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Full-Text Articles in Medicine and Health Sciences
Estimating The Effect Of A Community-Based Intervention With Two Communities, Mark Van Der Laan, Maya Petersen, Wenjing Zheng
Estimating The Effect Of A Community-Based Intervention With Two Communities, Mark Van Der Laan, Maya Petersen, Wenjing Zheng
Wenjing Zheng
Due to the need to evaluate the effectiveness of community-based programs in practice, there is substantial interest in methods to estimate the causal effects of community-level treatments or exposures on individual level outcomes. The challenge one is confronted with is that different communities have different environmental factors affecting the individual outcomes, and all individuals in a community share the same environment and intervention. In practice, data are often available from only a small number of communities, making it difficult if not impossible to adjust for these environmental confounders. In this paper we consider an extreme version of this dilemma, in …
Oral And Injectable Contraception Use And Risk Of Hiv Acquisition Among Women In Sub-Saharan Africa, Sandra Mccoy, Wenjing Zheng, Elizabeth Montgomery, Kelly Blanchard, Ariane Van Der Straten, Guy De Bruyn, Nancy Padian
Oral And Injectable Contraception Use And Risk Of Hiv Acquisition Among Women In Sub-Saharan Africa, Sandra Mccoy, Wenjing Zheng, Elizabeth Montgomery, Kelly Blanchard, Ariane Van Der Straten, Guy De Bruyn, Nancy Padian
Wenjing Zheng
OBJECTIVE:: Evaluate the effect of oral and injectable hormonal contraception (HC) on the risk of HIV acquisition among women in South Africa and Zimbabwe. DESIGN:: Secondary data analysis of 4913 sexually active women aged 18-49 years followed for up to 24 months in the MIRA phase III effectiveness trial of the diaphragm and lubricant gel for HIV prevention. METHODS:: Participants were interviewed quarterly about contraception and sexual behavior and were tested for pregnancy, HIV, and other sexually transmitted infections. We used a Cox proportional hazards marginal structural model, weighted by the inverse probability of HC use, to compare the risk …