Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis,
involves chronic inflammation of the gastrointestinal tract. In 2015, an estimated
3.1 million adults in the United States had ever received a diagnosis of IBD (
1
). Nationally representative samples of adults with IBD have been unavailable or too
small to assess relationships between IBD and other chronic conditions and health-risk
behaviors (
2
). To assess the prevalence of health-risk behaviors and chronic conditions among
adults with and without IBD, CDC aggregated survey data from the 2015 and 2016 National
Health Interview Survey (NHIS). An estimated 3.1 million (unadjusted lifetime prevalence = 1.3%)
U.S. adults had ever received a diagnosis of IBD. Adults with IBD had a significantly
lower prevalence of having never smoked cigarettes than did adults without the disease
(55.9% versus 63.5%). Adults with IBD had significantly higher prevalences than did
those without the disease in the following categories: having smoked and quit (26.0%
versus 21.0%; having met neither aerobic nor muscle-strengthening activity guidelines
(50.4% versus 45.2%); reporting <7 hours of sleep, on average, during a 24-hour period
(38.2% versus 32.2%); and having serious psychological distress (7.4% versus 3.4%).
In addition, nearly all of the chronic conditions evaluated were more common among
adults with IBD than among adults without IBD. Understanding the health-risk behaviors
and prevalence of certain chronic conditions among adults with IBD could inform clinical
practice and lead to better disease management.
The NHIS is a cross-sectional household health survey of the civilian noninstitutionalized
population. The survey provides nationally representative data on a broad range of
topics, including health status, health behaviors, and access to and use of health
care.* Data on diagnosed IBD (hereafter referred to as IBD) were collected with the
Sample Adult Core questionnaire using the following question: “Have you ever been
told by a doctor or other health professional that you had Crohn’s disease or ulcerative
colitis?” The sample adult is randomly selected from all adults aged ≥18 years in
the family and answers for himself/herself (unless physically or mentally unable to
do so, in which case a knowledgeable adult serves as a proxy respondent). Interviews
are conducted in respondents’ homes, although follow-ups by telephone to complete
missing sections are permitted. To ensure more precise estimates of IBD status, the
2015 and 2016 Sample Adult data files were combined with the 2-year response rate
of 54.7%.
†
The prevalence of IBD, with 95% confidence intervals, was estimated for the civilian,
noninstitutionalized U.S. adult population overall and by various sociodemographic
characteristics. These characteristics, collected with the Household Composition and
Family Core questionnaires, included age, sex, race/ethnicity, education level, marital
status, current employment status, nativity, health insurance coverage type (reported
separately for adults aged <65 and ≥65 years), urbanicity, and region of residence.
Next, the prevalence of five health-risk behaviors
§
(cigarette smoking status, binge drinking, body mass index [BMI] category, meeting
of federal physical activity guidelines, and short sleep duration), serious psychological
distress
¶
(a proxy for mental health symptoms), and several chronic conditions** (cardiovascular
disease, respiratory disease, cancer, diabetes, arthritis, weak or failing kidneys,
any liver condition, and ulcer) were estimated separately for adults with and without
IBD. All prevalence estimates met the reliability standard of relative standard errors
<30%
††
and were age-adjusted to the projected 2000 U.S. population
§§
(unless otherwise noted). For comparison of IBD prevalence by subgroup and prevalence
of health-risk behaviors and chronic conditions by IBD status, differences were considered
significant if two-tailed Z-tests yielded p-values <0.05. All comparisons described
in the results were statistically significant. All analyses were conducted using statistical
software to account for the stratified, complex cluster sampling design of the survey.
Estimates incorporated the final sample adult weights adjusted for nonresponse and
calibrated to population control totals to generalize the estimates to the civilian
noninstitutionalized population aged ≥18 years.
