Chapter Five: Health Problems in PGW Veterans

The epidemiology of illness in PGW veterans is not the focus of this report, and indeed was the subject of a distinct RAND effort. A summary of some factors related to epidemiology is provided here. This is in no way intended to be a complete review of the epidemiological data.

Gulf War Veterans Report Health Problems

Many PGW veterans (on the order of 100,000) have participated in health registries through the VA or DoD, and most of these veterans report having health problems. A variety of studies have characterized the symptoms and diagnoses in PGW veterans. Table 5.1 shows, as an example, the most frequent principal diagnoses in PGW registry personnel as of February 1997 (n = 74,653). Findings, while generally consistent, vary somewhat with the wording and category boundaries employed to define the symptoms and diagnoses.

Symptoms in PGW Veterans

Findings will be similarly reported from a single study examining symptoms in PGW veterans. Findings from other studies evaluating symptoms are qualitatively similar. "SSID," or "signs, symptoms and ill-defined conditions," constituted the primary diagnosis for 17.2 percent of the veterans, and the primary or secondary diagnosis for 41.8 percent.

Although the authors state that "more definitive, often psychological, diagnoses can be made by increasing the intensity of the evaluation and by multidisciplinary input," no evidence was provided that psychological diagnoses would be made on intensive scrutiny at a higher rate than in non-PGW personnel, or in personnel without symptoms (or perhaps those for whom symptoms were falsely "assigned," to deal with the possibility that diagnoses may be given precisely because of illness reporting).

Table 5.1

Most Frequent Principal Diagnoses in PGW Registry Personnel
February 1997 (N = 74,653)

Symptom Frequency (%)
No diagnosis 22.8
Missing diagnosis 5.1
Pain in joints 4.0
Person with feared complaint in whom no diagnosis was made 2.7
Psychalgia 2.0
Other specified adjustment reaction 1.9
Depressive disorder, not elsewhere classified 1.8
Contact dermatitis and other eczema, unspecified cause 1.6
Asthma, unspecified 1.6
Lumbago 1.6
Essential hypertension 1.5
Migraine 1.5
Malaise and fatigue 1.4
Allergic rhinitis, cause unspecified 1.3
Unspecified sinusitis (chronic) 1.3
Other and unspecified noninfectious gastroenteritis and colitis 1.3
Osteoarthritis, unspecified 1.1
Sleep disturbance 1.0
Irritable colon 0.9
Alopecia 0.9
Anxiety states 0.8
Headache 0.7

Comment on Headache

Of the approximately 10 percent of all subjects who had a primary diagnosis of headache, 35 percent were regarded as migraine (classified as neurological), 38 percent as tension (classified as psychological), and 27 percent as ill-defined SSID (Roy, Koslowe, et al., 1998). To further convey the element of arbitrariness in these designations, there was wide variation in diagnosis by region with migraine representing from 23 percent to 50 percent of all veterans; tension, 19 percent to 48 percent; and ill defined, 4 percent to 41 percent (Roy, Koslowe, et al., 1998). Table 5.2 lists the symptoms in order of prevalence.

In those with a primary diagnosis of good health, prevalences were as shown in Table 5.3.

Table 5.2

Symptom Prevalence as Primary and Any Diagnosis
Symptom Primary Diagnosis (%) Any Diagnosis (%)
Fatigue 26.8 30.3
Headache 14.5 21.3
Sleep disorders 11.7 19.0
Memory loss 9.9 16.9
Sleep apnea 7.4 5.5
Rash 3.8 5.7
Dyspnea 4.7 8.0
Chest pain 2.4 3.9
Digestive 1.8 2.6

SOURCE: Roy, Koslowe, et al., 1998.

