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Wednesday, March 12, 2014

IOM recommends VA use the term "Gulf War illness" and not "chronic multisymptom illness"



The following is from the Institute of Medicine report, "Chronic Multisymptom Illness in Gulf War Veterans: Case Definitions Reexamined", released March 12, 2014: 

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(pp. 97-99)

DISCUSSION OF EXISTING CASE DEFINITIONS

The committee reviewed the literature that identified the symptoms found in Gulf War
veterans through questionnaires and surveys, factor analysis, and clinical observation. After a
thorough discussion of that literature, the committee concluded that it was not feasible to develop
a new evidence-based definition of CMI. The case-definition studies do not all consistently
identify period of onset, duration, frequency, severity, exposure, exclusionary criteria, or a
uniform set of symptoms. There are no clinically validated tests or measures for diagnosing CMI.
Furthermore, the symptoms of CMI are not unique to Gulf War–deployed veterans although they
occur in the deployed at a higher frequency and with greater severity than in nondeployed era
veterans or those deployed elsewhere. That is evidenced by higher prevalences of a variety of
symptoms, as noted in the cohort studies (see Chapter 3) and depicted in the graph in Appendix
B. Thus, the committee has concluded that the available evidence is insufficient to develop a new
case definition of CMI inasmuch as the data are lacking for key elements of a case definition of a
symptom-defined condition, which might include, for example, onset, duration, and measures of
severity.

To move the field forward, the committee has developed an approach that is based on its
evaluation of the CMI literature and its collective judgment. In its review of CMI
symptomatology, factor analyses, and case definitions, the committee noted similarities
throughout the body of literature. A common set of symptoms has been identified in all the case definition studies summarized in this chapter (albeit not necessarily using the same terminology)
that includes symptoms of fatigue, pain, and neurocognitive dysfunction. Furthermore, the
different symptoms in the symptom-based studies—as summarized in Chapter 3, Table 4.2, and
Appendix B—were regularly reported with higher frequency in Gulf War veterans than in
nondeployed era veterans or veterans deployed elsewhere; they include gastrointestinal,
respiratory, and dermatologic symptoms in addition to the fatigue, pain, and neurocognitive
symptoms already identified. The committee recognized that two existing definitions—the CDC
definition and the Kansas definition (see Table 5.1)—capture the array of symptoms most
commonly identified. The CDC definition requires one or more symptoms in at least two of the
categories of fatigue, pain, and mood and cognition to identify a case. The Kansas definition
requires at least three of six symptoms in the domains of fatigue–sleep, pain, neurological–
cognitive–mood, gastrointestinal, respiratory, and skin to identify a case. Thus, both definitions
capture the array of symptoms highlighted by the evidence. The CDC case definition, which has
been widely used by researchers, identifies 29–60% of US Gulf War–deployed veterans as CMI
cases, depending on the population studied, whereas the Kansas definition identifies 34% of the
population studied (Kansas Gulf War veterans) (see Table 5.2).

The two definitions have important differences. The CDC definition has the greatest
concordance with all the other definitions (see Table 5.1) but is less restrictive than the Kansas
definition. The CDC definition requires fewer symptoms, does not include any exclusionary
criteria, and might identify a case without physical symptoms. The Kansas definition will define
fewer veterans as cases. The committee also noted particular strengths of each definition,
including the CDC definition’s inclusion of severity indicators and the Kansas definition’s
exclusionary criteria.

In the committee’s judgment, neither definition has been sufficiently validated. Given the
absence of validators, the committee recommends, with some reticence, the use of two current
case definitions. The CDC and Kansas definitions are the best reflection of the symptom
complexes demonstrated by the Gulf War veterans. The committee recognizes that the
definitions were developed in different study populations and that they differ in sensitivity and
specificity. However, in the committee’s judgment, those two definitions will provide the VA
with a framework that will further research and treatment.

In conclusion, the committee saw merits in both the CDC and Kansas definitions, but the
weight of the evidence does not support use of one rather than the other for all purposes. Given
the differences, the committee notes the importance of choosing a definition that is based on
specific needs. For example, the CDC definition may not be suitable for research that requires a
more narrowly defined study population whereas the Kansas definition may identify too few
cases and compromise statistical power. Another consideration in choosing a definition is the
ability to adapt a definition that is suitable for use in clinical settings.

