title: Confidence interval of difference of proportions in logistic regression in presence of covariates.
abstract: Comparison of treatment differences in incidence rates is an important objective of many clinical trials. However, often the proportion is affected by covariates, and the adjustment of the predicted proportion is made using logistic regression. It is desirable to estimate the treatment differences in proportions adjusting for the covariates, similarly to the comparison of adjusted means in analysis of variance. Because of the correlation between the point estimates in the different treatment groups, the standard methods for constructing confidence intervals are inadequate. The problem is more difficult in the binary case, as the comparison is not uniquely defined, and the sampling distribution more difficult to analyze. Four procedures for analyzing the data are presented, which expand upon existing methods and generalize the link function. It is shown that, among the four methods studied, the resampling method based on the exact distribution function yields a coverage rate closest to the nominal.
authors.affiliation: Quintiles, Inc., Morrisville, NC, USA.
authors.forename: Russell
authors.initials: R
authors.lastname: Reeve
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000628:therapy; D056808:Biostatistics; D003198:Computer Simulation; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D005260:Female; D005298:Fertility; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D015233:Models, Statistical; D015999:Multivariate Analysis; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires / Q000706:statistics & numerical data; D055815:Young Adult
keywords: Proportions; confidence interval; covariates; logistic regression; risk difference