ADF Health October 2005 - Volume 6 Number 2ResearchPrevalence of psychological trauma in operationally deployed Navy personnel: a baseline surveillance report
POST-TRAUMATIC STRESS DISORDER (PTSD) is characterised by a person being exposed to traumatic incidents with a strong emotional reaction, with a significant disturbance in functioning persisting for more than 1 month. 1 Early detection of PTSD is essential, as the pathology proceeds from an acute to a chronic condition, 2 and early therapy is more appropriate. 3,4 Military personnel form an "at-risk" group for trauma exposure, 5-7 and the 2000 Health Status Report of the Defence Health Service (DHS) 8 considered that mental health was a significant issue for the Australian Defence Force. Mental health monitoring and surveillance is considered by the Commonwealth Department of Health and Ageing to be a key aspect of a conceptual frame for the promotion, prevention and early intervention for mental health. 9 In 2001, the Fleet Health Support Unit (FHSU) of Maritime Headquarters began briefing and screening Royal Australian Navy personnel deploying to the Middle East Area of Operations (MEAO). In its infancy, the program involved personnel being provided a mental health brief and mental health screening at the commencement of, and upon return from, operational deployments. This program was initially adapted from a process used by the Australian Army. The DHS standardised the process across the ADF, 10 removing pre-deployment screening. The results of individual questionnaires from screening were recorded and stored on a FHSU database. This database provided an opportunity for review and surveillance of mental health for individuals, ship cohorts, deployments and subgroups within the RAN. This report establishes surveillance baselines for psychological trauma-related symptoms in personnel deploying to the MEAO. For this report, five questions were addressed:
MethodsData were recovered from a database of psychological screening records for personnel deployed to the MEAO between 2001 and 2005. Complete Post-traumatic stress disorder Checklist - Civilian version (PCL-C) results for RAN personnel (with identifying information removed) were incorporated into a single database for analysis. The PCL-C is a 17-item, self-report checklist based on key diagnostic criteria for PTSD. 1 Participants indicate, on a fivepoint scale, the experience of symptoms, giving an overall score in the range 17-85. There are three versions of the PCL, but all are very similar (with only slight wording differences in the questions) and the PCL-C is commonly used to screen for trauma. The PCL-C has good sensitivity and specificity, is positively correlated with other measures of PTSD, and has excellent test-retest reliability. 11,12 A score of >=50 on the PCL-C has been endorsed with an Australian military sample 13-16 and in assessing other Persian Gulf veterans 17 to indicate "caseness" for trauma. Responses to the PCL-C were significantly skewed because of the nature of the questionnaire and the non-clinical population. Assumptions of normality of the distribution of PCL-C scores were not met (confirmed with a Lilliefors statistic), and non-parametric statistics using SPSS18 were used. Approval for this study was provided by the Fleet Medical Officer as a means of monitoring the mental health of deployed Navy personnel.
ResultsBetween 2001 and 2005, 1739 people from 10 ship-cohorts were deployed to the MEAO. The mean size of individual ship-cohorts was 173.9 (range, 142-215). Men comprised 83.9% (range, 81.7%-91.0%) and women 16.1% (range, 9.0%-18.3%), and rank distribution was 68.4% (range, 64.1%-71.5%) junior sailors, 18.2% (range, 14.0%-21.8%) senior sailors, and 13.5% (range, 11.0%-15.4%) officers. This sex and rank-group distribution is representative of deployed or sea-going Navy personnel. Ship-cohorts included three Anzac class frigates, five Adelaide class frigates, and two Kanimbla class amphibious transports. Within the data, the same person may be recorded more than once if they deployed on different ship-cohorts. For the purposes of this study, such personnel are considered different cases. Although age was not specifically recorded, the usual age range of ADF personnel (17-55 years) would apply to this population.
