Background and Aim STI clinic visitors with a urogenital chlamydia infection (Ct) have a high re-infection rate. Retesting can be an effective strategy to prevent onward transmission and late sequelae. The optimal moment to offer a re-test is unknown.

Methods Between May 2012 and January 2013, all heterosexual visitors of the Amsterdam STI clinic, testing positive for urogenital Ct were offered retesting after receiving diagnosis, treatment and counselling. Participants were randomly assigned for re-testing after 2, 4 or 6 months. Participants were free to choose between two retest options; receive a home collection kit or an email/SMS invitation to return to the clinic for a self collected retest.

Results In total 1784 individuals were included of whom 47% were male, 74% were Dutch and the median age was 23 years (IQR 20–26). 779 (44%) opted for the home collection kit and 1005 (56%) for re-visiting the clinic. At this point, 795 are eligible to evaluate retesting; 265 home collection kits were returned (75%) and 237 individuals returned to the clinic for a retest (54%). Overall, the participation rate did not differ between the assigned time periods. A test result was available for 266, 126 and 49 individuals in the 2, 4 and 6 month group, respectively. The overall positivity rate at 2, 4 and 6 months was respectively 8%, 6% and 12%.

Conclusions Based on these preliminary data we found a high test uptake. Possibly because individuals were able to choose their preferred method of retesting. As the participation rate was not affected by the period of the retest and the positivity rate seemed to be highest after 6 months this might be an optimal time interval to offer a retest to STI clinic visitors. We conclude that retesting is feasible in identifying new Ct infections.