Table 5.3
Symptom Prevalence in Those with a Primary Diagnosis of Good Health

Symptom Percentage
Fatigue 20.7
Joint pain 20.1
Headache 12.5
Sleep disturbance 11.2
Memory loss 14.7
Problems concentrating 9.2
Rash 10.9
Depressed mood 7.1
Muscle pain 6.7
Diarrhea 6.7
Hair loss 5.9
Dyspnea 4.9
Abdominal pain 5.3
Bleeding gums 3.6

SOURCE: Roy, Koslowe, et al., 1998.

Symptoms for those given a diagnosis other than SSID (Table 5.4) and those diagnosed with SSID (Table 5.5) are qualitatively similar, and roughly similar in ordering, to those of other reports on symptoms in ill PGW veterans. Results from other studies will not be reviewed here.

Table 5.4
Symptom Prevalence in Those Given a Diagnosis Other Than SSID

Symptom Percentage
Fatigue 47.1
Joint pain 55.7
Headache 41.7
Sleep disturbance 34.6
Memory loss 35.6
Problems concentrating 27.9
Rash 32.2
Depressed mood 24.0
Muscle pain 23.7
Dyspnea 20.7
Diarrhea 19.2
Abdominal pain 17.9
Hair loss 13.2
Bleeding Gums 9.1
Weight loss 7.2

SOURCE: Roy, Koslowe, et al., 1998.

Table 5.5
Symptom Prevalence in Those Diagnosed with SSID

Symptom Percentage
Fatigue 59.5
Joint pain 47.4
Headache 44.3
Sleep disturbance 41.0
Memory loss 40.6
Problems concentrating 31.1
Rash 29.8
Depressed mood 21.5
Muscle pain 21.5
Dyspnea 20.2
Diarrhea 18.0
Abdominal Pain 15.6
Hair loss 13.0
Bleeding gums 8.5

SOURCE: Roy, Koslowe, et al., 1998.

Increased Symptom Reporting in PGW Veterans

Many of the problems reported by ill PGW veterans occur also in the general population. It is desirable to know whether and to what degree PGW veterans experience higher rates of illness than those who did not serve in the PGW. Several studies have shown that those deployed to the Gulf have higher rates of self-reported physical symptoms compared to those who were not deployed (Centers for Disease Control and Prevention, 1995; Stretch, 1995; Iowa Persian Gulf Study Group, 1997; Canadian Department of National Defence, 1998; Fukuda, Nisenbaum, et al., 1998; Lange, Tiersky, et al., 1998a; Lange, Tiersky, et al., 1998b; Tiersky, Natelson, et al., 1998; Wolfe, Proctor, et al., 1998c). Symptoms commonly reported by deployed veterans include those that might be expected from the diagnoses above: fatigue, joint pain and stiffness, diarrhea, unrefreshing sleep or sleep difficulties, diarrhea and abdominal discomfort, weakness, cognitive symptoms including difficulty remembering, problems with word finding, or impaired concentration, headaches, and weakness. Some recent efforts have been made at devising case definitions. One researcher has articulated case definitions for each of three syndromes identified by factor analysis (Haley, 1997). Another, from the CDC, requires symptoms in two of three major categories of fatigue, musculoskeletal symptoms, and mood-cognition (Fukuda, Nisenbaum, et al., 1998). Others have used criteria involving chronic fatigue, fibromyalgia, or chemical sensitivity (Lange, Tiersky, et al., 1998a; Lange, Tiersky, et al., 1998b; Tiersky, Natelson, et al., 1998).

Regarding findings of increased symptom reporting, one study conducted by the CDC evaluated symptoms in an Air National Guard unit from Pennsylvania ("Unit A") and three comparison units from Pennsylvania and Florida chosen for similarity in mission responsibility (Centers for Disease Control and Prevention, 1995). A total of 3,927 personnel from four units participated in a survey with response rates from 36 percent to 78 percent. In all units, the prevalence of each of 13 chronic symptoms (lasting six months or more) was significantly greater among subjects deployed to the Gulf than among those not deployed. (The symptoms most frequently reported and considered "moderate" or "severe" included fatigue (61 percent), joint pain (51 percent), nasal or sinus congestion (51 percent), diarrhea (44 percent), joint stiffness (44 percent), unrefreshing sleep (42 percent), excessive gas (41 percent), difficulty remembering (41 percent), muscle pain (41 percent), headaches (39 percent), abdominal pain (36 percent), general weakness (34 percent), and impaired concentration (34 percent). The prevalence of five symptom categories--diarrhea, other GI complaints, difficulty remembering or concentrating, "trouble finding words," and fatigue--was significantly greater among those deployed from Unit A than the other units. Both self-report and selective participation could have biased these results, however.

