Biostatistics Seminar: Susan Stewart, Public Health Sciences, UC Davis
DATE: Tuesday, April 16th, 2013
LOCATION: 1043 Gladys Valley Hall (map)
SPEAKER:Susan Stewart, Div. Biostatistics, Dept. Public Health Sciences, School of Medicine, UC Davis
TITLE: Assessing the effect of liver cancer screening on survival among patients with chronic hepatitis B
ABSTRACT: The American Association for the Study of Liver Diseases (AASLD) recommends that persons with chronic hepatitis B who are at increased risk for liver cancer—including Asian men over age 40, Asian women over age 50, people with cirrhosis, and people with a family history of liver cancer—undergo surveillance, i.e., regular screening, for liver cancer. Although there is evidence that screening reduces mortality in those with hepatitis B, including results from a large randomized trial in China, many reports of the benefits of screening are subject to concerns about lead time and length time bias. Assessing the effects of screening on survival requires making a number of definitions and decisions that can have considerable impact on results. In particular, different choices regarding patient inclusion and exclusion criteria, selection of the surveillance period and screening modalities, definition of adherence to guidelines, identification of screening vs. diagnostic tests, and handling of events occurring close to the time of hepatitis B diagnosis can result in vastly different conclusions regarding the benefits of screening. These issues are illustrated with the analysis of a cohort of 1870 Asian American public hospital patients who were diagnosed with chronic hepatitis B in 1996-2007 and followed for liver cancer incidence and survival. The implications of choices of methods on survival analysis results and their interpretation are discussed.