shifted in response to the earlier onset of puberty among boys and girls, calling into question the term that should be used to describe pre-teen children who exhibit signs of adolescent development. The widening delay in time between physical maturity and securing professional employment and independent living has also caused some researchers to designate the late teenage years and early 20s as a period of “emerging adulthood” (Arnett, 2000, 2004).
Before reviewing the current inventory of federally supported population health data systems in the chapters that follow, it is critical to understand what is meant by child and adolescent health. The World Health Organization (WHO) defines health as “not only the absence of infirmity and disease but also a state of physical, mental, and social well-being” (WHO, 1948). However, health involves more than physical wellness—it is affected by mental and emotional states as well. Moreover, those who are concerned with children’s health status want to know about more than the presence or absence of specific health problems in the general child population at a given point in time. They also want to know whether children’s health improved or diminished as compared with other periods. They often want to know as well how children with certain types of characteristics are