A semiparametric Bayesian approach to the random effects model.

K P Kleinman; J G Ibrahim

Home/Archive/PubMed

PubMed · 9750242

A semiparametric Bayesian approach to the random effects model.

K P Kleinman·J G Ibrahim

View original source ↗Export metadata ↓

Abstract

In longitudinal random effects models, the random effects are typically assumed to have a normal distribution in both Bayesian and classical models. We provide a Bayesian model that allows the random effects to have a nonparametric prior distribution. We propose a Dirichlet process prior for the distribution of the random effects; computation is made possible by the Gibbs sampler. An example using marker data from an AIDS study is given to illustrate the methodology.

Explore related subjects

Acquired Immunodeficiency Syndrome Anti-HIV Agents Bayes Theorem Biometry CD4 Lymphocyte Count Clinical Trials as Topic Didanosine Longitudinal Studies Models, Statistical Randomized Controlled Trials as Topic Zidovudine Journal Article Research Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

K P Kleinman, J G Ibrahim. 1998. A semiparametric Bayesian approach to the random effects model.. https://pubmed.ncbi.nlm.nih.gov/9750242/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Regression analysis of failure time data with informative interval censoring.

Interval censoring arises when a subject misses prescheduled visits at which the failure is to be assessed. Most existing approaches for analysing interval-censored failure time data assume that the censoring mechanism is independent of the true failure time. However, there are situations where this assumption may not hold. In this paper, we consider such a situation in which the dependence structure between the censoring variables and the failure time can be modelled through some latent variables and a method for regression analysis of failure time data is proposed. The method makes use of the proportional hazards frailty model and an EM algorithm is presented for estimation. Finite sample properties of the proposed estimators of regression parameters are examined through simulation studies and we illustrate the method with data from an AIDS study.

Acquired Immunodeficiency Syndrome↗

PubMed2007

Two and a half years of routine HIV testing in Botswana.

BACKGROUND: Botswana was the first African country to introduce routine HIV testing (RHT). OBJECTIVE: To report program data for the first 2.5 years of RHT. METHODS: RHT was introduced in 2004. Rapid HIV tests were introduced later the same year and are widely available. The main criteria for RHT are symptoms of HIV/AIDS, pregnancy, sexually transmitted infection, and attendance for medical examination. Testing may also be self-initiated. FINDINGS: There has been a rapid scale-up of RHT. A total of 60,846 persons were tested through RHT in 2004 versus 157,894 in 2005 and 88,218 in the first half of 2006. Testing rates in the population through RHT were 40 per 1000 persons, 93 per 1000 persons, and 104 per 1000 persons, respectively. In 2005, 89% of those offered testing accepted, with 69% of those tested being female and 31% male. The proportion of men who tested HIV-positive was 34% versus 30% for women. The main reasons for testing in 2005 were patient's wish (50%), pregnancy (25%), medical examination (7%), clinical suspicion (6%), and sexually transmitted infection (2%). Attendance at voluntary counseling and testing centers has increased parallel to the scale-up of RHT. CONCLUSIONS: RHT has been widely accepted by the population, and no adverse effects or instances have been reported. It has provided increased access to preventive services and earlier assessment for antiretroviral treatment. We believe the benefits of RHT clearly outweigh the risks.

Acquired Immunodeficiency Syndrome↗

PubMed2007

Risk factors for human Herpesvirus 8 infection and AIDS-associated Kaposi's sarcoma among men who have sex with men in a European multicentre study.

We aimed to identify risk factors for Kaposi's sarcoma (KS) among HIV-positive patients and behaviors associated with human Herpesvirus 8 (HHV-8) infection, as well as to assess KS incidence and mortality rates longitudinally. To fulfill the first objective, a European case-control study was designed in the early 1990s (each KS case was matched to 2 controls with another AIDS indicative disease). After the discovery of HHV-8, serology testing enabled us to assess risk factors for KS development among HHV-8 and HIV-1 coinfected men who have sex with men (MSM), as well as risk factors for HHV-8 infection. HHV-8 seroprevalence was determined using a latent immunofluorescence assay. Relevant information was obtained by means of a questionnaire and medical charts review. Assessment of risk factors for KS development and HHV-8 infection was performed using conditional and unconditional logistic regression models, respectively. A low CD4 count was the only significant risk factor for KS. HHV-8 infection was most strongly linked to the number of life-time sex partners, and multiple body fluids such as saliva and semen are quite likely involved in sexual transmission. Longitudinal follow up showed a significant protective role for highly-active antiretroviral therapy (HAART) both on KS development and mortality of KS patients. Although more conclusive data from cohort studies are needed to better define specific transmission mechanisms for HHV-8, our results contribute to explain why KS incidence is higher among MSM, and the decreasing KS incidence trend observed in countries with universal access to HAART.

Acquired Immunodeficiency Syndrome↗