Measurement of fibromyalgia treatment outcomes is often difficult. Not
everyone agrees on what outcomes can be measured or what’s important.
Historically, outcomes had the connotation of ending or finality,
appropriate for acute illness but unsuitable for a chronic illness like
In the early 1980’s, researchers and clinicians began to realize that
chronic illnesses required assessment over long periods of time and
attention to the daily experience of people living with symptoms and
limitations. For much of the last 20 years, researchers and clinicians have
struggled to define and measure concepts like health status, functioning,
disability, and quality of life for people with chronic illnesses.
Surprisingly, people with fibromyalgia or other chronic illnesses have, in
the past, rarely been consulted about what kinds of outcomes are important
to them. Because of the emphasis on disease processes, providers assumed
that they knew best what outcomes could and should be measured.
Fortunately, that has changed a great deal in the past few years, so that
patient preferences for outcomes are increasingly being sought. People with
fibromyalgia tell health care providers that they value freedom from pain,
anxiety and depression, increased energy, ability to do the things that are
important to them (work, care for their families, participate in
activities), and an overall high quality of life.
Impact Questionnaire (FIQ) was developed to meet the need for comprehensive
fibromyalgia patient evaluation. Rather than attempting to modify an
existing instrument from rheumatology, the fibromyalgia treatment team at
Oregon Health & Science University chose to develop a new instrument using
domains of importance gleaned from patient reports, health status
instruments, and clinical observations.
In its original form the FIQ contained items that measured physical
functioning (10 subitems), symptoms of pain, fatigue, morning tiredness,
stiffness, job difficulty, depression, and anxiety along with days of paid
work missed and number of good days in the past week. The scale was first
reported in 1989 and an article about it was published in 1991(1). Minor
revisions were made in 1997 when 1 item (climb stairs) was added to the
physical function subscale, hashmarks were added to the visual analogue
scales to make scoring easier, and the words "including housework" were
added to the 2 work-related items so that housework was recognized as a
legitimate type of work.
The FIQ has
been used to assess people in the community who have chronic pain (2), to
determine the impact of fibromyalgia on everyday life (3) and disability
(4), as well as outcomes in drug studies, exercise treatment,
multidisciplinary approaches and treatment program evaluation (5-10). A
study that assessed the sensitivity to change of several outcome measures
concluded that the FIQ is the most sensitive measure of change in FMS
treatment and recommended that it be used in future clinical trials (11). A
recent survey of medical databases found 93 references to the use of the FIQ
accessed 11/15/03. The FIQ has been translated into at least 16 languages,
including published versions in Dutch, French, German, Hebrew, Italian,
Korean, Spanish, Swedish and Turkish, and a children’s version has been
When an instrument is used to measure anything, it has to have at least two
qualities, reliability and validity. That is, it has to measure
consistently and accurately and it has to measure what it says it measures.
Reliability is usually measured by looking at how well the items are related
to each other using a test called Cronbach’s alpha and at the scores on the
instrument measured at two points in time called test-retest reliability.
Both of these scores can range from 0 to 1.0. A number higher than .70 is
considered good. Cronbach’s alpha for the total score has ranged from .72
to .93 in English, Swedish, Italian, Hebrew and German versions. Test-retest
scores for a 1-week interval have ranged from .56 to .96 in the same
Validity is measured in several ways. One type called content validity
measures how relevant fibromyalgia patients think the FIQ items are. The
Swedish researchers specifically asked patients about the about relevance of
items and all patients found the items relevant to their symptoms and
difficulties. A second way to measure validity is to see what relationship
the instrument has other measuring instruments. If the relationship is
expected to be high, the validity is called convergent. The FIQ items have
a significant relationship with the Health Assessment Questionnaire
disability scale, and tender point scores. Another form of validity,
discriminant, occurs when an instrument discriminates between groups that
are known to be different. The FIQ can discriminate between untreated
fibromyalgia patients, patients who had completed a 6-month
multidisciplinary treatment program, and people who do not have any chronic
painful illness (See Figure 1).
An essential quality for an outcome measure is sensitivity to change. FIQ
total scores and items change in the desired direction (decrease) as a
result of treatment. The average change in the total score in the clinical
trials referenced above is about 19% (9 points). Some people may not change
that much and some might change much more. In the 6-month fibromyalgia
treatment program at OHSU patients who finished were asked to assess how
much improved they were at the end of the program using a scale from 0 to
100%. The average self-evaluated improvement was 60%. Figure 2 shows a
graph of improvement and the corresponding average FIQ scores. Patients who
said they had changed very little, from 0 to 30%, had scores on the FIQ that
were virtually the same as when they started. Conversely, patients who
rated their improvement as more than 30% had FIQ changes ranging from 25 to
41 % (12 to 18 points).
The clinical question that a health care provider or a person with
fibromyalgia might ask is whether this change is meaningful. Clinical
researchers studying treatments in rheumatoid arthritis (RA) have long used
20% as a definition of improvement. Using those criteria a majority of the
patients who completed the 6-month program had a clinically significant
improvement. Clinical researchers who have studied chronic cancer pain
often use a cutoff point of 4 on a 0-10 point pain scale with scores at 4 or
below indicating adequate pain control when pain cannot be abolished
completely. Using those criteria, Figure 3 portrays the scores on the
physical functioning and pain subscales when divided by the percent of
improvement. The average physical function score was below 4 in the three
groups that had greater than 30% improvement. Only the group with the
highest improvement (greater than 70%) had average pain scores less than 4.
The FIQ is a
useful instrument for measuring the changes in groups of patients in
treatment programs and clinical trials. Whether it is beneficial for
helping individuals and their health care providers plot changes as a result
of individual treatment has not been formally tested but many clinicians use
it for that purpose. Figure 1 can be helpful for determining the degree of
fibromyalgia impact that an individual has in relation to averages for
healthy, untreated patients and patients treated in a multidisciplinary
program. The FIQ and scoring instructions are available at
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