Cox Regression Model with Doubly Truncated Data

• Published in: Biometrics Vol. 74; no. 2; pp. 725 - 733
• Main Authors: Rennert, Lior, Xie, Sharon X.
• Format: Journal Article
• Language: English
• Published: United States Wiley-Blackwell 01.06.2018; Blackwell Publishing Ltd
• Subjects: Alzheimer disease; Alzheimer Disease - mortality; Alzheimer's disease; Autopsies; Autopsy; Bias; BIOMETRIC PRACTICE; biometry; Computer Simulation; confidence interval; Confidence intervals; Cox regression model; Data Interpretation, Statistical; Education; equations; Estimators; Humans; Missing data; Models, Statistical; Neurodegenerative diseases; observational studies; patients; Proportional Hazards Models; Regression Analysis; Regression models; Statistical analysis; Survival Analysis; Truncation; Variance; Missing data; Survival analysis; Cox regression model; Truncation
• ISSN: 0006-341X; 1541-0420; 1541-0420
• DOI: 10.1111/biom.12809

Truncation is a well-known phenomenon that may be present in observational studies of time-to-event data. While many methods exist to adjust for either left or right truncation, there are very few methods that adjust for simultaneous left and right truncation, also known as double truncation. We propose a Cox regression model to adjust for this double truncation using a weighted estimating equation approach, where the weights are estimated from the data both parametrically and nonparametrically, and are inversely proportional to the probability that a subject is observed. The resulting weighted estimators of the hazard ratio are consistent. The parametric weighted estimator is asymptotically normal and a consistent estimator of the asymptotic variance is provided. For the nonparametric weighted estimator, we apply the bootstrap technique to estimate the variance and confidence intervals. We demonstrate through extensive simulations that the proposed estimators greatly reduce the bias compared to the unweighted Cox regression estimator which ignores truncation. We illustrate our approach in an analysis of autopsy-confirmed Alzheimer's disease patients to assess the effect of education on survival.