5Results
5.1Recruitment
Recruitment for the follow up study commenced in October 2011 and closed in August 2012. As described in Appendix 2, the cohort eligible for inclusion in the follow up study comprised the 1,456 Gulf War veterans and 1,588 comparison group members (N=3,044) who participated in the baseline health study.16
Of the 1,456 Gulf War veterans eligible for inclusion, 126 were removed from the recruitment denominator because they were identified as having deceased (n=25), to have previously refused further research (n=3) or because no valid mailing address could be found (n=98). Similarly, from the 1,588 comparison group members eligible for inclusion, 139 were removed from the recruitment denominator because they were identified as having deceased (n=15), to have previously refused further research (n=1) or because no valid mailing address could be found (n=123). Consequently, the recruitment denominators were 1,330 for the Gulf War veterans and 1,449 for the comparison group.
Table 14 Recruitment outcomes for the Gulf War veterans and comparison group at follow up
Recruitment outcome / Gulf War veterans(N=1,330) / Comparison group
(N=1,449) / Study total (N=2,779)
n (%) / n (%) / n (%)
Participant / 715 (53.8) / 675 (46.6) / 1,390 (50.0)
Completed health questionnaire / 712 (99.6) / 674 (99.9) / 1,386 (99.8)
Completed phone interview / 1,282 (92.2)
Consented to Medicare/PBS and RPBS linkage / 1,152 (82.9)
Consented to DVA health data linkage / 1,075 (77.3)
Refuser / 100 (7.5) / 156 (10.8) / 256 (9.2)
Non-responder / 515 (38.7) / 618 (42.6) / 1,133 (40.8)
Table 14 shows that 54% of the recruitable Gulf War veterans and 47% of the recruitable comparison group members participated in the study. Participation in the four study components was very complete, in that all but four participants (who consented to linkage only) completed the health questionnaire, 92% of all participants completed the over-the-phone psychological health interview, 83% consented to Medicare, PBS and RPBS linkage and 77% consented to DVA health data linkage.
Only 9% of the recruitable population advised the research team that they wished to decline participation (tabulated as “refusers”) while a further 41% did not respond with a decision about participation during the study recruitment period.
5.1.1Key findings
The recruitment rates achieved in the study were 54% for the Gulf War veterans and 47% for the comparison group. In total there were 1,390 participants at follow up, comprising 715 Gulf War veterans and 675 comparison group members. The health questionnaire was completed by 99% of all participants and the over-the-phone psychological health interview was completed by 92%. Eighty three percent and 77% of participants, respectively, consented to Medicare, PBS and RPBS linkage, and DVA health data linkage.
Australian Gulf War Veterans’ Follow Up Health Study: Technical Report 2015 Page 1