A second, more complete evaluation of the cohorts examined by the CDC entailed a cross-sectional survey of 3,273 currently active volunteers from four Air Force units (including 1,155 Gulf War veterans and 2,520 nondeployed personnel), together with a cross-sectional clinical evaluation of 158 PGW veterans from one unit, irrespective of health status (Fukuda, Nisenbaum, et al., 1998). A clinical case definition was determined, in which criteria were satisfied for a "case" if one or more chronic symptoms were present from at least two of three categories: fatigue, mood-cognition, and musculoskeletal symptoms. Severe cases were those in which there were "severe" symptoms from each category. A factor-derived case was defined as one in which the combined factor score was in the top 25 percent of questionnaires, including non-PGW veterans. Forty-five percent of PGW veterans and 15 percent of nondeployed personnel were symptom-category cases. Forty-seven percent of PGW veterans and 15 percent of nondeployed were factor score cases. This suggests that the authors selected the 25 percent cutoff to match the symptom-derived cases. The authors stated that the syndrome should be such that it embraces at least 25 percent of PGW veterans, but this is at once arbitrary and inappropriate; 25 percent of legionnaires or Four-Corners residents would obviously not need to be ill for Legionella pneumonia or hantavirus to have produced an illness syndrome in those groups. For symptom-derived cases, 39 percent of PGW veterans and 14 percent of nondeployed personnel met criteria for mild to moderate illness; while 6 percent versus 0.7 percent met criteria for severe illness. Illness was reportedly not associated with time or place of deployment or with duties during the war. There were no differences in lifetime report of medical illness of 35 medical and psychiatric conditions, including heart disease, hypertension, diabetes, alcohol and substance abuse, anorexia/bulimia, migraine or severe headache, anxiety, diarrhea, irritable bowel syndrome, or impotence. History of prior depression was significantly more common in severe cases (15 percent) than in noncases (0 percent; p < .05). Severe illness was associated with Gulf War service, female sex, enlisted rank, and smoking, on multivariate analysis. There was no association between illness and number of deployments, month/season of deployment, duration of deployment, military occupational specialty, direct participation in combat, or self-reported locality in the Gulf region (most were in Riyadh).

The Iowa Persian Gulf Study Group (1997) assessed the prevalence of self-reported symptoms in Iowa Gulf-deployed veterans and nondeployed personnel. From 238,968 persons, 4,886 were randomly selected from one of four groups: Gulf-deployed active-duty military, Gulf-deployed National Guard/Reserve, non-Gulf-deployed active-duty military, or non-Gulf-deployed National Guard/Reserve. A total of 3,695 completed a telephone interview. Symptom reporting was higher for Gulf-deployed veterans for fibromyalgia (19.2 percent versus 9.6 percent), cognitive dysfunction (18.7 percent versus 7.6 percent), alcohol abuse (17.4 percent versus 12.6 percent), depression (17 percent versus 10.9 percent), asthma (7.2 percent versus 4.1 percent), anxiety (4.0 percent versus 1.8 percent), bronchitis (3.7 percent versus 0.8 percent), Posttraumatic Stress Disorder (PTSD) (1.9 percent versus 0.8 percent), sexual discomfort (1.5 percent versus 1.1 percent), and chronic fatigue (1.3 percent versus 0.3 percent).

