Published in Biometrics
Copula is a popular method for modeling the dependence among marginal distributions in multivariate censored data. As many copula models are available, it is essential to check if the chosen copula model fits the data well for analysis. Existing approaches to testing the fitness of copula models are mainly for complete or right-censored data. No fo...
Published in American journal of epidemiology
Recurrent events-outcomes that an individual can experience repeatedly over the course of follow-up-are common in epidemiologic and health services research. Studies involving recurrent events often focus on time to first occurrence or on event rates, which assume constant hazards over time. In this paper, we contextualize recurrent event parameter...
Published in Annual Review of Statistics and Its Application
Dependent survival data arise in many contexts. One context is clustered survival data, where survival data are collected on clusters such as families or medical centers. Dependent survival data also arise when multiple survival times are recorded for each individual. Frailty models are one common approach to handle such data. In frailty models, th...
Published in Annual Review of Statistics and its Application
The Cox model is now 50 years old. The seminal paper of Sir David Cox has had an immeasurable impact on the analysis of censored survival data, with applications in many different disciplines. This work has also stimulated much additional research in diverse areas and led to important theoretical and practical advances. These include semiparametric...
Published in Journal of biopharmaceutical statistics
Protective efficacy of vaccines and pharmaceutical products for prevention of infectious diseases usually vary over time. Information on the trajectory of the level of protection is valuable. We consider a parsimonious, non-linear and non-monotonic function for modelling time-varying intervention effects and compare it with several alternatives. Th...
Published in Statistical methods in medical research
Recurrent event responses are frequently encountered during clinical trials of treatments for certain diseases, such as asthma. The recurrence rates of different treatments are often compared by applying the negative binomial model. In addition, a balanced treatment-allocation procedure that assigns the same number of patients to each treatment is ...
Published in Annals of the American Thoracic Society
Rationale: The long-term natural history of asthma in terms of successive severe exacerbations and the influence of each exacerbation on the course of the disease is not well studied. Objectives: To investigate the long-term natural history of asthma among patients who are hospitalized for asthma for the first time in terms of the risk of future se...
The rate reduction models have been widely used to model the recurrent failure data for their capabilities in quantifying the repair effects. Despite the widespread popularity, there have been limited studies on statistical inference of most failure rate reduction models. In view of this fact, this study proposes a semiparametric estimation framewo...
Published in Clinical infectious diseases : an official publication of the Infectious Diseases Society of America
Longitudinal analyses are needed to better understand long-term Ebola virus disease (EVD) sequelae. We aimed to estimate the prevalence, incidence, and duration of sequelae and to identify risk factors associated with symptom occurrence among EVD survivors in Guinea. We followed 802 EVD survivors over 48 months and recorded clinical symptoms with t...
Published in Pediatric transplantation
Epstein-Barr virus (EBV) can cause severe disease following hematopoietic stem cell transplant (HSCT), including post-transplant lymphoproliferative disorder (PTLD). The objective was to analyze risk factors associated with post-transplant EBV outcomes among pediatric allogeneic HSCT recipients. We used data from 156 pediatric allogeneic HSCT recip...
