Sexually transmitted infection (STI) incidence in men who have sex with men (MSM) followed since primary infection stage in the French ANRS-PRIMO cohort
Background: In France, in a context of rising at-risk sexual
behaviour in MSM, we estimated the incidence rate of STIs in HIV-infected MSM followed
since primary HIV infection. We compared these incidence rates according to the
viral load of patients at the visit preceding the STI diagnosis.
Methods: In
1996-2014, 1,226 MSM have been enrolled in the ANRS-PRIMO cohort during primary
HIV-infection. Patients are followed every 6 months. At each visit, a clinical
questionnaire is completed with lab measurements, antiretroviral treatment and
clinical information including STI occurrence since the last visit.
We focused
on syphilis, gonorrhea, Chlamydia trachomatis
infections, and other suspected bacterial infections such as unspecified uretritis,
rectitis, epididymitis, orchitis and balanitis. We assumed that two episodes of
the same STI were distinct infections if separated by ≥3 months, and by ≥1 year
for syphilis. We assessed the evolution over time in incidence rates and their
association with the viral load of the patients measured at the visit preceding
the STI diagnosis with a regression model of Poisson taking into account
longitudinal data.
Results: We observed
412 incident STIs in MSM, i.e. an incidence rate of 6.67/100 patient-years (PY)
[95%CI: 6.05-7.34], including 215 syphilis (incidence rate: 3.61/100PY [3.16-4.13])
and 197 other bacterial STIs (incidence rate: 3.19/100PY [2.77-3.66]).
The
syphilis incidence rate was null before 2000 and increased afterwards of 9% per
year on average (p< 0.0001) up to 4.91/100PY in 2013. As well, the other STIs
incidence rate increased over time of 4% per year (p=0.006) up to 4.40/PY in
2013.
Considering all STIs together throughout
1996-2014, the incidence rate during the periods when MSM had an undetectable
viral load was lower compared with the periods with detectable viral load (6.08/100PY
versus 7.72/100PY, p=0.02).
Conclusions: In these
HIV-infected MSM, STIs incidence has risen over calendar time, in syphilis as
well as in other bacterial infections. Although they may be underestimated
because of under-reporting or under-diagnosis, these incidence rates were high,
particularly when the viral load is detectable. With the diffusion of the concept
of Treatment as HIV Prevention, efforts should be done to help MSM to prevent transmission
of other STIs.
K. Champenois1, R. Seng1,2,3, A. Persoz1, A. Essat1, C. Goujard1,2,4, L. Meyer1,2,3, ANRS PRIMO Cohort Study Group
1Inserm UMR 1018, CESP-4, Epidemiology of HIV and STIs, Le Kremlin Bicêtre, France, 2South-Paris University, South-Paris Medical School, Le Kremlin Bicêtre, France, 3AP-HP, Bicêtre Hospital, Epidemiology and Public Health Service, Le Kremlin Bicêtre, France, 4AP-HP, Bicêtre Hospital, Internal Medicine Department, Le Kremlin Bicêtre, France