Abstract Book Vol. 1 [International Conference on AIDS (16th: 2006: Toronto, Canada)]

Conclusions: Almost two-thirds of HIV negative women screened for HPTN
035 had an abnormality identified during pelvic examination. Most abnormal
findings were not serious. Most findings that were exclusionary for the study
resolved spontaneously or after STI treatment.
TUPEO447
Microbicides development programme, Tanzania.
Are high-risk women who work in bars, guesthouses
and similar facilities a suitable study population for
clinical trials of vaginal microbicides in Africa?
A. Vallely', I. Hambleton', S. Kasindi2, L. Knight', R. Balira3, C. Tobias',
J. Changalucha3, D. Everett', D. Watson-Jones', D. Ross4, R. Hayes4. 'The
London School of Hygiene & Tropical Medicine, Mwanza, Tanzania, United
Republic of, 2African Medical and Research Foundation, Mwanza, Tanzania,
United Republic of, 3National Institute for Medical Research, Mwanza,
Tanzania, United Republic of, 4The London School of Hygiene & Tropical
Medicine, London, United Kingdom
Methods: 1573 women aged 16-54y working in bars, restaurants, hotels,
guesthouses or as local food-handlers were enrolled, interviewed and examined
at community-based reproductive health clinics, provided specimens for HIV/
STI and pregnancy testing, and asked to attend for follow-up every three
months. HIV positive and negative women were eligible to enter the feasibility
study and to receive free reproductive health services at any time.
Results: Baseline prevalence of HIV was 25.5%o; pregnancy 9.7%; herpes
simplex virus type-2 (HSV-2) infection 74.6%; active syphilis (TPPA+/RPR+)
10.2%, bacterial vaginosis 52.6%a; gonorrhoea 5.5%; chlamydia 5.9% and
trichomoniasis 12.3%. HIV prevalence at baseline increased with age, was
lower among local food-handlers and women working in traditional bars,
married women and those with fewer sexual partners, and was associated with
HSV-2 infection and bacterial vaginosis. The incidence of HIV was 3.5 / 100PYs
(95% CI 2.4, 5.2). Among 731 HIV sero-negative, non-pregnant women who
attended a second visit, subsequent follow-up at 3, 6, 9 months was 83.9%,
79.5% and 72.4%o respectively and 78.6% overall. Older women, those who
had not moved home or changed their place of work in the last year, and
women working in traditional bars or as local food handlers had the highest reattendance. HSV-2 incidence was 18 / 100PYs (95% CI 11.2, 28.9); bacterial
vaginosis 44.7 / 100PYs (95% CI 35.7, 55.9); active syphilis 3.4 / 100PYs (95%
CI 1.8, 6.4). The incidence of pregnancy was 44.7 / 100PYs (35.7, 55.9).
Conclusions: These findings suggest that women working in food and
recreational outlets are likely to be a suitable study population for microbicide
and other HIV prevention trials in Tanzania.
TU PE0448
The effect of one versus two efficacy trials on
statistical power, size and costs of phase III
programs for microbicides
P. Coplan. International Partnership for Microbicides, Executive Director, Site
Development and Regulatory Capacity, Plymouth Meeting, United States
Background: The FDA requires one pivotal trial or two trials that demonstrate
efficacy for licensure of microbicides, but if two trials are done, each must show
efficacy. Developers can conduct one pivotal or two smaller efficacy trials for
Phase III programs. We assess the impact of one versus two trials on statistical
power, sample size and cost of Phase III programs. Statistical Power = sensitivity
to detect efficacy. Low power equals high probability of rejecting truly effective
products by chance: 80% power represents 20% chance of rejecting effective
products by chance alone. A key observation is that the power of Phase III
programs with 2 trials is the product of each trial's power, e.g., 2 trials with 80%
power each has programmatic power of 0.64 (=0.8 x 0.8)
Methods: Sample size was calculated for overall Phase III programs to have
90% or 80% power, assuming 50% efficacy, 1: 1 randomized placebo-controlled
1-year-long trials, 30 HIV incidence, 150 drop-out using Stata. FDA indicated
p<0.005 is acceptable for one trial; p<0.001 was calculated for sensitivity
analysis. Costs used were US $9,000 per participant.
Results: Required sample size and costs for Phase III programs to have 90/%
or 80/% power are shown below:
Power of One Trial One Trial...OneTrial Trials Trials Trials
Program (p<Q0005) (p <0 005) (p <0i005) (p<0.05 (p <0,D5 (pc005......each) each) each)
Power Sample size Cost (mln) Power size (mon)
0.9 0.9 7,995 $72.095 10278 $92.
0.8 0.8 6,431. $58 0.89 7,,831 $70,

Conclusions: To achieve 90% power for microbicide Phase III programs, one
pivotal trial at p<0.005 provides savings of 57% in sample size and $41 million
versus 2 trials. With p<0.001, one versus two trials provides savings of 27%
in size and $24 million. One versus two trials provides significant savings if
statistical power for Phase III programs is held constant.