In 2015 and 2016, 3.1 million (unadjusted lifetime prevalence of 1.3%; age-adjusted
lifetime prevalence of 1.2%) U.S. adults had ever received a diagnosis of IBD (Table
1). The age-specific prevalence of IBD was higher among adults aged 45–64 and ≥65
years (both 1.7%) than among those aged 18–24 (0.5%) or 25–44 (1.0%) years. The prevalence
of IBD was higher among women (1.5%) than among men (1.0%); among non-Hispanic white
adults (1.4%) than among non-Hispanic black adults (0.6%) or other non-Hispanic adults
(0.8%); among those with less than a high school education (1.6%) than among those
with at least a bachelor’s degree (1.1%); among those who were divorced, separated,
or widowed (2.3%) than among persons who were married or cohabitating (1.1%); among
currently unemployed (1.6%) or U.S.-born (1.3%) adults than their employed (1.1%)
and non–U.S.-born (0.8%) counterparts; and among adults living in small metropolitan
statistical areas (MSAs) (1.4%) than among those living in large MSAs (1.1%). The
prevalence of IBD did not differ significantly among groups defined by health insurance
coverage type or region of residence.
TABLE 1
Prevalence of inflammatory bowel disease* among U.S. adults aged ≥18 years, by sociodemographic
characteristics — National Health Interview Survey, 2015–2016
Characteristic
Estimated no.†
Age-adjusted§
% (95% CI)
Total (unadjusted)
3,121,000
1.3 (1.2–1.4)
Total (age-adjusted)
3,121,000
1.2 (1.1–1.3)
Age group (yrs)
18–24
152,000
0.5 (0.3–0.8)
25–44
798,000
1.0 (0.8–1.1)
45–64
1,394,000
1.7 (1.5–1.9)
≥65
777,000
1.7 (1.4–1.9)
Sex
Men
1,219,000
1.0 (0.9–1.2)
Women
1,902,000
1.5 (1.3–1.6)
Race/Ethnicity
Non-Hispanic white
2,363,000
1.4 (1.3–1.6)
Non-Hispanic black
174,000
0.6 (0.4–0.8)
Hispanic
427,000
1.2 (0.9–1.6)
Non-Hispanic other¶
157,000
0.8 (0.6–1.2)
Education level
Less than high school
491,000
1.6 (1.2–2.0)
High school diploma/GED
748,000
1.2 (1.0–1.4)
Some college
971,000
1.3 (1.1–1.5)
Bachelor’s degree or higher
906,000
1.1 (1.0–1.3)
Current marital status
Married/Cohabitating
1,823,000
1.1 (1.0–1.3)
Never married
484,000
1.3 (1.0–1.6)
Divorced/Separated/Widowed
814,000
2.3 (1.4–3.7)
Current employment
Yes
1,538,000
1.1 (1.0–1.3)
No
1,583,000
1.6 (1.4–1.8)
U.S.-born**
Yes
2,741,000
1.3 (1.2–1.4)
No
381,000
0.8 (0.6–1.1)
Health insurance coverage
††
Age <65 years
Private
1,578,000
1.1 (1.0–1.3)
Medicaid and other public coverage
354,000
1.4 (1.1–1.8)
Other
179,000
1.3 (0.9–1.7)
Uninsured
231,000
1.0 (0.8–1.4)
Age ≥65 years
Private
338,000
1.7 (1.4–2.2)
Medicare and/or Medicaid
64,000
2.0 (1.2–3.1)
Medicare Advantage
215,000
1.8 (1.4–2.5)
Medicare only, excluding Medicare Advantage
104,000
1.3 (0.8–2.0)
Other
55,000
1.4 (0.9–2.4)
Uninsured§§
NA
NA
Urbanicity
¶¶
Large MSA
1,542,000
1.1 (1.0–1.3)
Small MSA
1,366,000
1.4 (1.2–1.6)
Not in MSA
213,000
1.4 (1.0–1.8)
Region***
Northeast
591,000
1.3 (1.1–1.6)
Midwest
752,000
1.3 (1.1–1.6)
South
1,092,000
1.2 (1.0–1.4)
West
686,000
1.2 (1.0–1.4)
Abbreviations: CI = confidence interval; GED = General Educational Development certificate;
MSA = metropolitan statistical area; NA = not applicable.
