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Objectives: HIV diagnoses among men who have sex with men (MSM) in several high-income countries, including Australia, have increased substantially over recent years. Australia, in line with global prevention strategies, has emphasised a 'test and treat' HIV prevention strategy which relies on timely detection of HIV through frequent testing by those at risk. We examined trends in repeat testing among MSM defined as 'high-risk' according to Australian testing guidelines., Methods: HIV test records from MSM attending high caseload clinics in Melbourne 2007-2013 and classified as high-risk were analysed. Binary outcomes of 'test within 3 months' and 'test within 6 months' were assigned to tests within individuals' panel of records. Negative binomial regressions assessed trends in overall HIV testing and returning within 3 and 6 months. Annualised proportions of return tests (2007-2012) were compared using two-sample z tests., Results: Across 18 538 tests among 7117 high-risk MSM attending primary care clinics in Melbourne (2007-2013), the number of annual HIV tests increased (p<0.01). Between 2007 and 2012 annualised proportions of tests with a subsequent test within 3 and 6 months also increased (p<0.01); however, by 2012 only 36.4% and 15.1% of tests were followed by another test inside 6 and 3 months, respectively., Conclusions: Repeat testing among high-risk MSM in Australia remains unacceptably low, with recent modest increases in testing unlikely to deliver meaningful prevention impact. Removing known barriers to HIV testing is needed to maximise the potential benefit of test and treat-based HIV prevention., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

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.)