considers several exemplar diseases, health conditions, and impairments in more detail, and examines the people living with these illnesses and the ways in which they are affected.1

THE SPECTRUM OF CHRONIC ILLNESSES: DIFFERENCES IN TIME COURSE/CHRONICITY, HEALTH BURDEN, AND CONSEQUENCES

In this section, we first consider the nature of chronic diseases, including their similarities and differences. We then discuss the effects of these illnesses on the ability to live well with them.

The National Center for Health Statistics has defined chronic diseases as those that persist for 3 months or longer or belong to a group of conditions that are considered chronic (e.g., diabetes), regardless of when they began. Although some (e.g., polymyalgia rheumatica, depression) may resolve, most are lifelong diseases. Chronic diseases can vary in multiple ways, including their stage at presentation and characteristic clinical symptoms and their natural history (time course). Some specific conditions have typical time courses for clinical progression. Other chronic diseases, such as treated breast or prostate cancers, may follow a quiescent pattern for many years. Similarly, the health burden in terms of symptoms and functional impairment, requirements for self-management, effects on significant others, and individual economic impact vary. This results in disparate patterns of human suffering across the spectrum of chronic illnesses. Table 2-1 displays selected patterns of chronic illnesses along important dimensions. For example, some illnesses (e.g., diabetes) have high self-management requirements, whereas others (e.g., Alzheimer’s disease) may require substantial care from others. Age of onset may also influence complications and burden; for example, older onset rheumatoid arthritis is associated with more shoulder involvement and symptoms of polymyalgia rheumatica and less frequent hand deformities compared with younger onset disease (Turkcapar et al., 2006). The stability of the condition over time is also an important determinant of overall health burden.

Below we summarize the spectrum of chronic diseases as early, moderate, and late stage. As highlighted in Table 2-1, individuals with certain chronic illnesses, such as congestive heart failure, chronic obstructive pulmonary disease (COPD), Parkinson’s disease, and diabetes mellitus, may

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1Some chronic illnesses have a recognized precursor state (e.g., osteopenia, hyperlipidemia, ductal carcinoma in situ) that may or may not progress to a chronic condition that people sense and suffer from. Although these presymptomatic states, if diagnosed, may cause symptoms (e.g., worry) or socioeconomic consequences (e.g., inability to obtain insurance), this report focuses on persons who actually have and are living with a chronic illness, not just a precursor state. Thus, such states as asymptomatic hypothyroidism or stage 3 chronic kidney disease are not considered.



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