Linear regression with a randomly censored covariate: application to an Alzheimer's study

摘要

The association between maternal age of onset of dementia and amyloid deposition (measured by in vivo positron emission tomography imaging) in cognitively normal older offspring is of interest. In a regression model for amyloid, special methods are required because of the random right censoring of the covariate of maternal age of onset of dementia. Prior literature has proposed methods to address the problem of censoring due to assay limit of detection, but not random censoring. We propose imputation methods and a survival regression method that do not require parametric assumptions about the distribution of the censored covariate. Existing imputation methods address missing covariates, but not right-censored covariates. In simulation studies, we compare these methods with the simple, but inefficient, complete-case analysis, and with thresholding approaches. We apply the methods to the Alzheimer's study.