“…However, if these clinical sites themselves have relatively low levels of testing (eg, general practices in Australia7) and testing in these sites is increasing, as is occurring in Australia, then even using the proportion of tests that are positive can provide misleading data because over time more low-risk individuals are likely to be tested. To overcome this, we have analysed data from a sexual health network that has consistently high levels of testing, and thus, the positivity rate can be used as a proxy for chlamydia prevalence among those attending the clinic 8 9.…”