Covariate adjustment and estimation of mean response in randomised trials

Pharmaceutical Statistics
Jonathan W Bartlett

Abstract

Analyses of randomised trials are often based on regression models which adjust for baseline covariates, in addition to randomised group. Based on such models, one can obtain estimates of the marginal mean outcome for the population under assignment to each treatment, by averaging the model-based predictions across the empirical distribution of the baseline covariates in the trial. We identify under what conditions such estimates are consistent, and in particular show that for canonical generalised linear models, the resulting estimates are always consistent. We show that a recently proposed variance estimator underestimates the variance of the estimator around the true marginal population mean when the baseline covariates are not fixed in repeated sampling and provide a simple adjustment to remedy this. We also describe an alternative semiparametric estimator, which is consistent even when the outcome regression model used is misspecified. The different estimators are compared through simulations and application to a recently conducted trial in asthma.

References

Jan 15, 1997·Statistics in Medicine·A Rotnitzky, J Robins
Dec 1, 2004·Statistics in Medicine·Ian R White, Simon G Thompson
Jul 16, 2010·The International Journal of Biostatistics·Michael Rosenblum, Mark J van der Laan
Dec 6, 2011·Statistics in Medicine·Brennan C Kahan, Tim P Morris
Mar 8, 2014·International Journal of Epidemiology·Clemma J Muller, Richard F MacLehose
Nov 19, 2014·Pharmaceutical Statistics·Yongming Qu, Junxiang Luo

❮ Previous
Next ❯

Citations

Dec 22, 2019·Pharmaceutical Statistics·Jixian Wang
Feb 29, 2020·Pharmaceutical Statistics·Amy LaLonde, Yongming Qu
Apr 7, 2020·Pharmaceutical Statistics·Jiexin DuanYongming Qu
Jun 5, 2019·Statistics in Medicine·Jon Arni Steingrimsson, Jiabei Yang

❮ Previous
Next ❯

Related Concepts

Related Feeds

Asthma

This feed focuses in Asthma in which your airways narrow and swell. This can make breathing difficult and trigger coughing, wheezing and shortness of breath.

Allergy and Asthma

Allergy and asthma are inflammatory disorders that are triggered by the activation of an allergen-specific regulatory t cell. These t cells become activated when allergens are recognized by allergen-presenting cells. Here is the latest research on allergy and asthma.