Why is action urgent?

Dr Peter White's research has looking into the issues of GU treatment

Britain has witnessed a massive resurgence in sexually transmitted infections (STIs) in the last ten years.

Between 1995 and 2004 Chlamydia rates more than trebled from 32,288 annual diagnoses to 103,932; Gonorrhoea rates rose from 10580 to 22320; Syphilis from 141 diagnoses to 2,252 (an increase of 1,497%).

Many Genito-Urinary (GU) clinics have not been able to keep pace with the massive increase in demand for services, which has led to increased waiting times. Some patients wait weeks to be seen, and some will not be able to access GU care at all, but will go to their GP, or perhaps may not get treated at all.

This would be a difficult situation on its own, but an added difficulty is the transmissible nature of the infections and that people do not stop having sex. The Parliamentary Health Select Committee (2005) cited research that 30% of people with STIs continue to have sex. But no-one had examined the effect of these long waiting times and untreated infections in promoting transmission, so causing new infections - until now.

New research

A team from Imperial College and UCL in London set out to create a computer model to explore what effect the growing waiting times would have on the spread of the STIs if left unchecked. The model would take account of the infectious nature of these diseases.

The model they constructed was a specifically based around gonorrhoea in heterosexuals aged 16-45. The team, led by Dr Peter White, took into account what effect long waiting times would have on the behaviour of GU patients - some would turn to their GP instead, and others would abandon their attempts to obtain care at all. The longer the waiting times, the greater the numbers concerned would be.

The team concluded that insufficient treatment capacity leads to high transmission rates, which puts more pressure on treatment capacity, forming a "vicious circle". This can be broken by increasing the capacity of the clinic.

They found that a substantial increase in the capacity of the GU clinic was needed to break this vicious circle and enter a "virtuous circle". There, patients would be treated promptly, so they did not have to go their GP instead, or give-up on seeking care, with the result that the infection would have less chance to spread.

In the end this would reduce the workload of the clinic, by reducing rates of infections - so the capacity increase need only be temporary. However, if the increase in GU capacity were too small then the vicious circle would not be broken, and high rates of infection would continue indefinitely - costing more in the long run.

Whilst an increase in capacity would cost extra money in the short term, the team believes that the extra investment actually offers cost savings by reducing future demand for treatment, so the increased capacity would only be needed temporarily. Promptly treating STIs reduces the chances that they may cause fertility problems later in life, as well as reducing rates of onward transmission.

BBC Panorama asked Dr Peter White to apply the computer model to Sheffield. The results were similar to the national average situation. Sheffield has higher rates of gonorrhoea than the national average, and also has greater treatment capacity - although still not enough capacity at present. In percentage terms, the capacity increase needed by Sheffield is similar to the national average - that is, 30-50%.

When infection spreading is out of control, there are many more infections than diagnoses, because some people (most often women) are not aware of their infection and so don't seek care, some infections are treated by GPs -and so not recorded by the GU clinic - and many infections are not treated at all. Waiting times for those who do get treated in the GU clinic are long.

Applying the model

On the graphs, the red line shows the numbers of gonorrhoea infections occurring and the blue line shows the number being treated in the GU clinic, plotted against time in years.

the effect of a 10% increase in funding in Dr White's model

Increasing GU-clinic capacity by 10% increases the numbers of people treated, and reduces infection rates - but it does not break the vicious circle, so infection rates remain high and the capacity increase has to be maintained indefinitely.

Increasing capacity by 20% breaks the vicious circle - by reducing rates of onward transmission of infection, numbers of future infections are greatly reduced, as infection is brought under control and waiting times are reduced - although it takes many years.

the effect of a 30% increase in funding in Dr White's model

Increasing capacity by 30% brings infection under control much faster than a 20% increase, so requires less money overall and offers cost-savings that occur sooner. Notice how rates of treatment in the clinic are eventually reduced below the starting level, so cost savings are made - even in terms of numbers of infections treated. In addition, there will be savings in reduced rates of infertility and ectopic pregnancy.

Three of the key policy implications from the work were that

• Under-pressure GU clinics throughout the country need a substantial increase in capacity.

• The larger the increase in investment, the shorter-term the need for the extra investment, because infections are brought under control more quickly, thus reducing demand.

• Once control has been gained, it must be maintained

Dr Peter White says "Increasing capacity by enough to break the vicious circle would be a genuine investment, with the pay-off that it would reduce the number of infections that occur in the future, and would reduce rates of complications like infertility, which are costly to treat."