Graduate Student Seminar

Speaker 1: Zhou Feng

Title

Brief Introduction of Propensity Score

Abstract

Many medical studies are motivated in causal nature, and they have great impact on policy and decision making. With a randomized clinical trial (RCT), it is easy to estimate the average causal effect (ACE). However, due to practical or ethical reasons, drawing causal inference from observational studies is in high demand, which needs to reduce or eliminate the effects of confounding. As one of the popular tools to control confounding in observational studies, a brief introduction of propensity score (PS) will be given. After introducing the definition and methodology of propensity score, four basic implementation techniques using propensity score will be discussed: matching, subclassification, inverse weighting, and regression adjustment. Last, a real application using subclassification based on propensity score to estimate the average causal effect will be given.

Speaker 2: Wenxin Lu

Title

Gender Differences in Frailty from Hip Fracture in Older Persons

Abstract

The rapid growth of aging population in the United States has raised the public health concerns and the awareness of functional frailty, and hip fracture leads to more functional frailty patients. Functional frailty has been one of the important geriatric syndromes. According to Fried’s definition on frailty (2001), it is a syndrome of deceased resiliency and reserves, which is characterized by five phenotypes: exhaustion, weight loss, weak grip strength, slow walking speed, and low energy expenditure.  If three or more criteria present on one patient, then the patient is frail. In 2006, Bandeen-Roche validated Fried’s definition on frailty.  Based on the five phenotypes, Xue (2008) gave a detailed explanation on the natural history of frailty development in the Women’s Health and Aging Study II (WHAS II). Building upon Fred’s definition on frailty, Gary (2012) evaluated frailty in older adults with cardiovascular disease (CVD).  However, the frailty has not been studied among hip fracture patients.  Actually, hip fracture can make the patient to have those phenotypes and lead to frailty. The objective of this study is to observe how the functional frailty and its phenotypes develop within one year after hip fracture, and do the comparison between male and female.