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Interim data monitoring to enroll higher-risk participants in HIV prevention trials.

ABSTRACT: Lower-than-expected incidence of HIV undermines sample size calculations and compromises the power of a HIV prevention trial. We evaluated the effectiveness of interim monitoring of HIV infection rates and on-going modification of recruitment strategies to enroll women at higher risk of HIV in the Cellulose Sulfate Phase III study in Nigeria.We analyzed prevalence and incidence of HIV and other sexually transmitted infections, demographic and sexual behavior characteristics aggregated over the treatment groups on a quarterly basis. The site investigators were advised on their recruitment strategies based on the findings of the interim analyses.A total of 3619 women were screened and 1644 enrolled at the Ikeja and Apapa clinics in Lagos, and at the Central and Peripheral clinics in Port Harcourt. Twelve months after study initiation, the overall incidence of HIV was less than one-third of the pre-study assumption, with rates of HIV that varied substantially between clinics. Due to the low prevalence and incidence rates of HIV, it was decided to close the Ikeja clinic in Lagos and to find new catchment areas in Port Harcourt. This strategy was associated with an almost two-fold increase in observed HIV incidence during the second year of the study.Given the difficulties in estimating HIV incidence, a close monitoring of HIV prevalence and incidence rates during a trial is warranted. The on-going modification of recruitment strategies based on the regular analysis of HIV rates appeared to be an efficient method for targeting populations at greatest risk of HIV infection and increasing study power in the Nigeria trial.The trial was registered with the ClinicalTrials.gov registry under #NCT00120770 http://clinicaltrials.gov/ct2/show/NCT00120770.

SUBMITTER: Halpern V

PROVIDER: S-EPMC2708194 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Interim data monitoring to enroll higher-risk participants in HIV prevention trials.

Halpern Vera V Obunge Orikomaba O Ogunsola Folasade F Otusanya Sakiru S Umo-Otong John J Wang Chin-Hua CH Mehta Neha N

BMC medical research methodology 20090623

<h4>Background</h4>Lower-than-expected incidence of HIV undermines sample size calculations and compromises the power of a HIV prevention trial. We evaluated the effectiveness of interim monitoring of HIV infection rates and on-going modification of recruitment strategies to enroll women at higher risk of HIV in the Cellulose Sulfate Phase III study in Nigeria.<h4>Methods</h4>We analyzed prevalence and incidence of HIV and other sexually transmitted infections, demographic and sexual behavior ch ...[more]

PMID: 19549331

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Project description:BackgroundThere is an abundance of guidance for the interim monitoring of individually randomised trials. While methodological literature exists on how to extend these methods to cluster randomised trials, there is little guidance on practical implementation. Cluster trials have many features which make their monitoring needs different. We outline the methodological and practical challenges of interim monitoring of cluster trials; and apply these considerations to a case study.Case studyThe E-MOTIVE study is an 80-cluster randomised trial of a bundle of interventions to treat postpartum haemorrhage. The proposed data monitoring plan includes (1) monitor sample size assumptions, (2) monitor for evidence of selection bias, and (3) an interim assessment of the primary outcome, as well as monitoring data completeness. The timing of the sample size monitoring is chosen with both consideration of statistical precision and to allow time to recruit more clusters. Monitoring for selection bias involves comparing individual-level characteristics and numbers recruited between study arms to identify any post-randomisation participant identification bias. An interim analysis of outcomes presented with 99.9% confidence intervals using the Haybittle-Peto approach should mitigate any concern regarding the inflation of type-I error. The pragmatic nature of the trial means monitoring for adherence is not relevant, as it is built into a process evaluation.ConclusionsThe interim analyses of cluster trials have a number of important differences to monitoring individually randomised trials. In cluster trials, there will often be a greater need to monitor nuisance parameters, yet there will often be considerable uncertainty in their estimation. This means the utility of sample size re-estimation can be questionable particularly when there are practical or funding difficulties associated with making any changes to planned sample sizes. Perhaps most importantly interim monitoring has the potential to identify selection bias, particularly in trials with post-randomisation identification or recruitment. Finally, the pragmatic nature of cluster trials might mean that the utility of methods to allow for interim monitoring of outcomes based on statistical testing, or monitoring for adherence to study interventions, are less relevant. Our intention is to facilitate the planning of future cluster randomised trials and to promote discussion and debate to improve monitoring of these studies.

Project description:Obtaining the definitive data necessary to determine the safety and efficacy of using antiretroviral treatment (ART) to reduce the sexual transmission of HIV in heterosexual couples encountered an array of ethical challenges that threatened to compromise HIV Prevention Trials Network (HPTN) 052, the multinational clinical trial addressing this issue that has profound public health implications.To describe and analyze the major ethical challenges faced in HPTN 052.The ethical issues and modifications of HPTN 052 in response to these issues were cataloged by the principal investigator, the lead coordinator, and the ethicist working on the trial. The major ethical issues that were unique to the trial were then described and analyzed in light of the published literature as well as guidances and policies. The ethical challenges that must be addressed in many clinical trials, such as those related to obtaining informed consent and making provisions for ancillary care, are not described.When HPTN 052 was being designed, ethical questions emerged related to the relevance of the research question itself given data from observational research and a range of beliefs about the appropriate means of preventing and treating HIV infection and AIDS. Furthermore, ethical challenges were faced regarding site selection since there was a scientific need to conduct the research in settings where HIV incidence was high, but alternatives to study participation should be available. As in most HIV-prevention research, ethical questions surrounded the determination of the appropriate prevention package for all of those enrolled. During the course of the trial, guidance documents and policies emerged that were of direct relevance to the research questions, calling for a balancing of concerns for the research subjects and trial integrity. When the study results were made public, there was a need to ensure access to the treatment shown to be effective that in some cases differed from the guidelines used at the sites where the research was being conducted. In addition, questions were raised about whether there was an obligation to notify subjects about 'unlinked' transmissions of HIV, that is, infections acquired from someone other than the designated sexual partner enrolled in the study.The ethical issues described are limited to those discerned by the authors and not those of other stakeholders who may have identified additional issues or had a different perspective in analyzing them.Understanding the ethical challenges faced in HPTN 052 promises to inform the design and conduct of future complex, long-term clinical trials aimed at addressing critical scientific and public health questions, where data and practice patterns emerge over the course of the trial.

Dataset Information

Interim data monitoring to enroll higher-risk participants in HIV prevention trials.

Publications

Interim data monitoring to enroll higher-risk participants in HIV prevention trials.

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