Overall 5547 (63.9%) of 8686 regulars who completed the questionnaire had participated in at least one deployment in the past three years. Royal Air Force personnel had less prolonged periods of deployments than personnel in the other services, whereas the Royal Navy and Royal Marines had proportionally more personnel with long periods of deployment (table 1). Most of those deployed had one or two deployments in the past three years. Almost a third of those with a combat role in their last deployment had been deployed for 13 months or more in the past three years.
Table 1 Duration and frequency of deployments since 2000 for about a three year period, by service and combat role (regulars only). Values are numbers (percentages)
A consistent association was found between prolonged deployments (≥13 months) and problems at home both during and after deployment (table 2). Although consistent the effect size was small and was reduced after adjustment for role in theatre, time spent in a forward area, and type of deployment (table 2). No association was found between number of deployments and problems at home, or between number and duration of deployments and intention to stay in the armed forces (data not shown).
Table 2 Association between duration and number of deployments since 2000, for about a three year period, and problems at home during and after deployment (n=5547)
The prevalence of all psychological symptoms was higher among those deployed for 13 months or more (table 3). This was shown by a consistent association between the time spent on deployment (category ≥13 months) and psychological symptoms when adjusted for the confounding factors in the first model. The prevalence of severe alcohol problems increased with duration of deployment (P for trend <0.001). Role in theatre, time spent in a forward area, type of deployment, and problems at home partly explained the associations in relation to the post-traumatic stress disorder checklist, psychological distress, and, to a lesser extent, multiple physical symptoms. No single variable explained the decrease of association between deployment for more than 13 months or more and psychological symptoms. This association was also observed for fatigue caseness but became non-significant after adjustment for problems at home, time spent in a forward area, type of deployment, and role in theatre (data not shown).
Table 3 Prevalence and association between duration and number of deployments since 2000, for about a three year period, and psychological symptoms, adjusted for confounders and explanatory factors (n=5547)
The relation between number of deployments and prevalence of psychological symptoms was less clear (table 3). An association was found between those with three or more deployments and caseness (P=0.05), but this became non-significant after adjustment for explanatory factors (table 3). Some evidence was found for an association between number of deployments and caseness on the post-traumatic stress disorder checklist and multiple physical symptoms, but the associations were non-significant (P>0.05).
Effect modifications were not found for deployment and type of service on each of the psychological outcomes. The results for the Royal Navy and for the army plus the Royal Marines were generally consistent with the results for all three services combined, but this was not the case for the Royal Air Force (data not shown). In the Royal Air Force, the group with three or more deployments was associated with caseness on the post-traumatic stress disorder checklist and psychological distress (associations were of borderline statistical significance). The association decreased after adjustment for the explanatory variables.
Table 4 shows the relation between the difference in actual and expected duration of deployment for the most recent deployment and psychological symptoms. A moderately strong association was found between a longer than expected period of deployment and caseness on the post-traumatic stress disorder checklist, which was not found for the other psychological outcomes. The association between longer than expected period of deployment and caseness on the post-traumatic stress disorder checklist persisted in analyses carried out separately for the Royal Navy (odds ratio 12.34, 95% confidence interval 1.02 to 148.73) and the army plus the Royal Marines (2.18, 1.09 to 4.36).
Table 4 Association between difference of expected and actual duration of last deployment and psychological symptoms