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Background Chlamydia (Chlamydia trachomatis) continues to be a public health challenge in Australia, with some contention as to the best screening approach. In the present study we examined chlamydia testing, positivity and sexual behaviour among women with the aim of informing targeted testing among women aged ≥30 years., Methods: A longitudinal analysis was conducted on retrospective surveillance data collected among women attending general practice, family planning and sexual health clinics participating in sentinel surveillance in Melbourne, Australia. Women were aged ≥16 years and underwent urogenital testing for C. trachomatis (chlamydia) at participating clinics between 2007 and 2014. Chlamydia incidence was calculated as positive chlamydia tests over person-years (PY) among women and reported by 5-year age groups. A Cox regression model examined correlates of a positive chlamydia test among women aged ≥30 years., Results: In all, 36770 women contributed 46432 PY and 52395 chlamydia tests, of which 2895 were positive. The overall chlamydia incidence rate was 6.2 per 100 PY (95% confidence interval (CI) 6.0-6.5). Chlamydia incidence declined with age, plateauing to <5 per 100 PY among women aged ≥30 years. Among women aged ≥30 years, being born in North-East Asia (adjusted hazard ratio (aHR) 2.9; 95% CI 1.9-4.5) and reporting multiple partners (aHR 2.5; 95% CI 1.8-3.5) in the past 12 months were associated with a positive chlamydia test., Conclusions: Chlamydia control remains challenging in Australia and optimising testing in primary care is a key priority. The results of the present study suggest that, at least among women aged ≥30 years, chlamydia testing should be risk-based and informed by appropriate sexual history taking.

Objectives: Directly measuring disease incidence in a population is difficult and not feasible to do routinely. We describe the development and application of a new method for estimating at a population level the number of incident genital chlamydia infections, and the corresponding incidence rates, by age and sex using routine surveillance data., Methods: A Bayesian statistical approach was developed to calibrate the parameters of a decision-pathway tree against national data on numbers of notifications and tests conducted (2001-2013). Independent beta probability density functions were adopted for priors on the time-independent parameters; the shapes of these beta parameters were chosen to match prior estimates sourced from peer-reviewed literature or expert opinion. To best facilitate the calibration, multivariate Gaussian priors on (the logistic transforms of) the time-dependent parameters were adopted, using the Matérn covariance function to favour small changes over consecutive years and across adjacent age cohorts. The model outcomes were validated by comparing them with other independent empirical epidemiological measures, that is, prevalence and incidence as reported by other studies., Results: Model-based estimates suggest that the total number of people acquiring chlamydia per year in Australia has increased by ∼120% over 12 years. Nationally, an estimated 356 000 people acquired chlamydia in 2013, which is 4.3 times the number of reported diagnoses. This corresponded to a chlamydia annual incidence estimate of 1.54% in 2013, increased from 0.81% in 2001 (∼90% increase)., Conclusions: We developed a statistical method which uses routine surveillance (notifications and testing) data to produce estimates of the extent and trends in chlamydia incidence., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Objective: To describe trends in chlamydia positivity from 2007 to 2011 among heterosexual people tested for chlamydia at selected clinics that provide services to people at high risk in Victoria, Australia., Design: The Victorian Primary Care Network for Sentinel Surveillance is a prospective system that collates pathology results from laboratories and demographic and behavioural data from a questionnaire., Setting: Two sexual health clinics and six other primary care clinics that target young people and women at high risk., Participants: All clients tested for chlamydia at sentinel clinics. Individuals aged less than 16 years, sex workers, or those reporting any same-sex sexual partners in the past 12 months were excluded from the analysis., Main Outcome Measures: Chlamydia positivity trends were assessed using three-level random-effects Poisson regression, with clinic and subject treated as nested random factors. Models were offset for total number of tests and adjusted for relevant covariates., Results: Between 2007 and 2011, chlamydia positivity among 31 682 tests in women increased from 5.1% to 6.3%, and positivity among 23 771 tests in men increased from 7.4% to 8.2%. Adjusting for age, country of birth, number of sex partners, condom use, and presence of symptoms, chlamydia positivity increased between 2007 and 2011 significantly among women (incidence rate ratio [IRR], 1.29; 95% CI, 1.11-1.50) and non-significantly among men (IRR, 1.07; 95% CI, 0.92-1.23). Over time, a decrease in reported inconsistent condom use was also observed in both men and women; however, men became more likely to report more than one partner in the past year., Conclusion: We identified a concerning increase in chlamydia positivity over time, particularly among young women.

Objectives: To assess notification trends for chlamydia and gonorrhoea infections in Indigenous Australians compared with non-Indigenous Australians in 2000-2009., Design and Setting: We assessed trends in national notification rates using univariate Poisson regression and summary rate ratios., Main Outcome Measures: Crude notification rates and summary rate ratios, by Indigenous status, sex, age and area of residence., Results: Over the 10-2012 period studied, chlamydia notification rates per 100,000 increased by 80% from 1383 in 2000 to 2494 in 2009 among Indigenous people, and by 335% from 51 in 2000 to 222 in 2009 among non-Indigenous people. The Indigenous versus non-Indigenous summary rate ratio was 23.92 (95% CI, 23.65-24.19; P<0.001). Gonorrhoea notification rates per 100,000 increased by 22% from 1347 in 2000 to 1643 in 2009 among Indigenous people, and by 70% from 10 in 2000 to 17 in 2009 among non-Indigenous people. The gonorrhoea summary notification rate ratio in Indigenous compared with non-Indigenous people was 173.78 (95% CI, 170.81-176.80; P<0.001). In Indigenous people, the highest chlamydia and gonorrhoea notification rates were in women, 15-19-2012-olds, and those living in remote areas., Conclusions: Chlamydia and gonorrhoea notification rates have increased in both populations but were higher among Indigenous people. Our findings highlight the need for targeted prevention programs for young people, especially Indigenous Australians residing in remote areas.

Introduction: Since 2000, notifications of HIV and other sexually transmitted infections (STIs) have increased significantly in Australian gay men. We evaluated the impact of a social marketing campaign in 2008-2009 aimed to increase health-seeking behavior and STI testing and enhance HIV/STI knowledge in gay men., Methods: A convenience sample of 295 gay men (18-66 years of age) was surveyed to evaluate the effectiveness of the campaign. Participants were asked about campaign awareness, HIV/STI knowledge, health-seeking behavior, and HIV/STI testing. We examined associations between recent STI testing and campaign awareness. Trends in HIV/STI monthly tests at 3 clinics with a high case load of gay men were also assessed. Logistic and Poisson regressions and χ tests were used., Results: Both unaided (43%) and aided (86%) campaign awareness was high. In a multivariable logistic regression, awareness of the campaign (aided) was independently associated with having had any STI test within the past 6 months (prevalence ratio = 1.5; 95% confidence interval = 1.0-2.4. Compared with the 13 months before the campaign, clinic data showed significant increasing testing rates for HIV, syphilis, and chlamydia among HIV-negative gay men during the initial and continued campaign periods., Conclusion: These findings suggest that the campaign was successful in achieving its aims of increasing health-seeking behavior, STI testing, and HIV/STI knowledge among gay men in Victoria.