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Faculty & Staff Honors

UNC: Preisser to Study Stepped-wedge Designs for Cluster-randomized Trials

Dr. John S. Preisser, professor of biostatistics at the University of North Carolina Gillings School of Global Public Health, has been approved for an $852,244 funding award by the Patient-Centered Outcomes Research Institute to study incomplete stepped-wedge designs for pragmatic cluster-randomized trials (CRTs).

CRTs are commonly used in public health research since they can be applied to large population samples instead of individual subjects. They are particularly useful for assessing the quality of care improvement programs and evaluating interventions to improve outcomes for vulnerable populations — including prisoners, victims of trauma and violence, people with mental health concerns and the institutionalized elderly. However, the planning of these trials involves carefully balancing logistics and necessary resources with the need to maintain internal validity and reduce bias.

A stepped-wedge design is sometimes chosen for public health CRTs, especially when logistical or financial limitations prevent all participants in a study sample from receiving treatment at the same time. Instead, treatment is introduced to clusters over a period of time. Most of the time, study planning methods account for a complete stepped-wedge design, where all clusters have data collected on outcomes in all periods. However, pragmatic CRTs often require intentionally incomplete stepped-wedge designs due to resource limitations.

Dr. Preisser’s study plans to “formally quantify trade-offs involved when logistical, resource and patient-centered considerations are balanced against methodological implications” in CRTs that choose to employ an incomplete stepped-wedge design as part of health care intervention research.

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