Article Text
Abstract
Introduction HIV notifications have increased significantly in Victoria since 2000. The majority of these are among men who have sex with men (MSM). Chlamydia, gonorrhoea and syphilis notifications have also increased among MSM in Victoria and reinfection occurs in approximately 15%–30% of MSM retested after a positive diagnosis of syphilis, chlamydia or gonorrhoea. Sexually transmissible infections (STI) have been associated with an increased risk of HIV acquisition. We aimed to test whether repeat infection increased the risk of HIV infection among MSM.
Methods A retrospective analysis of sentinel surveillance data was conducted. HIV negative MSM who attended three high case load clinics in Victoria from 2007 to 2014 with two or more HIV tests were eligible for inclusion. STI diagnosis and behavioural exposures were lagged to a patient’s prior test event and an individual level discrete-time survival analysis using generalised linear modelling estimated the cumulative effect of repeat STI diagnoses on HIV diagnosis risk.
Results 8941 individuals were included in the analysis among whom 2.5% (n=227) were diagnosed as HIV positive. After adjustment for number of sexual partners and condom use in the previous six months, repeat rectal gonorrhoea infection (adjusted hazard ratio [aHR]: 6.24, 95% confidence interval [95% CI]: 2.68–14.50), single-event rectal gonorrhoea (aHR: 2.09, 95% CI: 1.15–3.79), rectal chlamydia (aHR: 1.89, 95% CI: 1.12–3.18) and syphilis (aHR: 1.99, 95% CI: 1.00–3.96) infections were associated with an increased risk of HIV diagnosis. Repeat rectal chlamydia infection (aHR: 1.62, 95% CI: 0.73–3.59) and repeat syphilis infection (aHR: 0.93, 95% CI: 0.11–7.65) were not associated with an accumulated increased risk of HIV diagnosis.
Conclusion In addition to increased risk due to a single STI, repeat rectal gonorrhoea infection was strongly associated with an accumulated increased risk of HIV diagnosis. These findings suggest MSM with repeat rectal gonorrhoea infection represent a higher risk group for whom preventive interventions are encouraged.