Testing HIV patients for STIs as part of routine care prevents new infections and is cost effective

Routine screening for sexually transmitted infections (STI) as part of HIV outpatient care is feasible, cost effective and has the potential to avert new cases of HIV infection according to a study conducted in New Orleans and published in the August 15^th edition of the Journal of Acquired Immune Deficiency Syndromes.

The majority of HIV-positive people remain sexually active, and in recent years people with HIV have become the focus of HIV prevention campaigns in both the US and UK. The presence of an untreated STI can increase the chances of an HIV-positive person passing on HIV during unprotected sex. As STIs can be asymptomatic, screening integrated into routine HIV care can detect STIs and has the potential to prevent further cases of HIV. The US Center for Disease Control recently recommended that all HIV patients should be checked for the presence of bacterial STIs as part of their HIV care. In the UK, some HIV clinics now offer their patients sexual health check-ups as part of their routine care, and syphilis testing at every clinic visit was recently shown to be effective.

Investigators at a large HIV clinic in New Orleans examined the potential benefits of an STI screening programme. Their study involved calculating the prevalence of the bacterial STIs gonorrhoea and chlamydia amongst their patients and comparing this to the rates of the diseases seen in the general population. They also constructed a mathematical model to calculate how many new HIV infections the treatment of the STIs prevented and how cost effective the screening programme was.

Between October 1998 and June 2001, 7.5% of all patients attending the clinic provided a urine sample which was screened for the presence of gonorrhoea or chlamydia. Testing was more frequent amongst both white and black women than amongst white or black men. The majority of white men were gay.

Over the entire study period, 1.7% of samples tested positive for gonorrhoea and 2.1% for chlamydia. There were no significant differences based on race or sex, however, age was significant, with 4.8% of 15 –19 year olds positive for gonorrhoea or chlamyida compared to 0.9% of individuals aged over 35.

Rates of gonorrhoea were slightly higher in the HIV clinic patients than in 18 –29 year olds in the general populations (p=0.11), however the prevalence of chlamyida was slightly lower (p

The investigators used a mathematical model which included an estimation of the likelihood that two HIV serodiscordant people would have sex together and the likelihood of HIV transmission taking place. Chlamydia was estimated to increase the risk of HIV transmission five-fold and gonorrhoea ten-fold. Vaginal sex was regarded as the standard sexual behaviour, and anal sex was regarded as carrying a higher risk of HIV transmission and oral sex a lower risk. On the basis of this model the investigators estimated that their screening programme prevented nine new cases of HIV. A widely respected mathematical model used to calculate the cost-effectiveness of HIV prevention efforts was also used by the investigators who calculated that a programme which tested all HIV patients for STIs as part of their routine care would be cost effective, even when STI rates were very low, saving approximately $145,000 per case of HIV averted.

The investigators conclude, “this study supports the CDC recommendation that screening for gonorrhoea and chlamydia infection should be established in HIV clinics as part of routine care…Patients in these clinics found to have these and other STDs can be intensively counseled to reduce risky sexual behavior, their curable STDs can be treated, and confidential partner notification procedures initiated. Thus screening can initiate a series of actions with the potential to prevent HIV transmission to others.”

Further information on this website

Sexual health - factsheets

HIV-positive patients should be tested for syphilis every three months says UK study - news story