Another group distributed 16,167 survey questionnaires of which 31 percent were returned; they reported that deployed veterans had significantly more of any of 23 physical health symptoms than nondeployed veterans, an effect not significantly altered by controlling for smoking and drinking, age, rank, education, marital status, and branch of military service (Stretch, Bliese, et al., 1996a; Stretch, Bliese, et al., 1995; Stretch, Bliese, et al., 1996b).

A study examining exposures and symptoms in Gulf War veterans from a Fort Devens ODS Reunion Survey did not include a nondeployed control group, but found that the five most commonly endorsed symptoms among the 2,119 who returned the survey (of 2,313 subjects surveyed), were aches/pains, lack of energy, headaches, insomnia, and feeling nervous/tense (Wolfe, Proctor, et al., 1998c). PTSD was associated with health symptoms, but those with combat exposure were not more likely to report increased health symptoms.

A health survey returned by 3,113 PGW-deployed (73 percent) and 3,439 nondeployed (60.3 percent of those solicited) Canadian Forces veterans, from 9,947 personnel to whom the survey was sent (all Canadian Gulf-deployed and a sample of those serving elsewhere during the Gulf War) found that Gulf-deployed veterans reported higher prevalences of symptoms of chronic fatigue, cognitive dysfunction, multiple chemical sensitivity, major depression, PTSD, anxiety, fibromyalgia, and respiratory diseases (bronchitis and asthma together) (Canadian Department of National Defence, 1998). They also reported higher numbers of children with birth defects (before, during, and after the PGW).

Because these studies are based on self-reported illness, it is possible that reporting bias and self-selection could have influenced results. Although the degree to which these factors may influence self-reported symptomatology is unknown, it can by no means be assumed that bias serves as the sole explanation for the higher rates of symptom reporting in those deployed to the Persian Gulf.

Factors Associated with Registry Participation

Symptoms, then, appear more common in those deployed to the Gulf, although similar symptoms and illness may occur at lower rates in other military and civilian persons. Determination of what constitutes the cause or causes of illness may be helped by analysis of factors associated with illness development. Registry participation is not equivalent to illness. Many PGW veterans who have not participated in registries report health problems, and some who have participated in registries report no health problems. However, a rough relation between illness and registry participation is present. Table 5.6 shows predictors of registry participation and their associated odds ratios, from one study.

Table 5.6
Registry Participation Predictors

Factor Odds Ratio
Stationed in PGW theater 2.2
Age: younger than 31/older than 22 2.1
Enlisted 2.0
Construction worker 1.3
Female 1.3
Hospitalized during 12 months prior to PGW 1.2
Army 4.7 (4.6-4.9)
National Guard 2.6 (2.5-2.6)

SOURCE: Gray, 1998.

The degree to which predictors of registry participation predict illness as opposed to inclination to participate can only be determined by evaluating these predictors against more definitive criteria for illness. Indeed, others cite increased participation of reservists, who in one account represented nearly half of those reporting the problem, while making up only 17 percent of the troops serving there (Thompson, 1996). However, "the Pentagon attributes this discrepancy to the reluctance of active-duty soldiers to complain for fear of losing their jobs in a shrinking military, on the reservists' greater age and on the fact that the war disrupted their lives more severely than those of active-duty troops" (Thompson, 1996).

Limited Evidence is Consistent with the Possibility that PB, or Adverse Response to PB, May be Associated with Illness

A definitive link between PB and illness in PGW veterans is not present. Two factors have complicated determination of such a link. First, outcome data have been poor; until recently, no case definitions for illness in PGW veterans had been devised. Second, data on exposure have been poor; no records were made and preserved of who received PB, to permit a more definitive association between PB and illness to be identified or excluded. Two lines of information are available that are consistent with the possibility of a link between PB and illness, although they are not definitive for a causal connection.