* Respondents who had ever been told by a doctor or other health professional that
they had Crohn's disease or ulcerative colitis.
† The estimated annual numbers, rounded to 1,000s, were calculated based on 2015 and
2016 data. Counts for adults of unknown status (responses coded as “refused,” “don’t
know,” or “not ascertained”) with respect to inflammatory bowel disease status are
not shown separately in the table, nor are they included in the calculation of percentages
(as part of either denominator or the numerator), to provide a more straightforward
presentation of the data. In addition, frequencies presented in the table might be
underestimated because of item nonresponse and unknowns.
§ Estimates (except for age groups and crude total) are age-adjusted using the projected
2000 U.S. population distribution #8 as the standard population and four age groups:
18–24, 25–44, 45–64, and ≥65 years. https://www.cdc.gov/nchs/data/statnt/statnt20.pdf.
¶ Non-Hispanic other includes non-Hispanic American Indian and Alaska Native only,
non-Hispanic Asian only, non-Hispanic Native Hawaiian and Pacific Islander only, and
non-Hispanic multiple race.
** U.S.-born includes all persons born in the United States or a United States territory.
†† Based on a hierarchy of mutually exclusive categories. Adults with more than one
type of health insurance were assigned to the first category in the hierarchy. “Uninsured”
includes adults who had no coverage as well as those who had only Indian Health Service
coverage or had only a private plan that paid for one type of service such as accidents
or dental care.
§§ In the survey sample, zero adults aged ≥65 years and uninsured had ever been told
by a doctor or other health professional that they had Crohn's disease or ulcerative
colitis.
¶¶ Large MSAs have a population size of ≥1 million; small MSAs have a population size
of <1 million. Persons “Not in MSA” do not live in a metropolitan statistical area.
*** Northeast: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York,
Pennsylvania, Rhode Island, and Vermont. Midwest: Illinois, Indiana, Iowa, Kansas,
Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.
South: Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky,
Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee,
Texas, Virginia, West Virginia. West: Alaska, Arizona, California, Colorado, Hawaii,
Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.
Being a former smoker was more prevalent among adults with IBD (26.0%) than among
adults without IBD (21.0%), and having never smoked was less prevalent among adults
with IBD (55.9%) than among those without IBD (63.5%) (Table 2). In addition, adults
with IBD had higher prevalences than those without IBD of sleeping <7 hours per day
(38.2% versus 32.2%) and meeting neither aerobic nor muscle-strengthening physical
activity guidelines (50.4% versus 45.2%). No statistically significant difference
was detected in the prevalence of binge drinking or BMI category between the two groups.
The prevalence of experiencing serious psychological distress was reported twice as
frequently by adults with IBD (7.4%) than by those without IBD (3.4%). Among the selected
chronic conditions, with the exception of diabetes, all were significantly more prevalent
among adults with IBD than among those without IBD (Table 2). The prevalence of ulcer
was nearly five times higher among adults with IBD (26.0%) than among those without
IBD (5.5%).
TABLE 2
Age-adjusted prevalence of selected health-risk behaviors and chronic conditions by
inflammatory bowel disease* status among U.S. adults aged ≥18 years — National Health
Interview Survey, 2015–2016
Characteristic
Adults with IBD
Adults without IBD
Estimated no.†
Age-adjusted§
% (95% CI)
Estimated no.
