Introduction

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The term "Gulf war syndrome" has been used to describe a variety of symptoms and illnesses experienced by veterans of the 1991 Gulf war. There is no consensus as to how to define Gulf war syndrome, and attempts to specify and measure the syndrome have led to contradictory findings and interpretations.^1-3 In previous papers, we found that, although veterans deployed to the Gulf reported more symptoms than veterans deployed to Bosnia and those who were not deployed,⁴ the constellations of symptoms in all three groups were similar.³ We suggested that vaccination against biological warfare agents contributed to this ill health, but we also found that all military exposures were associated with all outcomes. ^{4 5} Several groups have confirmed that two to three times more Gulf war veterans report symptoms than appropriate controls, but conclude that there is no unique Gulf war syndrome. ^{2 4 6 7}

Some veterans believe that they have a condition called Gulf war syndrome and attribute their symptoms to this. We are not aware of any systematic studies investigating the views of veterans or estimating the prevalence of such a belief. This information is important as the beliefs and views of the veterans may determine symptom reporting, health perception, degree of associated disability, and help-seeking behaviour. For example, a belief that the syndrome is caused by vaccinations may hamper efforts to ensure that servicemen and servicewomen are protected against threats such as chemical and biological weapons.

The purpose of this paper was to determine how many veterans deployed to the Gulf believed they have Gulf war syndrome, to compare health outcomes between those who believed they have Gulf war syndrome and those who did not, and to examine factors associated with the belief.

	Methods

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Ethical approval was gained for the study. In August and September 1997, questionnaires were sent to a randomly chosen, large sample (n=4250) of British servicemen and servicewomen who served in the Gulf war in 1991.⁴ Two follow up mailings were completed by November 1998. All service personnel were asked questions about their age, sex, marital status, education, occupational factors (rank, current service status, and duties during the Gulf war), cigarette smoking habits, and alcohol consumption and about their experience of 30 military exposures including environmental exposures, such as smoke from fires in oil wells or depleted uranium, and military stressors, such as witnessing maimed or injured bodies or being under fire. In our previous paper, these exposures were universally associated with adverse health outcomes, although we could not detect specific associations.⁴ In this paper, therefore, we present data on exposures in categories according to the total number of recorded exposures. Participants were asked about the number of vaccines they received before and during deployment, and the data are presented as categories on the basis of the total number of vaccines received. Participants were also asked whether they thought they had Gulf war syndrome and whether they knew other people who had Gulf war syndrome.

Health outcomes were assessed using the general health questionnaire (a measure of psychological distress),⁸ the fatigue questionnaire,⁹ the health perception and physical functioning subscales of the SF-36 health survey,¹⁰ and a list of symptoms based on the Hopkins symptom checklist¹¹ tailored to the experience of Gulf war service personnel. A measure of post-traumatic stress reaction, a proxy for post-traumatic stress and the multisymptom illness as classified by Centers for Disease Control and Prevention,² was created from items in the symptom checklist.

Data were analysed in Stata 6 (StataCorp, College Station, TX). Logistic regression was used to examine univariate and multivariate associations between demographic variables, health outcomes, other specific risk factors, and the main explanatory variable (dependent variable)belief in having Gulf war syndrome. Multiple regression was used to examine differences in health perception, physical functioning, and physical symptoms between veterans who did and did not believe they had Gulf war syndrome.

	Results

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Response rates and differences between responders and non-responders have been reported.⁴ After three mailings, the response rate was 2961/4250 (69.7%). Overall, 513/2961 (17.3%, 95% confidence interval 15.9% to 18.7%) participants believed they had Gulf war syndrome; the remaining 2448 (82.7%) participants did not. Those who believed they had Gulf war syndrome were more likely to be of lower rank, were less likely to be still serving in the army, and were less well educated than those who did not believe they had Gulf war syndrome (table 1). There were more smokers among veterans who believed they had Gulf war syndrome (n=241/513, 47%) than among those who did not (n=174, 34%).

Of those who believed they had Gulf war syndrome, 462 (90%) fulfilled Centers for Disease Control and Prevention criteria for the illness.² When disability was also considered, only 221 (43%) of the veterans who believed they had Gulf war syndrome were symptomatic and disabled according to the criteria. Those who believed they had Gulf war syndrome were more fatigued, more distressed, more likely to have a post-traumatic stress reaction, and more likely to fulfil Centers for Disease Control and Prevention criteria for multisymptom illness (table 2). When we adjusted for rank, duty, education, and current service in the military, there was no substantial difference in the pattern of results.

Univariate analyses showed that those who believed they had Gulf war syndrome had worse health perceptions, were more physically disabled, and reported more symptoms than those who did not (table 3).

