Nonparametric estimation of the cumulative incidence function for doubly-truncated and interval-censored competing risks data.

Interval sampling is widely used for collection of disease registry data, which typically report incident cases during a certain time period. Such sampling scheme induces doubly truncated data if the failure time can be observed exactly and doubly truncated and interval censored (DTIC) data if the failure time is known only to lie within an interval. In this article, we consider nonparametric estimation of the cumulative incidence functions (CIF) using doubly-truncated and interval-censored competing risks (DTIC-C) data obtained from interval sampling scheme.

Bayesian phase II adaptive randomization by jointly modeling efficacy and toxicity as time-to-event outcomes.

The main goals of Phase II trials are to identify the therapeutic efficacy of new treatments and continue monitoring all the possible adverse effects. In Phase II trials, it is important to develop an adaptive randomization (AR) procedure that takes into account both the efficacy and toxicity. In most existing articles, toxicity is modeled as a binary endpoint through an unobservable random effect (frailty) to link the efficacy and toxicity.

The mean residual life model for the right-censored data in the presence of covariate measurement errors.

In this article, we consider the mean residual life regression model in the presence of covariate measurement errors. In the whole cohort, the surrogate variable of the error-prone covariate is available for each subject, while the instrumental variable (IV), which is related to the underlying true covariates, is measured only for some subjects, the calibration sample. Without specifying distributions of measurement errors but assuming that the IV is missing at random, we develop two estimation methods, the IV calibration and cohort estimators, for the regression parameters by solving estimation equations (EEs) based on the calibration sample and cohort sample, respectively.

Equivalence tests before end of follow-up under the class of log transformation model.

One important topic in clinical trials is to show that the effects of new and standard treatments are equivalent in terms of clinical relevance. In literature, many equivalence tests based on the maximal difference between two survival functions for the two treatments over the whole time axis have been proposed. However, since survival times can only be observed until the end of follow-up, an equivalence test should be based on a comparison only in the observed time-window dictated by the end of follow-up.

A robust association test with multiple genetic variants and covariates.

Due to the advancement of genome sequencing techniques, a great stride has been made in exome sequencing such that the association study between disease and genetic variants has become feasible. Some powerful and well-known association tests have been proposed to test the association between a group of genes and the disease of interest. However, some challenges still remain, in particular, many factors can affect the performance of testing power, e.

Nonparametric analysis of doubly truncated and interval-censored data.

In epidemiological studies, it is easier to collect data only from individuals whose failure events are within a calendar time interval, the so-called interval sampling, which leads to doubly truncated data. In many situations, the calendar time of the failure event can only be recorded within time intervals, leading to doubly truncated and interval censored (DTIC) data. Firstly, we point out that although the existing methods for DTIC data work adequately under the sampling scheme (Scheme 1) for doubly truncated data, Scheme 1 is not realistic for DTIC data.

Equivalence tests under the Cox-Aalen model and the partly Aalen model.

For the equivalence trial with survivor outcomes from two treatment groups, the most popular testing procedure is the test proposed by under the proportional hazards (PH) model. In this article, when the treatment effect is time invariant, we demonstrate that the result under the PH model can be extended to the Cox-Aalen model. When the treatment effect is time-variant, we propose an equivalent test for the differences of two cumulative hazard functions under the partly Aalen model.

Maximum likelihood estimation for length-biased and interval-censored data with a nonsusceptible fraction.

Left-truncated data are often encountered in epidemiological cohort studies, where individuals are recruited according to a certain cross-sectional sampling criterion. Length-biased data, a special case of left-truncated data, assume that the incidence of the initial event follows a homogeneous Poisson process. In this article, we consider an analysis of length-biased and interval-censored data with a nonsusceptible fraction.

Cost-effectiveness of freeze-all policy - A retrospective study based upon the outcome of cumulative live births.

Object: We have previously reported that cumulative live birth rates (CLBRs) are higher in the freeze-all group compared with controls (64.3% vs. 45.

Semiparametric mixture cure model analysis with competing risks data: Application to vascular access thrombosis data.

The article is motivated by a nephrology study in Taiwan, which enrolled hemodialysis patients who suffered from vascular access thrombosis. After treatment, some patients were cured of thrombosis, while some may experience recurrence of either type (acute or nonacute) of vascular access thrombosis. Our major interest is to estimate the cumulative incidence probability of time to the first recurrence of acute thrombosis after therapy.

Tests for equivalence of two survival functions: alternatives to the PH and PO models.

For the equivalence trial with survivor outcomes from two treatment groups, the most popular testing procedure is the extension of log-rank test under proportional hazards (PH) model. In literature, an alternative test has been proposed under the  proportional odds (PO) survival model. In practice, both PH and PO hazards assumptions can be violated.

Correction to: Nonparametric estimators of survival function under the mixed case interval-censored model with left truncation.

The original version of this article unfortunately contains mistakes. It has been corrected with this Correction.

Nonparametric estimators of survival function under the mixed case interval-censored model with left truncation.