RECOMMENDATIONS

Evidence is lacking in the studies reviewed to characterize most elements of a case
definition (for example, onset, duration, severity, and laboratory findings) with certainty.
Without that information, the committee could not develop a new definition for CMI.

Furthermore, because that information is lacking, few of the studies that proposed definitions
were able to describe many of the elements of a case definition. Although all the studies describe
clinical features (symptoms), many of the other criteria are not discussed. Therefore, the
committee cannot recommend one specific case definition over another. But it does recommend
the consideration of two case definitions on the basis of their concordance with the evidence and
their ability to identify specific symptoms commonly reported by Gulf War veterans.

There is a set of symptoms (fatigue, pain, neurocognitive) that are reported in all the
studies that have been reviewed. The CDC definition captures those three symptoms; the Kansas
definition also captures them, but it also includes the symptoms reported most frequently by Gulf
War veterans (see Appendix B). Other case-definition studies report additional symptoms that
are not seen with the same frequency or in all studies. Thus, the committee identified the CDC
definition (Fukuda et al., 1998) and the Kansas definition (Steele, 2000) as the two that capture
the array of symptoms most frequently reported by veterans as evidenced by the studies reviewed
(see Chapter 3 and Appendix B).

The committee recommends that the Department of Veterans Affairs consider the
use of the Centers for Disease Control and Prevention and Kansas definitions
because they capture the most commonly reported symptoms.

Neither definition addresses all the key features of a case definition, such as, symptom
onset, duration, severity, frequency of symptoms, and exclusionary criteria. Identifying those
features will contribute to a more accurate case definition. Those features were not regularly
reported in the studies considered. It is important to acknowledge that the two definitions,
although they cover the most common symptoms, do not reflect the complete array of symptoms
reported by Gulf War veterans. Although a standard set of criteria regarding time (a defined
period of onset), place, exposures, and clinical and laboratory findings would have been useful;
given the lag in time between first reports of illness and epidemiologic study, lack of exposure
monitoring, and the absence of validated laboratory tests, it is no longer possible to define many
of the typical elements associated with a case definition. However, review of existing data sets
might prove useful in detailing some of the needed information.

The committee recommends that the Department of Veterans Affairs, to the extent
possible, systematically assess existing data to identify additional features of
chronic multisymptom illness, such as onset, duration, severity, frequency of
symptoms, and exclusionary criteria to produce a more robust case definition.

Finally, VA asked the committee to evaluate the terminology used in referring to CMI in
1990–1991 Gulf War veterans and to recommend appropriate terminology. Multiple terms have
been used over the last 2 decades. Initially, Gulf War syndrome was used, but syndrome indicates
a new group of signs and symptoms not previously seen in medicine (IOM, 2000; King’s College
London, 2010). The Gulf War veterans report more symptoms and with greater frequency and
severity than nondeployed veterans or veterans who were deployed elsewhere, but the types and
patterns of symptoms are the same in all groups, and this suggests that no unique syndrome is
associated with Gulf War deployment.

Although chronic multisymptom illness is descriptive of the heterogeneity of the
symptoms, it is not specific to the population and its unique experience. Thus, to capture the
population of interest and the symptoms, a preferred term is Gulf War illness. Illnesses are
sometimes named after the geographic area or the group in which they were first identified
without meaning to convey a sole etiology (for example, the 1918 influenza pandemic referred to
as the Spanish flu, the 1968 and 1969 influenza outbreaks referred to as the Hong Kong flu, and
pneumonia in legionnaires referred to as Legionnaire’s disease). The committee’s
recommendation reflects both the geographic area and the unique experiences of this group of
veterans. Gulf War illness has been used by many researchers to identify the array of symptoms
expressed by the Gulf War veterans. Its consistent use in the literature might reduce confusion.

The committee recommends that the Department of Veterans Affairs use the term

Gulf War illness rather than chronic multisymptom illness.
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1 comment:

Dr. Dave said...

That's actually all very reasonable! Still not terribly happy they went on to recommend use of the CDC and Kansas definitions, even though they seemed to indicate they were talking about for research use, and not for clinical use. But the VA won't understand (or won't try to understand) that subtlety, unless the full report is a little more clear about the distinction. I want to read the entire report to see what it all says first. I'm pretty happy they came back with the "Gulf War Illness" name recommendation; after all, they were the a&&hats who started the whole CMI thing to start with (the IOM was, I mean).