A Study of Chlamydia Trachomatis: Sexual Risk Behaviour, Infection and Prevention in the Australian Defence Force
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A study of Chlamydia trachomatis: sexual risk behaviour, infection and prevention in the Australian Defence Force Stephen Mark Lambert Diploma of Teaching; Bachelor of Education; Masters in Public Health A thesis submitted for the degree of Doctor of Philosophy at The University of Queensland in 2014 School of Medicine I Abstract There is limited research in Australia focusing on C. trachomatis infection at a population level utilising systematic non-random recruitment methodologies. In addition, little is known in the Australian Defence Force (ADF) about the prevalence of C. trachomatis and of risk behaviours that may impact on sexual health. This study utilised an existing process in the ADF, the Annual Health Assessment, to source new information about C. trachomatis infection and about sexual risk and behaviour. The outcomes of this research may assist the ADF to maintain the health of personnel and consequently a high degree of operational preparedness, and may contribute to the understanding of C. trachomatis prevalence in Australia and across the world. The aims of this study were to determine the prevalence of C. trachomatis infection and to identify potential high risk populations in the ADF with a view to discussing secondary prevention interventions for the control of C. trachomatis infection within the ADF. Seven hundred and thirty-three ADF personnel were recruited into the study over a 24 month period. Participants were asked to complete an 8 page comprehensive survey about sexual behaviour and to provide a urine sample to be tested for C. trachomatis. Ethics approval was received from both the Australian Defence Human Research Ethics Committee and the University of Queensland Medical Research Ethics Committee. The study examined ADF personnel on deployment and on base in order to provide a comparison of populations across varying work environments. Similarly, this study examined ADF personnel who had recently taken a course of doxycycline for malaria prophylaxis as part of deployment and those who had not in order to assess whether the prophylactic use of antibiotics for other purposes may have had an effect on the acquisition of C. trachomatis. This study enrolled participants from the three services in the ADF, the army, navy and air force, across 10 sites in Australia and four deployments to obtain a wide cross section of the ADF population. The findings from this study provide a profile of ADF sexual health and sexual behaviour that is comparable to the Australian population and identifies, in some instances, greater levels of safe practice and lower levels of risk behaviour. Additionally, the ADF has a lower prevalence of C. trachomatis (1.87% age and gender adjusted ) than other comparable military populations as well as a healthier sexual health and behaviour profile. II C. trachomatis positivity was associated with the number of sexual partners. Those who had two or more partners were almost five times more likely to test positive than those who had one or less partners in the previous 12 months (p=0.026; OR, 4.71 95% CI 1.04- 21.21). Presence of an STI in the previous 12 months was also associated with the number of sexual partners (p=0.0002; OR, 4.35 95% CI 1.90-9.90) and relationship status, (p=0.041; OR, 2.22 95% CI 1.01-4.87); casual partners in the previous 12 months, (p=0.007; OR, 5.79 95% CI 1.37-24.40); condom use with casual partners, (p=0.067; OR, 3.32 95% CI 1.33-8.31); unsafe sex practice (p=0.0003; OR, 3.05 95% CI 1.62-5.75); and was trending toward being associated with use of doxycycline in the previous 12 months (p=0.054; OR, 2.06 95% CI 0.97-4.35). This study sample was frequently deployed. While 26% of the sample surveyed were currently on deployment (n=190), 42% (n=309) indicated they had been deployed at some stage over the previous 12 months. Those who had been deployed at any time during the previous 12 months (including those on deployment when participating in the study) were less likely to be C. trachomatis positive (1.67% vs 2.34%; p=0.54; OR, 0.71); and were as likely to have self-reported an STI as their colleagues who had not been deployed at any stage in the previous 12 months (5.82% vs 5.94%; p=0.95; OR, 0.98). This study examined rates of attendance at health services for sexual health concerns. 