TUPEO449
Sexually transmitted diseases (STD) clinic attenders
are feasible and suitable for HIV prevention trials in
Durban, South Africa
A.B. Kharsany, H. Carrara, B.P. Ncama, Z. Mkhize, B. Madlala, E. Khambule,
S.S. Abdool Karim, Q. Abdool Karim. University of KwaZulu-Natal, Centre for
the AIDS Programme of Research In South Africa, Durban, South Africa
Background: As the need for populations for Phase III HIV prevention trials
grow there is a need to identify multiple sources of potential cohorts. Given the
association between HIV and other STDs, STD patients may be suitable for such
trials depending on the ability to recruit and retain them in cohorts which have
high HIV incidence rates.
Methods: All women aged 16-35 years utilizing the STD Clinic in central
Durban between July 2005 and November 2005 were provided information and
education on STD, HIV and HIV testing. After individual counseling and HIV
testing, HIV negative women were invited to participate in a HIV seroincidence
cohort study being conducted in preparation for proposed microbicide and
vaccine trials. Following enrolment, study participants attended monthly followup visits and had repeat HIV testing quarterly.
Results: The prevalence of HIV infection in the 1259 women screened during
this period was 59.3% (95% CI: 56.4-61.9). On average, 21 HIV negative
women were accrued each month. A total of 104 women were enrolled. The
median age was 22 (IQR 21-24 years). A cohort retention rate of 95.0% per
annum was achieved. The women reported 2.2 (SD 1.8) coital acts per fortnight.
About 47% reported condom use; a third of them reported 100%a condom use.
The incidence rate of STIs is 223.7/100 (95% CI: 176.1-271.2) person years.
41 of the 104 women (39.4%) had at least one incident STD during follow-up,
whilst 10.6% had more than one incident STD. The HIV incidence rate in this
cohort to date is 7.9/100 (95% CI: 0-16.8) person-years.
Conclusions: It is feasible to recruit and retain a cohort of high risk women
attending a STD clinic. The high HIV and STD incidence rates in this cohort make
them well suited for Phase III microbicide, vaccine or other HIV prevention
trials.
TUPEO45O
The setting of new or anonymous sexual encounters
predicts risky sexual behavior and new sexually
transmitted infections among MSM in the
multicenter AIDS cohort study (MACS)
D.G. Ostrow', R.L. Cooke, V. Sundaram2, C. Cox3, W. Qiao3, B. Visscher',
J. Hylton, Multicenter AIDS Cohort Study (MACS). 'Multicenter AIDS Cohort
Study, Behavioral Working Group, VIg of Lakewood, United States, 2University
of Pittsburgh School of Medicine, Department of General Internal Medicine,
Pittsburg, United States, 3Johns Hopkins School of Public Health, Multicenter
AIDS Cohort Study-CAMACS, Baltimore, United States, 4University of
California-Los Angeles-School of Public Health, Epidemiology/Multicenter AIDS
Cohort Study, Los Angeles, United States, 5Johns Hopkins School of Public
Health, Epidemiology/Multicenter AIDS Cohort Study, Baltimore, United States
Background: Men who have sex with men (MSM) meet new sexual partners in a
variety of settings. We determined the settings in which the greatest proportion
of MACS participants met new sexual partners, studied the association of
these specific settings with risky sexual behavior and newly acquired sexually
transmitted infections (STI), and compared the findings in HIV-positive and
HIV-negative men.
Methods: 1683 men (794 HIV-positive, 889 HIV-negative) met new male
sexual partner(s) since the previous semiannual visit, 2003-2005. Participants
reported whether they met a new partner at one or more of 8 specific types
of settings. We assessed predictors of risky sexual behavior (unprotected
anal intercourse with >2 or more partners) and STI using multivariate logistic
regression overall and separately for HIV+ and HIV- men.
Results: The most common settings for meeting new sexual partners were
the internet (34.3%/), bars (31.80/), and bathhouses (28.7%/). Men were more
likely to report having risky anal sex if they met a new partner through the
internet (OR 1.91, 950/ CI 1.53 - 2.37), in a bathhouse (OR 1.77, 95%/ CI 1.42 -2.21), or in a bar (OR 1.30, 950/ CI 1.07 - 1.58), compared to men who did
not meet partners in these settings. Men were significantly more likely to report
having a new STI if they met a new partner through the internet (OR 1.59,
950/ CI 1.13-2.23) or a bathhouse (OR 1.51, 950/ CI 1.07 - 2.14). HIV- men
avoided unprotected receptive anal sex (URAS) with new partners, whereas
HIV+ men engaged in both URAS and unprotected insertive anal sex (UIAS) at
significantly higher rates than HIV- men regardless of venue.
Conclusions: The most commonly used settings where MSM in the MACS met
new partners were consistently associated with risky sexual behaviors and STI.
These settings should be high-priority targets for prevention interventions.

Tuesday
1 5 August
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Exhibit:ion

XVI INTERNATIONAL AIDS CONFERENCE * 13-18 AUGUST 2006 * TORONTO CANADA * ABSTRACT BOOK VOLUME 1