Comparison of sexual behavior and HIV risk between two HIV-1 serodiscordant couple cohorts: the CHAVI 002 study.
BACKGROUND
The CHAVI002 study was designed to characterize immune responses, particularly HIV-specific T-cell responses, amongst 2 cohorts of HIV-exposed seronegative (HESN) individuals. The absence of a clear definition of HESNs has impaired comparison of research within and between such cohorts. This report describes two distinct HESN cohorts and attempts to quantify HIV exposure using a 'HIV risk index' (RI) model.


METHODS
HIV serodiscordant couples (UK; 24, Uganda; 72) and HIV unexposed seronegative (HUSN) controls (UK; 14, Uganda; 26 couples, 3 individuals) completed sexual behavior questionnaires every 3 months over a 9 month period. The two cohorts were heterogeneous, with most HESNs in the UK men who have sex with men (MSM), while all HESNs in Uganda were in heterosexual relationships. Concordance of responses between partners was determined. Each participant's sexual behavior score (SBS) was estimated based on the number and type of unprotected sex acts carried out in defined time periods. Independent HIV acquisition risk factors (partner plasma viral load, STIs, male circumcision, pregnancy) were integrated with the SBS, generating a RI for each HESN.


RESULTS
96 HIV serodiscordant couples completed 929 SBQs. SBSs remained relatively stable amongst the UK cohort, whilst decreasing from Visit 1 to 2 in the Ugandan cohort. Compared to the Ugandan cohort, SBSs and RIs in the UK cohort were lower at visit 1, and generally higher at later visits. Differences between the cohorts, with lower rates of ART use in Uganda and higher risk per-act sex in the UK, had major impacts on the SBSs and RIs of each cohort. There was one HIV transmission event in the UK cohort.


CONCLUSIONS
Employment of a risk quantification model facilitated quantification and comparison of HIV acquisition risk across two disparate HIV serodiscordant couple cohorts.
Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom. adam.ritchie@imm.ox.ac.uk
Adam J
AJ
Ritchie
Kristin
K
Kuldanek
Zoe
Z
Moodie
Z Maggie
ZM
Wang
Julie
J
Fox
Rebecca N
RN
Nsubuga
Kenneth
K
Legg
Esther F
EF
Birabwa
Pontiano
P
Kaleebu
Andrew J
AJ
McMichael
Christine
C
Watera
Nilu
N
Goonetilleke
Sarah
S
Fidler
D000328:Adult; D015331:Cohort Studies; D005191:Family Characteristics; D005260:Female; D015658:HIV Infections / Q000523:psychology* / Q000635:transmission; D006679:HIV Seropositivity / Q000523:psychology* / Q000635:transmission; D020010:Heterosexuality / Q000523:psychology*; D018451:Homosexuality, Male / Q000523:psychology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D012309:Risk-Taking; D012725:Sexual Behavior / Q000523:psychology* / Q000706:statistics & numerical data; D012747:Sexual Partners / Q000523:psychology*; D014454:Uganda; D006113:United Kingdom; D019562:Viral Load