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National Center for Chronic Disease Prevention and Health Promotion
Division of Adult and Community Health
Health Care and Aging Studies Branch
Arthritis Program
Mailstop K-51
4770 Buford Highway NE
Atlanta, GA 30341-3724
Phone: 770.488.5464
Fax: 770.488.5964
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Data and Statistics
FAQs (Data Related)
Self-reported Arthritis Case Definition
Note: These questions refer to both NHIS and BRFSS surveys,
unless otherwise indicated.
- What is the current case definition for self-reported
arthritis?
- Why does CDC include the four types of arthritis to the
end of the survey question addressing doctor-diagnosed arthritis: “Have
you ever been told by a doctor or other health professional you have
some form of arthritis, rheumatoid arthritis, gout, lupus, or
fibromyalgia?”
- Are self-reports for arthritis valid?
- Which estimate best indicates the prevalence of
arthritis for the nation?
- Is self-reported information on the type of arthritis
valid?
- What changes are expected for future BRFSS surveys?
- How often are the Arthritis Burden Questions on the
BRFSS survey?
- What does the CDC Arthritis Program recommend state
arthritis programs do regarding the BRFSS survey in even years?
- Is there more than one way to define a “case” of
arthritis?
- Why did CDC decide to drop questions on chronic joint
symptoms and cease surveillance of “possible arthritis”?
Back to Question Categories
What is the current case definition for
self-reported arthritis?
Since 2002, CDC, partners, and outside experts have agreed on a case
definition of simply “doctor-diagnosed arthritis.”
Both the Behavioral Risk Factor Surveillance System and the National
Health Interview Survey use the following question to identify adults with
arthritis “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?
For more information on the evolution of the case definition
read more.
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Why does CDC include the four types of arthritis to
the end of the survey question addressing doctor-diagnosed arthritis: “Have
you ever been told by a doctor or other health professional you have some
form of arthritis, rheumatoid arthritis, gout, lupus, or fibromyalgia?”
For public health surveillance, we are trying to capture more than 100
diseases that are considered “arthritis or other rheumatic conditions.” Some
of these conditions may not be readily recognized as arthritis by survey
respondents. Experts recommended adding these conditions.
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Are self-reports for arthritis valid?
Self-reports have been shown to be valid for surveillance purposes. Sacks
JJ, Harrold LR, Helmick CG, Gurwitz JH, Emani S, Yood RA. Validation of a
surveillance case definition for arthritis. J Rheumatol
2005;32:340–347.
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Which estimate best indicates the prevalence of
arthritis for the nation?
National estimates should come from a national survey; CDC uses the
National Health Interview Survey (NHIS) for such estimates. Healthy People
2010 also recommends using NHIS data for national estimates.
Using NHIS data (2003-2005), we estimate that 46.4 million (21.6%) adults
had
doctor-diagnosed arthritis.
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Is self-reported information on the type of
arthritis valid?
The CDC Arthritis Program strongly discourages the collection and reporting of
self-reported data on arthritis type (e.g., osteoarthritis, rheumatoid
arthritis, lupus) because self-reported condition data have been shown to be
inaccurate based on studies done by the program and other researchers. For
example, the CDC Arthritis Program compared how frequently the arthritis
condition type reported by participants in the Medical Expenditure Panel
Survey1 (MEPS) agreed with each of the participants’ doctor’s
diagnosis. This study found that among persons whose doctor had diagnosed
them with osteoarthritis, only 9% of survey participants reported that they
had osteoarthritis. Since self-reported information on type of arthritis is
not valid, the CDC arthritis program discourages states and researchers from
measuring and using data on self-reported arthritis condition type. (Click
here for references.)
-
The Medical
Expenditure Panel Survey is a nationally representative survey of the
U.S. civilian non-institutionalized population.
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What changes are expected for future BRFSS surveys?
We expect the BRFSS Arthritis Burden Questions will continue to be asked in
all states in odd number years. New Arthritis Burden Questions are being
added to the survey in 2009. A list of
BRFSS Arthritis Core (Arthritis Burden Questions) by year is available.
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How often are the Arthritis Burden Questions on the
BRFSS survey?
Starting in 2003, the BRFSS Arthritis Core
(Arthritis Burden Questions) are offered on the core survey in odd
numbered years. State programs are encouraged to add the optional module
known as the BRFSS Arthritis Optional
Module (Arthritis Management Questions) in the same odd-numbered year.
Although states may be interested in using the questions every year, CDC
will NOT financially or analytically support the use of any arthritis
questions in even numbered years. States may add them as state-added
questions.
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What does the CDC Arthritis Program recommend state
arthritis programs do regarding the BRFSS survey in even years?
CDC is not supporting the use of arthritis questions in even years. This
means we are not funding the BRFSS to put the questions on the survey nor
are we providing our standard analytic tables, as we do for all states using
odd number year data. Any use of these questions in even years would have to
be as state-added questions. We do not feel it is necessary to have the data
each year, as the prevalence is unlikely to change rapidly and with lots of
programs competing for space on the questionnaire, one can quickly wear
their welcome out with the BRFSS coordinator. In infrequent instances, when
a state feels it is imperative for its program to make substate prevalence
estimates (e.g., for large cities), it may choose to use the arthritis
questions in even years. CDC is unable to provide any support for doing this
and we don’t recommend it.
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Is there more than one way to define a “case” of
arthritis?