Age-adjusted§
% (95% CI)
Cigarette smoking status
¶
Current smoker
557,000
18.0 (14.9–21.7)
36,561,000
15.5 (15.0–15.9)
Former smoker
949,000
26.0 (22.2–30.2)**
52,541,000
21.0 (20.6–21.5)
Never smoker
1,608,000
55.9 (51.3–60.5)**
150,357,000
63.5 (63.0–64.0)
Drinking status††
Binge drinking (≥12 days) in the past year
250,000
9.8 (6.9–13.6)
22,207,000
9.9 (9.5–10.2)
BMI groups (kg/m2)§§
Underweight (<18.5)
71,000
2.4 (1.4–4.0)
4,286,000
1.9 (1.7–2.0)
Normal (≥18.5 and <25.0)
1,007,000
35.9 (31.1–41.0)
78,296,000
34.2 (33.7–34.8)
Overweight (≥25.0 and <30.0)
995,000
31.0 (26.9–35.5)
79,812,000
34.2 (33.7–34.7)
Obese (≥30)
954,000
30.7 (26.2–35.6)
69,410,000
29.7 (29.2–30.3)
Met physical activity guidelines
¶¶
Neither aerobic nor muscle-strengthening activity
1,680,000
50.4 (45.6–55.2)**
108,231,000
45.2 (44.6–45.8)
Aerobic activity only
770,000
25.4 (21.7–29.5)
68,340,000
29.2 (28.7–29.7)
Muscle-strengthening activity only
116,000
3.4 (2.0–5.5)
8,360,000
3.5 (3.3–3.7)
Both aerobic and muscle-strengthening activities
509,000
20.9 (16.9–25.5)
50,666,000
22.1 (21.7–22.6)
Less than 7 hours of sleep, on average***
1,138,000
38.2 (33.4–43.3)**
74,316,000
32.2 (31.6–32.7)
Serious psychological distress
†††
259,000
7.4 (5.4–10.0)**
8,161,000
3.4 (3.2–3.6)
Chronic conditions
§§§
Cardiovascular disease
748,000
19.2 (16.3–22.5)**
31,229,000
12.0 (11.7–12.4)
Respiratory disease
870,000
27.3 (23.3–31.7)**
40,284,000
16.6 (16.2–17.0)
Cancer
547,000
13.7 (10.9–17.0)**
21,430,000
8.1 (7.9–8.3)
Diabetes
448,000
10.1 (8.2–12.4)
22,647,000
8.6 (8.4–8.9)
Arthritis
1,415,000
36.3 (32.8–40.0)**
55,114,000
21.1 (20.8–21.5)
Weak or failing kidneys
171,000
4.5 (3.2–6.3)**
4,703,000
1.8 (1.7–1.9)
Any liver condition
192,000
5.2 (3.7–7.2)**
4,207,000
1.7 (1.6–1.8)
Ulcer
800,000
26.0 (22.2–30.3)**
13,888,000
5.5 (5.3–5.7)
Abbreviations: BMI = body mass index; CI = confidence interval; IBD = inflammatory
bowel disease.
* Respondents who had ever been told by a doctor or other health professional that
they had Crohn's disease or ulcerative colitis.
† The estimated annual numbers, rounded to 1,000s, were calculated based on the 2015
and 2016 data. Counts for adults of unknown status (responses coded as “refused,”
“don’t know,” or “not ascertained”) with respect to IBD status are not shown separately
in the table, nor are they included in the calculation of percentages (as part of
either denominator or the numerator), to provide a more straightforward presentation
of the data. In addition, frequencies presented in the table might be underestimated
because of item nonresponse and unknowns.
§ Estimates are age-adjusted using the projected 2000 U.S. population as the standard
population and four age groups: 18–24, 25–44, 45–64, and ≥65 years.
¶ Cigarette smoking status was defined as current, former, or never smoker. Current
smokers reported having smoked ≥100 cigarettes in their lifetime and currently smoking
cigarettes some days or every day. Former smokers reported having smoked ≥100 cigarettes
in their lifetime but were not current smokers at the time of the survey. Never smokers
reported they had not smoked ≥100 cigarettes in their lifetime.
** Statistically significant (p<0.05) difference between adults with IBD and adults
without IBD.
†† Binge drinking ≥12 days in the past year was defined according to a response of
the number of days to the question “In the past year, on how many days did you have
5 or more [for men]/4 or more drinks [for women] of any alcoholic beverage?”
§§ BMI was calculated as weight (kg)/height (m2) based on responses to the questions
“How tall are you without shoes?” and “How much do you weigh without shoes?” BMI (kg/m2)
was categorized as underweight (<18.5), normal weight (≥18.5 and <25.0), overweight
(≥25.0 and <30.0), or obese (≥30.0).
