Population-level diagnosis and care cascade for chlamydia in Australia

Abstract

Objectives Key strategies to control chlamydia include testing, treatment, partner management and re-testing. We developed a diagnosis and care cascade for chlamydia to highlight gaps in control strategies nationally and to inform efforts to optimise control programmes. Methods The Australian Chlamydia Cascade was organised into four steps: (1) annual number of new chlamydia infections (including re-infections); (2) annual number of chlamydia diagnoses; (3) annual number of diagnoses treated; (4) annual number of diagnoses followed by a re-test for chlamydia within 42–180 days of diagnosis. For 2016, we estimated the number of infections among young men and women aged 15–29 years in each of these steps using a combination of mathematical modelling, national notification data, sentinel surveillance data and previous research studies. Results Among young people in Australia, there were an estimated 248\u2009580 (range, 240\u2009690–256\u2009470) new chlamydia infections in 2016 (96 470 in women; 152\u2009100 in men) of which 70\u2009164 were diagnosed (28.2% overall: women 43.4%, men 18.6%). Of the chlamydia infections diagnosed, 65\u2009490 (range, 59\u2009640–70 160) were treated (93.3% across all populations), but only 11\u2009330 (range, 7660–16 285) diagnoses were followed by a re-test within 42–180 days (17.3% overall: women 20.6%, men 12.5%) of diagnosis. Conclusions The greatest gaps in the Australian Chlamydia Cascade for young people were in the diagnosis and re-testing steps, with 72% of infections undiagnosed and 83% of those diagnosed not re-tested: both were especially low among men. Treatment rates were also lower than recommended by guidelines. Our cascade highlights the need for enhanced strategies to improve treatment and re-testing coverage such as short message service reminders, point-of-care and postal test kits.