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Full-Text Articles in Medicine and Health Sciences
Accounting For Missing Data In End-Of-Life Research, Paula Diehr, Laura Lee Johnson
Accounting For Missing Data In End-Of-Life Research, Paula Diehr, Laura Lee Johnson
Paula Diehr
End-of-life studies are likely to have missing data because sicker persons are less likely to provide information and because measurements cannot be made after death. Ignoring missing data may result in data that are too favorable, because the sickest persons are effectively dropped from the analysis. In a comparison of two groups, the group with the most deaths and missing data will tend to have the most favorable data, which is not desirable. Results based on only the available data may not be generalizable to the original study population. If most of the missing data are absent because of death, …
Methods For Incorporating Death Into Health-Related Variables In Longitudinal Studies, Paula Diehr
Methods For Incorporating Death Into Health-Related Variables In Longitudinal Studies, Paula Diehr
Paula Diehr
BACKGROUND AND OBJECTIVES: Longitudinal studies of health over time may be misleading if some people die. Self-rated health (excellent to poor) and the SF-36 profile scores have been transformed to incorporate death. We applied the same approaches to incorporate death into activities of daily living difficulties (ADLs), IADLs, mini-mental state examination, depressive symptoms, blocks walked per week, bed days, the timed walk, body mass index and blood pressure. STUDY DESIGN AND SETTING: The Cardiovascular Health Study of 5,888 older adults, was followed up to 9 years. Mean age was 73 at baseline, and 658 had an incident stroke during follow-up. …
Reliability, Effect Size, And Responsiveness Of Health Status Measures In The Design Of Randomized And Cluster-Randomized Trials, Paula Diehr
Paula Diehr
BACKGROUND: New health status survey instruments are often described by their psychometric (measurement) properties, such as Validity, Reliability, Effect Size, and Responsiveness. For cluster-randomized trials, another important statistic is the Intraclass Correlation (ICC) for the instrument within clusters. Studies using better instruments can be performed with smaller sample sizes, but better instruments may be more expensive in terms of dollars, opportunity cost, or poorer data quality due to the response burden of longer instruments. METHODS: We defined the psychometric statistics in terms of a mathematical model, and examined the power of a two-sample test as a function of the test-retest …