We examined factors that could potentially be associated with a belief in having Gulf war syndrome, such as number of exposures reported, number of vaccines received, and knowing other people with Gulf war syndrome. We adjusted for confounding factors that had the potential to distort the resultssuch as education, rank, whether serving in the army at the time of the questionnaire, and health outcomes, including distress, fatigue, physical symptoms, and physical functioning, that may have influenced individual's beliefs and behaviour. In the unadjusted analysis, more exposures, more vaccines, and knowing someone else with Gulf war syndrome were all associated the with belief. After adjustment, there was no association between the number of exposures and the belief. However, those who had received more vaccinations (7) and knew other people with Gulf war syndrome were more likely to believe they had Gulf war syndrome (P<0.05). The strongest association was knowing other people with Gulf war syndrome (P<0.001). The odds increased when confounding factors were controlled for, including health outcomes (table 4). Of the participants, 444 (86.5%) veterans who believed they had Gulf war syndrome attributed a change in functioning to their service in the Gulf. They were not asked about which aspect of their service was related to that change in functioning.

	Discussion

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In our sample of British Gulf war veterans 17% believed they had Gulf war syndrome. If this sample is representative,⁴ about 9000 of 53 000 British service personnel believe they have Gulf war syndrome. To the best of our knowledge this study is the first to report the number of British service personnel deployed to the Gulf who, six years after the conflict, believed they have Gulf war syndrome.

The strongest factor associated with the belief was knowing another person who held the same belief. The odds ratio was not affected by distress or disability, states that could have existed prior to, or resulted from, service in the Gulf.

Veterans who believed they had Gulf war syndrome reported worse health outcomes than those who did not. They were more symptomatic, distressed, and fatigued, and they were more likely to have a post-traumatic stress reaction. They were also more physically disabled, and their health perceptions matched their experience in that they perceived themselves to be unhealthy.

Veterans who have symptoms believe that they have Gulf war syndrome because the most likely explanation for the symptoms stems from something they have in commontheir active service. It is possible that the 17% of veterans who believed they had the syndrome had a unique adverse exposure not experienced by the 83% who do not. The greater the number of vaccinations veterans received, the more likely they were to believe they had Gulf war syndrome. The largest factor associated with the belief was knowing someone else who also believed they had the condition.

Collectively, Gulf war veterans shared in a hazardous situation resulting, for some, in ill health. Concern over one's health may lead a person to seek support from peers in a similar position. As a result, a system of beliefs around the illness in which the veterans shared ideas about the nature and cause of their symptoms may have evolved, and this may have had an integrating function on the group. This would fit in with the army's philosophy of encouraging two-man buddy systems, because members of close-knit groups are thought to be more able to cope with adversity.¹² However, social networks may have played a different role in this case and information about the "illness" transmitted from one person to another increased fear and awareness, resulting in more symptoms, more distress, and increased levels of disability.

At present, 2801 British veterans have attended the medical assessment programme that is organised by the Ministry of Defence and is available to any Gulf war veteran with concerns about their health.¹³ Recent parliamentary answers confirm that the number of veterans concerned about their health is declining, and the future of the programme is in doubt. However, our results are cause for concern and show that, at the time of the survey, many servicemen believed their health had been adversely affected by their service in the Gulf war. Given that the armed forces represent a group of people chosen because of their good health and fitness, this is alarming. It also has implications for the willingness of armed forces personnel to participate in future health protection programmes intended to protect against the threat of chemical and biological warfare.

More optimistically, although those who believe their symptoms are part of the Gulf war syndrome are disabled, they are not as incapacitated as might be expected. This may be related to attitudes to physical fitness in the armed forces, in which exercise is promoted and incorporated routinely into military life. It may also result from the way in which armies prepare personnel for exposure to adversity, in the hope that they will not become disabled and that the likelihood of subsequent illness is reduced.¹²

The future health needs of the all service personnel should now be considered. As research findings are published, pertinent information should be fed back to all service personnel in order to minimise misconceptions about the nature of the illness and to prevent competing models of illness that may be harmful.

	Acknowledgments

   Contributors: TC had the original idea for the study, framed the hypotheses, contributed to the analyses, prepared the manuscript, and acts as guarantor. MH conducted the main analyses. CU was the study coordinator. LH assisted with data collection. KI assisted in the study design and data collection. SW and AD were the grant holders and contributed to the manuscript.

	Footnotes

Funding: United States Department of Defense funded this study. Neither United States Department of Defense nor British Ministry of Defence contributed to the design, analysis, or reporting of the study.

Competing interests: None declared.

	References

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(Accepted 24 May 2001)