Actual dataThe prevalence of trauma (PCL-C score >=50) in RAN personnel returning from the MEAO per ship-cohort ranged from 0 to 5 cases (0-3.0%), with a total of 24 personnel (1.4%) (Box 1). The prevalence rate for women (2.5%) was twice that for men (1.2%). The overall mean PCL-C score was 23.4. There was no significant difference in PCL-C scores between rank groups, and the mean scores for all rank groups were well below the threshold for caseness. For a subgroup (n = 460 from four ship-cohorts), psychological screening had been undertaken both before and after deployment. Six personnel (1.3%; 4 men, 2 women) changed from non-cases before deployment to cases after deployment; while four members (0.9%; all men) moved from cases before deployment to non-cases after deployment (Box 2). One member (0.2%; male) was classed as a case at both pre- and post-deployment screening. Box 3 includes Spearman’s rank-order18 correlations of preand post-deployment caseness and PCL-C scores, indicating that pre- and post-deployment cases are positively associated at a low level, and pre- and post-deployment PCL-C scores are positively associated at a high level. For 313 personnel (68.0%), there was no change in PCL-C scores from pre- to post-deployment. Forty-one personnel (8.9%) had lower scores after deployment than before deployment, and 106 (23.0%) had higher scores after deployment than before deployment. The magnitude of this change was an average of 0.87 (SD, 5.91), with variation in PCL-C scores over the course of deployment of three or fewer points for 397 personnel (86.3%). Women displayed significantly greater variation between pre- and post-deployment PCL-C scores than men (Mann-Whitney z = - 2.28, P <0.05, 2-tailed). There was no significant difference in variation between pre- and post-deployment PCL-C scores by naval rank (Kruskal-Wallis χ2 = 1.184, df=2, P>0.05). Adjusted dataThe prevalence of identified psychological trauma symptoms at the completion of deployment reflects both cases that developed during the deployment and cases (one person in this study) that existed before deployment. Pre-existing cases may inflate the actual prevalence rate attributable to the deployment. To estimate the prevalence of trauma attributable only to the deployment, personnel classified as cases at both pre- and post-deployment screening should be removed. With this correction (removal of one in seven or 14.3% of cases), the prevalence rate of cases (excluding pre-existing cases) from the larger normative cohort (n =1739) of 24 (1.4%) would be reduced to 21 (1.2%). With an unequal sex distribution (83.9% male) in the study group, comparability between this sample and general population samples (about 50% male) may be limited. To approximate the general population, the prevalence data from this study were converted using the formula: Estimated number of cases = 50/actual percentage distribution x actual number of cases This formula was applied to both sex subgroups using an estimated sex-equal sample size of 870 (total sample pool divided by 2). If this study group had been sex-equal (with 870 per sex group), 10 men (1.1% of men) and 22 women (2.5% of women) would have exceeded the PCL-C threshold. The overall prevalence rate of indicated PTSD in an estimated sexneutral sample would be 32 cases (1.8% of the total sample). Correcting both for sex distribution and for pre-existing caseness gives a prevalence of 27 cases (1.6%) for the total sample. DiscussionThe study group (1739 personnel from 10 ship-cohorts) was relatively consistent across ship-cohorts with regard to size, sex, and rank-group distribution. As such, prevalence rates and PCL-C scores can be considered normative data for RAN personnel operationally deployed to the MEAO. Women were identified as cases at about twice the frequency of men. Although the difference between male and female PCL-C scores was significant, the mean PCL-C scores for both sex subgroups were well below the threshold for caseness. This suggests the statistical difference has little clinical meaning. Based on the prevalence rate adjusted to exclude preexisting cases, it could be expected that, for Anzac class and Adelaide class frigates with usual crews of 175 and 185, two cases of indicated psychological trauma at the end of deployment could be considered typical. For Kanimbla class transports with a usual crew of 215, two to three cases at the end of deployment could be considered typical. Box 4 summarises the prevalence of psychological trauma symptoms in other studies of military personnel that used the PCL. RAN personnel in our sample reported lower prevalence rates for trauma than ADF forces from the 1991 Gulf War 14 (data collected 10 years post-war). Further, the prevalence rate was lower than for US Army and Marine Corps personnel returning from operational deployment in Afghanistan and Iraq, 17 and about the same as ADF tri-Service forces returning from East Timor. 