Assessing age-at-onset risk factors with incomplete covariate current status data under proportional odds models
Article first published online: 10 OCT 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Statistics in Medicine
Volume 32, Issue 12, pages 2001–2012, 30 May 2013
How to Cite
Wen, C.-C. and Chen, Y.-H. (2013), Assessing age-at-onset risk factors with incomplete covariate current status data under proportional odds models. Statist. Med., 32: 2001–2012. doi: 10.1002/sim.5656
- Issue published online: 7 MAY 2013
- Article first published online: 10 OCT 2012
- Manuscript Accepted: 27 SEP 2012
- Manuscript Received: 30 MAR 2012
- interval censoring;
- missing at random;
- semiparametric regression
Motivated by an epidemiological survey of fracture in elderly women, we develop a semiparametric regression analysis of current status data with incompletely observed covariate under the proportional odds model. To accommodate both the interval-censored nature of current status failure time data and the incompletely observed covariate data, we propose an analysis based on the validation likelihood (VL), which is derived from likelihood pertaining to the validation sample, namely the subset of the sample where the data are completely observed. The missing data mechanism is assumed to be missing at random and is explicitly modeled and estimated in the VL approach. We propose implementing the VL method by integrating self-consistency and Newton–Raphson algorithms. Asymptotic normality and standard error estimation for the proposed estimator of the regression parameter are guaranteed. Simulation results reveal good performance of the VL estimator. The VL method has some gain in efficiency compared with the naive complete case method. But the VL method leads to unbiased estimators, whereas the complete case method does not when missing covariates are not missing completely at random. Application of the VL approach to the fracture data confirms that osteoporosis (low bone density) is a strong risk factor for the age at onset of fracture in elderly women. Copyright © 2012 John Wiley & Sons, Ltd.