Expressions are found for the cumulants needed to analyze and improve the accuracy of Cox regression up to order O(n−3/2), and consistent estimators for these are given. In addition, the Bartlett identities are shown to hold for the Cox partial likelihood (and, in a broad sense, for partial likelihood in general), so that the cumulant estimators found can be used to adjust statistics in accorda...

Methods During 2009, 167 MRSA-infected and 25766 MRSAuninfected control patients were included in a multistate model where occurrence of MRSA infection was the time-dependent exposure and discharge or death was the study endpoint. Infections were stratified by anatomical site. Excess LoS was extracted computing the Aalen-Johansen estimator of the matrix of transition probabilities. 95% confiden...

Typically in cohort studies, the time-scale used in Cox regression models is time-on-study, adjusting for age as a covariate. However, age can also be used as the time-scale, where subjects enter the analysis at their baseline age (left-truncation) and exit at their event/censoring age. Using SAS PROC PHREG, we compared five methods using time-on-study and age as the time-scales. We used a subs...

The present study was conducted to predict survival time in patients with diffuse large B-cell lymphoma, DLBCL, based on microarray data using Cox regression model combined with seven dimension reduction methods. This historical cohort included 2042 gene expression measurements from 40 patients with DLBCL. In order to predict survival, a combination of Cox regression model was used with seven m...

We present an asymptotic exponential bound for the deviation of the survival function estimator of the Cox model. We show that the bound holds even when the proportional hazards assumption does not hold.

Evidence of an association between survival time and date of birth would suggest an etiologic role for a seasonally variable environmental exposure occurring within a narrow perinatal time period. Risk factors that may exhibit seasonal epidemicity include diet, infectious agents, allergens, and antihistamine use. Typically data has been analyzed by simply categorizing births into months or seas...

OBJECTIVE This study aimed to analyze the effect of HbA1c variability on the occurrence of diabetic retinopathy in type 1 diabetes patients. PATIENTS AND METHODS 35,891 patients with childhood, adolescent or adult onset of type 1 diabetes from a large multicentre survey, the German/Austrian prospective documentation system (DPV), were analysed. Cox proportional hazard models were used to exam...

The Cox (1972) regression model is extended to include discrete and mixed continuous/discrete failure time data by retaining the multiplicative hazard rate form of the absolutely continuous model. Application of martingale arguments to the regression parameter estimating function show the Breslow(1974) estimator to be consistent and asymptotically Gaussian under this model. A computationally co...