The value of site preparedness studies for future implementation of phase 2/IIb/III HIV prevention trials: experience from the HPTN 055 study

Abstract

Objectives: To evaluate the preparedness for phase 2/IIb/III microbicide trials at 4 clinical trial sites: Durban and Hlabisa (South Africa), Lusaka (Zambia), and Moshi (Tanzania).

Design: A prospective cohort study was undertaken to assess site suitability for microbicide efficacy studies. Study objectives included assessing sites' ability to recruit and retain high-risk women with the appropriate HIV incidence rates needed to conduct microbicide efficacy studies.

Methods: Nine hundred fifty-eight consenting women were enrolled and followed for up to 1 year. Demographic, behavioral, laboratory, and clinical data were collected to determine the incidence rates of HIV, sexually transmitted infections, and pregnancy.

Results: Accrual was completed in 6.3, 6.7, 7.1, and 8.3 months in Durban, Hlabisa, Moshi, and Lusaka, respectively. The highest month 12 participant retention rate was recorded in Durban (97%), followed by Hlabisa (94%), Moshi (86%), and Lusaka (93%). Mean overall age of enrolled participants was 28.6 years (ranging from 27.0 to 32.2 years) across sites. Despite condom counseling, rates of condom use were slightly lower at study end. Pregnancy incidence in the study as a whole was 20.2 per 100 women-years (wy). Overall HIV prevalence was 32.5%, and overall HIV incidence was 3.8 per 100 wy (95% confidence interval [CI]: 2.6 to 5.2). HIV incidence per site was 5.3 per 100 wy in Durban (95% CI: 2.7 to 9.2), 6.2 per 100 wy in Hlabisa (95% CI: 3.4 to 10.5); 2.6 per 100 wy in Lusaka (95% CI: 1.0 to 5.8), and 1.4 per 100 wy in Moshi (95% CI: 0.3 to 4.0).

Conclusions: Preparatory studies provide accurate local estimates of HIV incidence, recruitment and retention rates, and behavioral characteristics of targeted populations for large-scale clinical trials. Determining these factors allows for better preparation for design, sample size, and appropriate population for future selection of trial sites. Because of the lower than expected HIV incidence observed at the Moshi site, only the South African and Zambian sites were selected for the phase 2/IIb trial.