High rates of sexually transmissible infections in HIV-positive patients in the Australian HIV Observational Database: a prospective cohort study

Abstract

Background Sexually transmitted infections (STI) may directly increase the risk of HIV infection, or may indicate sexual practices that increase the risk of HIV infection. In persons with HIV they probably also increase the infectiousness of HIV, even in the context of treatment with antiretroviral drugs (ARV). Estimating STI in this group has proved problematic, and there are few longitudinal studies able to accurately measure incidence. Methods In 2010, we established a cohort of individuals from ten widely dispersed sexual health clinics that were already enrolled in the Australian HIV Observational Database (AHOD). We calculated retrospective diagnosis rates for four STI (chlamydia, gonorrhoea, infectious syphilis, anogenital warts) from 2005-2010, and prospective incidence rates from 2010-2011. Results At baseline (2010) , the patient characteristics (n=554) were similar to the rest of AHOD (n=1767), namely they were predominantly male, homosexual, middle-aged, and pre- treated with ARV. Overall, the incidence of any STI was 12.5/100 person years (py). There was a gradual increase in chlamydial infections , from 3.4/100 py (95% CI 1.9-5.7) in 2005 to 6.7/100py (95% CI 4.5-9.5) in 2011, with a substantial peak of 8.1/100py (95% CI 5.6-11.2) in 2010. The cases were distributed between rectal ( 61.9%), urethral (34%), and pharyngeal (6.3%) sites. Similarly, gonococcal infections increased, with a peak in 2010 of 4.7/100py (95% CI 5.6-11.2), (p value for trend=0.0099), distributed between rectal (63.9%), urethral (27.9%), and pharyngeal (14.8%) sites. Infectious syphilis showed several peaks, the largest in 2008 (5.3/100py , (95% CI 3.3-8.0), but the overall trend was not significant (p=0.113). Diagnoses of genital warts declined from 7.5/100py (95% CI 4.8-11.3) in 2005 (95% CI 4.8-11.3) to 2.4/100py (95% CI 1.1-4.5) in 2011 (p value for trend=0.0016). Conclusions The incidence of chlamydial and gonococcal infections in this cohort was higher than previous estimates in Australia among HIV-infected men who have sex with men (MSM), and increased during the 2005-2011 study period. Rectal infections greatly outnumbered infections at other sites. The incidence of infectious syphilis remained high, but did not increase, and the incidence of genital warts was lower, and decreased. These are the first measurements of STI incidence among persons being treated for HIV in Australia. They may underestimate the true incidence of these infections in the HIV-infected population.

Risk factors associated with incident sexually transmitted infections in HIV‐positive patients in the Australian HIV Observational Database: a prospective cohort study

“…We previously found a high incidence of STI diagnoses in the AHOD . Routine STI screening of HIV‐positive patients is recommended , and has been pretty universally implemented over the period from 2010 onwards – especially in the STI clinics included in this analysis.…”

“…However, there are limitations to our study design. First, although our sample is representative of the parent cohort , the latter may not be representative of the general population with HIV infection. Secondly, although the pharynx accounted for only 7% of known site diagnoses, this does not necessarily mean that oral transmission is rare.…”

“…There is a broad consensus that the increased incidence of some STIs may be attributable to the increased prevalence of condomless intercourse in both HIV‐negative and HIV‐positive MSM . By combining retrospective and prospective data, we previously showed high levels of four STIs in a subcohort of HIV‐positive individuals enrolled in the Australian HIV Observational Database (AHOD) .…”

Australian consensus statement on doxycycline post‐exposure prophylaxis (doxy‐PEP) for the prevention of syphilis, chlamydia and gonorrhoea among gay, bisexual and other men who have sex with men

“…11 Known risk factors for STIs include sexual behaviour history (eg, sex without condoms, casual sex partners, sexualised drug use), current use of PrEP, and HIV-positive status. [12][13][14] A recent analysis of clinical data from Boston, United States, explored the effectiveness of different doxy-PEP prescribing strategies to prevent one case of bacterial STI. 15 This analysis found that prescribing doxy-PEP for 12 months to individuals with one or more recent STI diagnosis (within the previous 12 months) was an efficient strategy for reducing the amount of doxy-PEP prescribed, with the number needed to treat (NNT) ranging from 1.3 to 1.5 to prevent one bacterial STI case over 12 months.…”

“…Known risk factors for STIs include sexual behaviour history (eg, sex without condoms, casual sex partners, sexualised drug use), current use of PrEP, and HIV‐positive status 12‐14 . A recent analysis of clinical data from Boston, United States, explored the effectiveness of different doxy‐PEP prescribing strategies to prevent one case of bacterial STI 15 .…”