Estimating mono- and bi-phasic regression parameters using a mixture piecewise linear Bayesian hierarchical model.

The dynamics of tumor burden, secreted proteins or other biomarkers over time, is often used to evaluate the effectiveness of therapy and to predict outcomes for patients. Many methods have been proposed to investigate longitudinal trends to better characterize patients and to understand disease progression. However, most approaches assume a homogeneous patient population and a uniform response trajectory over time and across patients.

Can computer-based feedback improve emergency department patient uptake of rapid HIV screening?

Objective: We determine whether (1) an audiocomputer-delivered tailored feedback intervention increases emergency department (ED) patient uptake of opt-in, nontargeted rapid HIV screening; and (2) uptake is greater among patients who report more HIV risk and among those whose self-perceived HIV risk increases from baseline after completion of an HIV risk assessment.

Methods: ED patients aged 18 to 64 years were randomly assigned to receive either an assessment about reported and self-perceived HIV risk or an identical assessment plus feedback about their risk for having or acquiring an HIV infection, tailored according to their reported risk. All participants were offered a fingerstick rapid HIV test.

Statistical interpretation of the RV144 HIV vaccine efficacy trial in Thailand: a case study for statistical issues in efficacy trials.

Recently, the RV144 randomized, double-blind, efficacy trial in Thailand reported that a prime-boost human immunodeficiency virus (HIV) vaccine regimen conferred ∼30% protection against HIV acquisition. However, different analyses seemed to give conflicting results, and a heated debate ensued as scientists and the broader public struggled with their interpretation. The lack of accounting for statistical principles helped flame the debate, and we leverage these principles to provide a more scientific interpretation.

The relationship of reported HIV risk and history of HIV testing among emergency department patients.

Objective: Among a random sample of emergency department (ED) patients, we sought to determine the extent to which reported risk for human immunodeficiency virus (HIV) is related to ever having been tested for HIV.

Methods: A random sample of patients (aged 18-64 years) from an adult, urban, northeastern United States, academic ED were surveyed about their history of ever having been tested for HIV and their reported HIV risk behaviors. A reported HIV risk score was calculated from the survey responses and divided into 4 levels, based on quartiles of the risk scores.

Effectiveness of increasing emergency department patients' self-perceived risk for being human immunodeficiency virus (HIV) infected through audio computer self-interview-based feedback about reported HIV risk behaviors.

Objectives: Prior research has demonstrated that emergency department (ED) patient acceptance of human immunodeficiency virus (HIV) screening is partially dependent on patients' self-perceived risk of infection. The primary objective of this study was to determine the effectiveness of audio computer-assisted self-interview (ACASI)-based feedback. The intervention aimed to increase patient's self-perceived risk of being HIV infected by providing immediate feedback on their risk behaviors.

Demographic variations in HIV testing history among emergency department patients: implications for HIV screening in US emergency departments.

Objective: To determine the proportion of emergency department (ED) patients who have been tested for human immunodeficiency virus (HIV) infection and assess if patient history of HIV testing varies according to patient demographic characteristics.

Design: From July 2005-July 2006, a random sample of 18-55-year-old English-speaking patients being treated for sub-critical injury or illness at a northeastern US ED were interviewed on their history of HIV testing. Logistic regression models were created to compare patients by their history of being tested for HIV according to their demography.

Emergency department patient perceptions and preferences on opt-in rapid HIV screening program components.

The aim of this investigation was to assess emergency department (ED) patients' perceptions and preferences about an opt-in, universal, rapid HIV screening program and identify patient groups who expressed stronger beliefs about components of the testing program. From July 2005 to July 2006, ED patients in the opt-in, universal, rapid HIV screening program were interviewed in person. Multivariable regression models were used to compare participants on their beliefs about the program components.

Emergency department patient acceptance of opt-in, universal, rapid HIV screening.

Objectives: We assessed emergency department (ED) patient acceptance of opt-in, rapid human immunodeficiency virus (HIV) screening and identified demographic characteristics and HIV testing-history factors associated with acceptance of screening.

