High burden of STIs among people living with HIV in Cape Town in period before they start ART

Sexually transmitted infection (STI) rates are high among people living with HIV in the period before they start antiretroviral therapy (ART), investigators from South Africa report in the online edition of Sexually Transmitted Infections.

“This is the first study to systematically examine treatment for STIs among those already infected with HIV in the periods prior to and since ART initiation,” comment the authors. “Those on ART were approximately seven times more likely to seek treatment for an STI in the period prior to ART initiation compared with the period once on ART.” The investigators believe their findings have important implications for “test and treat” HIV prevention strategies.

It is well known that STIs increase the probability of HIV transmission. Some studies looking at the prevalence of STIs among people living with HIV have reported higher rates in the period before beginning ART, but little prior research has been conducted in sub-Saharan Africa. Because of this uncertainty, investigators designed a study to examine the burden of STIs among a cohort of patients in South Africa in the periods before and after they started ART.

The study population comprised 1465 people who started ART in Cape Town between 2009 and 2011. Data on STI rates were obtained from centrally collected Cape Town prevalence records.

Women made up 65% of the sample and the mean age was 33 years. The participants contributed a total of 4212 person-years of follow-up. This was equally divided between the pre-therapy and on-therapy periods.

A total of 232 STI events were reported. Of these, 203 (88%) were observed in the pre-ART period, the other 12% occurred during ART. However, the authors believe these figures likely underestimate the true burden of STIs among the patients as many infections will have been asymptomatic and a proportion of patients will have sought treatment at private healthcare providers.

STI rates were seven times higher in the period before the patients started HIV therapy compared to the on-therapy period (RR = 7.01; 95% CI, 4.64-10.59).

“The high rates of STIs that we observed among people already infected with HIV during the period prior to ART initiation represent an important opportunity for prevention and suggest a more comprehensive approach to HIV transmission is needed beyond ART,” comment the authors.

After controlling for potential confounders, the authors calculated that the STI incidence was 9.57 per 100 person-years in the pre-treatment period and 5.5 per 100 person-years after starting therapy.

STI rates were 70% higher among men than women (RR = 1.73; 95% CI, 1.18-2.55) and doubled among younger compared to older (35 years and above) patients (p < 0.001). People with more advanced HIV disease had a lower risk of STIs (RR = 0.33; 95% CI, 0.15-0.69).

“The failure to detect and treat STIs increases the likelihood of further HIV and STI transmissions to uninfected partners,” write the investigators. “The high burden of STIs in the period prior to ART initiation may undermine the projected efficacy of universal treatment as a prevention strategy, primarily because of the increased infectiousness of people with HIV/STI co-infections.”