15 The actual and sex-adjusted prevalence rates of indicated PTSD in the sample are in the low end of the general community range (1%-14%), 1 and consistent with the general US population rate. 19,20 Both the actual and adjusted prevalence rates of indicated PTSD for the study group were considerably lower than for at-risk groups (3%-58%). 1 Thus, the prevalence could be classed as low for operationally deployed military personnel (who would usually be considered at risk). Our study did not include the entire dataset of RAN personnel deployed to the MEAO between 2001 and 2005 (data are predominantly from 2001-2002). Furthermore, some groups within the RAN (such as clearance diving teams and submariners) could constitute unique subgroups. Nevertheless, this study provides a generally representative sample of three major surface ship types and a typical distribution of rank and sex in major fleet units operationally deployed in the MEAO during 2001-2005. The PCL-C is a screening instrument and as such does not assess all aspects of PTSD. Therefore, caseness and indication of trauma does not constitute a diagnosis of PTSD - but rather, indicates the characteristic trauma symptoms of PTSD (criteria B, C and D of the diagnostic criteria for PTSD). 1 Further, the use of the PCL-C in this study does not consider possible delayed-onset PTSD, which, while rare, is a recognised variation of the disorder. 21 The PCL-C was one of two structured questionnaires provided for each screening. However, although the PCL-C was used consistently for all personnel included in this project, the other screening questionnaire (used to indicate general psychological distress) was varied between ship-cohorts. Using only the PCL-C for this analysis allowed for the largest possible population sample. It is beyond the scope of this study to explain the prevalence of psychological trauma symptoms or why it compares as it does to other military groups. Although different rates of exposure to trauma for the study group and comparison groups would be the most obvious speculation, other factors include differences in working conditions, group cohesion, leadership, training, general mental health, esprit de corps, and individual factors. An obvious area of further research is to examine those who displayed the greatest change in PCL-C scores from pre- to post-deployment. Six members of the pre- and postdeployment subgroup developed caseness during deployment, and four remitted from caseness. Although the numbers of each are very small (1.3% and 0.9%, respectively), they represent a clinically interesting subgroup for further study - those whose psychological trauma presentations appear to be affected by deployment, in both positive and negative ways. ConclusionThis study provides normative data on psychological trauma caseness for RAN personnel from three classes of surface ship. The prevalence of trauma caseness in this study group (using both uncorrected and corrected prevalence rates) is at the low end of community and at-risk groups, and is considerably lower than trauma prevalence identified among ADF personnel 10 years after their return from the 1991 Gulf War. AcknowledgementsPre- and post-deployment psychological screening was initiated in the Royal Australian Navy in 2001 by the Fleet Medical Officer and Deputy Fleet Medical Officers (Captain M Loxton and Commander R Walker) and first undertaken by Lieutenant Commander S Latimer. Personnel principally involved in providing these screens from which data was gathered were Lieutenant Commander S Latimer, Lieutenant Commander M Woodruff, Lieutenant Commander G Waghorn, Lieutenant G Currie, Lieutenant A Gordon, Lieutenant B Sheridan, Lieutenant P Sneesby, Lieutenant F Van Damme, and Lieutenant K Young and Lieutenant S Rayner. Many thanks go to Mrs N Steele for her support and diligence in reviewing this article, and to Commander Latimer for his coaching with statistical analysis. Competing interestsNone identified. References
Fleet Health Support Unit, Maritime Headquarters, HMAS Kuttabul, Sydney, NSW.Lieutenant Stephen P S Rayner, MA, MClinPsych, RANR, Clinical Psychologist. Correspondence: Lieutenant Stephen P S Rayner, Fleet Health Support Unit, Maritime Headquarters, HMAS Kuttabul, Wylde Street, Potts Point, Sydney, NSW 2011. stephen.rayner1@defence.gov.au
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Lieutenant Stephen Rayner is a clinical psychologist working as a civilian at Balmoral Naval Hospital, as a Navy reservist and as a consultant. His area of clinical and academic interest is disaster and trauma mental health, and he has experience working with prisons, the military, emergency services, and medical providers.