Health Study Methods Participants A detailed description of the inclusion and exclusion criteria for the Gulf War veteran group and the comparison group is shown in Appendix 2. The cohort eligible for inclusion in the follow up health study comprised the 1,456 Gulf War veterans and 1,588 comparison group members (N=3,044) who participated in the baseline health study. They represented 80.5% and 56.8% of all eligible Gulf War veterans and comparison group members respectively who had been invited to take part at baseline. Removal of deceased participants from the recruitable sample In August 2011 the 3,044 members of the study population were matched against the National Death Index to identify those who had deceased since the baseline study. This linkage identified 40 deaths and those participants were removed from the cohort eligible for inclusion in the follow up health study. Removal of participants from the recruitable sample for other reasons In the period since the baseline study, four participants had contacted the research team to indicate that they wished to decline participation in any further health research. Those four participants were removed from the cohort eligible for inclusion in the follow up study. Despite numerous search strategies, valid contact details could not be located for a further 221 baseline study participants, and they were removed from the cohort eligible for inclusion in the follow up study because no invitation to participate could be issued to them. Final sample size In total 265 cohort members were removed from the initial recruitment denominator of 3,044. The final eligible cohort for participation totalled 2,779 which comprised 1,330 Gulf War veterans and 1,449 comparison group members. Contact and recruitment methods The study cohort was invited to participate by mailed invitation. The invitation package is shown in Appendix 5; it contained:
Health Study Methods Participants A detailed description of the inclusion and exclusion criteria for the Gulf War veteran group and the comparison group is shown in Appendix 2. The cohort eligible for inclusion in the follow up health study comprised the 1,456 Gulf War veterans and 1,588 comparison group members (N=3,044) who participated in the baseline health study. They represented 80.5% and 56.8% of all eligible Gulf War veterans and comparison group members respectively who had been invited to take part at baseline. Removal of deceased participants from the recruitable sample In August 2011 the 3,044 members of the study population were matched against the National Death Index to identify those who had deceased since the baseline study. This linkage identified 40 deaths and those participants were removed from the cohort eligible for inclusion in the follow up health study. Removal of participants from the recruitable sample for other reasons In the period since the baseline study, four participants had contacted the research team to indicate that they wished to decline participation in any further health research. Those four participants were removed from the cohort eligible for inclusion in the follow up study. Despite numerous search strategies, valid contact details could not be located for a further 221 baseline study participants, and they were removed from the cohort eligible for inclusion in the follow up study because no invitation to participate could be issued to them. Final sample size In total 265 cohort members were removed from the initial recruitment denominator of 3,044. The final eligible cohort for participation totalled 2,779 which comprised 1,330 Gulf War veterans and 1,449 comparison group members. Contact and recruitment methods The study cohort was invited to participate by mailed invitation. The invitation package is shown in Appendix 5; it contained:
030-055health_study_methods.docx