18.12% (age and gender adjusted) of participants indicated they attended a health service for a sexual health concern in the previous 12 months. Females were significantly more likely to attend a health service than males (26.45% vs 16.52%; p=0.005; OR 1.81 95% CI 1.19-2.76) for a sexual health matter. Participants were three times more likely to attend an ADF health service for testing and treatment of an STI than to attend a civilian health service (16.4% vs 5.61% p<0.0001). Those who engaged in some unsafe sex were significantly more likely to attend a health service for a sexual health matter (30.67% vs 13.86%; p<0.0001; OR 2.75 95% CI 1.87-4.04). Support for sexual health screening already occurs in the ADF implicitly through the encouragement of operational preparedness and explicitly through the Comprehensive Preventive Health Examination (CPHE). Further utilisation of existing mechanisms for education and screening such as the CPHE and pre- and post-deployment health checks is warranted. III Declaration by author This thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis. I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, and any other original research work used or reported in my thesis. The content of my thesis is the result of work I have carried out since the commencement of my research higher degree candidature and does not include a substantial part of work that has been submitted to qualify for the award of any other degree or diploma in any university or other tertiary institution. I have clearly stated which parts of my thesis, if any, have been submitted to qualify for another award. I acknowledge that an electronic copy of my thesis must be lodged with the University Library and, subject to the policy and procedures of The University of Queensland, the thesis be made available for research and study in accordance with the Copyright Act 1968 unless a period of embargo has been approved by the Dean of the Graduate School. I acknowledge that copyright of all material contained in my thesis resides with the copyright holder(s) of that material. Where appropriate I have obtained copyright permission from the copyright holder to reproduce material in this thesis. IV Publications during candidature Poster at the 2007 Australian Sexual Health Conference, Sydney, Oct 2007. Sexual Health and the Australian Defence Force. Lambert S, Debattista J, Kitchener S, Nasveld P, Bennett S. Poster presentation at the 2009 Australasian Sexual Health Conference, Brisbane, September 2009. Sexual Health and the Australian Defence Force. Lambert S, Bennett S, Debattista J, Donald K Donovan B, Kitchener S. Invited speaker at the 2013 Australasian Sexual Health Conference, Darwin, September 2013. A study of Chlamydia trachomatis: sexual risk behaviour, infection and prevention in the Australian Defence Force. Lambert S. Publications included in this thesis No publications included V Contributions by others to the thesis The following individuals were involved in the conception and design of the study: Prof Scott Kitchener Prof Ken Donald Prof Basil Donovan Dr Sonya Bennett Dr Joe Debattista Dr Peter Nasveld. The following individuals were involved in non-routine technical work: Mr Brad Reuter (data entry and data cleaning) Mr Justin Pointon (data entry and data cleaning, proof reading). I undertook 70% of data entry and data cleaning myself. The following individuals were involved in preliminary analysis of research data: Ms Sara Bell I undertook almost all data analyses utilising Excel and teaching myself statistical formulae to better understand the data. The following individuals were involved in the interpretation of research data and critically revising this document: Prof Scott Kitchener Prof Ken Donald Prof Basil Donovan Dr Sonya Bennett Dr Joe Debattista I conducted initial interpretations of the data and worked with my supervisors above to refine the interpretation. I drafted all sections of this work and my supervisors assisted by critically revising this work. Statement of parts of the thesis submitted to qualify for the award of another degree None VI Acknowledgements A number of individuals have made significant contributions to this thesis. Firstly, I would like to thank my supervisors, Prof Scott Kitchener, Dr Joe Debattista, Prof Basil Donovan, Prof Ken Donald and Dr Sonya Bennett who offered unwavering support and advice over the years. During most of my candidature I was based at the University of Queensland, School of Medicine, HIV & HCV Education Projects. I wish to thank all the team who graciously travelled the road with me during that time. Personnel in all sections of the Australian Defence Force were the drivers of this research. Without the support and practical assistance from health service managers and staff, base commanding officers, and those key individuals interested in sexual health, the practicalities of recruitment and participation would not have been possible.