7 November 2018

Chlamydia retesting better bang for buck than screening

Clinical Communicable Disease Sex

Opportunistic screening won’t be enough to spell the end of chlamydia, according to Melbourne researchers.

The study, published in The Lancet, challenged the idea that widespread testing would reduce the harms from chlamydia, instead suggesting that better management, retesting and partner treatment was more effective.    

As people are increasingly diagnosed with chlamydia, some countries have introduced annual screening for young adults. But due to a lack of good evidence around the effectiveness of annual screening, the Australian government decided to fund a clinical trial to answer the question of whether boosting screening rates in general practice would reduce the incidence of diagnosis. 

“Our premise for doing the trial was that we thought if we could get testing rates to high enough levels we should see a reduction in chlamydia, and potentially a reduction in pelvic inflammatory disease and epididymitis,” Professor Jane Hocking, head of the sexual health unit at the University of Melbourne’s school of population and global health, said.  

From previous mathematical modelling, the team knew that if it could get testing rates above 20% and maintain that for 10 years, it would see a reduction. 

So the researchers looked at the rates of diagnosis and infection in 90,000 young adults across 130 GP clinics in rural Australia. They enlisted all the GP clinics in the included towns, and randomised the clinics into practice as usual, or the intervention arm which included reminders to test, education, incentive payments for chlamydia testing, quarterly feedback on testing rates and how they compared with other GPs in the trial, and incentives for nurses performing tests. 

They achieved testing rates of above 20%, up from 8%, but this was not enough to see a reduction in chlamydia diagnoses, Professor Hocking said. 

“There are a number of reasons for that,” she said. “Maybe we needed to get testing rates to higher levels, or keep it at 20% for a 10-year period, like our modelling suggested.” Clinics participated for an average of three years. 

She said they had hoped to see a reduction, “but I think what our results show is this is what we can expect with achievable levels of chlamydia testing in general practice”.

Given how busy general practitioners were, the rates of testing found in this study reflected what would be achievable and the impact this intervention was likely to have on screening prevalence, Professor Hocking said. 

“We did see a reduction in severe pelvic inflammatory disease that required hospitalisation, but did not see any change in the much  milder forms of pelvic inflammatory diseases that are regularly managed in general practice.”

Regardless, for an individual patient it was still important to be screened whenever possible, Professor Hocking said. 

“Our recommendations from this trial are that GPs should continue to regularly test young people for chlamydia and other STIs, as per the guidelines, but we also think we need to improve the management of chlamydia in general practice. 

“A risk factor for a person with chlamydia developing pelvic inflammatory disease is increased after having had multiple chlamydia diagnoses in the past.” 

For a young woman, having two or more chlamydia infections increased her risk of pelvic inflammatory disease as much as fourfold, Professor Hocking said. 

And 15-20% would have a repeat positive diagnosis, and yet only around one in three patients diagnosed with chlamydia got retested within three months, she said. 

So reducing repeat chlamydia infections was important, especially among young patients. 

This included getting sexual partners tested and treated and improving repeated testing three months after treatment, as per the guidelines, she said.  

“This should help detect repeat infection searly, before they go on to develop complications.”

Depending on the state, some practitioners could also prescribe antibiotics for the patient to take home to their partner, she added. 

Lancet 2018; online 20 October