Laura B. Balzer, Harvard T.H. Chan School of Public Health
Estimating the Impact of Cluster-Based Interventions: the SEARCH trial and HIV prevention in East Africa.
Dr. Laura Balzer is a Post-Doctoral Fellow in the Department of Biostatistics at the Harvard T.H. Chan School of Public Health. She earned her PhD in Biostatistics from the University of California, Berkeley under the guidance of Drs. Maya Petersen and Mark van der Laan. Her research is on the development of optimal designs and estimators for causal effects with highly dependent data. Applications of this work include impact evaluation for HIV prevention and treatment strategies and understanding the neighborhood determinants of health. Laura is also passionate about teaching more advanced causal and statistical methods to applied audiences. Jointly with Dr. Maya Petersen, she was awarded the 2014 ASA’s Causality in Statistics Education Award. (More info: )
Evaluation of cluster-based interventions presents significant methodological challenges. In this talk, we describe the design and analysis of the SEARCH trial, an ongoing community randomized trial to evaluate the impact of early HIV diagnosis and immediate treatment with streamlined care in rural Uganda and Kenya. We focus on 3 choices to optimize the design and analysis: pair-matching over complete randomization, targeting the sample effect instead of a population average parameter, and data-adaptive adjustment through a pre-specified targeted maximum likelihood estimator (TMLE). These choices are compared theoretically and with finite sample simulations. We demonstrate each choice improves efficiency relative to standard practice, while maintaining nominal confidence interval coverage. We conclude with practical implications and some ongoing challenges.