How Do You Solve a Problem Like Chlamydia?

An expert on sexually transmitted infections and public health physician, Dr Nicola Low is not happy with the current state of chlamydia screening. MedWire Reporter Nadine Woogara asks what must change before chlamydia rates start to reduce.

As more countries begin to adopt opportunistic screening programs for chlamydia, it feels like the problem is being tackled head on. But Nicola Low believes otherwise.

She says governments have not hit upon the right formula to successfully reduce chlamydia transmission.

“We know that we’ve got effective tests and we know that we’ve got effective treatment so we jumped to the conclusion that screening would also be effective,” says Low.

“It’s something that we all very much want to believe in, because we want to improve sexual health.”

Low, an epidemiologist at the University of Bern in Switzerland, is the author of the controversial British Medical Journal (BMJ) article: “Screening programs for chlamydia infection: when will we learn?”

What is opportunistic screening?

Select patients are offered a chlamydia test when they attend healthcare services for unrelated reasons.

Why do you think opportunistic screening for chlamydia will not work?

It’s not organized in a way that will get enough people screened regularly enough to interrupt chlamydia transmission. We’re talking about an asymptomatic infectious disease, so unless you screen people regularly, you might find their infection once but then when they get re-infected they may be missed and become infertile anyway. In which case, you will not have done anything to reduce their morbidity and you will not have had any impact on transmission.

Could opportunistic screening do more harm than good?

If the system forgets to offer screening at regular intervals and people get re-infected and then become infertile, you have harmed your patient. A program that they believed was in place for their benefit would have failed.

BMJ editorialists suggested an alternative pharmacy-based opportunistic screening program, could that work?

You might reach some people because they come into the chemist and say: “I’d like a chlamydia test” when they weren’t intending on going to their GP. But when are they going to get their next test? Unless you’ve engaged them in a systematic process that is getting them tested regularly, then screening is not going to work.

Was enough research carried out before opportunistic screening was put in place?

We did not look critically enough at the evidence that was in front of us to find out whether what was planned would actually deliver the benefits. We need a randomized controlled trial. It’s very simple. You cannot say by observing what might have happened in other countries that opportunistic screening works. You just have to show that something works before you spend the money on rolling it out.

Why adopt opportunistic screening without a randomized controlled trial?

There have been randomized controlled trials but they have all been of proactive approaches to screening. I think people wanted to extrapolate from the existing evidence. It is clearly time consuming to do a randomized controlled trial, so they wanted to take the evidence from proactive screening and from other sources. The problem is that none of these other sources of evidence actually answered the question. There is a fundamental desire to do good. And I think that there is a great desire to believe that something worked. So they ignored the fact that it was actually not plausible.

What are the alternatives to opportunistic screening?

You could think of ways to combine opportunistic and proactive screening. So you could use the fact that lots of people use healthcare services to offer them an initial test to get them into a register that then invites them again. Why not do that?

What is proactive screening?

Population registers invite members of the population thought to be at high risk for screening at appropriate intervals.

Would you say proactive screening could be better than opportunistic screening?

Proactive screening is a way of achieving continuous screening. Having once been invited to take part, people will then be invited the following year.

Which would be the most cost effective?

The cost of administering opportunistic screening is the same as the cost of establishing a proactive screening program. But that is not the same as the cost effectiveness. Our analysis of proactive screening shows that it’s an expensive intervention. You would have to increase the uptake considerably to make it something that people would regard as cost effective. If the uptake of opportunistic screening was the same as that of proactive screening, then that too would be cost effective.

Editorialists in the BMJ pointed out that a proactive approach could be considered ‘unacceptable’ as it would screen 16-year-olds who may not yet be sexually active. How do you respond to this?

It doesn’t have to be portrayed negatively. We can use the 16th birthday as an opportunity to provide lots of information about girl’s sexual health. We’re trying to de-stigmatize sexually transmitted diseases. We’re trying to say this is common. It happens. It’s not your fault. It can be promoted in a very positive way with very positive messages about improving sexual health and then you would have access to all the population at risk.

Has this sort of thinking stopped proactive screening from going ahead?

At the very start of the debate about whether we should have chlamydia screening, proactive screening was discounted out of hand because it was said that it might be unacceptable. They didn’t even think about whether it could be done. This continues to be the opinion. The department of health think that it is impractical and inefficient, unnecessary, and unacceptable.

Could people be persuaded to change their minds?

As you do it, the more you do it, the more it becomes a part of life. People will expect invitations to come through the door and it may very well become much better accepted and appreciated.

According to the BMJ editorial, chlamydia is currently the only sexually transmitted infection (STI) for which population screening is carried out. Do you think countries are likely to adopt population screening for other STIs?

I hope not. There is no other infection that is as common as chlamydia. Widespread population screening for any other STI is not really feasible because there aren’t the methods to do it.

Chlamydia screening around the globe

UK
The National Chlamydia Screening Program is due to start in 2008, screening all women and men under 25 years who attend health care services.

US
Infertility Prevention Program provides opportunistic screening for women on low incomes.

France, Romania, Slovenia, Ireland, The Netherlands, and Australia are all considering introducing opportunistic chlamydia screening programs.

What does the future hold for chlamydia screening?

It depends on whether anyone decides that it is worth doing a randomized controlled trial to find out whether opportunistic screening works. If opportunistic screening carries on in the way that it is at the moment, my prediction is that it will not affect chlamydia transmission and it will not affect reproductive tract morbidity.

When will governments start listening to the doubts of academics?

I hope that they’re listening now.

BMJ Analysis
‘Screening Programs for chlamydia infection: when will we learn?’ [pdf]

BMJ Editorial
‘Screening for chlamydia trachomatis, opportunistic approaches have little evidence to support them.’