¶¶ The definition of physical activity categories followed 2008 Physical Activity
Guidelines for Americans (https://health.gov/paguidelines/pdf/paguide.pdf). Both aerobic
and muscle-strengthening guidelines are met if participants reported ≥150 minutes
of moderate or ≥75 minutes of vigorous equivalent aerobic activity per week and muscle
strengthening activities on ≥2 days per week.
*** Short sleep duration was defined as <7 hours in response to the question “On average,
how many hours of sleep do you get in a 24-hour period?”
††† Serious psychological distress is based on responses to six questions that ask
how often a respondent experienced certain symptoms (feeling so sad nothing could
cheer you up; nervous; restless or fidgety; hopeless; that everything was an effort;
worthless) of psychological distress during the past 30 days. The response codes (0–4)
of the six items for each person are summed to yield a scale with a 0–24 range. A
value of ≥13 for this scale is used here to define serious psychological distress.
§§§ Cardiovascular disease included a history of any of the following conditions:
coronary heart disease, angina, myocardial infarction, stroke, or any heart disease.
Respiratory disease included a history of any of the following conditions: emphysema,
chronic bronchitis, chronic obstructive pulmonary disease, or asthma. Cancer included
cancer or a malignancy of any kind. Diabetes was defined as an affirmative response
to the question “Other than during pregnancy, have you ever been told by a doctor
or other health professional that you have diabetes or sugar diabetes?” Arthritis
was defined as an affirmative response to the question “Have you ever been told by
a doctor or other health professional that you have some form of arthritis, rheumatoid
arthritis, gout, lupus, or fibromyalgia?” Weak or failing kidneys was defined as an
affirmative response to the question “During the past 12 months, have you been told
by a doctor or other health professional that you had weak or failing kidneys? Do
not include kidney stones, bladder infections or incontinence.” Any liver condition
was defined as an affirmative response to the question “During the past 12 months,
have you been told by a doctor or other health professional that you had any kind
of liver condition?” Ulcer was defined as an affirmative response to the question
“Have you ever been told by a doctor or other health professional that you had an
ulcer?”
Discussion
Based on a nationally representative sample, during 2015–2016, an estimated 3.1 million
U.S. adults had ever received a diagnosis of IBD. IBD might require lifelong disease
management, including a combination of prescription medications, surgery, and medical
treatment in outpatient, inpatient, emergency department, or ambulatory care settings.
The symptoms and complications of IBD are associated with substantially impaired health-related
quality of life (
3
). The total direct and indirect costs from loss of earnings or productivity attributable
to IBD in the United States were estimated in 2014 to be $14.6 billion–$31.6 billion
¶¶
; however, because this estimate was based on a lower prevalence of IBD than that
presented in this report, and given the impact of inflation, the current costs might
be substantially higher.
In this study, the prevalence of IBD was higher among women, non-Hispanic whites,
and older, less educated, and unemployed adults, which is consistent with the findings
of previous studies (
1
,
4
,
5
). For example, in a previous study using insurance claims data, the prevalence of
Crohn’s disease and ulcerative colitis was higher among older adults, and although
the prevalence of ulcerative colitis did not differ significantly by sex, women were
more likely than men to have Crohn’s disease (
4
). In this study, however, the survey question did not differentiate Crohn’s disease
from ulcerative colitis. This study also found IBD to be more prevalent among unemployed
adults, reinforcing previous findings on the employment burden of the disease (
5
). However, unlike other studies (
4
,
6
), no evidence was found of a difference in IBD prevalence by region of residence,
which might be a result of different data collection modes and target populations
in different studies.