Methods: A random sample of 18- to 55-year-old ED patients was offered rapid HIV screening. Patient acceptance or decline of screening and the reasons for acceptance or decline were analyzed with multivariable regression models.

Video as an effective method to deliver pretest information for rapid human immunodeficiency testing.

Objectives: Video-based delivery of human immunodeficiency virus (HIV) pretest information might assist in streamlining HIV screening and testing efforts in the emergency department (ED). The objectives of this study were to determine if the video "Do you know about rapid HIV testing?" is an acceptable alternative to an in-person information session on rapid HIV pretest information, in regard to comprehension of rapid HIV pretest fundamentals, and to identify patients who might have difficulties in comprehending pretest information.

Methods: This was a noninferiority trial of 574 participants in an ED opt-in rapid HIV screening program who were randomly assigned to receive identical pretest information from either an animated and live-action 9.

Accommodating uncertainty in a tree set for function estimation.

Multiple branching trees have been used to model the acquisition of HIV drug resistance mutations, and several different algorithms have been developed to construct the tree set that best describes the data. These algorithms have mainly focused on the structure of the tree set. The focal point of this paper is estimation of functions of the tree set parameters that incorporate uncertainty in the tree set.

Two-sample tests of area-under-the-curve in the presence of missing data.

The commonly used two-sample tests of equal area-under-the-curve (AUC), where AUC is based on the linear trapezoidal rule, may have poor properties when observations are missing, even if they are missing completely at random (MCAR). We propose two tests: one that has good properties when data are MCAR and another that has good properties when the data are missing at random (MAR), provided that the pattern of missingness is monotonic. In addition, we discuss other non-parametric tests of hypotheses that are similar, but not identical, to the hypothesis of equal AUCs, but that often have better statistical properties than do AUC tests and may be more scientifically appropriate for many settings.

Comparison of patient comprehension of rapid HIV pre-test fundamentals by information delivery format in an emergency department setting.

Background: Two trials were conducted to compare emergency department patient comprehension of rapid HIV pre-test information using different methods to deliver this information.

Methods: Patients were enrolled for these two trials at a US emergency department between February 2005 and January 2006. In Trial One, patients were randomized to a no pre-test information or an in-person discussion arm.

A resampling-based approach to multiple testing with uncertainty in phase.

Characterizing the genetic correlates to complex diseases requires consideration of a large number of potentially informative biological markers. In addition, attention to alignment of alleles within or across chromosomal pairs, commonly referred to as phase, may be essential for uncovering true biological associations. In the context of population based association studies, phase is generally unobservable.

What constitutes efficacy for a human immunodeficiency virus vaccine that ameliorates viremia: issues involving surrogate end points in phase 3 trials.

Initial human immunodeficiency virus (HIV) vaccines are unlikely to prevent acquisition of HIV in all recipients. Moreover, several HIV vaccines are under evaluation that are designed to reduce viremia after acquisition of infection. Such vaccines could provide important benefits to delay HIV progression and to reduce transmission.

Baseline predictors of CD4 T-lymphocyte recovery with combination antiretroviral therapy.

CD4 T-cell recovery with potent antiretroviral therapy varies considerably among HIV-1-infected patients. Data from two studies that enrolled subjects at different stages of disease progression were retrospectively combined. This analysis assessed the association between patient-specific factors and three measures of CD4 T-cell recovery after the initiation of triple-drug therapy: overall changes in CD4 cell counts; changes in CD4 cell counts during the first 8 weeks (phase I); and changes in CD4 cell counts during weeks 8-24 (phase II).

Modelling HIV viral rebound using non-linear mixed effects models.

Individuals infected with the human immunodeficiency virus type 1 (HIV-1) who initiate antiretroviral therapy typically experience a marked decline in concentrations of HIV-1 RNA in plasma. Often, however, viral rebound occurs within the first year of treatment and this rebound may be associated with resistance to antiretroviral therapy. For this reason, it is important to study the patterns of virological response of HIV-1 RNA to treatment.