One study found that two of three syndromes, derived by factor analysis in a group of ill PGW veterans, were significantly associated with self-report of adverse response to PB during the PGW (Haley, 1997). This study is described in somewhat more detail in Chapter Seven, "Individual Differences in Reactions to PB." This finding might suggest that individuals with a combination of exposure and special susceptibility may have had increased risk of illness, although recall bias could contribute to the finding.

One recent report found that, among British servicemen (findings for men only were reported), service in the PGW was associated with increased risk of illness (using the CDC case definition for Gulf War Illness (Fukuda, Nisenbaum, et al., 1998)) more than could be accounted for by deployment to an unfamiliar hostile environment (based on comparison to Bosnia and nondeployed PGW-era cohorts): an odds ratio of 2.5 (2-2.8) (Unwin, 1999). Among PGW, Bosnia, and Era cohorts, 61.9 percent, 36.8 percent, and 36.4 percent met CDC PGW illness criteria, respectively, with 25.3 percent, 11.8 percent, and 12.2 percent meeting criteria for severe symptoms (Unwin, 1999). As seen in Table 5.7, various self-reported exposures were associated with illness in PGW veterans. In particular, self-report of PB exposure in British veterans was associated with increased odds ratios for CDC-defined PGW illness (Unwin, 1999). For Gulf War and Bosnia troops, the odds ratios associated with PB were comparatively high, constituting the highest odds ratios for the Bosnia-deployed; and for PGW troops, coming in an approximate tie to use of nuclear, biological, and chemical warfare protective suits (which could represent a proxy for PB use or heavy PB use, signifying perceived threat of imminent CW attack). Recall and reporting bias remain possibilities; and many other exposures were also apparently associated with likelihood of illness. The degree to which recall bias is likely to be responsible for the findings is, however, small: confirmation in official records of vaccination status was present for some veterans, and for these personnel the odds ratios of illness as a function of vaccination status were similar to those in the population overall, suggesting that illness status did not strongly influence recall of exposures.

In summary, many PGW veterans report health problems, and reporting of health problems occurs at a higher rate in PGW veterans compared to other deployed and nondeployed veterans. Moreover, self-reported exposures in the PGW are associated with increased likelihood of illness, with PB showing a particularly strong odds ratio. The likelihood that this is the result of recall bias in ill veterans is reduced by information showing that for risk factors for which records are available for some (British) veterans, comparable odds ratios are seen.

Table 5.7
Odds Ratios for CDC-Defined Persian Gulf War Illness, in Veterans from the PGW, Bosnia, or Gulf-Era Veterans Not Deployed to the Gulf

Factor PGW Bosnia PGW Era(not deployed)
PB 2.6 (2.2-3.1) 3.4 (1.7-6.8) 1.9 (1.4-2.8)
Pesticides on clothes or bedding 1.9 (1.6-2.2) 1.7 (1.4-2.2) 1.9 (1.5-2.3)
Personal pesticides 2.2 (1.9-2.6) 1.8 (1.5-2.2) 1.8 (1.5-2.2)
Exhaust from heaters or generators 1.9 (1.6-2.2) 2.8 (2.1-3.7) 2.4 (1.9-2.8)
NBC suits (indicator of higher PB usage?) 2.7 (2.3-3.3) 2.7 (1.6-4.8) 2.3 (1.5-3.7)
Anthrax vax 1.5 (1.3-1.7) 1.5 (0.7-2.9) NA
With records 1.4 (1.0-1.8) 2.6 (0.9-7.4) NA
Any biological 1.5 (1.3-1.7) 1.5 (0.8-2.8) NA
With records 1.4 (1.1-1.9) 2.5 (0.9-6.6) NA
Yellow fever 1.3 (1.1-1.7) 1.0 NA
With records 1.4 (0.9-2.0) 0.8 NA
Tetanus 1.3 (1.1-1.5) 1.0 NA
With records 1.1 (0.8-1.4) 1.0 NA
Any routine 1.2 (1.1-1.4) 1.1 (0.9-1.3) NA
With records 1.0 (0.7-1.3) 1.0 (0.7-1.3) NA

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