BMC Public Health 2004, 4:27 http://www.biomedcentral.com/1471-2458/4/27 veterans who did not serve there (NGWV) [1-7]. In terms of the types of reported symptoms, different studies have discovered a range of nonspecific chronic conditions. Many research groups have noted that GWV are more likely to suffer from substantial fatigue, symptoms of post-traumatic stress, and psychological distress [1,2,4]. Others have also described peripheral, respiratory, gas- trointestinal, psychological and concentration problems [3]. Despite millions of dollars of funding and several inde- pendent investigations in a number of countries [8], the increased morbidity of GWV remains an unexplained phenomenon. Media interest and anecdotal reports have fuelled speculation concerning the existence of a Gulf War syndrome (GWS), linking reports of ill health to certain hazardous exposures experienced during the conflict. Most notably these include anti-chemical warfare nerve agent prophylaxis (NAPS), depleted uranium, multiple vaccinations, smoke from oil fires and pesticide use. It is hypothesised that exposure to these hazards has led to the development of a unique syndrome among some GWV, including symptoms of post-traumatic stress disorder [4], fibromyalgia [9], chronic fatigue [1,10] and multiple chemical sensitivity [10,11]. However, attempts to specify and measure the syndrome have led to contradictory find- ings and interpretations [12]. Current opinion does not support the existence of a unique syndrome affecting GWV, but findings support an excess of non-specific self- reported ill health in this group [13,14]. This is the largest UK study of post-Gulf War morbidity to date, and the first to approach all veterans of the Gulf war (rather than a sample), including both serving and dis- charged personnel. The questionnaire focused on repro- duction and child health, but a page was included which asked for information on the study participants' changes in health status since 1990. Since the focus of the study was on reproduction and child health, we reasoned that selection bias relating to the ill health of the veterans themselves might be reduced. Previous studies have included tick-boxes or grading scales with a list of possible symptoms for respondents to mark and GWV have tended to report increased frequencies of almost all symptoms included in questionnaires [1,3,4]. In contrast, we asked participants to respond to an open-ended question about 'any new medical problems or changes in general health since 1990'. By allowing veterans to report on a full and non-specific range of symptoms using free text it was hoped that they would report only those symptoms which they felt were most important to them. The main objective of this analysis was to quantify and describe symptoms and diseases reported by UK GWV and a comparison group since 1990. We aimed to determine whether GWV still report more ill health, and/or a differ- ent profile of symptoms and diseases than NGWV when, i) their children's rather than their own health was the focus of the study; and ii) details of their own ill health were requested in a non-specific way using free-text. In addition, we aimed to estimate the number of GWV who believed that they had Gulf war syndrome (GWS), and to compare their reported disease/symptom profiles with GWV who did not believe they had the syndrome. Methods Full details of the study are reported elsewhere [15]. In brief, the Gulf War cohort (GWV) consisted of all UK armed forces personnel deployed to the Gulf area at any time between August 1990 and June 1991 (51,581 men and 1,230 women). Special forces were excluded for secu- rity reasons. The comparison cohort (NGWV) comprised demographically similar personnel who were in service on 1st January 1991 and were appropriately fit, but were not deployed to the Gulf (51,688 men and 1,236 women). The group was stratum-matched on sex, age (five-year groups), service (Army, Navy, Air Force), rank (officer, other ranks), serving status at the time of the Gulf War (regular, reservist) and on fitness to be deployed (Army and Air Force only). 42,818 men and 1,269 women responded to the survey, representing response rates of 48% and 66% respectively after adjusting for undelivered mail. For reasons of statistical power, the analyses reported in this paper were restricted to the 42,818 male responders. Basic demographic details and last known address for all surviving cohort members were obtained from the Minis- try of Defence (MoD). Information was collected using a validated postal questionnaire sent to both serving and discharged military personnel between August 1998 and March 2001. In addition to questions on reproduction and pregnancy outcome, information was collected on the study participant's current health, and on changes in health status since 1990. Questions on service history, smoking status, current alcohol consumption, and details of vaccinations and exposure to specific chemical and environmental factors during the Gulf war (1990–91 for NGWV) were included. GWV were also asked if they con- sidered that they had 'Gulf War syndrome' (Yes /No/Not Sure). Missing information was checked by letter or tele- phone, and an Intensive Tracing Study (ITS) of non- responders was conducted. The primary outcome measure was the reporting of one or more new medical problems or changes in general health since 1990. Reported symptoms/diseases were coded into one of 36 different categories (based loosely on ICD-10 classification), and the data were examined by these ill health categories. Subjects were counted only once in the Page 2 of 10 (page number not for citation purposes)