Adults with IBD were more frequently former smokers and less frequently never smokers
than were those without IBD. Some smokers might possibly have quit smoking because
of a diagnosis of IBD. The role of smoking in the development of IBD is not fully
understood. Smoking among persons with Crohn’s disease, however, has been found to
be associated with disease development, progression, and inferior treatment outcomes
(
7
). Smoking cessation, therefore, is particularly recommended among patients with diagnosed
Crohn’s disease (
7
). Many chronic conditions are more common among adults who report a short sleep duration.***
Similarly, this study found that short sleep duration was more prevalent among adults
with IBD. In addition, the prevalence of meeting neither aerobic nor muscle-strengthening
physical activity guidelines was higher among adults with IBD, which might be an indication
of severity of symptoms. Although there is no current exercise recommendation to adults
with IBD, mild exercise in those with mild or moderate symptoms might not worsen disease
symptoms (
8
). Furthermore, exercise might help build muscle mass, bone density, and improve sleep
quality, and its benefits outweigh the risks for almost everyone. Adults with IBD
who have mild to moderate disease activity should be encouraged to consult their clinicians
about their exercise engagement.
Several chronic conditions were more prevalent among adults with IBD than among those
without IBD. Although few comprehensive studies of IBD comorbidities exist, the disease
has been found to be associated with multiple diseases, only some of which were gastrointestinal-related
(
9
). For example, adults with IBD are at increased risk for certain cancers and osteoporosis
(
7
). In this study, the prevalence of having experienced serious psychological distress
in the last 30 days was higher among adults with IBD. This is consistent with past
research that found adults with IBD have an increased prevalence of psychological
or psychosocial disorders, including depression, anxiety, and impaired social interactions
(
10
). Psychological disorders were also predictive of poor health-related quality of
life, regardless of the severity of IBD (
10
). The presence of certain chronic conditions in addition to IBD might impair health-related
quality of life among affected persons and further complicate disease progression
and care management (
9
).
The findings in this study are subject to at least six limitations. First, because
NHIS responses are self-reported and not corroborated by medical records, they are
subject to reporting bias. Second, diagnosis of Crohn’s disease and ulcerative colitis
could not be assessed separately as they are combined in a single survey question
of IBD. Third, questions on other chronic conditions likely to be associated with
IBD, such as anemia and osteoporosis, are not asked in the NHIS. Fourth, a short-term
measure of serious psychological distress (within the last 30 days) was used as a
proxy measure for mental health symptoms; therefore, the prevalence of serious psychological
distress among adults with IBD could be underestimated. Fifth, although the sample
weights include adjustments for survey nonresponse, the potential for nonresponse
bias in the IBD estimates remains, given the Sample Adult Core response rate of 54.7%
for the 2 years under analysis. Finally, the NHIS survey excluded active duty military
personnel and institutionalized adults; therefore, the results cannot be generalized
to the entire U.S. adult population.
Understanding the extent to which adults with IBD experience comorbidities helps further
elucidate the impact of IBD. Further, assessing the health-risk behaviors of persons
with IBD might aid in identifying opportunities to improve their overall health, quality
of life, and disease management. Given the disease’s complexity and the effects of
chronic conditions and symptoms, optimal IBD care might require a multidisciplinary
approach that includes gastroenterologists, preventive medicine specialists, and other
medical practitioners.
Summary
What is already known about this topic?
In 2015, an estimated 3 million U.S. adults had inflammatory bowel disease (IBD).
The prevalence of IBD was higher among adults who were aged ≥45 years, white, U.S.-born,
unemployed, and who had less than a high school education.
What is added by this report?
Based on 2015 and 2016 National Health Interview Survey data, being a former smoker
was more prevalent and having never smoked was less prevalent among adults with IBD
than among adults without IBD. In addition, meeting neither aerobic nor muscle-strengthening
physical activity guidelines, sleeping <7 hours, on average during a 24-hour period,
and experiencing serious psychological distress were more prevalent among adults with
IBD than among those without IBD, as were several chronic conditions, including cardiovascular
disease, respiratory disease, cancer, arthritis, weak or failing kidneys, any liver
condition, and ulcer.
What are the implications for public health practice?
Adults with IBD who have mild to moderate disease activity should be encouraged to
consult their clinicians about their exercise engagement. Clinicians should be aware
of potential adverse health consequences of the health-risk behaviors that are more
prevalent among adults with IBD, such as having insufficient sleep. Because certain
chronic conditions are more prevalent among adults with IBD, disease management might
involve multidisciplinary clinical care.