Can higher retention be achieved in mdp301 than implied by the preceding cohort studies?
Background: MDP 301 is a randomised, blinded, placebo-controlled trial to assess the anti-HIV vaginal microbicide PRO 2000/5, being conducted in 6 sites, 3 in South Africa and one each in Tanzania, Uganda and Zambia. Feasibility (cohort) studies preceding the trial (2002-2004) suggested that retention decreased with time, and this contributed to censoring the primary scientific analysis at week 40. The objective of this study was to explore the hypothesis that experience from the feasibility study and access to the product helped increase retention rates in the trial. Method: Data were extracted from the merge of 15/09/07. Each participant visit has a 2 week window beyond the date predicted by enrolment within which it should occur, except for the week 52 visit which can occur 6 weeks beyond its scheduled date. Expected attendance was calculated for visits where the 14 day window had passed (and where this fell before or on the 1st September 2007), to allow for data entry of the specimen collection CRF (= women seen). Women that have been withdrawn are not included after the withdrawal visit. Results: 124 (2%) of 6252 women enrolled have been withdrawn in this dataset; 2667 and 1511 were expected at weeks 40 and 52 respectively. At 5 sites, retention at week 40 was higher than in the feasibility study, with 86% (range 79-92%) of the cohort seen. Retention remained high at week 52, with 88% seen (range 80-94%). At the other site, 50% of the participants were retained at week 40, and 3 (43%) of the 7 expected seen at week 52. These figures are lower than indicated by manual records from the site, and may be due to delays in CRF entering. Conclusions: In spite of the challenging setting, high (>85%) retention rates are achievable. Results do not support the hypothesis that retention falls between weeks 40 and 52; it maybe appropriate to revisit the decision to censor at week 40. Other parameters like gel adherence, pregnancy and HIV incidence rates over time are considered.
Govender, S. Can higher retention be achieved in mdp301 than implied by the preceding cohort studies? Presented at Microbicides 2008, New Delhi, India, 24-27 February 2008. (2008)