Repeat emergency department visits by nursing home residents: a cohort study using health administrative data.

Background: Nursing home (NH) residents are frequent users of emergency departments (ED) and while prior research suggests that repeat visits are common, there is little data describing this phenomenon. Our objectives were to describe repeat ED visits over one year, identify risk factors for repeat use, and characterize "frequent" ED visitors.

Methods: Using provincial administrative data from Ontario, Canada, we identified all NH residents 65 years or older who visited an ED at least once between January 1 and March 31, 2010 and then followed them for one year to capture all additional ED visits.

Estimating and testing direct genetic effects in directed acyclic graphs using estimating equations.

In genetic association studies, it is important to distinguish direct and indirect genetic effects in order to build truly functional models. For this purpose, we consider a directed acyclic graph setting with genetic variants, primary and intermediate phenotypes, and confounding factors. In order to make valid statistical inference on direct genetic effects on the primary phenotype, it is necessary to consider all potential effects in the graph, and we propose to use the estimating equations method with robust Huber-White sandwich standard errors.

Breast cancer detection among young survivors of pediatric Hodgkin lymphoma with screening magnetic resonance imaging.

Background: Female survivors of pediatric Hodgkin lymphoma (HL) who have received chest radiotherapy are at increased risk of breast cancer. Guidelines for early breast cancer screening among these survivors are based on little data regarding clinical outcomes. This study reports outcomes of breast cancer screening with MRI and mammography (MMG) after childhood HL.

Anti-Müllerian hormone screening to assess ovarian reserve among female survivors of childhood cancer.

Purpose: Anti-Müllerian hormone (AMH) is an indicator of oocyte reserve in healthy females. The role of AMH testing in oncology remains investigational, although its sensitivity and stability over the menstrual cycle make it an attractive screening test for fertility assessment among female cancer survivors. We measured AMH level in survivors of childhood cancer and evaluated its association with treatment and patient factors.

A multi-institutional study of factors influencing the use of stereotactic radiosurgery for brain metastases.

Purpose: Stereotactic radiosurgery (SRS) for brain metastases is a relatively well-studied technology with established guidelines regarding patient selection, although its implementation is technically complex. We evaluated the extent to which local availability of SRS affected the treatment of patients with brain metastases.

Methods And Materials: We identified 3030 patients who received whole-brain radiation therapy (WBRT) for brain metastases in 1 of 7 cancer centers in Ontario.

Comparing the cohort design and the nested case-control design in the presence of both time-invariant and time-dependent treatment and competing risks: bias and precision.

PURPOSE: Observational studies using electronic administrative healthcare databases are often used to estimate the effects of treatments and exposures. Traditionally, a cohort design has been used to estimate these effects, but increasingly, studies are using a nested case-control (NCC) design. The relative statistical efficiency of these two designs has not been examined in detail.