Aquarius Population Health

We collaborated with St George’s, University of London, on a NIHR-funded ‘Test n Treat’ (TnT) study. This study assessed the cost of providing same-day chlamydia and gonorrhoea testing and treatment service at higher education colleges. The paper presenting this work was published in BMC Health Services Research and is now available online.

The prevalence of sexually transmitted infections (STIs) such as chlamydia (CT) and gonorrhoea (NG) is comparatively high in young people, whilst testing rates are low. STI screening is widely available in NHS sexual health clinics and via free online services which distribute home testing kits. However, offering same-day testing and treatment in higher education colleges could increase screening uptake and diagnosis rates in this group.

The TnT research team approached students, aged 16 to 24 years old, in six technical colleges in South London1. Students were offered a free screen for chlamydia and gonorrhoea at the college, and, in some colleges, were also offered a £10 incentive. Students then self-collected a sample which was tested on-site using the 90-minute Cepheid Xpert® CT/NG test. They received their result via text message and those testing positive for chlamydia were given treatment on the same day by a visiting nurse or health adviser and were supported with partner notification. Students testing positive for gonorrhoea were advised to attend a local sexual health clinic to receive treatment. The main results of the TnT study were published in 20192.

To assess the cost of running such a service, data collected during the TnT trial were used to calculate the cost per screen, per chlamydia diagnosis and per gonorrhoea diagnosis, allowing comparison with the costs associated with different types of STI screening services.

The approach typically used to calculate pathway costs (i.e. calculating the staff and consumable costs per patient seen) were adapted. Costs were split into fixed daily costs (such as staff time, set up costs and waste disposal) and costs per screen (such as the sample collection kit and diagnostic assay). Then different uptake scenarios were assessed. The results indicate that the cost per screen is hugely dependent on screening uptake. If the daily capacity for screening is achieved (49 screens/day), the cost per screen was £47 (including incentive). At the average uptake observed on the trial (19 screens/day) the cost per screen was £91 (including incentive).

The paper concludes that while delivering this type of service is more expensive than screening provided in sexual health clinics, targeting areas with high infection rates, combined with high incentivised uptake, could make costs comparable.

This is one of many cost analyses we have supported on for diagnostic companies, government bodies and healthcare providers in the UK and internationally. If you are interested in finding out more about Aquarius and the evidence generation we provide, please email


1 TnT Study Protocol. Kerry-Barnard et al. 2018

2 TnT results from the cluster randomized feasibility trial. Oakeshott et al. 2019