Se encontraron 15 investigaciones
The increasing popularity of cluster-randomized trials has created many opportunities and challenges for statisticians. In recent years a variation of the traditional cluster randomized trial has been proposed called stepped wedge design trial. However, several questions have been raised about the advantages and disadvantages of the stepped wedge design compared to the traditional cluster randomized design, in particular with regard to difference in power and sample size needed to properly measure the effect of an intervention. In this project, we will develop statistical methods to 1) study the advantages/disadvantages of the stepped wedge design vs. the cluster-randomized trial, 2) develop statistical models for bounded or even fractional response variables, 3) adjust them to the analysis of a stepped wedge study and 4) develop guidelines for data analysis and reporting of stepped wedge studies. In addition, we plan to implement the methods in freely available software, which will allow it to be used by other statisticians and public health researchers. Our proposal searches not only to give a statistical insight in the discussion above but also to propose new flexible statistical models in the analysis of the response variable when we deal with cross-sectional and longitudinal data.
Participantes:
Instituciones participantes:
El estudio de modelos de datos longitudinales que son capaces de incluir características complejas de datos, como la observada en datos agrupados, datos multinivel, datos espacialmente correlacionadas, datos multivariados, etc., en el contexto de problemas de la vida real, particularmente el análisis del comportamiento del VIH, sigue siendo un problema actualmente abierto. Por tal razón, es necesario realizar investigaciones en ese contexto con el fin de desarrollar modelos estadísticos flexibles.
Participantes:
Instituciones participantes:
The increasing popularity of cluster-randomized trials has created many opportunities and challenges for statisticians. In recent years a variation of the traditional cluster randomized trial has been proposed called stepped wedge design trial. However, several questions have been raised about the advantages and disadvantages of the stepped wedge design compared to the traditional cluster randomized design, in particular with regard to difference in power and sample size needed to properly measure the effect of an intervention. In this project, we will develop statistical methods to 1) study the advantages/disadvantages of the stepped wedge design vs. the cluster-randomized trial, 2) develop statistical models for bounded or even fractional response variables, 3) adjust them to the analysis of a stepped wedge study and 4) develop guidelines for data analysis and reporting of stepped wedge studies. In addition, we plan to implement the methods in freely available software, which will allow it to be used by other statisticians and public health researchers. Our proposal searches not only to give a statistical insight in the discussion above but also to propose new flexible statistical models in the analysis of the response variable when we deal with cross-sectional and longitudinal data.
Participantes:
Instituciones participantes:
Advancements in the field of medicine and biology have created new opportunities and challenges for statisticians in the form of new data structures. One of those structures is interval censored data type I that arises when a failure time 'T' can not be observed, but can only be determined to lie before or after an examination times 'Y'. A fundamental problem of interest is to estimate the distribution function of 'T' when 'T' and 'Y' are not independent (also called informative censoring) and when the indicator variable that measures whether or not 'T' occurs before 'Y' is misclassified. With this funding we plan to focus on developing copula and non-parametric statistical models to properly estimate the distribution function of 'T' with this type of data structure. The emphasis will be on methods that are computationally feasible in order to make it available to applied scientists. A number of approaches have been proposed to control for informative censoring in the case of interval censored data type I also know as current status data including sensitive analysis, copula and non-parametric models. In the case of outcome misclassification, the applicant recently developed methods to properly adjust for this problem in the case of interval censored data type I. We proposed to develop statistical methods to 1) estimate the cumulative distribution function of 'T' (one sample problem), 2) propose statistics to test the difference in the cumulative distribution functions between two groups, and 3) propose regression models to measure the effect of several factors on 'T'.
Participantes:
Instituciones participantes:
This is three-step study. Step 1 will screen men who have sex with men (MSM) and transgender women who are unaware of their HIV status and 1) report high risk behaviors for acquiring HIV-1 infection or 2) who have symptoms of acute retroviral syndrome or 3) who have a sexual partner with newly-diagnosed acute or recent HIV infection. HIV testing will be conducted for several thousand MSM and transgender women from study opening until July 2015. In Step 2, high risk HIV-1 uninfected MSM and transgender women with high risk for acquiring HIV will be tested at regular intervals for incident HIV-1 (using tests for HIV p24 and/or HIV RNA). (During this period, men will receive standard HIV prevention interventions.) In Step 3, individuals with acute or recent HIV-1 infection will be enrolled in a 48-week randomized, open-label study of the effects of immediate vs. deferred ART on the decay dynamics of HIV viral load in plasma, semen and rectal secretions. (ART will be provided prior to 24 weeks for any participant in the deferred ART arm who meets initiation criteria.) All participants will be followed for 48 weeks after which they will continue ART from other sources.
Participantes:
Instituciones participantes:
Women coinfected with HIV and HSV-2 experience more genital herpes outbreaks than women infected only with HSV-2. Frequent or recurrent herpes outbreaks in women infected with HIV can lead to an increase in both HIV plasma viral load and cervical shedding of HIV. Some preliminary clinical studies have shown that acyclovir treatment for the management of HSV-2 infection can help lower HIV viral load in patients coinfected with both HIV and HSV-2. Supplementing highly active antiretroviral therapy (HAART) with HSV-2 treatment in patients coinfected with both HIV and HSV-2 may help strengthen the effects of HAART by more effectively lowering plasma and genital HIV viral load. This study will determine whether HSV-2 treatment with acyclovir is effective in controlling HIV plasma viral load and cervical shedding of HIV in women starting on HAART as per Peruvian guidelines. This study will last 24 weeks. Participants will be randomly assigned into one of two groups. Group 1 participants will receive twice-daily 800 mg of acyclovir for 24 weeks. Group 2 participants will receive twice-daily placebo for 24 weeks. Both groups will receive HAART from the Peruvian Ministry of Health. There will be 15 visits during this study. Medical history; a physical exam; blood collection; family planning counseling; and cervical, vaginal, and vulvar swab collection will begin prior to study entry and will occur at all study visits.
Participantes:
Instituciones participantes:
The governments of Peru and Ecuador signed an agreement with the Global Fund to Fight AIDS, Tuberculosis, and Malaria to help guarantee comprehensive quality of care to people living with HIV, including access to antiretrovirals (ARVs). Current methods of surveillance are inadequate in estimating the true burden of disease. Broad access to ARVs in countries without regular drug resistance testing can also cause rapid development of ARV resistance. By establishing a more sophisticated surveillance system able to capture HIV incidence, prevalence, patterns of HIV resistance, and genetic variability of viral strains, Peru and Ecuador will be better equipped to monitor the HIV epidemic, develop personalized prevention and control measures, and track patterns of HIV resistance among infected patients. This study will estimate the incidence of HIV, syphilis, and herpes simplex virus 2 (HSV-2) among MSM in Peru and Ecuador, as well as examine the number and variability of ARV-resistant HIV strains. This study will last about 2 weeks. Medical history, a physical exam, an HIV rapid test, and HIV pre- and post-test counseling will occur at study entry. Those who test HIV positive will be asked to return to the test site in about 2 weeks to receive confirmatory test results. Patients confirmed to be infected with HIV will be referred to HIV treatment clinics in their area. At study entry, participants will also undergo a syphilis test. Those who test positive for syphilis will receive same-day treatment at the clinic and be asked to return during Week 1 and 2 to complete treatment for sexually transmitted diseases (STDs) according to local guidelines. STD treatment will not be provided by the study. Those who test negative to both the HIV rapid test and the syphilis test at screening will not participate in any more study visits. Patients who consent to having samples stored for further investigations will also have their samples tested for HSV-2 infection following comp
Participantes:
Instituciones participantes: