Table 1.

Characteristics of studies that have investigated the association between deployment to the Gulf War and symptoms of pain amongst veterans

Study	Sample	Study design	Measured outcomes	Response rate and bias	Confounding	Notes
Sutker 1993	215 GWV 44 NGV Sampled from 5 National Guard and Army Reserve units as part of debriefing programme	Questionnaire administered by VA staff 4–10 months after return from Operation Desert Shield/Storm	General aches and pains as measured by the Health symptom checklists	70% GWV response (306 eligible) 91 GWV excluded from analysis for failure to complete the majority of measures administered, however, they 'did not differ on descriptive variables' from those that were analysed. Number of eligible NGVs unclear	Bonferonni adjustment showed no sig. effects for sex/race although women and non-white participants tended to report more health complaints	Symptom presence included the report of the symptom at least once a week over the past 30 days
Sostek 1996	57 GWV 44 NGV members of a single National Guard Unit	Questionnaire survey	Joint pain Abdominal pain (infra or supra umbilical location)	62% GWV (92 sampled) 100% NGV (44 sampled) Unclear what percentage of the unit was sampled	No adjustments were made for confounding. Groups were said to be similar on a range of socio-demographic variables with the exception of age. Gulf veterans were significantly older.	Authors suggest that bias may be present in their study as a significantly higher proportion (p≤0.05) of Gulf veterans report experiencing a 'change in the colour of fingernails' (a control symptom)
Iowa 1997	1896 GWV 1799 NGV DoD Manpower Data Center used to create a stratified random sample from 28,968 military personnel from Iowa	Cross-sectional telephone interview survey Sept 1995 – May 1996	Bodily pain	78% GWV (2421 eligible) 73% NGV (2465 eligible) Those who were regulars, enlisted, navy or coast guard, aged up to 25 years and black or other ethnic background less likely to participate	Controlled for stratification variables: military service (regular/National Guard), age, sex, race, branch of service and rank	Response reliability for 165 interviews kappa 0.39–0.79
Doebbeling 2000	see Iowa 1997	see Iowa 1997	Pain or aches in more than 1 joint Back pain	see Iowa 1997	see Iowa 1997
Voelker 2002	See Iowa 1997	see IOWA 1997	Bodily pain on SF-36	see Iowa 1997	See Iowa 1997	Effect size is the standardised mean difference on the bodily pain subscale of the SF36
Peloso 2002	See Iowa 1997	See Iowa 1997	Chronic widespread pain	See Iowa 1997	See Iowa 1997	Outcome – pain present in last year and last month, moderate or greater severity and involvement of upper and lower extremities and trunk
Fukuda 1998	1163 GWV 2538 NGV Sampled veterans were active duty members of the Air Force, from Florida or Pennsylvania and who were on base at the time of the survey	Cross-sectional population survey Jan – March 1995	Joint pain Muscle pain Chest pain	Veterans were not sampled according to Gulf status so no differential response rates are given. Unit response rate 35% – 73%	No report of adjustment made for potential confounders.
Goss Gilroy 1998	3113 Canadian GWV 3439 Canadian NGV Sampled from Department of National Defence human resources data files	Cross-sectional survey	Serious trouble with back pain	73% GWV (4262 eligible) 60% NGV (5699 eligible)	NGVs matched on sex, age group and regular/reserve status	Only data for male veterans is presented.
Proctor 1998	186 GWV from Fort Devens 66 GWV from New Orleans 48 Germany deployed veterans	Cohort study Spring 1994 – Autumn 1996	Joint pain Chest pain	53% Fort Devens (353 sampled, 2949 eligible) 34% New Orleans (194 sampled, 928 eligible) 51% Germany deployed. Participants were recruited after taking part in a previous study	Published odds ratios were weighted for sampling design and adjusted for age, sex and education
Proctor 2001	See Proctor 1998	See Proctor 1998	Chronic back pain Bodily pain on SF-36	See Proctor 1998	See Proctor 1998
Ishoy 1999	686 GWV 231 NGV Selected from Danish Armed Forces personnel database	Cross-sectional survey Feb 1997-Jan 1998	Joint pain Muscle pain	84% GWV (821 eligible) 58% NDV (400 sampled) Non-response meant GWV more likely to be older males	Controls matched for gender, age and profession
Unwin 1999	3284 GWV 1815 Bosnia veterans 2408 Era controls Random sample taken from the UK MoD database Service men only	Cross-sectional postal survey August 1997-Nov 1998	Pain without redness or swelling in several joints Chest pain	70% GWV (4250 eligible) 62% Bosnia (4250 eligible) 63% Era (4246 eligible) Responders were significantly older and more likely to be in service but didn't differ on SF36 ratings	Sample was stratified by service, status, sex, age, rank and fitness. Analyses restricted to male veterans. Potential confounders (age, marital status, rank, education, employment, still serving or discharged, smoking, alcohol consumption and GHQ score) are adjusted for by logistic regression
Unwin 2002	236 GWV 217 Bosnia veterans 192 Era controls Service women only	See Unwin 1999	Pain without redness or swelling in several joints	72% GWV 66% Bosnia 58% Era	Analyses restricted to female veterans.
Kang 2000	11441 GWV 9476 NGV Stratified random sample taken from the DoD Manpower Data Center	Population based survey 1995–1997	Joint pain Muscle pain Back pain Abdominal pain	76% GWV (15000 eligible) 63% NGV (15000 eligible) Non responders were more likely to be younger, unmarried, non-white and enlisted	Estimates were weighted to control for stratification variables: gender and unit component
Knoke 2000	524 GWV 935 NGV Sampled from active duty US Naval mobile construction battalion personnel (Seabees). Personnel had to be in residence at either Port Hueneme or Gulfport	Questionnaire survey carried out in 1994	Pains in lower back Pains in heart/chest Moving joint pain Unusual muscle pain Chest pain Abdominal pain Earlobe pain	65% GWV 46% NGV	Analyses restricted to male veterans.	'Earlobe pain' was included as a validity symptom as it was thought not to have a physiologic basis
Steele 2000	1435 GWV 409 NGV DoD Manpower Data Center used to create a stratified random sample from 16,566 military personnel from Kansas	Population based telephone survey Feb – Aug 1998	Joint pain Muscle pain Body pain (hurts all over) Abdominal pain or cramping Moderate/multiple pain symptoms	65% response (3138 eligible) Overall, Gulf and female veterans were more likely to respond.	Published odds ratios are adjusted for sex, age, income level and education level.	Women and reservists deliberately over sampled due to increased reporting of ill health in those groups. Veterans had to be either separated or retired from military or currently serving in the reserves.
Cherry 2001	8210 GWV 3981 NGV Random sample taken from the UK MoD database	Cross-sectional survey Dec 1997-Sept 1999	Stomach pain Pain in your chest Widespread pain	86% GWV (9505 eligible) 84% NGV (4749 eligible) Non responders were younger	NGV sample stratified by sex, age, service and rank to frequency match GWV sample.	Widespread pain defined as "axial skeletal and contra lateral body pain" for at least 24 hours in the past month
Gray 2002	3831 GWV 4933 deployed elsewhere 3104 non-deployed All active duty Seabees regardless of whether still in service at time of study identified through Defense Manpower Data Center	Cross-sectional survey May 1997 – May 1999	Unusual muscle pain Joint pain Chest pain Stomach pain/ulcer	Total eligible 18,945 64% response Respondents more likely to be reservists, married, Caucasian, and deployed elsewhere.	Published odds ratios adjusted for age, gender, active-duty/reserve status, ethnicity, smoking, alcohol use.	Reliability for self-reported physician-diagnosed medical conditions in 519 subjects retested 6 months apart: Kappa = 0.6
Simmons 2004	23,358 GWV 17,730 NGV Stratified random sample from UK MoD database	Cross-sectional postal survey Aug 1998-March 2001	Muscular pain/weakness Chest pains/tightness	48% response overall. Pain data available for: 45% GWV (51581 eligible) 34% NGV (51688 eligible)	Analysis restricted to male veterans. Published odds ratios adjusted for age, service, rank, service status at time of survey, alcohol and smoking
Kelsall 2004	1456 GWV 1588 NGV Stratified random sample from Australian Defence Force database	Cross-sectional postal survey Aug 2000-April 2002	General muscle pain Pain without redness or swelling in several joints Low back pain	78% GWV (1871 eligible) 54% NGV (2924 eligible) Non responders were younger and of lower rank.	Analyses restricted to male veterans. Published odds ratios adjusted for sex, 3 yr age band, service and rank.

GWV – Gulf War veteran

NGV – Non-Gulf veteran

DoD – US Department of Defense

MoD – British Ministry of Defence