Yes, the purpose (e.g., estimating prevalence or assessing burden) and
source of the data determine the arthritis case definition to be
used. In general, data used in arthritis surveillance falls into two broad
categories, self-reported data and health care system data.
For the purpose of estimating the population prevalence of arthritis, we
recommend using self-reported data as the data source and using
doctor-diagnosed arthritis as the case definition. Both the state-based
Behavioral Risk Factor Surveillance System (BRFSS) and National Health
Interview Survey (NHIS) are self-reported data surveys, and use
doctor-diagnosed arthritis as the case definition. A “case” of
doctor-diagnosed arthritis in these surveys is defined as a “yes” answer to
the following 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?” Further information on the CDC arthritis
case definition is available.
For assessing the burden of arthritis using health care system data
(e.g. hospital discharge data, ambulatory care, death.) a “case” of
arthritis is defined by the National Arthritis Data Workgroup definition
using
arthritis related ICD–9–CM codes
(PDF-73K) and is labeled “arthritis and other rheumatic conditions”.
The CDC discourages states from pursuing these assessments unless there is a
direct link to program activity that is consistent with the state arthritis
plan.
Be aware that other studies (e.g., clinical trials) including some statistics
and studies cited elsewhere on this Website, have different data sources and
use different arthritis case definitions.
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Why did CDC decide to drop questions on chronic
joint symptoms and cease surveillance of “possible arthritis”?
The state-based Behavioral Risk Factor Surveillance System (BRFSS) included
2 questions on joint symptoms between the years of 2002 and 2007. “Possible
arthritis” is defined as a person without doctor-diagnosed arthritis who
answers “yes” to both of the following questions: “During the past 30 days,
have you had any symptoms of pain, aching or stiffness in or around a
joint?” and “Did your joint symptoms first begin more than 3 months ago?”
CDC conducted an expanded data collection in 4 states in 2005 to learn more
about people with “possible arthritis.” Results indicate that over 90% of
persons with possible arthritis who had seen a doctor did not appear to have
arthritis and that the majority of those who had not seen a doctor did not
deem their symptoms serious enough for medical intervention. The CDC
arthritis program reasons that persons with possible arthritis would not be
amenable to public health programmatic interventions for arthritis and that
maintaining surveillance of this group is currently not necessary.
Further analysis of BRFSS data on “possible arthritis” indicated the
group has a different profile than those with doctor diagnosed arthritis.
Unlike doctor-diagnosed arthritis, “possible arthritis” decreases with age
and is more common in men than women. A smaller proportion of people with
possible arthritis report activity limitation due to joint symptoms compared
to those with doctor-diagnosed arthritis. In 2009 the 2 joint symptoms
questions were dropped from the BRFSS. These questions continue to be
collected through the National Health Interview Survey (NHIS).
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References
- Star VL, Scott JC, Sherwin R, Lane N, Nevitt MC, Hochberg MC.
Validity of self-reported rheumatoid arthritis in elderly women. J
Rheum 1996;23:1862-5.
- Ling SM, Fried LP, Garrett E, Hirsch R, Guralnik JM, Hochberg
MC, et al. The accuracy of self-report of physician diagnosed
rheumatoid arthritis in moderately to severely disabled older women.
J Rheum 2000; 27:1390-4.
- Brinton LA, Buckley LM, Dvorkina O, Lubin JH, Colton T, Murray
MC, Hoover RN. Risk of connective tissue disorder among breast
implant patients. Am J Epidemiol 2004;160:619-27.
- March LM, Schwarz JM, Carfrae BH, Bagge E. Clinical validation
of self-reported osteoarthritis. Osteoarthritis and Cartilage
1998;6:87-93.
- Kvien TK, Glennas A, Knudsrod OG, Smedstad LM, The validity of
self-reported diagnosis of rheumatoid arthritis: results from a
population survey followed by clinical examinations. J Rheum
1996;23:1866-71.
Some documents on this page are available in Portable Document Format (PDF). Learn more
about viewing and printing PDF documents with
Acrobat Reader.
A note about “possible arthritis”
“Possible arthritis” is another variant of self-reported data. It is defined
as a person without doctor-diagnosed arthritis who answers “yes” to both
of the following questions: “During the past 30 days, have you had any symptoms
of pain, aching or stiffness in or around a joint?” and “Did your joint symptoms
first begin more than 3 months ago?” The state-based Behavioral Risk Factor
Surveillance System (BRFSS) and National Health Interview Survey (NHIS) can
identify persons with “possible arthritis.” Analysis of BRFSS data on
“possible arthritis” indicates
the group has a different demographic profile than those with doctor
diagnosed arthritis. Unlike doctor-diagnosed arthritis,
“possible arthritis” decreases
with age and is more common in men than women. A smaller proportion of
people with possible arthritis report activity limitation due to joint
symptoms compared to those with doctor-diagnosed arthritis. CDC is currently
analyzing data from 4 states collected in 2005 to learn more about people
with “possible arthritis.” Additionally, CDC will be analyzing data for people
with possible arthritis from a national sample collected in 2005 through the
Arthritis Conditions Health Effects Survey (ACHES). We are still learning
who these people are and whether or not they fit into the larger arthritis
picture.
Back to Question Categories
Page last reviewed: June 8, 2008
Page last modified: September 9, 2008
Content Source: Division of
Adult and Community Health,
National Center for Chronic Disease Prevention and Health Promotion
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