It is well known that the nonparametric maximum likelihood estimator (NPMLE) can severely underestimate the survival probabilities at early times for left-truncated and interval-censored (LT-IC) data. For arbitrarily truncated and censored data, Pan and Chappel (JAMA Stat Probab Lett 38:49-57, 1998a, Biometrics 54:1053-1060, 1998b) proposed a nonparametric estimator of the survival function, called the iterative Nelson estimator (INE). Their simulation study showed that the INE performed well in overcoming the under-estimation of the survival function from the NPMLE for LT-IC data.

One-year outcomes of a suture-less laparoscopic sacral hysteropexy using polypropylene Y-mesh grafts and fibrin sealant spray: A prospective comparative study.

Background: Laparoscopic sacral hysteropexy (SH) is a minimally invasive and effective treatment for uterovaginal prolapse in women who wish to retain the uterus. However, this procedure is limited by a steep learning curve and a long operating time. In this study, we aim to evaluate the surgical outcomes of a modified laparoscopic SH procedure using innovative methods of vaginal mesh attachment, which we hypothesized to be equally effective and time-saving.

Hyaluronic acid improves pain symptoms more than bladder storage symptoms in women with interstitial cystitis.

Objective: Intravesical hyaluronic acid (HA) therapy is one of acceptable methods to treat bladder pain and storage symptoms (i.e., urgency, frequency and nocturia) of interstitial cystitis/bladder pain syndrome (IC/BPS).

Semiparametric transformation models for interval-censored data in the presence of a cure fraction.

Mixed case interval-censored data arise when the event of interest is known only to occur within an interval induced by a sequence of random examination times. Such data are commonly encountered in disease research with longitudinal follow-up. Furthermore, the medical treatment has progressed over the last decade with an increasing proportion of patients being cured for many types of diseases.

Semiparametric regression analysis of failure time data with dependent interval censoring.

Interval-censored failure-time data arise when subjects are examined or observed periodically such that the failure time of interest is not examined exactly but only known to be bracketed between two adjacent observation times. The commonly used approaches assume that the examination times and the failure time are independent or conditionally independent given covariates. In many practical applications, patients who are already in poor health or have a weak immune system before treatment usually tend to visit physicians more often after treatment than those with better health or immune system.

Factors that affect outcomes of prolapse repair using single-incision vaginal mesh procedures.

Aims: Single-incision vaginal mesh (SIVM) procedures for pelvic organ prolapse (POP) differed in mesh fabrication and implantation that may affect treatment outcomes. We aim to evaluate and compare the safety and effectiveness of two SIVM procedures, and explore factors that may have associations with surgical effectiveness.

Methods: Our data of using two SIVM procedures for a total (anterior and posterior) vaginal mesh repair were studied.

Conditional maximum likelihood estimation in semiparametric transformation model with LTRC data.

Left-truncated data often arise in epidemiology and individual follow-up studies due to a biased sampling plan since subjects with shorter survival times tend to be excluded from the sample. Moreover, the survival time of recruited subjects are often subject to right censoring. In this article, a general class of semiparametric transformation models that include proportional hazards model and proportional odds model as special cases is studied for the analysis of left-truncated and right-censored data.

A semiparametric mixture cure survival model for left-truncated and right-censored data.

In follow-up studies, the disease event time can be subject to left truncation and right censoring. Furthermore, medical advancements have made it possible for patients to be cured of certain types of diseases. In this article, we consider a semiparametric mixture cure model for the regression analysis of left-truncated and right-censored data.

Nonparametric association analysis of bivariate left-truncated competing risks data.

We develop time-varying association analyses for onset ages of two lung infections to address the statistical challenges in utilizing registry data where onset ages are left-truncated by ages of entry and competing-risk censored by deaths. Two types of association estimators are proposed based on conditional cause-specific hazard function and cumulative incidence function that are adapted from unconditional quantities to handle left truncation. Asymptotic properties of the estimators are established by using the empirical process techniques.

The partly Aalen's model for recurrent event data with a dependent terminal event.

Recurrent event data are commonly observed in biomedical longitudinal studies. In many instances, there exists a terminal event, which precludes the occurrence of additional repeated events, and usually there is also a nonignorable correlation between the terminal event and recurrent events. In this article, we propose a partly Aalen's additive model with a multiplicative frailty for the rate function of recurrent event process and assume a Cox frailty model for terminal event time.

Two-stage estimation for multivariate recurrent event data with a dependent terminal event.

Recurrent event data arise in longitudinal follow-up studies, where each subject may experience the same type of events repeatedly. The work in this article is motivated by the data from a study of repeated peritonitis for patients on peritoneal dialysis. Due to the aspects of medicine and cost, the peritonitis cases were classified into two types: Gram-positive and non-Gram-positive peritonitis.

A comparative study of laparoscopic sacrocolpopexy and total vaginal mesh procedure using lightweight polypropylene meshes for prolapse repair.

Objective: Use of vaginal meshes for treatment of pelvic organ prolapse (POP) remains controversial. A trend toward abdominal approaches and the development of new meshes has been noted. We compared the 1-year results of two different approaches using new lightweight meshes.