depending on race. For example, Hispanic females have a life expectancy of
83.7 years compared to non-Hispanic white females whose life expectancy is
81.1 years, while non-Hispanic black females have a shorter life expectancy at
77.8 years (Centers for Disease Control and Prevention [CDC], 2013a).
Place
A second way to examine descriptive characteristics is by place. These also contrib-
ute to the frequency of disease or other health-related outcome (see Table 8-2).
For example, obesity is an epidemic in the United States. The frequency
of obesity can be examined by state to identify patterns, also called spatial
clustering (see Figure 8-2). Nurses will note that in the South and in some
Midwestern states the prevalence of adult obesity is reported to be between
30% and 35% (CDC, 2016).
Time
A third way that descriptive epidemiology is used is to investigate by time. Sev-
eral temporal factors contribute to disease frequency and other health-related
outcomes (see Box 8-2). Trends can be secular, cyclical, or short term.
Secular trends, changes in disease patterns that occur over a long period of
time, are often difficult to interpret but can yield important information. For
example, the CDC has trended diabetes over decades. The incidence of diabetes
in adults, aged 18 to 79 years, in the United States has more than tripled from
493,000 in 1980 to more than 1.4 million in 2014 (CDC, 2015).
Cyclical trends, changes in disease patterns that are often predictable and
that recur over time, are seen more readily in health care, particularly as they
Altitude City
Country County
Distance from exposure site Latitude
Pollution Rainfall
Rural State
Sunlight Urban
Zip codeTABLE 8-2
Examples of Descriptive
Characteristics by Place8.4 Descriptive Epidemiology 201